NUMAR CORP
8-K, 1997-06-16
OIL & GAS FIELD MACHINERY & EQUIPMENT
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<PAGE>
 
                      SECURITIES AND EXCHANGE COMMISSION

                            Washington, D.C.  20549



                             ____________________


                                   FORM 8-K

                                Current Report
                    Pursuant to Section 13 or 15(d) of the
                        Securities Exchange Act of 1934


        Date of Report (Date of earliest event reported)   June 9, 1997
                                                          --------------



                               NUMAR CORPORATION
                       ---------------------------------
              (Exact name of registrant as specified in charter)



   Pennsylvania                 000-23718           232750939         
- -------------------           -------------       -------------                 
 (State or other               (Commission         (I.R.S. Employer
 jurisdiction of               File Number)       Identification No.)
 incorporation)



                  508 Lapp Road, Malvern, Pennsylvania 19355
             -----------------------------------------------------
            (Address of principal executive offices)     (Zip Code)



        Registrant's telephone number, including area code 610-251-0116
                                                           ------------



                                Not Applicable
- --------------------------------------------------------------------------------
        (Former name or former address, if changed since last report.)
<PAGE>
 
ITEM 5.   OTHER EVENTS

     On June 9, 1997, NUMAR Corporation ("NUMAR") entered into an Agreement and
Plan of Merger (the "Merger Agreement") by and among NUMAR, Halliburton Company
("Halliburton") and Halliburton M.S. Corp., a wholly-owned subsidiary of
Halliburton ("Acquisition"), a copy of which is attached hereto as Exhibit 2(a).

     Pursuant to the Merger Agreement, Acquisition will merge with and into
NUMAR, which is the surviving entity in the merger, and each share of NUMAR will
be converted into 0.4832 of one share of common stock of Halliburton.  Following
the merger, the separate existence of Acquisition will cease and NUMAR will
continue as the surviving corporation under Pennsylvania law as a wholly-owned
subsidiary of Halliburton.

     The proposed merger is subject to the approval of NUMAR's shareholders and
Hart-Scott-Rodino antitrust clearance.  The merger will be structured as a
pooling of interests and, for federal income tax purposes, as a tax-free
exchange to NUMAR shareholders.  The companies anticipate completion of the
acquisition during the third quarter of 1997.

     In addition to the Merger Agreement, NUMAR concurrently executed and
delivered a Stock Option Agreement dated as of June 9, 1997 with Halliburton
pursuant to which Halliburton is entitled to purchase, at a price of $36.00 per
share, authorized but unissued common stock from NUMAR in an amount equal to up
to 15% of the outstanding common stock of NUMAR upon the occurrence of certain
events.  Furthermore, five holders of NUMAR stock, who in the aggregate own
approximately 25.3% of the total number of outstanding shares of NUMAR stock,
have each entered into Voting Agreements dated as of June 9, 1997 with
Halliburton pursuant to which such holders have agreed to vote in favor of the
Merger Agreement at the meeting of holders of NUMAR common stock to be called to
consider approval of the Merger Agreement.  The five holders are:  Dr. Melvin N.
Miller, Barry M. Davis, Seymour G. Mandell, James H. Simon and the Bermuda Trust
Company Limited as Trustee of the Lord Jim Trust.

     Following the merger, Dr. Melvin N. Miller will continue as president and
chief executive officer of NUMAR.

ITEM 7.   FINANCIAL STATEMENTS AND EXHIBITS.

     List below the financial statements, pro forma financial statements and
exhibits, if any, filed as part of this report.

          (c)  Exhibits

               EXHIBIT 2(A) - Agreement and Plan of Merger, dated as of June 9,
1997, by and among NUMAR Corporation, Halliburton Company and Halliburton M.S.
Corp.

               EXHIBIT 2(B) - Stock Option Agreement, dated as of June 9, 1997,
between NUMAR Corporation and Halliburton Company.

               EXHIBIT 2(C) - Voting Agreements entered into between Halliburton
Company and each of Dr. Melvin N. Miller, Barry M. Davis, Seymour G. Mandell,
James H. Simons and the Bermuda Trust Company Limited as Trustee of the Lord Jim
Trust.

               EXHIBIT 20 - Press release dated June 10, 1997.
<PAGE>
 
                                   SIGNATURE


          Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.


                                   NUMAR CORPORATION



                                   By:/s/ Melvin N. Miller
                                      ------------------------------------------
                                         Dr. Melvin N. Miller
                                         President and Chief Executive Officer
 


Date:  June __, 1997

                                      -3-
<PAGE>
 
                                 EXHIBIT INDEX

Exhibit                                                             
- -------                                                        


2(A) Agreement and Plan of Merger, dated as of June 9, 1997,
     by and among NUMAR Corporation, Halliburton Company and
     Halliburton M.S. Corp.

2(B) Stock Option Agreement, dated as of June 9, 1997, between
     NUMAR Corporation and Halliburton Company.

2(C) Voting Agreements entered into between Halliburton Company
     and each of Dr. Melvin N. Miller, Barry M. Davis, Seymour G.
     Mandell, James H. Simons and the Bermuda Trust Company
     Limited as Trustee of the Lord Jim Trust.

20   Press release dated June 10, 1997.


<PAGE>
 
                                                                     EXHIBIT 2.A


                         AGREEMENT AND PLAN OF MERGER

                           DATED AS OF JUNE 9, 1997

                                 BY AND AMONG

                             HALLIBURTON COMPANY,

                            HALLIBURTON M.S. CORP.

                                      AND

                               NUMAR CORPORATION
<PAGE>
 
                               TABLE OF CONTENTS

<TABLE> 
<CAPTION> 
                                                                                                            Page
                                                                                                            ----
<S>                                                                                                         <C> 
                             ARTICLE I DEFINITIONS
SECTION 1.01   Definitions.................................................................................   -1-
               -----------
SECTION 1.02   Rules of Construction.......................................................................   -2-
               ---------------------

                           ARTICLE II TERMS OF MERGER
SECTION 2.01    Statutory Merger...........................................................................   -2-
                ----------------
SECTION 2.02    Effective Time.............................................................................   -2-
                --------------
SECTION 2.03    Effect of the Merger.......................................................................   -2-
                --------------------
SECTION 2.04    Articles of Incorporation; Bylaws..........................................................   -2-
                ---------------------------------
SECTION 2.05    Directors and Officers.....................................................................   -3-
                ----------------------

         ARTICLE III CONVERSION OF SECURITIES; EXCHANGE OF CERTIFICATES
SECTION 3.01    Merger Consideration; Conversion and Cancellation of Securities............................   -3-
                ---------------------------------------------------------------
SECTION 3.02    Exchange of Certificates...................................................................   -4-
                ------------------------
SECTION 3.03    Closing....................................................................................   -7-
                -------
SECTION 3.04    Stock Transfer Books.......................................................................   -7-
                --------------------

            ARTICLE IV REPRESENTATIONS AND WARRANTIES OF THE COMPANY
SECTION 4.01    Organization and Qualification; Subsidiaries...............................................   -7-
                --------------------------------------------
SECTION 4.02    Articles of Incorporation and Bylaws.......................................................   -7-
                ------------------------------------
SECTION 4.03    Capitalization.............................................................................   -8-
                --------------
SECTION 4.04    Authorization of Plan......................................................................   -9-
                ---------------------
SECTION 4.05    Approvals..................................................................................  -10-
                ---------
SECTION 4.06    No Violation...............................................................................  -10-
                ------------
SECTION 4.07    Reports....................................................................................  -10-
                -------
SECTION 4.08    No Material Adverse Effect; Conduct........................................................  -11-
                -----------------------------------
SECTION 4.09    Title to Properties........................................................................  -11-
                -------------------
SECTION 4.10    Certain Obligations........................................................................  -12-
                --------------------
SECTION 4.11    Authorizations; Compliance.................................................................  -12-
                --------------------------
SECTION 4.12    Litigation; Compliance with Laws...........................................................  -12-
                --------------------------------
SECTION 4.13    Employee Benefit Plans.....................................................................  -13-
                ----------------------
SECTION 4.14    Taxes......................................................................................  -16-
                -----
SECTION 4.15    Environmental Matters......................................................................  -16-
                ---------------------
SECTION 4.16    Intellectual Property......................................................................  -17-
                ---------------------
SECTION 4.17    Insurance..................................................................................  -19-
                ---------
SECTION 4.18    Pooling; Tax Matters.......................................................................  -19-
                --------------------
SECTION 4.19    Affiliates.................................................................................  -20-
                ----------
SECTION 4.20    Certain Business Practices.................................................................  -20-
                --------------------------
SECTION 4.21    Opinion of Financial Advisor...............................................................  -20-
                ----------------------------
SECTION 4.22    Brokers....................................................................................  -20-
                -------
</TABLE>

                                     -iii-
<PAGE>
 
<TABLE>
<S>                                                                                                          <C>
SECTION 4.23    AntiTakeover Law...........................................................................  -20-
                ----------------

              ARTICLE V REPRESENTATIONS AND WARRANTIES OF ACQUIROR
SECTION 5.01    Organization and Qualification; Subsidiaries...............................................  -21-
                --------------------------------------------
SECTION 5.02    Certificate of Incorporation and Bylaws....................................................  -21-
                ---------------------------------------
SECTION 5.03    Capitalization.............................................................................  -21-
                --------------
SECTION 5.04    Authorization of Plan......................................................................  -23-
                ---------------------
SECTION 5.05    Approvals..................................................................................  -23-
                ---------
SECTION 5.06    No Violation...............................................................................  -23-
                ------------
SECTION 5.07    Reports....................................................................................  -24-
                -------
SECTION 5.08    No Material Adverse Effect; Conduct........................................................  -24-
                -----------------------------------
SECTION 5.09    Title to Properties........................................................................  -25-
                -------------------
SECTION 5.10    Certain Obligations........................................................................  -25-
                -------------------
SECTION 5.11    Authorizations; Compliance.................................................................  -25-
                --------------------------
SECTION 5.12    Litigation; Compliance with Laws...........................................................  -26-
                --------------------------------
SECTION 5.13    Employee Benefit Plans.....................................................................  -26-
                ----------------------
SECTION 5.14    Taxes......................................................................................  -27-
                -----
SECTION 5.15    Environmental Matters......................................................................  -27-
                ---------------------
SECTION 5.16    Pooling; Tax Matters.......................................................................  -28-
                --------------------
SECTION 5.17    Insurance..................................................................................  -29-
                ---------
SECTION 5.18    Affiliates.................................................................................  -29-
                ----------
SECTION 5.19    Certain Business Practices.................................................................  -29-
                --------------------------
SECTION 5.20    Brokers....................................................................................  -29-
                -------
SECTION 5.21    Acquiring Person...........................................................................  -29-
                ----------------

                              ARTICLE VI COVENANTS
SECTION 6.01    Affirmative Covenants......................................................................  -30-
                ---------------------
SECTION 6.02    Negative Covenants.........................................................................  -30-
                ------------------
SECTION 6.03    No Solicitation............................................................................  -35-
                ---------------
SECTION 6.04    Access and Information.....................................................................  -35-
                ----------------------
SECTION 6.05    Confidentiality Agreement..................................................................  -36-
                --------------------------

                       ARTICLE VII ADDITIONAL AGREEMENTS
SECTION 7.01    Meeting of Shareholders....................................................................  -36-
                -----------------------
SECTION 7.02    Registration Statement; Proxy Statements...................................................  -36-
                ----------------------------------------
SECTION 7.03    Appropriate Action; Consents; Filings......................................................  -38-
                -------------------------------------
SECTION 7.04    Affiliates; Pooling; Tax Treatment.........................................................  -40-
                ----------------------------------
SECTION 7.05    Public Announcements.......................................................................  -40-
                --------------------
SECTION 7.06    NYSE Listing...............................................................................  -41-
                ------------
SECTION 7.07    Comfort Letters............................................................................  -41-
                ---------------
SECTION 7.08    Assumption of Obligations to Issue Stock and Obligations of Employee Benefit Plans.........  -41-
                ----------------------------------------------------------------------------------
SECTION 7.09    Operations of Company......................................................................  -42-
                ---------------------
SECTION 7.10    Indemnification of Directors and Officers..................................................  -42-
                -----------------------------------------
</TABLE>

                                     -iv-
<PAGE>
 
<TABLE>
<S>                                                                                                          <C>
SECTION 7.11    Newco......................................................................................  -44-
                -----
SECTION 7.12    Event Notices..............................................................................  -44-
                -------------

                        ARTICLE VIII CLOSING CONDITIONS
SECTION 8.01    Conditions to Obligations of Each Party Under This Plan....................................  -44-
                -------------------------------------------------------
SECTION 8.02    Additional Conditions to Obligations of the Acquiror Companies.............................  -45-
                --------------------------------------------------------------
SECTION 8.03    Additional Conditions to Obligations of the Company........................................  -46-
                ---------------------------------------------------

                  ARTICLE IX TERMINATION, AMENDMENT AND WAIVER
SECTION 9.01    Termination................................................................................  -46-
                -----------
SECTION 9.02    Effect of Termination......................................................................  -48-
                ---------------------
SECTION 9.03    Amendment..................................................................................  -48-
                ---------
SECTION 9.04    Waiver.....................................................................................  -48-
                ------
SECTION 9.05    Fees, Expenses and Other Payments..........................................................  -49-
                ---------------------------------

                          ARTICLE X GENERAL PROVISIONS
SECTION 10.01    Effectiveness of Representations, Warranties and Agreements...............................  -50-
                 -----------------------------------------------------------
SECTION 10.02    Notices...................................................................................  -50-
                 -------
SECTION 10.03    Headings..................................................................................  -51-
                 --------
SECTION 10.04    Severability..............................................................................  -51-
                 ------------
SECTION 10.05    Entire Agreement..........................................................................  -52-
                 ----------------
SECTION 10.06    Assignment................................................................................  -52-
                 ----------
SECTION 10.07    Parties in Interest.......................................................................  -52-
                 -------------------
SECTION 10.08    Failure or Indulgence Not Waiver;  Remedies Cumulative....................................  -52-
                 ------------------------------------------------------
SECTION 10.09    Governing Law.............................................................................  -52-
                 -------------
SECTION 10.10    Specific Performance......................................................................  -52-
                 --------------------
SECTION 10.11    Counterparts..............................................................................  -53-
                 ------------
</TABLE>
                                    ANNEXES

Annex A Schedule of Defined Terms
Annex B NUMAR Affiliate's Agreement
Annex C Halliburton Affiliate's Agreement

                                      -v-
<PAGE>
 
                         AGREEMENT AND PLAN OF MERGER


     THIS AGREEMENT AND PLAN OF MERGER, dated as of June 9, 1997 (this "Plan"),
is by and among Halliburton Company, a Delaware corporation ("Acquiror"),
Halliburton M.S. Corp., a Delaware corporation and a wholly owned subsidiary of
Acquiror ("Newco"), and NUMAR Corporation, a Pennsylvania corporation (the
"Company").  The Acquiror and Newco are sometimes referred to herein as the
"Acquiror Companies."

                                   RECITALS:
                                        
     The Board of Directors of the Company has determined that the business
combination to be effected by means of the Merger is consistent with and in
furtherance of the long-term business strategy of the Company and is fair to,
and in the best interests of, the Company and has approved and adopted this Plan
and recommended approval and adoption of this Plan by the shareholders of the
Company.

     The Board of Directors of the Acquiror has determined that the business
combination to be effected by means of the Merger is consistent with and in
furtherance of the long-term business strategy of the Acquiror and is fair to,
and in the best interests of, the Acquiror and its stockholders and has approved
and adopted this Plan.

     Upon the terms and subject to the conditions of this Plan and in accordance
with the PBCL, Newco will merge with and into the Company and the Company will
be the Surviving Corporation.

     For federal income tax purposes, it is intended that the Merger will
qualify as a reorganization within the meaning of the provisions of Section
368(a) of the Code.

     The Merger is intended to be treated as a "pooling of interests" for
accounting purposes.

     The parties hereto acknowledge the execution and delivery of the Stock
Option Agreement and the Voting Agreements concurrently with the execution and
delivery of this Plan.

     NOW, THEREFORE, in consideration of the foregoing and the respective
representations, warranties, covenants and agreements set forth in this Plan,
the parties hereto agree as follows:
<PAGE>
 
                                   ARTICLE I

                                  DEFINITIONS

      SECTION 1.01  Definitions.  Certain capitalized and other terms used in
                    -----------                                              
this Plan are defined in Annex A hereto and are used herein with the meanings
ascribed to them therein.

      SECTION 1.02  Rules of Construction.  Unless the context otherwise
                    ---------------------                               
requires, as used in this Plan:  (a) a term has the meaning ascribed to it;  (b)
an accounting term not otherwise defined has the meaning ascribed to it in
accordance with GAAP; (c) "or" is not exclusive; (d) "including" means
"including, without limitation;" (e) words in the singular include the plural;
(f) words in the plural include the singular; (g) words applicable to one gender
shall be construed to apply to each gender; (h) the terms "hereof," "herein,"
"hereby," "hereto" and derivative or similar words refer to this entire Plan;
and (i) the terms "Article" or "Section" shall refer to the specified Article or
Section of this Plan.

                                   ARTICLE II

                                TERMS OF MERGER

      SECTION 2.01  Statutory Merger.  Subject to the terms and conditions and
                    ----------------                                          
in reliance upon the representations, warranties, covenants and agreements
contained herein, Newco shall merge with and into the Company at the Effective
Time.  The terms and conditions of the Merger and the mode of carrying the same
into effect shall be as set forth in this Plan.  As a result of the Merger, the
constituent corporations shall be a single corporation which shall be the
Company as the corporation herein designated as the Surviving Corporation, and
the separate corporate existence of each of the constituent corporations shall
cease except that of the Company, which shall continue as the Surviving
Corporation.

      SECTION 2.02  Effective Time.  As soon as practicable after the
                    --------------                                   
satisfaction or, if permissible, waiver of the conditions set forth in Article
VIII, the parties hereto shall cause the Merger to be consummated by filing
Articles of Merger with the Secretary of State of the Commonwealth of
Pennsylvania and a Certificate of Merger with the Secretary of State of the
State of Delaware, in such form as required by, and executed in accordance with,
the relevant provisions of the PBCL and the DGCL.

      SECTION 2.03  Effect of the Merger.  At the Effective Time, the effect of
                    --------------------                                       
the Merger shall be as provided in the applicable provisions of the PBCL,
including Section 1929 thereof. Without limiting the generality of the foregoing
but subject thereto, all the property, real, personal and mixed, and franchises
of each of the constituent corporations, and all debts due on whatever account
to either of them, including subscriptions for shares and other choses in action
belonging to either of them, shall be deemed to be transferred to and vested in
the Surviving Corporation without further action, and the title to any real
estate, or any interest therein, vested in either of the corporations shall not
revert or be in any way impaired by reason 

                                      -2-
<PAGE>
 
of the Merger. The Surviving Corporation shall from and after the Effective Time
be responsible for all the liabilities of each of the corporations so merged.

      SECTION 2.04  Articles of Incorporation; Bylaws.  At the Effective Time,
                    ---------------------------------                         
the articles of incorporation and the bylaws of the Company, as in effect
immediately prior to the Effective Time, shall become the articles of
incorporation and the bylaws of the Surviving Corporation.

      SECTION 2.05  Directors and Officers.  The directors of Newco immediately
                    ----------------------                                     
prior to the Effective Time shall be the directors of the Surviving Corporation,
each to hold office in accordance with the articles of incorporation and bylaws
of the Surviving Corporation, and the officers of the Company immediately prior
to the Effective Time shall be the officers of the Surviving Corporation, in
each case until their respective successors are duly elected or appointed and
qualified.

                                  ARTICLE III

               CONVERSION OF SECURITIES; EXCHANGE OF CERTIFICATES

      SECTION 3.01  Merger Consideration; Conversion and Cancellation of
                    ----------------------------------------------------
Securities.  The manner and basis of converting in the Merger the shares of each
- ----------                                                                      
corporation into shares of the Surviving Corporation or the shares or other
obligations of the Acquiror shall be as set forth in this Article III.  At the
Effective Time, by virtue of the Merger and without any action on the part of
the Acquiror Companies, the Company or the holders of any of the following
securities:

          (a) Subject to the other provisions of this Article III, each share of
     Company Common Stock issued and outstanding immediately prior to the
     Effective Time (excluding Dissenters' Shares and any Company Common Stock
     described in Section 3.01(c)) shall be converted into 0.4832 of one share
     of Acquiror Common Stock. Notwithstanding the foregoing, if between the
     date of this Plan and the Effective Time the outstanding shares of Acquiror
     Common Stock or Company Common Stock shall have been changed into a
     different number of shares or a different class, by reason of any stock
     dividend, subdivision, reclassification, recapitalization, split,
     combination or exchange of shares, the Common Stock Exchange Ratio shall be
     correspondingly adjusted to reflect such stock dividend, subdivision,
     reclassification, recapitalization, split, combination or exchange of
     shares.

          (b) All shares of Company Common Stock shall, upon conversion thereof
     into shares of Acquiror Common Stock at the Effective Time, cease to be
     outstanding and shall be automatically canceled and retired, and each
     certificate previously evidencing Company Common Stock outstanding
     immediately prior to the Effective Time (other than Dissenters' Shares and
     Company Common Stock described in Section 3.01(c)) shall thereafter be
     deemed, for all purposes, other than the payment of dividends or

                                      -3-
<PAGE>
 
     distributions, to represent that number of shares of Acquiror Common Stock
     determined pursuant to the Common Stock Exchange Ratio and, if applicable,
     the right to receive cash pursuant to Section 3.02(e). The holders of
     certificates previously evidencing Company Common Stock shall cease to have
     any rights with respect to such Company Common Stock except as otherwise
     provided herein or by law.

          (c) Notwithstanding any provision of this Plan to the contrary, each
     share of Company Common Stock held in the treasury of the Company and each
     share of Company Common Stock, if any, owned by the Acquiror or any direct
     or indirect wholly owned Subsidiary of the Acquiror or of the Company
     immediately prior to the Effective Time shall be canceled and extinguished
     without conversion thereof.

          (d) Each share of common stock, par value $1.00 per share, of Newco
     issued and outstanding immediately prior to the Effective Time shall be
     converted into one share of common stock, par value $1.00 per share, of the
     Surviving Corporation.

          (e) Notwithstanding anything herein to the contrary, shares of Company
     Common Stock outstanding immediately prior to the Effective Time and held
     by a holder who has not voted in favor of the Plan or consented thereto in
     writing and who has demanded the right to be paid the fair value for such
     shares of Company Common Stock in accordance with Section 1930 of the PBCL
     ("Dissenters' Shares") shall not be converted into shares of Acquiror
     Common Stock as otherwise provided in this Section 3.01 unless and until
     such holder fails to continue perfection of, or withdraws or otherwise
     loses, such right to be paid the fair value for such shares. If after the
     Effective Time any such holder fails to continue perfection of, or
     withdraws or loses, such right of appraisal, such Dissenters' Shares shall
     thereupon be deemed to have been, and shall be treated as if they had been,
     converted into shares of Acquiror Common Stock as provided in this Section
     3.01

      SECTION 3.02  Exchange of Certificates.
                    ------------------------ 

          (a) Exchange Fund.  At the Closing, the Acquiror shall deposit, or
              -------------                                                 
     cause to be deposited, with the Exchange Agent, for the benefit of the
     former holders of Company Common Stock and for exchange through the
     Exchange Agent in accordance with this Article III, certificates evidencing
     that number of shares of Acquiror Common Stock equal to the product of the
     Common Stock Exchange Ratio and the number of shares of Company Common
     Stock issued and outstanding immediately prior to the Effective Time
     (exclusive of any Dissenters' Shares and any such shares to be canceled
     pursuant to Section 3.01(c)). The Exchange Agent shall, pursuant to
     irrevocable instructions from the Acquiror, deliver certificates evidencing
     Acquiror Common Stock, together with any cash to be paid in lieu of
     fractional interests in shares of Acquiror Common Stock pursuant to Section
     3.02(e) and any dividends or distributions related to such Acquiror Common
     Stock, in exchange for certificates theretofore evidencing Company Common
     Stock surrendered to the Exchange Agent  pursuant to Section 3.02(c).
     Except as 

                                      -4-
<PAGE>
 
     contemplated by Sections 3.02(e) and (h), the Exchange Fund shall not be
     used for any other purpose.

          (b) Letter of Transmittal.  Promptly after the Effective Time, the
              ---------------------                                         
     Acquiror will cause the Exchange Agent to send to each record holder of
     Company Common Stock immediately prior to the Effective Time (other than
     Dissenters' Shares) a letter of transmittal and other appropriate materials
     for use in surrendering to the Exchange Agent certificates that prior to
     the Effective Time evidenced shares of Company Common Stock.

          (c) Exchange Procedures.  Promptly after the Effective Time, the
              -------------------                                         
     Exchange Agent shall distribute to each former holder of Company Common
     Stock, upon surrender to the Exchange Agent for cancellation of one or more
     certificates that theretofore evidenced shares of Company Common Stock,
     certificates evidencing the appropriate number of shares of Acquiror Common
     Stock into which such shares of Company Common Stock were converted
     pursuant to the Merger. If shares of Acquiror Common Stock are to be issued
     to a Person other than the Person in whose name the surrendered certificate
     or certificates are registered, it shall be a condition of issuance of the
     Acquiror Common Stock that the surrendered certificate or certificates
     shall be properly endorsed, with signatures guaranteed, or otherwise in
     proper form for transfer and that the Person requesting such payment shall
     pay any transfer or other taxes required by reason of the issuance of
     Acquiror Common Stock to a Person other than the registered holder of the
     surrendered certificate or certificates or such Person shall establish to
     the satisfaction of the Acquiror that such tax has been paid or is not
     applicable.

          (d) Distributions with Respect to Unexchanged Shares of Company Common
              ------------------------------------------------------------------
     Stock.  No dividends or other distributions declared or made with respect
     -----                                                                    
     to Acquiror Common Stock with a record date after the Effective Time shall
     be paid to the holder of any certificate that theretofore evidenced shares
     of Company Common Stock until the holder of such certificate shall
     surrender such certificate.  Subject to the effect of any applicable
     escheat laws, following surrender of any such certificate, there shall be
     paid to the holder of the certificates evidencing whole shares of Acquiror
     Common Stock issued in exchange therefor, without interest, (i) promptly,
     the amount of any cash payable with respect to a fractional share of
     Acquiror Common Stock to which such holder is entitled pursuant to Section
     3.02(e) and the amount of dividends or other distributions with a record
     date after the Effective Time theretofore paid with respect to such whole
     shares of Acquiror Common Stock and (ii), at the appropriate payment date,
     the amount of dividends or other distributions, with a record date after
     the Effective Time but prior to surrender and a payment date occurring
     after surrender, payable with respect to such whole shares of Acquiror
     Common Stock.

          (e) No Fractional Shares.  Notwithstanding anything herein to the
              --------------------                                         
     contrary, no certificates or scrip evidencing fractional shares of Acquiror
     Common Stock shall be issued in connection with the Merger, and any such
     fractional share interests to which 

                                      -5-
<PAGE>
 
     a holder of record of Company Common Stock at the Effective Time would
     otherwise be entitled shall not entitle such holder to vote or to any
     rights of a stockholder of the Acquiror. In lieu of any such fractional
     shares, each holder of record of Company Common Stock at the Effective Time
     who but for the provisions of this Section 3.02(e) would be entitled to
     receive a fractional interest of a share of Acquiror Common Stock by virtue
     of the Merger shall be paid cash, without any interest thereon, as
     hereinafter provided. The Acquiror shall instruct the Exchange Agent to
     determine the number of whole shares and fractional shares of Acquiror
     Common Stock allocable to each holder of record of Company Common Stock at
     the Effective Time, to aggregate all such fractional shares into whole
     shares, to sell the whole shares obtained thereby in the open market at
     then prevailing prices on behalf of holders who otherwise would be entitled
     to receive fractional share interests and to distribute to each such holder
     such holder's ratable share of the total proceeds of such sale, after
     making appropriate deductions of the amount, if any, required for federal
     income tax withholding purposes and after deducting any applicable transfer
     taxes. All brokers' fees and commissions incurred in connection with such
     sales shall be paid by the Acquiror.

          (f) Termination of Exchange Fund.  Any portion of the Exchange Fund
              ----------------------------                                   
     that remains unclaimed by the former holders of Company Common Stock for 12
     months after the Effective Time shall be delivered to the Acquiror, upon
     demand, and any former holders of Company Common Stock who have not
     theretofore complied with this Article III shall thereafter look only to
     the Acquiror for the Acquiror Common Stock and any cash to which they are
     entitled.  Notwithstanding any other provisions herein, neither the
     Exchange Agent nor any party hereto shall be liable to any former holder of
     Company Common Stock for any Acquiror Common Stock, cash in lieu of
     fractional share interests or dividends or distributions thereon delivered
     to a public official pursuant to any applicable abandoned property, escheat
     or similar law. If any certificates evidencing Company Common Stock shall
     not have been surrendered prior to the seventh anniversary of the Effective
     Time (or such earlier date on which any shares of Acquiror Common Stock,
     any cash in lieu of fractional share interests or dividends or
     distributions with respect to Acquiror Common Stock to which the holder of
     such certificates would otherwise be entitled would escheat to or become
     the property of any governmental entity), then, immediately prior to such
     date, any such shares, cash, dividends or distributions in respect of such
     shares shall, to the extent permitted by applicable Law, become the
     property of the Acquiror, free and clear of all adverse claims and
     interests of any Person previously entitled thereto.

          (g) Withholding of Tax.  The Acquiror shall be entitled to deduct and
              ------------------                                               
     withhold from the consideration otherwise payable pursuant to this Plan to
     any former holder of Company Common Stock such amounts as the Acquiror (or
     any affiliate thereof) or the Exchange Agent is required to deduct and
     withhold with respect to the making of such payment under the Code or any
     state, local or foreign tax Law.  To the extent that amounts are so
     withheld by the Acquiror, such withheld amounts shall be treated for all

                                      -6-
<PAGE>
 
     purposes of this Plan as having been paid to the former holder of Company
     Common Stock in respect of which such deduction and withholding was made by
     the Acquiror.

          (h) Investment of Exchange Fund.  The Exchange Agent may invest any
              ----------------------------                                   
     cash included in the Exchange Fund in deposit accounts or short-term money
     market instruments, as directed by the Acquiror, on a daily basis.  Any
     interest and other income resulting from such investments shall be paid to
     the Acquiror.  The Acquiror shall deposit with the Exchange Agent as part
     of the Exchange Fund cash in an amount equal to any loss of principal
     resulting from such investments promptly after the incurrence of such a
     loss.

      SECTION 3.03  Closing.  The Closing shall take place at the offices of
                    -------                                                 
Vinson & Elkins L.L.P., 2001 Ross Avenue, Dallas, Texas 75201 promptly after
satisfaction or, if permissible, waiver of the conditions to Closing set forth
in Article VIII herein.  At the conclusion of the Closing on the Closing Date,
the parties hereto shall cause the Articles of Merger to be filed with the
Secretary of State of the Commonwealth of Pennsylvania and the Certificate of
Merger with the Secretary of State of the State of Delaware.

      SECTION 3.04  Stock Transfer Books.  At the Effective Time, the stock
                    --------------------                                   
transfer books of the Company shall be closed and there shall be no further
registration of transfers of shares of Company Common Stock thereafter on the
records of the Company other than to reflect transfers of shares through the
date on which the Effective Time occurs.

                                  ARTICLE IV

                 REPRESENTATIONS AND WARRANTIES OF THE COMPANY

     The Company hereby represents and warrants to the Acquiror Companies that:

      SECTION 4.01  Organization and Qualification; Subsidiaries.  The Company
                    --------------------------------------------              
and each Subsidiary of the Company are legal entities duly organized, validly
existing and in good standing under the Laws of their respective jurisdictions
of incorporation or organization, have all requisite corporate power and
authority to own, lease and operate their respective properties and to carry on
their businesses as they are now being conducted and are duly qualified and in
good standing to do business in the jurisdictions in which the nature of the
businesses conducted by them or the ownership or leasing of their respective
properties makes such qualification necessary, other than any matters, including
the failure to be so qualified and in good standing, that could not reasonably
be expected to have a Material Adverse Effect on the Company. Section 4.01 of
the Company's Disclosure Letter sets forth, as of the date of this Plan, a true
and complete list of all the Company's directly or indirectly owned
Subsidiaries, together with (A) a specification of the nature of legal
organization of such Subsidiary, (B) the jurisdiction of incorporation or other
organization of such Subsidiary and (C) an indication of whether such Subsidiary
is a Significant Subsidiary. Neither the Company nor any of its Subsidiaries
owns an 

                                      -7-
<PAGE>
 
equity interest in any other partnership, joint venture arrangement or other
business entity that is Material to the Company.

     SECTION 4.02  Articles of Incorporation and Bylaws.  The Company has
                   ------------------------------------                  
heretofore marked for identification and delivered to the Acquiror complete and
correct copies of the articles of incorporation and the bylaws or the equivalent
organizational documents, in each case as amended or restated to the date
hereof, of the Company and each of its Subsidiaries. Neither the Company nor any
of its Subsidiaries is in violation of any of the provisions of its articles of
incorporation or bylaws (or equivalent organizational documents).

     SECTION 4.03  Capitalization.
                   -------------- 

          (a) The authorized capital stock of the Company consists of (i)
     50,000,000 shares of Company Common Stock, of which, as of March 31, 1997,
     8,389,653 shares were issued and outstanding, all of which are duly
     authorized, validly issued, fully paid and nonassessable and not subject to
     preemptive rights created by statute, the Company's articles of
     incorporation or bylaws or any agreement to which the Company is a party or
     is bound, and (ii) 10,000,000 shares of Preferred Stock, par value $0.01
     per share, none of which is issued and outstanding. Between March 31, 1997
     and the date of this Plan, no shares of Company Common Stock have been
     issued by the Company, except upon exercise of Company Stock Options
     outstanding under the Company Option Plans.  Except as set forth in Section
     4.03(a) of the Company's Disclosure Letter, the Company has not, since
     March 31, 1997, granted any options for, or other rights to purchase,
     shares of Company Common Stock.

          (b) Except for shares reserved for issuance upon exercise of Company
     Stock Options granted pursuant to the Company Option Plans or the Company
     Warrants and, in each case, listed in Section 4.03(b) of the Company's
     Disclosure Letter, no shares of Common Stock are reserved for issuance,
     and, except for such Company Stock Options, there are no contracts,
     agreements, commitments or arrangements obligating the Company (i) to
     offer, sell, issue or grant any shares of, or any options, warrants or
     rights of any kind to acquire any shares of, or any securities that are
     convertible into or exchangeable for any shares of, capital stock of the
     Company or (ii) to redeem, purchase or acquire, or offer to purchase or
     acquire, any outstanding shares of, or any outstanding options, warrants or
     rights of any kind to acquire any shares of, or any outstanding securities
     that are convertible into or exchangeable for any shares of, capital stock
     of the Company.

          (c) Section 4.03(c) of the Company's Disclosure Letter sets forth with
     respect to each Subsidiary of the Company (i) the numbers of shares of
     authorized, issued and outstanding capital stock of, or other equity
     interests in, each such Subsidiary, (ii) the number of such shares of
     capital stock or other equity interests owned of record and beneficially by
     the Company or another Subsidiary of the Company, together with the name of
     such holder or holders, and (iii) the names and addresses of any holders,
     other 

                                      -8-
<PAGE>
 
     than the Company or another Subsidiary, of record or beneficially of the
     capital stock or other equity interests of such Subsidiary. Except as set
     forth in Section 4.03(c) of the Company's Disclosure Letter, (x) the issued
     and outstanding shares of capital stock of, or other equity interests in,
     each of the Subsidiaries of the Company that are owned by the Company or
     any of its Subsidiaries have been duly authorized and are validly issued,
     and, with respect to capital stock, are fully paid and nonassessable, and
     were not issued in violation of any preemptive or similar rights of any
     past or present equity holder of such Subsidiary; (y) all such issued and
     outstanding shares, or other equity interests, that are indicated as owned
     by the Company or one of its Subsidiaries in Section 4.03(c) of the
     Company's Disclosure Letter are owned (A) beneficially as set forth therein
     and (B) free and clear of all Liens; (z) no shares of capital stock of, or
     other equity interests in, any Subsidiary of the Company are reserved for
     issuance, and there are no contracts, agreements, commitments or
     arrangements obligating the Company or any of its Subsidiaries (A) to
     offer, sell, issue, grant, pledge, dispose of or encumber any shares of
     capital stock of, or other equity interests in, or any options, warrants or
     rights of any kind to acquire any shares of capital stock of, or other
     equity interests in, or any securities that are convertible into or
     exchangeable for any shares of capital stock of, or other equity interests
     in, any of the Subsidiaries of the Company or (B) to redeem, purchase or
     acquire, or offer to purchase or acquire, any outstanding shares of capital
     stock of, or other equity interests in, or any outstanding options,
     warrants or rights of any kind to acquire any shares of capital stock of,
     or other equity interest in, or any outstanding securities that are
     convertible into or exchangeable for, any shares of capital stock of, or
     other equity interests in, any of the Subsidiaries of the Company or (C) to
     grant any Lien on any outstanding shares of capital stock of, or other
     equity interest in, any of the Subsidiaries of the Company; except for any
     matter under clause (x), (y) or (z) of this Section 4.03(c) that could not
     reasonably be expected to have a Material Adverse Effect on the Company.

          (d) Except for the Company Stock Options and the Company Warrants
     listed in Section 4.03(b) of the Company's Disclosure Letter, there are no
     voting trusts, proxies or other agreements, commitments or understandings
     of any character to which the Company or any of its Subsidiaries is a party
     or by which the Company or any of its Subsidiaries is bound with respect to
     the voting of any shares of capital stock of the Company or any of its
     Subsidiaries, with respect to the registration of the offering, sale or
     delivery of any shares of capital stock of the Company or any of its
     Subsidiaries under the Securities Act or otherwise relating to any shares
     of capital stock of the Company or any of its Subsidiaries, except in the
     case of any Subsidiaries of the Company that are not Significant
     Subsidiaries for any matters that could not reasonably be expected to have
     a Material Adverse Effect on the Company.

     SECTION 4.04  Authorization of Plan.  The Company has all requisite
                   ---------------------                                
corporate power and authority to execute and deliver this Plan and, subject to
approval of the Plan by the shareholders of the Company as required by the
applicable provisions of the PBCL, each instrument required hereby to be
executed and delivered by it at the Closing, to perform its 

                                      -9-
<PAGE>
 
obligations hereunder and thereunder and to consummate the transactions
contemplated hereby. The execution and delivery by the Company of this Plan and
each instrument required hereby to be executed and delivered by it at the
Closing and the performance of its obligations hereunder and thereunder have
been duly and validly authorized by all requisite corporate action on the part
of the Company (other than, with respect to the Merger, the approval and
adoption of this Plan by the holders of a majority of the outstanding shares of
Company Common Stock in accordance with the applicable provisions of the PBCL
and the Company's articles of incorporation). This Plan has been duly executed
and delivered by the Company and (assuming due authorization, execution and
delivery hereof by the other parties hereto) constitutes a legal, valid and
binding obligation of the Company, enforceable against the Company in accordance
with its terms, except as the same may be limited by legal principles of general
applicability governing the application and availability of equitable remedies.

      SECTION 4.05  Approvals.  Except for the applicable requirements, if any,
                    ---------                                                  
of (a) the Securities Act, (b) the Exchange Act, (c) state securities or blue
sky laws, (d) the HSR Act, (e) the NASD, (f) the filing and recordation of
appropriate merger documents as required by the PBCL and (g) those Laws,
Regulations and Orders noncompliance with which could not reasonably be expected
to have a material adverse effect on the ability of the Company to perform its
obligations under this Plan or to have a Material Adverse Effect on the Company,
no filing or registration with, no waiting period imposed by and no
Authorization of, any Governmental Authority is required under any Law,
Regulation or Order applicable to the Company or any of its Subsidiaries to
permit the Company to execute, deliver or perform this Plan or any instrument
required hereby to be executed and delivered by it at the Closing.
 
     SECTION 4.06  No Violation.  Assuming effectuation of all filings and
                   ------------                                           
registrations with, termination or expiration of any applicable waiting periods
imposed by and receipt of all Authorizations of Governmental Authorities
indicated as required in Section 4.05 and receipt of the approval of the Plan by
the shareholders of the Company as required by the applicable provisions of the
PBCL, neither the execution and delivery by the Company of this Plan or any
instrument required hereby to be executed and delivered by it at the Closing nor
the performance by the Company of its obligations hereunder or thereunder will
(a) violate or breach the terms of or cause a default under (i) any Law,
Regulation or Order applicable to the Company, (ii) the articles of
incorporation or bylaws of the Company or (iii) any contract or agreement to
which the Company or any of its Subsidiaries is a party or by which it or any of
its properties or assets is bound, or (b) with the passage of time, the giving
of notice or the taking of any action by a third Person, have any of the effects
set forth in clause (a) of this Section, except in any such case for any matters
described in this Section (other than clause (ii) hereof) that could not
reasonably be expected to have either a material adverse effect upon the ability
of the Company to perform its obligations under this Plan or a Material Adverse
Effect on the Company.  Prior to the execution of this Plan, the Board of
Directors of the Company has taken all necessary action to cause this Plan and
the transactions contemplated hereby to be exempt from the provisions of
Subchapter F (Business Combinations) of Chapter 25 of the PBCL.

                                     -10-
<PAGE>
 
     SECTION 4.07  Reports.
                   ------- 

          (a)  Since April 14, 1994, the Company has filed (i) all SEC Reports
     required to be filed by it with the Commission and (ii) the Company and its
     Subsidiaries have filed all other Reports required to be filed by any of
     them with any other Governmental Authorities, including state securities
     administrators, except where the failure to file any such Reports could not
     reasonably be expected to have a Material Adverse Effect on the Company.
     Such Reports, including all those filed after the date of this Plan and
     prior to the Effective Time, (x) were prepared in all material respects in
     accordance with the requirements of applicable Law (including, with respect
     to SEC Reports, the Securities Act and the Exchange Act, as the case may
     be, and the applicable Regulations of the Commission thereunder) and (y),
     in the case of the SEC Reports, did not at the time they were filed contain
     any untrue statement of a material fact or omit to state a material fact
     required to be stated therein or necessary in order to make the statements
     therein, in the light of the circumstances under which they were made, not
     misleading.

          (b)  The Company Consolidated Financial Statements and any
     consolidated financial statements of the Company (including any related
     notes thereto) contained in any SEC Reports filed by the Company with the
     Commission after the date of this Plan (i) have been or will have been
     prepared in accordance with the published Regulations of the Commission and
     in accordance with GAAP (except (A) to the extent required by changes in
     GAAP and (B), with respect to the SEC Reports filed by the Company prior to
     the date of this Plan, as may be indicated in the notes thereto) and (ii)
     fairly present the consolidated financial position of the Company and its
     Subsidiaries as of the respective dates thereof and the consolidated
     results of their operations and cash flows for the periods indicated
     (including, in the case of any unaudited interim financial statements,
     reasonable estimates of normal and recurring year-end adjustments).

          (c)  Except as set forth in Section 4.07(c) of the Company's
     Disclosure Letter, there exist no liabilities or obligations of the Company
     and its Subsidiaries that are Material to the Company, whether accrued,
     absolute, contingent or threatened, and that would be required to be
     reflected, reserved for or disclosed under GAAP in consolidated financial
     statements of the Company as of and for the period ended on the date of
     this representation and warranty, other than (i) liabilities or obligations
     that are adequately reflected, reserved for or disclosed in the Company's
     Consolidated Financial Statements, (ii) liabilities or obligations incurred
     in the ordinary course of business of the Company since March 31, 1997 and
     (iii) liabilities or obligations the incurrence of which is permitted by
     Section 6.02(a).

     SECTION 4.08  No Material Adverse Effect; Conduct.
                   ----------------------------------- 

          (a)  Since March 31, 1997, no event  (other than any event that is of
     general application to all or a substantial portion of the Company's
     industry and other than any event that is expressly subject to any other
     representation or warranty contained in 

                                     -11-
<PAGE>
 
     Article IV) has, to the Knowledge of the Company, occurred that,
     individually or together with other similar events, could reasonably be
     expected to constitute or cause a Material Adverse Effect on the Company.

          (b) Except as set forth in Section 4.08(b) of the Company's Disclosure
     Letter, during the period from March 31, 1997 to the date of this Plan,
     neither the Company nor any of its Subsidiaries has engaged in any conduct
     that is proscribed during the period from the date of this Plan to the
     Effective Time by subsections (i) through (xii) of Section 6.02(a).

     SECTION 4.09  Title to Properties.  The Company or its Subsidiaries,
                   -------------------                                   
individually or together, have indefeasible title to all of the properties
reflected in the Company's Consolidated Balance Sheet, other than any properties
reflected in the Company's Consolidated Balance Sheet that have been sold or
otherwise disposed of since the date of the Company's Consolidated Balance Sheet
or  are not, individually or in the aggregate, Material to the Company, free and
clear of Liens, other than (x) Liens the existence of which is reflected in the
Company's Consolidated Financial Statements, (y) Permitted Encumbrances and (z)
Liens that, individually or in the aggregate, are not Material to the Company.
The Company or its Subsidiaries, individually or together, hold under valid
lease agreements all real and personal properties reflected in the Company's
Consolidated Balance Sheet as being held under capitalized leases, and all real
and personal property that is subject to the operating leases to which reference
is made in the notes to the Company's Audited Consolidated Financial Statements,
and enjoy peaceful and undisturbed possession of such properties under such
leases, other than (i) any properties as to which such leases have terminated in
the ordinary course of business since the date of the Company's Consolidated
Balance Sheet and (ii) any properties that, individually or in the aggregate,
are not Material to the Company.  Neither the Company nor any of its
Subsidiaries has received any written notice of any adverse claim to the title
to any properties owned by them or with respect to any lease under which any
properties are held by them, other than any claims that, individually or in the
aggregate, could not reasonably be expected to have a Material Adverse Effect on
the Company.

      SECTION 4.10  Certain Obligations.    Except for those listed in Section
                    -------------------                                       
4.10 of the Company's Disclosure Letter or filed as Exhibits to the Company's
SEC Reports, neither the Company nor any of its Subsidiaries is a party to or
bound by any Material Contract.  Except as set forth in Section 4.10 of the
Company's Disclosure Letter, all Material Contracts to which the Company or any
of its Subsidiaries is a party are in full force and effect, the Company or the
Subsidiary of the Company that is a party to or bound by such Material Contract
has performed its obligations thereunder to date and, to the Knowledge of the
Company, each other party thereto has performed its obligations thereunder to
date, other than any failure of a Material Contract to be in full force and
effect or any nonperformance thereof that could not reasonably be expected to
have a Material Adverse Effect on the Company.

      SECTION 4.11  Authorizations; Compliance.  The Company and its
                    --------------------------                      
Subsidiaries have obtained all Authorizations that are necessary to carry on
their businesses as currently 

                                     -12-
<PAGE>
 
conducted, except for any such Authorizations as to which, individually or in
the aggregate, the failure to possess could not reasonably be expected to have a
Material Adverse Effect on the Company. Such Authorizations are in full force
and effect, have not been violated in any respect that could reasonably be
expected to have a Material Adverse Effect on the Company and there is no
action, proceeding or investigation pending or, to the Knowledge of the Company,
threatened regarding suspension, revocation or cancellation of any such
Authorization, except in the case of any suspension, revocation or cancellation
of any such Authorization that could not reasonably be expected to have a
Material Adverse Effect on the Company.

      SECTION 4.12  Litigation; Compliance with Laws.    There are no actions,
                    --------------------------------                          
suits, investigations or proceedings (including any proceedings in arbitration)
pending or, to the Knowledge of the Company, threatened against the Company or
any of its Subsidiaries, at law or in equity, in any Court or before or by any
Governmental Authority, except actions, suits or proceedings that  are set forth
in Section 4.12 or Section 4.15 of the Company's Disclosure Letter or ,
individually or, with respect to multiple actions, suits or proceedings that
allege similar theories of recovery based on similar facts, in the aggregate,
could not reasonably be expected to have a Material Adverse Effect on the
Company.  There are no claims pending or, to the Knowledge of the Company,
threatened by any Persons against the Company or any of its Subsidiaries for
indemnification pursuant to any statute, organizational document, contract or
otherwise with respect to any action, suit, investigation or proceeding pending
in any Court or before or by any Governmental Authority.  Except as set forth in
Section 4.12 of the Company's Disclosure Letter, the Company and its
Subsidiaries are in substantial compliance with all applicable Laws and
Regulations and are not in default with respect to any Order applicable to the
Company or any of its Subsidiaries, except such events of noncompliance or
defaults that, individually or in the aggregate, could not reasonably be
expected to have a Material Adverse Effect on the Company.

      SECTION 4.13  Employee Benefit Plans.
                    ---------------------- 

          (a) Each Benefit Plan of the Company and its Subsidiaries is listed in
     Section 4.13(a) of the Company's Disclosure Letter, including, with respect
     to Terminated Benefit Plans, the date of termination.  True and correct
     copies of each of the following have been made available to the Acquiror:
     the most recent annual report (Form 5500) relating to each such Current
     Benefit Plan filed with the IRS,  each such Current Benefit Plan,  the
     trust agreement, if any, relating to each such Current Benefit Plan,  the
     most recent summary plan description for each such Current Benefit Plan for
     which a summary plan description is required by ERISA, the most recent
     actuarial report or valuation relating to each such Current Benefit Plan
     subject to Title IV of ERISA and  the most recent determination letter, if
     any, issued by the IRS with respect to any such Current Benefit Plan
     qualified under Section 401 of the Code.

          (b) Except as set forth in Section 4.13(b) of the Company's Disclosure
     Letter, with respect to such Benefit Plans, no event has occurred and, to
     the Knowledge of the Company, there exists no condition or set of
     circumstances in connection with which the 

                                     -13-
<PAGE>
 
     Company or any of its Subsidiaries could be subject to any liability under
     the terms of such Benefit Plans, ERISA, the Code or any other applicable
     Law, other than any condition or set of circumstances that could not
     reasonably be expected to have a Material Adverse Effect on the Company.

          (c) As to any such Current Benefit Plan intended to be qualified under
     Section 401 of the Code, such Benefit Plan satisfies in form the
     requirements of such Section, except to the extent amendments are not
     required by Law to be made until a date after the Effective Time.  There
     has been no termination or partial termination of any such Benefit Plan
     within the meaning of Section 411(d)(3) of the Code.

          (d) As to any such Terminated Benefit Plan intended to have been
     qualified under Section 401 of the Code, such Terminated Benefit Plan
     received a favorable determination letter from the IRS with respect to its
     termination.

          (e) There are no actions, suits or claims pending (other than routine
     claims for benefits) or, to the Knowledge of the Company, threatened
     against, or with respect to, any of such Benefit Plans or their assets that
     could reasonably be expected to have a Material Adverse Effect on the
     Company.

          (f) There is no matter pending (other than routine qualification
     determination filings) with respect to any of such Benefit Plans before the
     IRS, the Department of Labor or the PBGC.

          (g) All contributions required to be made to such Benefit Plans
     pursuant to their terms and provisions have been made timely.

          (h) As to any such Current Benefit Plan subject to Title IV of ERISA,
     (i) there has been no event or condition which presents a significant risk
     of plan termination, (ii) no accumulated funding deficiency, whether or not
     waived, within the meaning of Section 302 of ERISA or Section 412 of the
     Code has been incurred, (iii) no reportable event within the meaning of
     Section 4043 of ERISA (for which the disclosure requirements of Regulation
     section 2615.3 and section 4043.1 et seq., promulgated by the PBGC, have
     not been waived) has occurred within six years prior to the date of this
     Plan, (iv) no notice of intent to terminate such Benefit Plan has been
     given under Section 4041 of ERISA, (v) no proceeding has been instituted
     under Section 4042 of ERISA to terminate such Benefit Plan, (vi) no
     liability to the PBGC has been incurred (other than with respect to
     required premium payments) and (vii) the assets of the Benefit Plan equal
     or exceed the actuarial present value of the benefit liabilities, within
     the meaning of Section 4041 of ERISA, under the Benefit Plan, based upon
     reasonable actuarial assumptions and the asset valuation principles
     established by the PBGC.

          (i) Except as set forth in Section 4.13(i) of the Company's Disclosure
     Letter, in connection with the consummation of the transactions
     contemplated by this Plan, no 

                                     -14-
<PAGE>
 
     payments have been or will be made under any such Current Benefit Plans or
     any of the programs, agreements, policies or other arrangements described
     in Section 4.13(k) of the Company's Disclosure Letter which, in the
     aggregate, would be nondeductible under Section 280G of the Code.

          (j) Except as set forth in Section 4.13(j) of the Company's Disclosure
     Letter, the execution and delivery of this Plan and the consummation of the
     transactions contemplated hereby will not (i) require the Company or any of
     its Subsidiaries to make a larger contribution to, or pay greater benefits
     under, any Current Benefit Plan or any of the programs, agreements,
     policies or other arrangements described in Section 4.13(k) of the
     Company's Disclosure Letter than it otherwise would or (ii) create or give
     rise to any additional vested rights or service credits under any Current
     Benefit Plan or any of such programs, agreements, policies or other
     arrangements.

          (k) Except as set forth in Section 4.13(k) of the Company's Disclosure
     Letter, neither the Company nor any of its Subsidiaries is a party to or is
     bound by any severance agreement (involving $50,000 or more), program or
     policy.  True and correct copies of  all employment agreements and change-
     in-control agreements with officers and employees of the Company and its
     Subsidiaries, and all vacation, overtime and other compensation policies of
     the Company and its Subsidiaries relating to their employees have been made
     available to the Acquiror.

          (l) Except as set forth in Section 4.13(l) of the Company's Disclosure
     Letter,  no Benefit Plan provides retiree medical or retiree life insurance
     benefits to any Person and neither the Company nor any of its Subsidiaries
     is contractually or otherwise obligated (whether or not in writing) to
     provide any Person with life insurance or medical benefits upon retirement
     or termination of employment, other than as required by the provisions of
     Sections 601 through 608 of ERISA and Section 4980B of the Code.  Each
     Benefit Plan or other arrangement described in Section 4.13(l) of the
     Company's Disclosure Letter may be unilaterally amended or terminated in
     its entirety without liability except as to benefits accrued thereunder
     prior to such amendment or termination.

          (m) Neither the Company nor any of its Subsidiaries contributes or has
     an obligation to contribute, and has not within six years prior to the date
     of this Plan contributed or had an obligation to contribute, to a
     multiemployer plan within the meaning of Section 3(37) of ERISA.
 
          (n) The vacation policies of the Company and its Subsidiaries do not
     provide for carryover of vacation from one calendar year to the next.

          (o) No collective bargaining agreement to which the Company or any of
     its Subsidiaries is a party is currently in effect or is being negotiated
     by the Company or any of its Subsidiaries.  There is no pending or, to the
     Knowledge of the Company, threatened labor dispute, strike or work stoppage
     against the Company or any of its 

                                     -15-
<PAGE>
 
     Subsidiaries that could reasonably be expected to have a Material Adverse
     Effect on the Company. To the Knowledge of the Company and except as set
     forth in Section 4.13(o) of the Company's Disclosure Letter, neither the
     Company or any of its Subsidiaries nor any representative or employee of
     the Company or any of its Subsidiaries has committed any unfair labor
     practices in connection with the operation of the business of the Company
     and its Subsidiaries, and there is no pending or, to the Knowledge of the
     Company, threatened charge or complaint against the Company or any of its
     Subsidiaries by the National Labor Relations Board or any comparable agency
     of any state of the United States.
 
      SECTION 4.14  Taxes.
                    ----- 

          (a) Except for such matters as could not reasonably be expected to
     have a Material Adverse Effect on the Company,  all returns and reports of
     or with respect to any Tax ("Tax Returns") that are required to be filed by
     or with respect to the Company or any of its Subsidiaries on or before the
     Effective Time have been or will be timely filed,  all Taxes that are due
     on or before the Effective Time have been or will be timely paid in full,
     all withholding Tax requirements imposed on or with respect to the Company
     or any of its Subsidiaries have been or will be satisfied in full in all
     respects and no penalty, interest or other charge is or will become due
     with respect to the late filing of any such Tax Return or late payment of
     any such Tax.

          (b) Except as set forth in Section 4.14(b) of the Company's Disclosure
     Letter, all such Tax Returns have been audited by the applicable
     Governmental Authority or the applicable statute of limitations has expired
     for the period covered by such Tax Returns.

          (c) Except as set forth in Section 4.14(c) of the Company's Disclosure
     Letter, there is not in force any extension of time with respect to the due
     date for the filing of any such Tax Return or any waiver or agreement for
     any extension of time for the assessment or payment of any Tax due with
     respect to the period covered by any such Tax Return.

          (d) There is no claim against the Company or any of its Subsidiaries
     for any Taxes, and no assessment, deficiency or adjustment has been
     asserted or proposed with respect to any such Tax Return, that, in either
     case, could reasonably be expected to have a Material Adverse Effect on the
     Company.

          (e) Except as set forth in Section 4.14(e) of the Company's Disclosure
     Letter, none of the Company and its Subsidiaries, during the last ten
     years, has been a member of an affiliated group filing a consolidated
     federal income Tax Return.

      SECTION 4.15   Environmental Matters.  Except for matters disclosed in
                     ---------------------                                  
Section 4.15 of the Company's Disclosure Letter and except for matters that,
individually or in the aggregate, could not reasonably be expected to have a
Material Adverse Effect on the 

                                     -16-
<PAGE>
 
Company, (a) the properties, operations and activities of the Company and its
Subsidiaries are in compliance with all applicable Environmental Laws; (b) the
Company and its Subsidiaries and the properties and operations of the Company
and its Subsidiaries are not subject to any existing, pending or, to the
Knowledge of the Company, threatened action, suit, investigation, inquiry or
proceeding by or before any Court or Governmental Authority under any
Environmental Law; (c) all Authorizations, if any, required to be obtained or
filed by the Company or any of its Subsidiaries under any Environmental Law in
connection with the business of the Company and its Subsidiaries have been
obtained or filed and are valid and currently in full force and effect; (d)
there has been no release of any hazardous substance, pollutant or contaminant
into the environment by the Company or its Subsidiaries or in connection with
their properties or operations; (e) there has been no exposure of any Person or
property to any hazardous substance, pollutant or contaminant in connection with
the properties, operations and activities of the Company and its Subsidiaries;
and (f) the Company and its Subsidiaries have made available to the Acquiror all
internal and external environmental audits and studies and all correspondence on
substantial environmental matters (in each case relevant to the Company or any
of its Subsidiaries) in the possession of the Company or its Subsidiaries.

      SECTION 4.16  Intellectual Property.
                    --------------------- 

     (a) Schedule 4.16(a) to the Company's Disclosure Letter contains:

          (i)    A listing and identification of all unexpired U.S. and foreign
     patents, pending patent applications and unpatented, but identified,
     inventions which are owned by the Company or its Subsidiaries (the "Patents
     List");

          (ii)   A listing of all U.S. and all foreign trademarks, service
     marks, registrations and pending applications for registrations of marks,
     trade names and registered U.S. and foreign copyrights which are owned by
     the Company or any Subsidiary of the Company (the "Trademark/Copyright
     List");

          (iii)  A listing (the "Agreements List") of all agreements to which
     the Company or any Subsidiary of the Company is a party (A) under which
     royalties presently are payable or in the future will or may become payable
     by or to the Company or any Subsidiary of the Company, or (B) which concern
     rights to patents, technology, processes or proprietary information of any
     Person relating to the businesses of the Company and its Subsidiaries as
     they presently are conducted, have been conducted in the past or may be
     conducted in the future, or (C) which in any other way affect ownership,
     control, use or disclosure of intellectual property or technology material
     in any way to the businesses of the Company and its Subsidiaries as they
     presently are conducted, have been conducted in the past or may be
     conducted in the future.

     (b) Except as disclosed in Schedule 4.16(b) to the Company's Disclosure
Letter:

                                      -17-
<PAGE>
 
          (i)     The Company or a Subsidiary of the Company is the record owner
     of, and has good title, free of any liens or other encumbrances, to all of
     the items on the Patents List and the Trademark/Copyright List;

          (ii)    To the Knowledge of the Company, no Person has asserted that
     either the Company or any Subsidiary of the Company or any licensee of the
     Company or any Subsidiary of the Company, is infringing or has infringed
     within the six years prior to the date hereof, any foreign or domestic
     patent, trademark, service mark, trade name, or copyright, or has
     misappropriated or improperly used or disclosed any trade secret,
     confidential information or know how or any Person;

          (iii)   To the Knowledge of the Company, no Person is infringing or
     has infringed, within the six years prior to the date hereof, any item on
     the Patents List or the Trademark/Copyright List, or has misappropriated or
     improperly used or disclosed any trade secret, confidential information or
     know-how of the Company or any Subsidiary of the Company;

          (iv)    To the Knowledge of the Company, no operations of the Company
     or its Subsidiaries are infringing, or have infringed within the six years
     prior to the date hereof, any foreign or domestic patent, trademark,
     service mark, trade name or copyright of any Person, or has involved any
     misappropriation or improper use or disclosure of any trade secret,
     confidential information or know-how of any Person;

          (v)     All necessary working requirements, all proofs of use,
     renewals and all fees, annuities and other payments which are due on or
     before the date of this Plan for any items in the Patents List and/or
     Trademark/Copyright List have been met or paid;

          (vi)    None of the items in the Patents List or the
     Trademark/Copyright List is the subject of any pending or, to the Knowledge
     of the Company, threatened interference, re-examination, opposition,
     cancellation or other protest proceeding;

          (vii)   To the Knowledge of the Company, the claims contained in the
     issued patents on the Patents List are valid;

          (viii)  It has been the policy and practice of the Company and its
     Subsidiaries to require that all employees, consultants and other Persons
     to whom confidential information relating to the business of the Company
     and its Subsidiaries is disclosed shall execute and deliver written
     agreements  (A) not to use or disclose any such confidential information,
     except pursuant to the terms of such agreements or with the written consent
     of the Company or its Subsidiary, as the case may be, and (B) to reduce to
     writing, disclose and assign to the Company or its Subsidiary, as the case
     may be, all inventions, discoveries and improvements, patentable or
     unpatentable, and there has been no material deviation from such policy and
     practice;

                                     -18-
<PAGE>
 
          (ix)    To the Knowledge of the Company, there is no foreign or
     domestic patent which is reasonably expected by the Company or any of its
     Subsidiaries to restrict materially the Acquiring Companies or their
     Affiliates from practicing, licensing or otherwise exploiting the
     intellectual property of the Company and its Subsidiaries, comprising, (A)
     the items on the Patents List and the Trademark/Copyright List and (B) the
     Company's and its Subsidiaries' confidential business information and trade
     secrets;

          (x)     To the Knowledge of the Company and its Subsidiaries, all
     Material obligations required to be performed to date, by the Company, its
     Subsidiaries and any other Person pursuant to the agreements on the
     Agreements List have been performed and no party to any such agreement is
     materially in default in any respect thereunder.

      SECTION 4.17  Insurance.  The Company and its Subsidiaries own and are
                    ---------                                               
beneficiaries under all such insurance policies underwritten by reputable
insurers that, as to risks insured, coverages and related limits and
deductibles, are customary in the industry in which the Company and its
Subsidiaries operate.  All premiums due with respect to all such insurance
policies that are Material have been paid and, to the Knowledge of the Company,
all such policies are in full force and effect.  Section 4.17 of the Company's
Disclosure Letter sets forth a list, including the name of the underwriter, the
risks insured, coverage and related limits and deductibles, expiration dates and
significant riders, of the principal insurance policies currently maintained by
the Company and its Subsidiaries.

      SECTION 4.18  Pooling; Tax Matters.  Neither the Company nor, to the
                    --------------------                                  
Knowledge of the Company, any of its Affiliates has taken or agreed to take any
action that would prevent (a) the Merger from being treated as a "pooling of
interests" in accordance with GAAP and the Regulations of the Commission or (b)
the Merger from constituting a reorganization within the meaning of section
368(a) of the Code.  Without limiting the generality of the foregoing:

          (a) There is no plan or intention by any shareholder of the Company
     who owns 5% or more of the Company Common Stock, and to the Knowledge of
     the management of the Company, there is no plan or intention on the part of
     any of the remaining shareholders of the Company, to sell, exchange or
     otherwise dispose of a number of shares of Acquiror Common Stock to be
     received in the Merger that would reduce the ownership of Acquiror Common
     Stock by the holders of Company Common Stock who will receive such Acquiror
     Common Stock in the Merger to a number of shares having a value, as of the
     Effective Time, of less than 50% of the value of all Company Common Stock
     (including shares of Company Common Stock sold for cash in lieu of
     fractional shares of Acquiror Common Stock and Dissenters' Shares)
     outstanding immediately prior to the Effective Time.

          (b) To the Knowledge of the Company, there is no agreement, plan or
     intention by any shareholder of the Company that owns 5% or more of the
     outstanding Company Common Stock to sell, exchange or otherwise dispose of
     any of the shares of Acquiror Common Stock to be received by such
     shareholder in the Merger.

                                     -19-
<PAGE>
 
          (c) The Company and the shareholders of the Company will each pay
     their respective expenses, if any, incurred in connection with the Merger.

          (d) There is no intercorporate indebtedness existing between the
     Company and the Acquiror or between the Company and Newco that was issued,
     acquired or will be settled at a discount.

          (e) The Company is not an investment company as defined in section
     368(a)(2)(F)(iii) and (iv) of the Code.

          (f) The Company is not under the jurisdiction of a court in a title 11
     or similar case within the meaning of section 368(a)(3)(A) of the Code.

     SECTION 4.19   Affiliates.  Section 4.19 of the Company's Disclosure Letter
                    ----------                                                  
contains a true and complete list of all Persons who are directors or executive
officers of the Company and any other Persons who, to the Knowledge of the
Company, may be deemed to be Affiliates of the Company. Concurrently with the
execution and delivery of this Plan, the Company has delivered to the Acquiror
an executed letter agreement, substantially in the form of Annex B hereto, from
each such Person so identified.

     SECTION 4.20   Certain Business Practices.  As of the date of this Plan,
                    --------------------------                               
neither the Company or any of its Subsidiaries nor any director, officer,
employee or  agent of the Company or any of its Subsidiaries has (a) used any
funds for unlawful contributions, gifts, entertainment or other unlawful
expenses relating to political activity, (b) made any unlawful payment to any
foreign or domestic government official or employee or to any foreign or
domestic political party or campaign or violated any provision of the Foreign
Corrupt Practices Act of 1977, as amended, (c) consummated any transaction, made
any payment, entered into any agreement or arrangement or taken any other action
in violation of Section 1128B(b) of the Social Security Act, as amended, or (d)
made any other unlawful payment, except for any such matters that could not
reasonably be expected to have a Material Adverse Effect on the Company.

     SECTION 4.21   Opinion of Financial Advisor.  The Company has received the
                    ----------------------------                               
opinion of Schroder Wertheim & Co. Incorporated on the date of this Plan to the
effect that the Common Stock Exchange Ratio is fair, from a financial point of
view, to the holders of Company Common Stock in the Merger.

     SECTION 4.22   Brokers.  Except as set forth in Section 4.22 of the
                    -------                                             
Company's Disclosure Letter, no broker, finder or investment banker (other than
Schroder Wertheim & Co. Incorporated and B. G. Consulting Corp.) is entitled to
any brokerage, finder's or other fee or commission in connection with the
transactions contemplated by this Plan based upon arrangements made by or on
behalf of the Company.  Prior to the date of this Plan, the Company has made
available to the Acquiror a complete and correct copy of all agreements between
the Company and Schroder Wertheim & Co. Incorporated and B. G. Consulting Corp.

                                     -20-
<PAGE>
 
pursuant to which such firms will be entitled to any payment relating to the
transactions contemplated by this Plan.

      SECTION 4.23  AntiTakeover Law.   None of the provisions of Subchapters E,
                    -----------------                                           
G and H of Chapter 25 of the PBCL is applicable to the Plan or the Merger by
virtue of the operation of Article 9 of the Company's articles of incorporation.
The provisions of Subchapter F of Chapter 25 of the PBCL are not applicable to
the Plan or the Merger by virtue of the actions of the Board of Directors of the
Company in adopting the Plan on June 9, 1997.

                                   ARTICLE V

                  REPRESENTATIONS AND WARRANTIES OF ACQUIROR

   The Acquiror Companies hereby represent and warrant to the Company that:

      SECTION 5.01  Organization and Qualification; Subsidiaries.  The Acquiror,
                    --------------------------------------------                
Newco and each other Significant Subsidiary of the Acquiror are legal entities
duly organized, validly existing and in good standing under the laws of their
respective jurisdictions of incorporation or organization, have all requisite
corporate power and authority to own, lease and operate their respective
properties and to carry on their businesses as they are now being conducted and
are duly qualified and in good standing to do business in each jurisdiction in
which the nature of the business conducted by them or the ownership or leasing
of their respective properties makes such qualification necessary, other than
any matters, including the failure to be so qualified and in good standing, that
could not reasonably be expected to have a Material Adverse Effect on the
Acquiror. Section 5.01 of the Acquiror's Disclosure Letter sets forth, as of the
date of this Plan, a true and complete list of all Significant Subsidiaries of
the Acquiror, together with the jurisdiction of incorporation of each such
Subsidiary and the percentage of each such Subsidiary's outstanding capital
stock or other equity interests owned by the Acquiror or another Subsidiary of
the Acquiror.

      SECTION 5.02  Certificate of Incorporation and Bylaws.  The Acquiror has
                    ---------------------------------------                   
heretofore marked for identification and furnished to the Company complete and
correct copies of the certificate of incorporation and the bylaws or the
equivalent organizational documents, in each case as amended or restated to the
date hereof, of the Acquiror and each of its Significant Subsidiaries. Neither
the Acquiror nor any of its Significant Subsidiaries is in violation of any of
the provisions of its certificate of incorporation or bylaws (or equivalent
organizational documents).

      SECTION 5.03  Capitalization.
                    -------------- 

          (a) The authorized capital stock of the Acquiror consists of (i)
     400,000,000 shares of Acquiror Common Stock of which as of March 31, 1997
     126,455,962 shares were issued and outstanding, all of which are duly
     authorized, validly issued, fully paid and nonassessable and not subject to
     preemptive rights created by statute, the Acquiror's 

                                     -21-
<PAGE>
 
     certificate of incorporation or bylaws or any agreement to which the
     Acquiror is a party or is bound and (ii) 5,000,000 shares of Preferred
     Stock, without par value, of which none is issued but of which 2,000,000
     shares have been designated as Series A Junior Participating Preferred
     Stock. Between March 31, 1997 and the date of this Plan, no shares of
     Acquiror Common Stock have been issued by the Acquiror except Acquiror
     Common Stock issued pursuant to the exercise of outstanding Acquiror Stock
     Options, Acquiror Restricted Stock and Acquiror Common Stock issued
     otherwise as set forth in Section 5.03(a) of the Acquiror's Disclosure
     Letter. Except as set forth in Section 5.03(a) of the Acquiror's Disclosure
     Letter, the Acquiror has not, since March 31, 1997, granted any options
     for, or other rights to purchase, shares of Acquiror Common Stock.

          (b) Except as set forth in Section 5.03(b) of the Acquiror's
     Disclosure Letter and except for shares reserved for issuance pursuant to
     the Acquiror Stock Plans, no shares of Common Stock are reserved for
     issuance, and, except for Acquiror Stock Options, Acquiror Restricted Stock
     agreements and for the Acquiror's obligations under the Acquiror's Rights
     Agreement, there are no contracts, agreements, commitments or arrangements
     obligating the Acquiror  to offer, sell, issue or grant any shares of, or
     any options, warrants or rights of any kind to acquire any shares of, or
     any securities that are convertible into or exchangeable for any shares of,
     capital stock of the Acquiror,  to redeem, purchase or acquire, or offer to
     purchase or acquire, any outstanding shares of, or any outstanding options,
     warrants or rights of any kind to acquire any shares of, or any outstanding
     securities that are convertible into or exchangeable for any shares of,
     capital stock of the Acquiror or  to grant any Lien on any shares of
     capital stock of the Acquiror.

          (c) Except as set forth in Section 5.03(c) of the Acquiror's
     Disclosure Letter, (i) all the issued and outstanding shares of capital
     stock of, or other equity interests in, each Significant Subsidiary of the
     Acquiror are owned by the Acquiror or one of its Subsidiaries, have been
     duly authorized and are validly issued, and, with respect to capital stock,
     are fully paid and nonassessable, and were not issued in violation of any
     preemptive or similar rights of any past or present equity holder of such
     Subsidiary; (ii) all such issued and outstanding shares, or other equity
     interests, that are owned by the Acquiror or one of its Subsidiaries are
     owned free and clear of all Liens; (iii) no shares of capital stock of, or
     other equity interests in, any Significant Subsidiary of the Acquiror are
     reserved for issuance, and there are no contracts, agreements, commitments
     or arrangements obligating the Acquiror or any of its Significant
     Subsidiaries (A) to offer, sell, issue, grant, pledge, dispose of or
     encumber any shares of capital stock of, or other equity interests in, or
     any options, warrants or rights of any kind to acquire any shares of
     capital stock of, or other equity interests in, or any securities that are
     convertible into or exchangeable for any shares of capital stock of, or
     other equity interests in, any of the Significant Subsidiaries of the
     Acquiror or (B) to redeem, purchase or acquire, or offer to purchase or
     acquire, any outstanding shares of capital stock of, or other equity
     interests in, or any outstanding options, warrants or rights of any kind to
     acquire any shares of capital stock of, or other equity interests in, or
     any 

                                     -22-
<PAGE>
 
     outstanding securities that are convertible into or exchangeable for, any
     shares of capital stock of, or other equity interests in, any of the
     Significant Subsidiaries of the Acquiror or (C) to grant any Lien on any
     outstanding shares of capital stock of, or other equity interests in, any
     of the Significant Subsidiaries of the Acquiror; except for any matter
     under clause (i), (ii) or (iii) of this Section 5.03(c) that could not
     reasonably be expected to have a Material Adverse Effect on the Acquiror.

          (d) Except for revocable proxies granted by the Acquiror or its
     Subsidiaries with respect to the capital stock of Subsidiaries owned by the
     Acquiror or its Subsidiaries, there are no voting trusts, proxies or other
     agreements, commitments or understandings of any character to which the
     Acquiror or any of its Significant Subsidiaries is a party or by which the
     Acquiror or any of its Significant Subsidiaries is bound with respect to
     the voting of any shares of capital stock of the Acquiror or any of its
     Significant Subsidiaries.

      SECTION 5.04  Authorization of Plan.  Each of the  Acquiror and Newco has
                    ---------------------                                      
all requisite corporate power and authority to execute and deliver this Plan and
each instrument required hereby to be executed and delivered by it at the
Closing, to perform its obligations hereunder and thereunder and to consummate
the transactions contemplated hereby.  The execution and delivery by each of
Acquiror and Newco of this Plan and each instrument required hereby to be
executed and delivered by each of them at the Closing and the performance of
their respective obligations hereunder and thereunder have been duly and validly
authorized by all requisite corporate action on the part of the Acquiror and
Newco, respectively.  This Plan has been duly executed and delivered by the
Acquiror and Newco and (assuming due authorization, execution and delivery
hereof by the other party hereto) constitutes a legal, valid and binding
obligation of the Acquiror and Newco, enforceable against the Acquiror and Newco
in accordance with its terms, except as the same may be limited by legal
principles of general applicability governing the application and availability
of equitable remedies.

      SECTION 5.05  Approvals.  Except for the applicable requirements, if any,
                    ---------                                                  
of (a) the Securities Act, (b) the Exchange Act, (c) state securities or blue
sky laws, (d) the HSR Act, (e) the NYSE, (f) the filing and recordation of
appropriate merger documents as required by the PBCL and the DGCL and (g) those
Laws, Regulations and Orders noncompliance with which could not reasonably be
expected to have a material adverse effect on the ability of the Acquiror or
Newco to perform its obligations under this Plan or to have a Material Adverse
Effect on the Acquiror, no filing or registration with, no waiting period
imposed by and no Authorization of, any Governmental Authority is required under
any Law, Regulation or Order applicable to the Acquiror or Newco to permit the
Acquiror or Newco to execute, deliver or perform this Plan or any instrument
required hereby to be executed and delivered by it at the Closing.  To the
Knowledge of the Acquiror, there are no facts or circumstances that could
reasonably be expected to preclude the Acquiror Common Stock to be issued in the
Merger from being approved for listing on the NYSE.

                                     -23-
<PAGE>
 
      SECTION 5.06  No Violation.  Assuming effectuation of all filings and
                    ------------                                           
registrations with, termination or expiration of any applicable waiting periods
imposed by, and receipt of all Authorizations of, Governmental Authorities
indicated as required in Section 5.05, neither the execution and delivery by the
Acquiror or Newco of this Plan or any instrument required hereby to be executed
and delivered by it at the Closing nor the performance by the Acquiror or Newco
of its obligations hereunder or thereunder will  (a) violate or breach the terms
of or cause a default under (i) any Law, Regulation or Order applicable to the
Acquiror or Newco, (ii) the certificate of incorporation or bylaws of the
Acquiror or Newco or (iii) any contract or agreement to which the Acquiror or
any of its Subsidiaries is a party or by which it or any of its properties or
assets is bound, or (b) with the passage of time, the giving of notice or the
taking of any action by a third Person, have any of the effects set forth in
clause (a) of this Section, except in any such case for any matters described in
this Section that could not reasonably be expected to have a material adverse
effect upon the ability of the Acquiror or Newco to perform its obligations
under this Plan or a Material Adverse Effect on the Acquiror.

      SECTION 5.07  Reports.
                    ------- 

          (a) Since December 31, 1993, the Acquiror has filed all SEC Reports
     required to be filed by the Acquiror with the Commission. The Acquiror's
     SEC Reports, including those filed after the date of this Plan and prior to
     the Effective Time, (i) were prepared in all material respects in
     accordance with the applicable requirements of the Securities Act and the
     Exchange Act, as the case may be, and the applicable Regulations of the
     Commission thereunder and (ii) did not at the time they were filed contain
     any untrue statement of a material fact or omit to state a material fact
     required to be stated therein or necessary in order to make the statements
     therein, in the light of the circumstances under which they were made, not
     misleading.

          (b) The Acquiror's Consolidated Financial Statements and any
     consolidated financial statements of the Acquiror (including any related
     notes thereto) contained in any SEC Reports filed by the Acquiror with the
     Commission after the date of this Plan (i) have been or will have been
     prepared in accordance with the published Regulations of the Commission and
     in accordance with GAAP (except (A) to the extent required by changes in
     GAAP and (B), with respect to SEC Reports filed by the Acquiror prior to
     the date of this Plan, as may be indicated in the notes thereto) and (ii)
     fairly present the consolidated financial position of the Acquiror and its
     Subsidiaries as of the respective dates thereof and the consolidated
     results of their operations and cash flows for the periods indicated
     (including, in the case of any unaudited interim financial statements,
     reasonable estimates of normal and recurring year-end adjustments).
 
          (c) Except as set forth in Section 5.07(c) of the Acquiror's
     Disclosure Letter, there exist no liabilities or obligations of the
     Acquiror and its Subsidiaries that are Material to the Acquiror, whether
     accrued, absolute, contingent or threatened, that would be required to be
     reflected, reserved for or disclosed under GAAP in consolidated financial
     statements of the Acquiror as of and for the period ended on the date of
     this 

                                     -24-
<PAGE>
 
     representation and warranty, other than (i) liabilities or obligations
     that are adequately reflected, reserved for or disclosed in the Acquiror's
     Consolidated Financial Statements, (ii) liabilities or obligations incurred
     in the ordinary course of business of the Acquiror since March 31, 1997,
     (iii) liabilities or obligations the incurrence of which is permitted by
     Section 6.02(b) and (iv) liabilities or obligations that are not Material
     to the Acquiror.

      SECTION 5.08  No Material Adverse Effect; Conduct.
                    ----------------------------------- 

          (a) Since March 31, 1997, no event  (other than any event that is of
     general application to all or a substantial portion of the Acquiror's
     industries and other than any event that is expressly subject to any other
     representation or warranty contained in Article V) has, to the Knowledge of
     the Acquiror, occurred that, individually or together with other similar
     events, could reasonably be expected to constitute or cause a Material
     Adverse Effect on the Acquiror.

          (b) Except as set forth in Section 5.08(b) of the Acquiror's
     Disclosure Letter, during the period from March 31, 1997 to the date of
     this Plan, neither the Acquiror nor any of its Subsidiaries has engaged in
     any conduct that is proscribed during the period from the date of this Plan
     to the Effective Time by subsections (i) through (viii) of Section 6.02(b).

      SECTION 5.09  Title to Properties.  The Acquiror or its Subsidiaries,
                    -------------------                                    
individually or together, have indefeasible title to all of the properties
reflected in the Acquiror's Consolidated Balance Sheet, other than any
properties reflected in the Acquiror's Consolidated Balance Sheet that have been
sold or otherwise disposed of since the date of the Acquiror's Consolidated
Balance Sheet or  are not, individually or in the aggregate, Material to the
Acquiror, free and clear of Liens, other than (x) Liens the existence of which
is reflected in the Acquiror's Consolidated Financial Statements, (y) Permitted
Encumbrances and (z) Liens that, individually or in the aggregate, are not
Material to the Acquiror. The Acquiror or its Subsidiaries, individually or
together, hold under valid lease agreements all real and personal properties
reflected in the Acquiror's Consolidated Balance Sheet as being held under
capitalized leases, and all real and personal property that is subject to the
operating leases to which reference is made in the notes to the Acquiror's
Audited Consolidated Financial Statements, and enjoy peaceful and undisturbed
possession of such properties under such leases, other than (i) any properties
as to which such leases have terminated in the ordinary course of business since
the date of the Acquiror's Consolidated Balance Sheet and (ii) any properties
that, individually or in the aggregate, are not Material to the Acquiror.

      SECTION 5.10  Certain Obligations.    Except as set forth in Section 5.10
                    -------------------                                        
of the Acquiror's Disclosure Letter, all Material Contracts to which the
Acquiror or any of its Subsidiaries is a party are in full force and effect, the
Acquiror or the Subsidiary of the Acquiror that is a party to or bound by such
Material Contract has performed its obligations thereunder to date and, to the
Knowledge of the Acquiror, each other party thereto has performed its
obligations thereunder to date, other than any failure of any such Material
Contract to be in full 

                                     -25-
<PAGE>
 
force and effect or any nonperformance thereof that could not reasonably be
expected to have a Material Adverse Effect on the Acquiror.

      SECTION 5.11  Authorizations; Compliance.  To the Knowledge of the
                    --------------------------                          
Acquiror, the Acquiror and its Subsidiaries have obtained all Authorizations
that are necessary to carry on their businesses as currently conducted, except
for any such Authorizations as to which the failure to possess, individually or
in the aggregate, could not reasonably be expected to have a Material Adverse
Effect on the Acquiror.  Such Authorizations are in full force and effect, have
not been violated in any respect that could reasonably be expected to have a
Material Adverse Effect on the Acquiror and there is no action, proceeding or
investigation pending or threatened regarding suspension, revocation or
cancellation of any of such Authorizations, except in the case of any
suspension, revocation or cancellation of such Authorizations that could not
reasonably be expected to have a Material Adverse Effect on the Acquiror.

      SECTION 5.12  Litigation; Compliance with Laws.  There are no actions,
                    --------------------------------                        
suits, investigations or proceedings (including any proceedings in arbitration)
pending or, to the Knowledge of the Acquiror, threatened against the Acquiror or
any of its Subsidiaries, at law or in equity, in any Court or before or by any
Governmental Authority, except actions, suits or proceedings that are set forth
in Section 5.12 or Section 5.15 of the Acquiror's Disclosure Letter or ,
individually or, with respect to multiple actions, suits or proceedings that
allege similar theories of recovery based on similar facts, in the aggregate,
could not reasonably be expected to have a Material Adverse Effect on the
Acquiror.  The Acquiror and its Subsidiaries are in substantial compliance with
all applicable Laws and Regulations and are not in default with respect to any
Order applicable to the Acquiror or any of its Subsidiaries, except such events
of noncompliance or defaults that, individually or in the aggregate, could not
reasonably be expected to have a Material Adverse Effect on the Acquiror.

      SECTION 5.13  Employee Benefit Plans.  Except as set forth in Section 5.13
                    ----------------------                                      
of the Acquiror's Disclosure Letter:

          (a) No event has occurred and, to the Knowledge of the Acquiror, there
     exists no condition or set of circumstances in connection with which the
     Acquiror or any of its Subsidiaries could be subject to any liability under
     the terms of any Benefit Plans of the Acquiror or any of its Significant
     Subsidiaries or, with respect to any such Benefit Plan, under ERISA, the
     Code or any other applicable Law, other than any condition or set of
     circumstances that could not reasonably be expected to have a Material
     Adverse Effect on the Acquiror.

          (b) As to any such Current Benefit Plan intended to be qualified under
     Section 401 of the Code, such Benefit Plan satisfies in form the
     requirements of such Section, except to the extent amendments are not
     required by Law to be made until a date after the Effective Time. There has
     been no termination or partial termination of any such Benefit Plan within
     the meaning of Section 411(d)(3) of the Code.

                                     -26-
<PAGE>
 
          (c) As to any such Terminated Benefit Plan intended to have been
     qualified under Section 401 of the Code, such Terminated Benefit Plan
     received a favorable determination letter from the IRS with respect to its
     termination.

          (d) There are no actions, suits or claims pending (other than routine
     claims for benefits) or, to the Knowledge of the Acquiror, threatened
     against, or with respect to, any of such Benefit Plans or their assets that
     could reasonably be expected to have a Material Adverse Effect on the
     Acquiror.
 
          (e) As to any such Current Benefit Plan subject to Title IV of ERISA,
     (i) there has been no event or condition which presents the material risk
     of plan termination, (ii) no accumulated funding deficiency, whether or not
     waived, within the meaning of Section 302 of ERISA or Section 412 of the
     Code has been incurred, (iii) no reportable event within the meaning of
     Section 4043 of ERISA (for which the disclosure requirements of Regulation
     section 2615.3 and section 4043.1 et seq., promulgated by the PBGC, have
     not been waived) has occurred within six years prior to the date of this
     Plan, (iv) no notice of intent to terminate such Benefit Plan has been
     given under Section 4041 of ERISA, (v) no proceeding has been instituted
     under Section 4042 of ERISA to terminate such Benefit Plan, (vi) no
     liability to the PBGC has been incurred (other than with respect to
     required premium payments) and (vii) the assets of the Benefit Plan equal
     or exceed the actuarial present value of the benefit liabilities, within
     the meaning of Section 4041 of ERISA, under the Benefit Plan, based upon
     reasonable actuarial assumptions and the asset valuation principles
     established by the PBGC.
 
          (f) Neither the Acquiror nor any of its Subsidiaries contributes or
     has an obligation to contribute, and has not within six years prior to the
     date of this Plan contributed or had an obligation to contribute, to a
     multiemployer plan within the meaning of Section 3(37) of ERISA.
 
      SECTION 5.14  Taxes.
                    ----- 

          (a) Except for such matters as could not reasonably be expected to
     have a Material Adverse Effect on the Acquiror,  all Tax Returns that are
     required to be filed by or with respect to the Acquiror or any of its
     Subsidiaries on or before the Effective Time have been or will be timely
     filed,  all Taxes that are due on or before the Effective Time have been or
     will be timely paid in full,  all withholding Tax requirements imposed on
     or with respect to the Acquiror or any of its Subsidiaries have been or
     will be satisfied in full in all respects and  no penalty, interest or
     other charge is or will become due with respect to the late filing of any
     such Tax Return or late payment of any such Tax.
 
          (b) There is no claim against the Acquiror or any of its Subsidiaries
     for any Taxes, and no assessment, deficiency or adjustment has been
     asserted or proposed with 

                                     -27-
<PAGE>
 
     respect to any such Tax Return, that, in either case, could reasonably be
     expected to have a Material Adverse Effect on the Acquiror.

      SECTION 5.15  Environmental Matters.  Except for matters disclosed in
                    ---------------------                                  
Section 5.15 of the Acquiror's Disclosure Letter and except for matters that,
individually or in the aggregate, could not reasonably be expected to have a
Material Adverse Effect on the Acquiror, (a) the properties, operations and
activities of the Acquiror and its Subsidiaries are in compliance with all
applicable Environmental Laws; (b) the Acquiror and its Subsidiaries and the
properties and operations of the Acquiror and its Subsidiaries are not subject
to any existing, pending or, to the Knowledge of the Acquiror, threatened
action, suit, investigation, inquiry or proceeding by or before any Court or
Governmental Authority under any Environmental Law; (c) all Authorizations, if
any, required to be obtained or filed by the Acquiror or any of its Subsidiaries
under any Environmental Law in connection with the business of the Acquiror and
its Subsidiaries have been obtained or filed and are valid and currently in full
force and effect; (d) there has been no release of any hazardous substance,
pollutant or contaminant into the environment by the Acquiror or its
Subsidiaries or in connection with their properties or operations; and (e) there
has been no exposure of any Person or property to any hazardous substance,
pollutant or contaminant in connection with the properties, operations and
activities of the Acquiror and its Subsidiaries.
 
      SECTION 5.16  Pooling; Tax Matters.  Neither the Acquiror nor, to the
                    --------------------                                   
Knowledge of the Acquiror, any of its Affiliates has taken or agreed to take any
action that would prevent (a) the Merger from being treated for financial
accounting purposes as a "pooling of interests" in accordance with GAAP and the
Regulations of the Commission or (b) the Merger from constituting a
reorganization within the meaning of  section 368(a) of the Code.  Without
limiting the generality of the foregoing:

               (a) Following the Merger, the Surviving Corporation will hold at
          least 90 percent of the fair market value of the Company's net assets,
          at least 70 percent of the fair market value of the Company's gross
          assets, at least 90 percent of the fair market value of the net assets
          of Newco and at least 70 percent of the fair market value of the gross
          assets of Newco, held immediately prior to the Merger, taking into
          account amounts paid for Dissenters' Shares and used to pay Merger
          Expenses and any distributions other than regular dividends.

               (b) The Acquiror has no plan or intention to (A) liquidate the
          Surviving Corporation, (B) merge the Surviving Corporation  with or
          into another corporation, (C) sell or otherwise dispose of the stock
          of the Surviving Corporation except for transfers of stock to
          corporations controlled (within the meaning of section 368(c) of the
          Code) by the Acquiror, (D) cause or permit the Surviving Corporation
          to issue additional shares of its capital stock that would result in
          the Acquiror's losing control (within the meaning of section 368(c) of
          the Code) of the Surviving Corporation, (E) cause or permit the
          Surviving Corporation to sell or otherwise dispose of any of its
          assets or of any of the assets 

                                     -28-
<PAGE>
 
          acquired from Newco except for dispositions made in the ordinary
          course of business or transfers of assets to a corporation controlled
          by the Surviving Corporation or (F) reacquire any of the Acquiror
          Common Stock issued to the holders of Company Common Stock in the
          Merger.

               (c) Newco has no liabilities that will be assumed by the
          Surviving Corporation in the Merger and will not transfer to the
          Surviving Corporation in the Merger any assets subject to liabilities.

               (d) Following the Merger, the Surviving Corporation will continue
          the historic business of the Company or use a significant portion of
          its assets in a business.

               (e) There is no intercorporate indebtedness existing between the
          Company and the Acquiror or between the Company and Newco that was
          issued, acquired, or will be settled at a discount.

               (f) The Acquiror does not own, nor has it owned during the past
          five years, any shares of capital stock of the Company.

      SECTION 5.17  Insurance.  The Acquiror and its Subsidiaries own and are
                    ---------                                                
beneficiaries under all such insurance policies underwritten by reputable
insurers that, as to risks insured, coverages and related limits and
deductibles, are customary for a company of the size and nature of the Acquiror
and which is similarly situated. All premiums due with respect to all such
insurance policies that are Material have been paid and, to the Knowledge of the
Acquiror, all such policies are in full force and effect.

      SECTION 5.18  Affiliates.  Section 5.18 of the Acquiror's Disclosure
                    ----------                                            
Letter contains a true and complete list of all Persons who, to the Knowledge of
the Acquiror, may be deemed to be Affiliates of the Acquiror, including all
directors and executive officers of the Acquiror. Concurrently with the
execution and delivery of this Plan, the Acquiror has delivered to the Company
an executed letter agreement, substantially in the form of Annex C hereto, from
each such Person so identified as an Affiliate of the Acquiror.
 
      SECTION 5.19  Certain Business Practices.  As of the date of this Plan,
                    --------------------------                               
neither the Acquiror or any of its Subsidiaries nor any director, officer,
employee or  agent of the Acquiror or any of its Subsidiaries has (a) used any
funds for unlawful contributions, gifts, entertainment or other unlawful
expenses relating to political activity, (b) made any unlawful payment to any
foreign or domestic government official or employee or to any foreign or
domestic political party or campaign or violated any provision of the Foreign
Corrupt Practices Act of 1977, as amended, (c) consummated any transaction, made
any payment, entered into any agreement or arrangement or taken any other action
in violation of Section 1128B(b) of the Social Security Act, as amended, or (d)
made any other unlawful payment, except for any such matters that could not
reasonably be expected to have a Material Adverse Effect on the Acquiror.
 
                                     -29-
<PAGE>
 
      SECTION 5.20  Brokers.  Except as set forth in Section 5.20 of the
                    -------                                             
Acquiror's Disclosure Letter, no broker, finder or investment banker (other than
Dillon, Read & Co. Inc.) is entitled to any brokerage, finder's or other fee or
commission in connection with the transactions contemplated by this Plan based
upon arrangements made by or on behalf of the Acquiror.

      SECTION 5.21  Acquiring Person.  Based on the information set forth in the
                    ----------------                                            
Company's SEC Reports, no holder of 5% or more of the outstanding Company Common
Stock whose existence is disclosed therein will at the Effective Time become an
"Acquiring Person," as such term is defined in the Acquiror's Rights Agreement,
as a result of any of the transactions contemplated by this Plan.

                                  ARTICLE VI

                                   COVENANTS

      SECTION 6.01  Affirmative Covenants.  The Company hereby covenants and
                    ---------------------                                   
agrees that, prior to the Effective Time, unless otherwise expressly
contemplated by this Plan or consented to in writing by the Acquiror, it will
and will cause its Subsidiaries to:

          (a) operate its business in the usual and ordinary course consistent
     with past practices;

          (b) use all reasonable efforts to preserve substantially intact its
     business organization, maintain its rights and franchises, retain the
     services of its respective key employees and maintain its relationships
     with its respective customers and suppliers;

          (c) maintain and keep its properties and assets in as good repair and
     condition as at present, ordinary wear and tear excepted, and maintain
     supplies and inventories in quantities consistent with its customary
     business practice; and

          (d) use all reasonable efforts to keep in full force and effect
     insurance and bonds comparable in amount and scope of coverage to that
     currently maintained;

except for any matters that, individually or in the aggregate, could not
reasonably be expected to have a Material Adverse Effect on the Company.

      SECTION 6.02  Negative Covenants.
                    ------------------ 

          (a) The Company covenants and agrees that, except as expressly
     contemplated by this Plan or otherwise consented to in writing by the
     Acquiror, from the date of this Plan until the Effective Time, it will not
     do, and will not permit any of its Subsidiaries to do, any of the
     following:

                                     -30-
<PAGE>
 
              (i)   (A) increase the compensation payable to or to become
          payable to any director or executive officer, except for increases in
          salary or wages payable or to become payable upon promotion to an
          office having greater operational responsibilities or otherwise in the
          ordinary course of business and consistent with past practice; (B)
          grant any severance or termination pay (other than pursuant to the
          normal severance policy of the Company or its Subsidiaries as in
          effect on the date of this Plan) to, or enter into any employment or
          severance agreement with, any director, officer or employee, either
          individually or as part of a class of similarly situated persons; (C)
          establish, adopt or enter into any Benefit Plan or (D), except as may
          be required by applicable Law and actions that are not inconsistent
          with the provisions of Section 7.08 of this Plan, amend or take any
          other actions (including the acceleration of vesting, waiving of
          performance criteria or the adjustment of awards or any other actions
          permitted upon a change in control of such party or a filing under
          Section 13(d) or 14(d) of the Exchange Act with respect to such party)
          with respect to any of the Benefit Plans of such party;

              (ii)  declare or pay any dividend on, or make any other
          distribution in respect of, outstanding shares of capital stock,
          except for dividends by a wholly owned Subsidiary of the Company to
          the Company or another wholly owned Subsidiary of the Company;

              (iii) (A) redeem, purchase or acquire, or offer to purchase or
          acquire, any outstanding shares of capital stock of, or other equity
          interests in, or any securities that are convertible into or
          exchangeable for any shares of capital stock of, or other equity
          interests in, or any outstanding options, warrants or rights of any
          kind to acquire any shares of capital stock of, or other equity
          interests in, the Company or any of its Subsidiaries (other than (1)
          any such acquisition by the Company or any of its wholly owned
          Subsidiaries directly from any wholly owned Subsidiary of the Company,
          (2) any repurchase, forfeiture or retirement of shares of Company
          Common Stock or Company Stock Options occurring pursuant to the terms
          (as in effect on the date of this Plan) of any existing Benefit Plan
          of the Company or any of its Subsidiaries or (3) any periodic purchase
          of Company Common Stock for allocation to employee's accounts
          occurring pursuant to the terms (as in effect on the date of this
          Plan) of any existing employee stock purchase plan); (B) to effect any
          reorganization or recapitalization; or (C) to split, combine or
          reclassify any of the capital stock of, or other equity interests in,
          the Company or any of its Subsidiaries or to issue or to authorize or
          propose the issuance of any other securities in respect of, in lieu of
          or in substitution for, shares of such capital stock or such equity
          interests;

              (iv)  (A) offer, sell, issue or grant, or authorize the offering,
          sale, issuance or grant, of any shares of capital stock of, or other
          equity interests in, any securities convertible into or exchangeable
          for any shares of capital stock of, 

                                     -31-
<PAGE>
 
          or other equity interests in, or any options, warrants or rights of
          any kind to acquire any shares of capital stock of, or other equity
          interests in, the Company or any of its Subsidiaries, other than
          issuances of Company Common Stock (1) upon the exercise of Company
          Stock Options outstanding at the date of this Plan in accordance with
          the terms thereof (as in effect on the date of this Plan), (2) upon
          the expiration of any restrictions upon issuance of any grant existing
          at the date of this Plan of restricted stock or bonus stock pursuant
          to the terms (as in effect on the date of this Plan) of any Benefit
          Plans of the Company or any of its Subsidiaries or (3) any periodic
          issuance of shares of Company Common Stock required by the terms (as
          in effect on the date of this Plan) of any Benefit Plans of the
          Company or any of its Subsidiaries, (B) amend or otherwise modify the
          terms (as in effect on the date of this Plan) of any outstanding
          options, warrants or rights the effect of which shall be to make such
          terms more favorable to the holders thereof (except as may be required
          by ERISA or other applicable Law); (C) take any action to accelerate
          the vesting of any outstanding Company Stock Options or (D) grant any
          Lien with respect to any shares of capital stock of, or other equity
          interests in, any Subsidiary of the Company;

              (v)    acquire or agree to acquire, by merging or consolidating
          with, by purchasing an equity interest in or all or a portion of the
          assets of, or in any other manner, any business or any corporation,
          partnership, association or other business organization or division
          thereof or otherwise to acquire any assets of any other Person (other
          than the purchase of assets from suppliers or vendors in the ordinary
          course of business and consistent with past practice);

              (vi)   sell, lease, exchange or otherwise dispose of, or grant any
          Lien (other than a Permitted Encumbrance) with respect to, any of the
          assets of the Company or any of its Subsidiaries that are Material to
          the Company, except for dispositions of assets and inventories in the
          ordinary course of business and consistent with past practice and
          dispositions of assets and purchase money Liens incurred in connection
          with the original acquisition of assets and secured by the assets
          acquired in an amount not to exceed $50,000 in the aggregate;

              (vii)  adopt any amendments to its charter or bylaws or other
          organizational documents that would alter the terms of its capital
          stock or other equity interests or would have a material adverse
          effect on the ability of the Company to perform its obligations under
          this Plan;

              (viii) (A) change any of its methods of accounting in effect at
          December 31, 1996, except as may be required to comply with GAAP, (B)
          make or rescind any election relating to Taxes (other than any
          election which must be made periodically which is made consistent with
          past practice), (C) settle or compromise any claim, action, suit,
          litigation, proceeding, arbitration, investigation, audit or
          controversy relating to Taxes (except where the cost to the 

                                     -32-
<PAGE>
 
          Company and its Subsidiaries of such settlements or compromises,
          individually or in the aggregate, does not exceed $50,000) or (D)
          change any of its methods of reporting income or deductions for
          federal income tax purposes from those employed in the preparation of
          the federal income tax returns for the taxable year ending December
          31, 1995, except, in each case, as may be required by Law and for
          matters that could not reasonably be expected to have a Material
          Adverse Effect on the Company;

              (ix)   incur any obligations for borrowed money or purchase money
          indebtedness (other than purchase money indebtedness as to which Liens
          may be granted as permitted by Section 6.02(a)(vi)) that are Material
          to the Company, whether or not evidenced by a note, bond, debenture or
          similar instrument, except drawings under credit lines existing at the
          date of this Plan or otherwise in the ordinary course of business
          consistent with past practice and, in the latter instance, in no event
          (including purchase money indebtedness as to which Liens may be
          granted pursuant to Section 6.02(a)(vi)) in excess of $50,000;

              (x)    release any third Person from its obligations under any
          existing standstill agreement relating to a Competing Transaction or
          otherwise under any confidentiality agreement or similar agreement;

              (xi)   enter into any Material Contract with any third Person that
          provides for an exclusive arrangement with that third Person or is
          substantially more restrictive on the Company or any of its
          Subsidiaries or substantially less advantageous to the Company or any
          of its Subsidiaries than Material Contracts existing on the date
          hereof; or

              (xii)  agree in writing or otherwise to do any of the foregoing.

          (b) The Acquiror covenants and agrees that, except as expressly
     contemplated by this Plan or otherwise consented to in writing by the
     Company, from the date of this Plan until the Effective Time, it will not
     do, and will not permit any of its Subsidiaries to do, any of the
     following:
 
              (i)    declare or pay any extraordinary dividend or distribution
          (such term not including the Acquiror's regular quarterly dividend or
          any change thereto) in cash or property other than Acquiror Common
          Stock, except for dividends by a wholly owned Subsidiary of the
          Acquiror to the Acquiror or another wholly owned Subsidiary of the
          Acquiror;

               (ii)  (A) redeem, purchase or acquire, or offer to purchase or
          acquire, any outstanding shares of capital stock of, or other equity
          interests in, or any securities that are convertible into or
          exchangeable for any shares of capital stock of, or other equity
          interests in, or any outstanding options, warrants or rights of 

                                     -33-
<PAGE>
 
          any kind to acquire any shares of capital stock of, or other equity
          interests in, the Acquiror or any of its Subsidiaries (other than (1)
          any such acquisition by the Acquiror or any of its wholly owned
          Subsidiaries directly from any wholly owned Subsidiary of the
          Acquiror, (2) any repurchase, forfeiture or retirement of shares of
          Acquiror Common Stock or Acquiror Stock Options occurring pursuant to
          the terms of any existing Benefit Plan of the Acquiror or any of its
          Subsidiaries or (3) any periodic purchase of Acquiror Common Stock for
          allocation to employee's accounts occurring pursuant to the terms of
          any existing Benefit Plan of the Acquiror or any of its Subsidiaries)
          or (B) effect any reorganization or recapitalization other than any
          reorganization or recapitalization that could not reasonably be
          expected to have a material adverse effect on the ability of the
          Acquiror to perform its obligations under this Plan;

              (iii)  offer, sell, issue or grant, or authorize the offering,
          sale, issuance or grant, of any shares of capital stock of, or other
          equity interests in, any securities convertible into or exchangeable
          for any shares of capital stock of, or other equity interests in, or
          any options, warrants or rights of any kind to acquire any shares of
          capital stock of, or other equity interests in, the Acquiror or any of
          its Subsidiaries, other than issuances of Acquiror Common Stock (A)
          upon the exercise of Acquiror Stock Options outstanding at the date of
          this Plan in accordance with the terms thereof, (B) as Acquiror
          Restricted Stock, (C) upon the expiration of any restrictions upon
          issuance of any grant existing at the date of this Plan of restricted
          stock or bonus stock pursuant to the terms of any Benefit Plans of the
          Acquiror or any of its Subsidiaries, (D) any periodic issuance of
          shares of Acquiror Common Stock occurring pursuant to the terms of any
          Benefit Plan of the Acquiror or any of its Subsidiaries or (E) any
          issuance of shares of Acquiror Common Stock for cash or in connection
          with any acquisition of equity interests, assets or businesses that
          could not reasonably be expected to have a material adverse effect on
          the ability of the Acquiror to perform its obligations under this
          Plan;

              (iv)   acquire or agree to acquire, by merging or consolidating
          with, by purchasing an equity interest in or all or a portion of the
          assets of, or in any other manner, any business or any corporation,
          partnership, association or other business organization or division
          thereof, or otherwise to acquire any assets of any other Person (other
          than the purchase of assets from suppliers or vendors in the ordinary
          course of business and consistent with past practice and acquisitions
          of equity interests, assets and businesses that could not reasonably
          be expected to have a material adverse effect on the ability of the
          Acquiror to perform its obligations under this Plan);

              (v)    sell, lease, exchange or otherwise dispose of, or grant any
          Lien (other than a Permitted Encumbrance) with respect to, any of the
          assets of the Acquiror or any of its Subsidiaries that are Material to
          the Acquiror, except for 

                                     -34-
<PAGE>
 
          dispositions of assets and inventories in the ordinary course of
          business and consistent with past practice and dispositions of assets
          and incurrences of Liens that could not reasonably be expected to have
          a material adverse effect on the ability of the Acquiror to perform
          its obligations under this Plan;

              (vi)   adopt any amendments to its charter or bylaws or other
          organizational documents that would alter the terms of the Acquiror's
          Common Stock or could reasonably be expected to have a material
          adverse effect on the ability of the Acquiror to perform its
          obligations under this Plan;
 
              (vii)  incur any obligations for borrowed money or purchase money
          indebtedness that are Material to the Acquiror, whether or not
          evidenced by a note, bond, debenture or similar instrument, except
          drawings under credit lines existing at the date of this Plan,
          obligations incurred in the ordinary course of business consistent
          with past practice and obligations that could not reasonably be
          expected to have a material adverse effect on the ability of the
          Acquiror to perform its obligations under this Plan; or
 
              (viii) agree in writing or otherwise to do any of the foregoing.

      SECTION 6.03  No Solicitation.  From the date of this Plan until the
                    ---------------                                       
Effective Time or the termination of this Plan pursuant to Section 9.01, the
Company agrees that it will not (a) initiate, solicit or encourage (including by
way of furnishing information or assistance), or take any other action knowingly
to facilitate, any inquiries from any Person or the making of any proposal by
any Person that constitutes, or may reasonably be expected to lead to, any
Competing Transaction, (b) enter into discussions or negotiate with any Person
in furtherance of such inquiries or to obtain a Competing Transaction, (c) agree
to or endorse any Competing Transaction or (d) authorize or permit any of the
Company's Representatives to take any such action, and the Company shall
promptly notify the Acquiror of all relevant terms of any such inquiries and
proposals received by the Company, any of its Subsidiaries or any Company
Representative relating to any of such matters and, if such inquiry or proposal
is in writing, the Company shall promptly deliver or cause to be delivered to
the Acquiror a copy of such inquiry or proposal; provided, however, that nothing
contained in this Section 6.03 shall prohibit the Board of Directors of the
Company from complying with Rule 14e-2 promulgated under the Exchange Act with
regard to a tender offer or exchange offer for shares of Company Common Stock
commenced prior to the Company Shareholders' Meeting. Pending the Effective Time
or the termination of the Plan, the Company shall not, through action of its
Board of Directors, approve the acquisition of Company Common Stock by any
Person, other than the Acquiror and any of its Subsidiaries and Affiliates, who,
following such acquisition, would be an "interested shareholder" under
Subchapter F of Chapter 25 of the PBCL.
 
                                     -35-
<PAGE>
 
      SECTION 6.04   Access and Information.
                     ---------------------- 

          (a) Each of the Company and the Acquiror shall, and shall cause its
     Subsidiaries to,  (i) afford to the other and its officers, directors,
     employees, accountants, consultants, legal counsel, agents and other
     representatives (collectively, in the case of the Company, the "Company's
     Representatives" and, in the case of the Acquiror, the "Acquiror's Repre
     sentatives") access, at reasonable times upon reasonable prior notice, to
     the officers, employees, agents, properties, offices and other facilities
     of the other and to its books and records and (ii) furnish promptly to the
     other and its Representatives such information concerning its business,
     properties, contracts, records and personnel (including financial,
     operating and other data and information) as may be reasonably requested,
     from time to time, by or on behalf of the other party.
 
          (b) If this Plan is terminated for any reason pursuant to Article IX
     hereof, each of the Company and the Acquiror shall, within ten days after a
     request therefor from the other, return or destroy (and provide the other
     party within such ten day time period with a certificate of an executive
     officer certifying such destruction) all of the information furnished to
     such party and its Representatives pursuant to the provisions of Section
     6.04(a) and all internal memoranda, analyses, evaluations and other similar
     material containing, reflecting or prepared from any such information, in
     each case other than information available to the general public without
     restriction.

      SECTION 6.05  Confidentiality Agreement.   The parties shall comply with,
                    --------------------------                                 
and shall cause their respective Representatives to comply with, all of their
respective obligations under the Confidentiality Agreement.

                                  ARTICLE VII

                             ADDITIONAL AGREEMENTS

      SECTION 7.01  Meeting of Shareholders.  The Company shall, promptly after
                    -----------------------                                    
the date of this Plan, take all actions necessary in accordance with the PBCL
and the Company's articles of incorporation and bylaws to convene a special
meeting of the Company's shareholders to consider adoption of this Plan (the
"Company Shareholders' Meeting"), and the Company shall consult with the
Acquiror in connection therewith.  The Company covenants and agrees that (i) the
Board of Directors of the Company shall recommend approval of the Plan to the
shareholders of the Company at the Company Shareholders' Meeting, (ii) the
Company Proxy Statement shall include the recom  mendation of the Company's
Board of Directors in favor of the Plan; and (iii) the Company shall use all
reasonable efforts to solicit from shareholders of the Company proxies in favor
of the adoption of this Plan and to secure the vote or consent of shareholders
required by the PBCL and the Company's articles of incorporation and bylaws to
approve and adopt this Plan; provided, however, that the Board of Directors of
the Company may withdraw, modify or change its recommendation of this Plan to
the extent necessary to conform such recommendation to a recommendation adopted
in good faith by the Board of 

                                     -36-
<PAGE>
 
Directors pursuant to section 14e-2 of the Exchange Act in response to a tender
offer or exchange offer for the Company Common Stock commenced after the date of
this Plan and prior to the Effective Time.

      SECTION 7.02  Registration Statement; Proxy Statements.
                    ---------------------------------------- 

          (a) As promptly as practicable after the date of this Plan, the
     Acquiror shall prepare a registration statement on Form S-4 (such
     registration statement, together with any amendments thereof or supplements
     thereto, being the "Registration Statement"), which, with the assistance of
     the Company, shall contain a prospectus/proxy statement relating to the
     vote of shareholders of the Company at the Company Shareholders' Meeting
     (the "Prospectus/Proxy Statement"), in connection with the registration
     under the Securities Act of the offering, sale and delivery of Acquiror
     Common Stock to be issued in the Merger pursuant to this Plan. As promptly
     as practicable after the date of this Plan, the Company shall assist the
     Acquiror in preparing the Prospectus/Proxy Statement and shall, pursuant to
     the Proxy Rules under the Exchange Act, file the same, in preliminary form,
     with the Commission, together with a form of proxy, in connection with the
     vote of the Company's shareholders with respect to this Plan (such
     Prospectus/Proxy Statement, together with any amendments thereof or
     supplements thereto, in each case in the form or forms mailed to the
     Company's shareholders, being the "Company Proxy Statement").  The Acquiror
     and the Company agree to use all reasonable efforts to effect such filing
     on or before June 17, 1997 and to mail such Prospectus/Proxy Statement to
     the shareholders of the Company on or before July 30, 1997; provided,
     however, that neither party shall be compelled by such undertaking to make
     any concession to any Governmental Authority that it in good faith regards
     as inappropriate. As soon as reasonably appropriate, the Acquiror shall
     file the Registration Statement with the Commission pursuant to the
     registration provisions of the Securities Act.  The Acquiror and the
     Company will use all reasonable efforts to have or cause the Registration
     Statement to become effective as promptly as practicable, and shall take
     any action required to be taken under any applicable federal or state
     securities Laws in connection with the issuance of shares of Acquiror
     Common Stock in the Merger.  Each of the Acquiror Companies and the Company
     shall furnish all information concerning it and the holders of its capital
     stock as the other may reasonably request in connection with such actions.
     As promptly as practicable after the Registration Statement shall have
     become effective, the Company shall mail the Company Proxy Statement to its
     shareholders entitled to notice of and to vote at the Company Shareholders'
     Meeting.

          (b) The information supplied by the Company for inclusion in the
     Registration Statement shall not, at the time the Registration Statement is
     declared effective, contain any untrue statement of a material fact or omit
     to state any material fact required to be stated therein or necessary in
     order to make the statements therein not misleading.  The information
     supplied by the Company for inclusion in the Company Proxy Statement to be
     sent to the shareholders of the Company in connection with the Company
     Shareholders' Meeting shall not, at the date the Company Proxy Statement
     (or any 

                                     -37-
<PAGE>
 
     supplement thereto) is first mailed to shareholders or at the time of the
     Company Shareholders' Meeting, contain any untrue statement of a material
     fact or omit to state any material fact required to be stated therein or
     necessary in order to make the statements therein, in the light of the
     circumstances under which they were made, not misleading. If at any time
     prior to the Effective Time any event or circumstance relating to the
     Company or any of its Affiliates, or its or their respective officers or
     directors, should be discovered by the Company that should be set forth in
     an amendment to the Registration Statement or a supplement to the Company
     Proxy Statement, the Company shall promptly inform the Acquiror. All
     documents that the Company is responsible for filing with the SEC in
     connection with the transactions contemplated herein shall comply as to
     form in all material respects with the applicable requirements of the
     Securities Act and the Regulations thereunder and the Exchange Act and the
     Regulations thereunder.

          (c) The information supplied by the Acquiror Companies for inclusion
     in the Registration Statement shall not, at the time the Registration
     Statement is declared effective, contain any untrue statement of a material
     fact or omit to state any material fact required to be stated therein or
     necessary in order to make the statements therein not misleading.  The
     information supplied by the Acquiror Companies for inclusion in the Company
     Proxy Statement to be sent to the shareholders of the Company in connection
     with the Company Shareholders' Meeting shall not, at the date the Company
     Proxy Statement (or any supplement thereto) is first mailed to shareholders
     or at the time of the Company Shareholders' Meeting, contain any untrue
     statement of a material fact or omit to state any material fact required to
     be stated therein or necessary in order to make the statements therein, in
     the light of the circumstances under which they are made, not misleading.
     If at any time prior to the Effective Time any event or circumstance
     relating to the Acquiror or any of its Affiliates, or to their respective
     officers or directors, should be discovered by the Acquiror that should be
     set forth in an amendment to the Registration Statement or a supplement to
     the Company Proxy Statement, the Acquiror shall promptly inform the
     Company.  All documents that the Acquiror Companies are responsible for
     filing with the Commission in connection with the transactions contemplated
     hereby shall comply as to form in all material respects with the applicable
     requirements of the Securities Act and the Regulations thereunder and the
     Exchange Act and the Regulations thereunder.

          (d) No amendment or supplement to the Registration Statement or the
     Company Proxy Statement will be made by the Acquiror or the Company without
     the approval of the other party which will not be unreasonably withheld or
     delayed.  The Acquiror and the Company each will advise the other, promptly
     after it receives notice thereof, of the time when the Registration
     Statement has become effective or any supplement or amendment has been
     filed, the issuance of any stop order suspending the effectiveness of the
     Registration Statement or the solicitation of proxies pursuant to the
     Company Proxy Statement, the suspension of the qualification of the
     Acquiror Common Stock issuable in connection with the Merger for offering
     or sale in any jurisdiction, any request by the staff of the Commission for
     amendment of the Registration Statement or 

                                     -38-
<PAGE>
 
     the Company Proxy Statement, the receipt from the staff of the Commission
     of comments thereon or any request by the staff of the Commission for
     additional information with respect thereto.

      SECTION 7.03  Appropriate Action; Consents; Filings.
                    ------------------------------------- 

          (a) The Company and the Acquiror shall each use all reasonable efforts
     (i) to take, or to cause to be taken, all actions, and to do, or to cause
     to be done, all things that, in either case, are necessary, proper or
     advisable under applicable Law or otherwise to consummate and make
     effective the transactions contemplated by this Plan, (ii) to obtain from
     any Governmental Authorities any Authorizations or Orders required to be
     obtained or made by the Acquiror or the Company or any of their
     Subsidiaries in connection with the authorization, execution, delivery and
     performance of this Plan and the consummation of the transactions
     contemplated hereby, including the Merger, (iii) to make all necessary
     filings, and thereafter make any other required submissions, with respect
     to this Plan and the Merger required under (A) the Securities Act (in the
     case of Acquiror) and the Exchange Act and the Regulations thereunder, and
     any other applicable federal or state securities Laws, (B) the HSR Act and
     (C) any other applicable Law.  The Acquiror and the Company shall cooperate
     with each other in connection with the making of all such filings,
     including providing copies of all such documents to the nonfiling party and
     its advisors prior to filings and, if requested, shall accept all
     reasonable additions, deletions or changes suggested in connection
     therewith. The Company and the Acquiror shall furnish all information
     required for any application or other filing to be made pursuant to any
     applicable Law or any applicable Regulations of any Governmental Authority
     (including all information required to be included in the Company Proxy
     Statement or the Registration Statement) in connection with the
     transactions contemplated by this Plan.

          (b) Each of the Company and the Acquiror shall give prompt notice to
     the other of (i) any notice or other communication from any Person alleging
     that the consent of such Person is or may be required in connection with
     the Merger, (ii) any notice or other communication from any Governmental
     Authority in connection with the Merger, (iii) any actions, suits, claims,
     investigations or proceedings commenced or threatened in writing against,
     relating to or involving or otherwise affecting the Company, the Acquiror
     or their Subsidiaries that relate to the consummation of the Merger; (iv)
     the occurrence of a default or event that, with notice or lapse of time or
     both, will become a default under any Material Contract of the Acquiror or
     Material Contract of the Company; and (v) any change that is reasonably
     likely to have a Material Adverse Effect on the Company or the Acquiror or
     is likely to delay or impede the ability of either the Acquiror or the
     Company to consummate the transactions contemplated by this Agreement or to
     fulfill their respective obligations set forth herein.

          (c) The Acquiror Companies and the Company agree to cooperate and use
     all reasonable efforts vigorously to contest and resist any action,
     including legislative, 

                                     -39-
<PAGE>
 
     administrative or judicial action, and to have vacated, lifted, reversed or
     overturned any Order (whether temporary, preliminary or permanent) of any
     Court or Governmental Authority that is in effect and that restricts,
     prevents or prohibits the consummation of the Merger or any other
     transactions contemplated by this Plan, including the vigorous pursuit of
     all available avenues of administrative and judicial appeal and all
     available legislative action. Each of the Acquiror Companies and the
     Company also agree to take any and all actions, including the disposition
     of assets or the withdrawal from doing business in particular
     jurisdictions, required by any Court or Governmental Authority as a
     condition to the granting of any Authorization or Order necessary for the
     consummation of the Merger or as may be required to avoid, lift, vacate or
     reverse any legislative or judicial action which would otherwise cause any
     condition to the Closing not to be satisfied; provided, however, that in no
     event shall either party take, or be required to take, any action that
     could reasonably be expected to have an Material Adverse Effect on the
     Company or the Acquiror.

          (d) (i)    Each of the Company and Acquiror shall give (or shall cause
          their respective Subsidiaries to give) any notices to third Persons,
          and use, and cause their respective Subsidiaries to use, all
          reasonable efforts to obtain any consents from third Persons (A)
          necessary, proper or advisable to consummate the transactions
          contemplated by this Plan, (B) otherwise required under any contracts,
          licenses, leases or other agreements in connection with the
          consummation of the transactions contemplated hereby or (C) required
          to prevent a Material Adverse Effect on the Company from occurring
          prior to or after the Effective Time or a Material Adverse Effect on
          the Acquiror from occurring after the Effective Time.

              (ii)   If any party shall fail to obtain any consent from a third
          Person described in subsection (d)(i) above, such party shall use all
          reasonable efforts, and shall take any such actions reasonably
          requested by the other parties, to limit the adverse effect upon the
          Company and Acquiror, their respective Subsidiaries, and their
          respective businesses resulting, or which could reasonably be expected
          to result after the Effective Time, from the failure to obtain such
          consent.

      SECTION 7.04  Affiliates; Pooling; Tax Treatment.
                    ---------------------------------- 

          (a) The Company shall use all reasonable efforts to obtain from any
     Person who may be deemed to have become an Affiliate of the Company after
     the date of this Plan and on or prior to the Effective Time a written
     agreement substantially in the form of Annex B hereto as soon as
     practicable after attaining such status.
 
          (b) The Acquiror Companies shall not be required to maintain the
     effectiveness of the Registration Statement for the purpose of resale by
     shareholders of the Company who may be Affiliates of the Company pursuant
     to Rule 145 under the Securities Act.

                                     -40-
<PAGE>
 
          (c) Each party hereto shall use all reasonable efforts to cause the
     Merger to be treated for financial accounting purposes as a Pooling
     Transaction, and shall not take, and shall use all reasonable efforts to
     prevent any Affiliate of such party from taking, any actions which could
     prevent the Merger from being treated for financial accounting purposes as
     a Pooling Transaction.

          (d) Each party hereto shall use all reasonable efforts to cause the
     Merger to qualify, and shall not take, and shall use all reasonable efforts
     to prevent any Affiliate of such party from taking, any actions which could
     prevent the Merger from qualifying, as a reorganization under the
     provisions of Section 368(a) of the Code.

      SECTION 7.05  Public Announcements.  The Acquiror and the Company shall
                    --------------------                                     
consult with each other before issuing any press release or otherwise making any
public statements with respect to the Merger and shall not issue any such press
release or make any such public statement prior to such consultation.

      SECTION 7.06  NYSE Listing.  The Acquiror shall use all reasonable efforts
                    ------------                                                
to cause the shares of Acquiror Common Stock to be issued in the Merger to be
approved for listing (subject to official notice of issuance) on the NYSE prior
to the Effective Time.
 
      SECTION 7.07  Comfort Letters.
                    --------------- 

          (a) The Company shall use all reasonable efforts to cause Coopers &
     Lybrand LLP, the Company's independent accountants, to deliver a letter
     dated as of the date of the Company Proxy Statement, and addressed to the
     Company and the Acquiror, in form and substance reasonably satisfactory to
     Acquiror and customary in scope and substance for agreed upon procedures
     letters delivered by independent public accountants in connection with
     registration statements and proxy statements similar to the Registration
     Statement and the Company Proxy Statement.

          (b) The Acquiror shall use all reasonable efforts to cause Arthur
     Andersen LLP, the Acquiror's independent accountants, to deliver a letter
     dated as of the date of the Prospectus/Proxy Statement, and addressed to
     the Acquiror and the Company, in form and substance reasonably satisfactory
     to the Company and customary in scope and substance for agreed upon
     procedures letters delivered by independent public accounts in connection
     with registration statements and proxy statements similar to the
     Registration Statement and the Prospectus/Proxy Statement.

       SECTION 7.08 Assumption of Obligations to Issue Stock and Obligations of
                    -----------------------------------------------------------
                    Employee Benefit Plans.
                    ---------------------- 

          (a) At the Effective Time, automatically and without any action on the
     part of the holder thereof, each outstanding Company Stock Option shall be
     assumed by the Surviving Corporation and shall become an option to purchase
     that number of shares of 

                                     -41-
<PAGE>
 
     Acquiror Common Stock obtained by multiplying the number of shares of
     Company Common Stock issuable upon the exercise of such option by the
     Common Stock Exchange Ratio at an exercise price per share equal to the per
     share exercise price of such option divided by the Common Stock Exchange
     Ratio and otherwise upon the same terms and conditions as such outstanding
     option to purchase Company Common Stock; provided, however, that in the
     case of any option to which Section 421 of the Internal Revenue Code
     applies by reason of the qualifications under Section 422 or 423 of such
     Code, the exercise price, the number of shares purchasable pursuant to such
     option and the terms and conditions of exercise of such option shall be
     determined in a manner that complies with Section 424(a) of the Code.

          (b) On or prior to the Effective Time, the Company shall take or cause
     to be taken all such actions, reasonably satisfactory to the Acquiror, as
     may be necessary or desirable in order to authorize the transactions
     contemplated by subsection (a) of this Section.

          (c) The Acquiror shall take all corporate actions necessary to reserve
     for issuance a sufficient number of shares of Acquiror Common Stock for
     delivery upon exercise of the Company Stock Options assumed by the
     Surviving Corporation pursuant to Section 7.08(a) above.

          (d) As promptly as practicable after the Effective Time, the Acquiror
     shall file one or more Registration Statements on Form S-8 (or any
     successor or other appropriate forms) with respect to the shares of
     Acquiror Common Stock subject to the Company Stock Options and shall use
     its reasonable efforts to maintain the effectiveness of such registration
     statement or registration statements (and maintain the current status of
     the prospectus or prospectuses contained therein) for so long as such
     options remain outstanding and to comply with applicable state securities
     and blue sky laws.

          (e) Except as provided herein or as otherwise agreed to by the
     parties, each of the Company Option Plans providing for the issuance or
     grant of Company Stock Options shall be assumed as of the Effective Time by
     the Surviving Corporation with such amendments thereto as may be required
     to reflect the Merger.

          (f) Provided that the Acquiror shall not be obligated with respect to
     any action taken by the Company or its Subsidiaries with respect to the
     Employee Benefit Plans of the Company or its Subsidiaries in violation of
     the provisions of Section 6.02(a), the Acquiror hereby agrees to guarantee
     and to cause the Surviving Corporation and each Subsidiary of the Surviving
     Corporation to honor and perform all obligations of the Surviving
     Corporation and each Subsidiary of the Surviving Corporation under all
     Benefit Plans of the Company and such Subsidiaries listed on Section
     4.13(a) of the Company's Disclosure Letter and all employment contracts of
     the Company listed on Section 4.10 of the Company's Disclosure Letter.

                                     -42-
<PAGE>
 
      SECTION 7.09  Operations of Company.  Section 7.09 of the Acquiror
                    ----------------------                              
Disclosure Letter sets forth the intentions of the Acquiror with respect to the
method of operating the business of the Company and its Subsidiaries from and
after the Effective Time and with respect to the continuation by the Company and
its Subsidiaries of the employment of their respective employees. Such matters
are the intentions of the Acquiror as of the date of the Plan, are subject to
change in the discretion of the Acquiror and shall not be construed to create
any third party rights in any Person other than the parties to this Agreement.

      SECTION 7.10  Indemnification of Directors and Officers.
                    ----------------------------------------- 

          (a) Until six years from the Effective Time, the articles of
     incorporation and bylaws of the Surviving Corporation as in effect
     immediately after the Effective Time shall not be amended to reduce or
     limit the rights of indemnity afforded to the present and former directors
     and officers of the Company thereunder or to reduce or limit the ability of
     the Company to indemnify such persons or to hinder, delay or make more
     difficult the exercise of such rights of indemnity or the ability to
     indemnify.  The Surviving Corporation will at all times exercise the powers
     granted to it by its articles of incorporation, its bylaws and applicable
     law to indemnify to the fullest extent possible the present and former
     directors, officers, employees and agents of the Company against claims
     made against them arising from their service in such capacities prior to
     the Effective Time.
 
          (b) If any claim or claims shall, subsequent to the Effective Time and
     within six years thereafter, be made against any present or former
     director, officer, employee or agent of the Company based on or arising out
     of the services of such Person prior to the Effective Time in the capacity
     of such Person as a director, officer, employee or agent of the Company,
     the provisions of subsection (a) of this Section respecting the articles of
     incorporation and bylaws of the Surviving Corporation shall continue in
     effect until the final disposition of all such claims.

          (c) The Acquiror hereby agrees after the Effective Time to guarantee
     the payment of the Surviving Corporation's indemnification obligations
     described in Section 7.10(a) up to an amount determined as of the Effective
     Time equal to (i) the fair market value of any assets of the Surviving
     Corporation or any of its Subsidiaries distributed to the Acquiror or any
     of its Subsidiaries (other than the Surviving Corporation and its
     Subsidiaries), minus (ii) any liabilities of the Surviving Corporation or
     any of its Subsidiaries assumed by the Acquiror or any of its Subsidiaries
     (other than the Surviving Corporation and its Subsidiaries), minus (iii)
     the fair market value of any assets of the Acquiror or any of its
     Subsidiaries (other than the Surviving Corporation and its Subsidiaries)
     contributed to the Surviving Corporation or any of its Subsidiaries and
     (iv) plus any liabilities of the Acquiror or any of its Subsidiaries (other
     than the Surviving Corporation and its Subsidiaries) assumed by the
     Surviving Corporation or any of its Subsidiaries.

                                     -43-
<PAGE>
 
          (d) Notwithstanding subsections (a), (b) and (c) of this Section 7.10,
     the Acquiror and the Surviving Corporation shall be released from the
     obligations imposed by such subsection if the Acquiror shall assume the
     obligations of the Surviving Corporation thereunder by operation of Law or
     otherwise.  Notwithstanding anything to the contrary in this Section 7.10,
     neither the Acquiror nor the Surviving Corporation shall be liable for any
     settlement effected without its written consent, which shall not be
     unreasonably withheld.

          (e) The Acquiror shall cause to be maintained in effect until six
     years from the Effective Time the current policies of directors' and
     officers' liability insurance maintained by the Company (or substitute
     policies providing at least the same coverage and limits and containing
     terms and conditions that are not materially less advantageous) with
     respect to claims arising from facts or events which occurred before the
     Effective Time; provided, however, that in no event shall the Acquiror or
     the Surviving Corporation be required to expend more than 200 percent of
     the current annual premiums paid by the Company for such insurance.

          (f) The provisions of this Section 7.10 are intended to be for the
     benefit of, and shall be enforceable by, each Person entitled to
     indemnification hereunder and the heirs and representatives of such Person.

      SECTION 7.11  Newco. Prior to the Effective Time, Newco shall not conduct
                    ------                                                     
any business or make any investments other than as specifically contemplated by
this Plan and will not have any assets (other than the minimum amount of cash
required to be paid to Newco for the valid issuance of its stock to the
Acquiror).

      SECTION 7.12  Event Notices.  From and after the date of this Agreement
                    -------------                                            
until the Effective Time, each party hereto shall promptly notify the other
party hereto of (i) the occurrence or nonoccurrence of any event the occurrence
or nonoccurrence of which would be likely to cause any condition to the
obligations of such party to effect the Merger and the other transactions
contemplated by this Agreement not to be satisfied and (ii) the failure of such
party to comply with any covenant or  agreement to be complied with by it
pursuant to this Agreement which would be likely to result in any condition to
the obligations of such party to effect the Merger and the other transactions
contemplated by this Agreement not to be satisfied.  No delivery of any notice
pursuant to this Section 7.12 shall cure any breach of any representation or
warranty of such party contained in this Agreement or otherwise limit or affect
the remedies available hereunder to the party receiving such notice.

                                     -44-
<PAGE>
 
                                  ARTICLE VII

                              CLOSING CONDITIONS

      SECTION 8.01  Conditions to Obligations of Each Party Under This Plan.
                    -------------------------------------------------------  
The respective obligations of each party to effect the Merger and the other
transactions contemplated hereby shall be subject to the satisfaction at or
prior to the Effective Time of the following conditions, any or all of which may
be waived by the parties hereto, in whole or in part, to the extent permitted by
applicable Law:

          (a) Effectiveness of the Registration Statement.  The Registration
              -------------------------------------------                   
     Statement shall have been declared effective by the Commission under the
     Securities Act.  No stop order suspending the effectiveness of the
     Registration Statement shall have been issued by the Commission and no
     proceedings for that purpose shall have been initiated by the Commission.

          (b) Shareholder Approval.  This Plan shall have been approved and
              --------------------                                         
     adopted by the requisite votes of the shareholders of the Company.

          (c) No Order.  No Court or Governmental Authority shall have enacted,
              --------                                                         
     issued, promulgated, enforced or entered any Law, Regulation or Order
     (whether temporary, preliminary or permanent) that is in effect and has the
     effect of making the Merger illegal or otherwise prohibiting consummation
     of the Merger.

          (d) HSR Act.  The applicable waiting period under the HSR Act shall
              -------                                                        
     have expired or been terminated.

          (e) Pooling of Interests.  The Acquiror and the Company shall have
              --------------------                                          
     been advised in writing by Arthur Andersen LLP on the date upon which the
     Effective Time is to occur that, in reliance in part on the concurrent
     opinion of Coopers & Lybrand LLP that the Company is a "poolable entity",
     the Merger should for financial accounting purposes be treated as a Pooling
     Transaction.

          (f) Dissenters' Rights.  The holders of record of no more than 7% of
              ------------------                                              
     the outstanding Company Common Stock shall, immediately prior to the
     Closing, have perfected and continued to perfect statutory dissenters'
     rights under Subchapter D of the PBCL.

      SECTION 8.02  Additional Conditions to Obligations of the Acquiror
                    ----------------------------------------------------
Companies.  The obligations of the Acquiror Companies to effect the Merger and
- ---------                                                                     
the other transactions contemplated hereby shall be subject to the satisfaction
at or prior to the Effective Time of the following conditions, any or all of
which may be waived by the Acquiror Companies, in whole or in part, to the
extent permitted by applicable Law:

                                     -45-
<PAGE>
 
          (a) Representations and Warranties.  Each of the representations and
              ------------------------------                                  
     warranties of the Company contained in this Plan shall be true and correct
     as of the date of this Plan and as of the Effective Time as though made
     again on and as of the Effective Time except to the extent that any
     misrepresentations and breaches of warranty at the Closing shall not in the
     aggregate be Material to the Company.  The Acquiror Companies shall have
     received a certificate of the President and the Chief Financial Officer of
     the Company, dated the date of the Effective Time, to such effect.

          (b) Agreements and Covenants.  The Company shall have performed or
              ------------------------                                      
     complied in all material respects with all agreements and covenants
     required by this Plan to be performed or complied with by it on or prior to
     the Effective Time.  The Acquiror Companies shall have received a
     certificate of the President and the Chief Financial Officer of the
     Company, dated the date of the Effective Time, to such effect.

          (c) Tax Opinion.  The Acquiror shall have received the opinion dated
              ------------                                                    
     on or prior to the effective date of the Registration Statement of Vinson &
     Elkins L.L.P. to the effect that (i) the Merger will constitute a
     reorganization under section 368(a) of the Code, (ii) the Acquiror, the
     Company and Newco will each be a party to that reorganization, and (iii) no
     gain or loss will be recognized by the Acquiror, the Company or Newco by
     reason of the Merger.

      SECTION 8.03  Additional Conditions to Obligations of the Company.  The
                    ---------------------------------------------------      
obligations of the Company to effect the Merger and the other transactions
contemplated hereby shall be subject to the satisfaction at or prior to the
Effective Time of the following conditions, any or all of which may be waived by
the Company, in whole or in part, to the extent permitted by applicable Law.

          (a) Representations and Warranties.  Each of the representations and
              ------------------------------                                  
     warranties of the Acquiror Companies contained in this Plan shall be true
     and correct as of the date of this Plan and as of the Effective Time as
     though made again on and as of the Effective Time except to the extent that
     any misrepresentations and breaches of warranty at the Closing shall not in
     the aggregate be Material to the Acquiror. The Company shall have received
     a certificate of the Chairman of the Board, the President or any Vice
     President and the Chief Financial Officer of each of the Acquiror
     Companies, dated the date of the Effective Time, to such effect.

          (b) Agreements and Covenants.  The Acquiror Companies shall have
              ------------------------                                    
     performed or complied in all material respects with all agreements and
     covenants required by this Plan to be performed or complied with by them on
     or prior to the Effective Time.  The Company shall have received a
     certificate of the Chairman of  the Board, the President or any Vice
     President and the Chief Financial Officer of each of the Acquiror
     Companies, dated the date of the Effective Time, to such effect.

                                     -46-
<PAGE>
 
          (c) Tax Opinion.  The Company shall have received the opinion dated on
              -----------                                                       
     or prior to the effective date of the Registration Statement of Drinker
     Biddle & Reath LLP to the effect that (i) the Merger will constitute a
     reorganization under section 368(a) of the Code, (ii) the Acquiror, the
     Company and Newco will each be a party to that reorganization, and (iii) no
     gain or loss will be recognized by the shareholders of the Company upon the
     receipt of shares of Acquiror Common Stock in exchange for shares of
     Company Common Stock pursuant to the Merger except with respect to any cash
     received in lieu of fractional share interests.

          (d) Investment Banker's Opinion.  The Company shall have received, on
              ----------------------------                                     
     or prior to the date of mailing of the Company Proxy Statement to the
     holders of Company Common Stock, a written opinion from Schroder Wertheim &
     Co. Incorporated, dated the date of such mailing, confirming the opinion to
     which reference is made in Section 4.21.

                                  ARTICLE IX

                       TERMINATION, AMENDMENT AND WAIVER

      SECTION 9.01  Termination.  This Plan may be terminated at any time prior
                    -----------                                                
to the Effective Time, whether before or after approval of this Plan and the
Merger by the shareholders of the Company:

          (a) by mutual consent of the Acquiror and the Company;

          (b) by the Acquiror, upon a material breach of any representation,
     warranty, covenant or agreement on the part of the Company set forth in
     this Plan, or if any representation or warranty of the Company shall have
     become untrue in any material respect, in either case such that the
     conditions set forth in Section 8.02(a) or Section 8.02(b) would not be
     satisfied (a "Terminating Company Breach"); provided that, if such
     Terminating Company Breach is curable by the Company through the exercise
     of reasonable efforts and for so long as the Company continues to exercise
     such reasonable efforts, the Acquiror may not terminate this Plan under
     this Section 9.01(b);

          (c) by the Company, upon a material breach of any representation,
     warranty, covenant or agreement on the part of the Acquiror Companies set
     forth in this Plan, or if any representation or warranty of the Acquiror
     Companies shall have become untrue in any material respect, in either case
     such that the conditions set forth in Section 8.03(a) or Section 8.03(b)
     would not be satisfied (a "Terminating Acquiror Breach"); provided that, if
     such Terminating Acquiror Breach is curable by the Acquiror Companies
     through the exercise of their reasonable efforts and for so long as the
     Acquiror Companies continue to exercise such reasonable efforts, the
     Company may not terminate this Plan under this Section 9.01(c);

                                     -47-
<PAGE>
 
          (d) by either Acquiror or the Company, if there shall be any Order
     which is final and nonappealable preventing the consummation of the Merger,
     unless the party relying on such Order has not complied with its
     obligations under Section 7.03;

          (e) by either Acquiror or the Company, if the Merger shall not have
     been consummated before December 31, 1997; provided, however, that this
     Plan may be extended by written notice of either Acquiror or the Company to
     a date not later than February 28, 1998, if the Merger shall not have been
     consummated as a result of the Company or the Acquiror Companies having
     failed by December 31, 1997 to receive all required Authorizations and
     Orders with respect to the Merger or as a result of the entering of an
     Order by a Court or Governmental Authority; and provided, further, that,
     prior to February 28, 1998, no party shall be entitled to terminate this
     Plan pursuant to this Section 9.01(e) if such party is in material breach
     of any representation, warranty, covenant or agreement on the part of such
     party set forth in this Plan;

          (f) by either Acquiror or the Company, if this Plan shall fail to
     receive the requisite vote for approval and adoption by the shareholders of
     the Company at the Company Shareholders' Meeting;
 
          (g) by the Acquiror, if

              (i)    any Person (other than the Acquiror or any Affiliate of the
          Acquiror) shall have commenced (as such term is defined in Rule 14d-2
          under the Exchange Act) a tender or exchange offer to purchase any
          shares of Company Common Stock such that, upon consummation of such
          offer, such Person would own or control 35% or more of the then
          outstanding Company Common Stock and the Board of Directors of the
          Company, within 10 Business Days thereafter, either fails to recommend
          against acceptance of such tender or exchange offer by the Company's
          shareholders or takes no position with respect thereto; or

              (ii)   any Person (other than the Acquiror, the Company or any of
          their Subsidiaries) shall, subsequent to the date of this Agreement,
          acquire beneficial ownership (as such term is defined in Rule 13d-3
          under the Exchange Act) or the right to acquire beneficial ownership
          of, or any Group shall have been formed that beneficially owns, or has
          the right to acquire beneficial ownership (as such term is defined in
          Rule 13d-3 under the Exchange Act) of, (A) 35% or more of the then
          outstanding Company Common Stock and the Plan has failed to receive
          the requisite vote at the Company Shareholders' Meeting or (B) 45% or
          more of the then outstanding Company Common Stock.
 
     The right of any party hereto to terminate this Plan pursuant to this
Section 9.01 shall remain operative and in full force and effect regardless of
any investigation made by or on behalf of any party hereto, any Person
controlling any such party or any of their respective officers, directors,
representatives or agents, whether prior to or after the execution of this Plan.

                                     -48-
<PAGE>
 
      SECTION 9.02   Effect of Termination.  Except as provided in Section 9.05
                     ---------------------                                     
of this Plan, in the event of the termination of this Plan pursuant to Section
9.01, this Plan shall forthwith become void, there shall be no liability on the
part of the Acquiror Companies or the Company or any of their respective
officers or directors to the other and all rights and obligations of any party
hereto shall cease, except that nothing herein shall relieve any party from
liability for any misrepresentation or breach of any covenant or agreement under
this Plan.

      SECTION 9.03  Amendment.  This Plan may be amended by the parties hereto
                    ---------                                                 
by action authorized by their respective Boards of Directors at any time prior
to the Effective Time; provided, however, that, after approval of the Plan by
the shareholders of the Company, no amendment may be made which would reduce the
amount or change the type of consideration into which each share of Company
Common Stock shall be converted pursuant to this Plan upon consummation of the
Merger.  This Plan may not be amended except by an instrument in writing signed
by the parties hereto.

      SECTION 9.04  Waiver.  At any time prior to the Effective Time, any party
                    ------                                                     
hereto may (a) extend the time for the performance of any of the obligations or
other acts of the other party hereto, (b) waive any inaccuracies in the
representations and warranties of the other party contained herein or in any
document delivered pursuant hereto and (c) waive compliance by the other party
with any of the agreements or conditions contained herein.  Any such extension
or waiver shall be valid only if set forth in an instrument in writing signed by
the party or parties to be bound thereby. For purposes of this Section 9.04, the
Acquiror Companies shall be deemed to be one party.

      SECTION 9.05  Fees, Expenses and Other Payments.
                    --------------------------------- 

          (a) Except as provided in subsections (b) and (c) of this Section
     9.05, all Expenses incurred by the parties hereto shall be borne solely and
     entirely by the party that incurred such Expenses; provided, however, that
     the allocable share of the Acquiror Companies as a group and the Company
     for all Expenses of printing, filing and mailing the Registration Statement
     and the Company Proxy Statement and all Commission and other regulatory
     filing fees incurred in connection with the Registration Statement and  the
     Company Proxy Statement shall be one-half each; and provided, further that
     Acquiror may, at its option, pay any Expenses of the Company.
 
              (b)    (i)  The Company agrees that, if  the Acquiror shall
          terminate this Plan pursuant to Section 9.01(g)(i) or 9.01(g)(ii),
          then in each such case the Company shall pay to the Acquiror $ 9
          million.

              (ii)   The Company agrees that, if (A) Acquiror shall terminate
          this Plan pursuant to Section 9.01(b) and such termination is the
          result of an intentional or willful breach by the Company of any
          agreement, covenant, representation or warranty herein and (B) either
          (1) within 12 months after such termination of this Plan the Company
          shall have entered into a definitive agreement with respect to 

                                     -49-
<PAGE>
 
          a Competing Transaction with any Person or Group, other than Acquiror,
          its Subsidiaries or Affiliates, to which the Company shall have
          furnished information or with which the Company shall have had any
          contacts or entered into any discussions or negotiations relating to a
          Competing Transaction at any time during the period commencing 12
          months prior to the date of this Plan through the date of termination
          of this Plan or (2) within 12 months after such termination of this
          Plan, any Person or Group to which the Company shall have furnished
          such information or with which it shall have had such contacts,
          discussions or negotiations shall have acquired beneficial ownership,
          by tender offer or exchange offer or otherwise, of 35% or more of the
          outstanding Company Common Stock and, in either case, the
          consideration received or to be received by the shareholders of the
          Company participating in such transaction shall be higher on a per
          share basis than the consideration payable to the shareholders of the
          Company under this Plan on a per share basis or such transaction shall
          be on more favorable terms to the shareholders of the Company than the
          Merger, then in such case the Company shall pay to Acquiror $9
          million.

              (iii)  For purposes of subsection (b)(ii) of this Section 9.05,
          the value of the consideration received or to be received by the
          Company's shareholders shall be determined as of the date of the
          agreement or the transaction therein referenced, the value of the
          consideration payable to such shareholders under this Plan shall be
          determined as of the date of termination of this Plan and the
          consideration per share received or to be received by the shareholders
          of the Company in any transaction other than the Merger shall be
          equitably adjusted to give effect to any stock dividend, stock split
          or stock combination effected subsequent to the date of this Plan.

          (c) Any payment required to be made pursuant to Section 9.05(b) of
     this Plan shall be made to the Acquiror not later than two Business Days
     after delivery to the Company of notice of demand for payment, and shall be
     made by wire transfer of immediately available funds to an account
     designated by the Acquiror in the notice of demand for payment delivered
     pursuant to this Section 9.05(c).

                                   ARTICLE X

                              GENERAL PROVISIONS

      SECTION 10.01 Effectiveness of Representations, Warranties and Agreements.
                    ----------------------------------------------------------- 

          (a) Except as set forth in Section 10.01(b) of this Plan, the
     representations, warranties and agreements of each party hereto shall
     remain operative and in full force and effect regardless of any
     investigation made by or on behalf of any other party hereto, any Person
     controlling any such party or any of their officers, directors,
     representatives or agents whether prior to or after the execution of this
     Plan.

                                     -50-
<PAGE>
 
          (b) The representations and warranties in this Plan shall terminate at
     the Effective Time.

      SECTION 10.02 Notices.  All notices and other communications given or made
                    -------                                                     
pursuant hereto shall be in writing and shall be deemed to have been duly given
upon receipt, if delivered personally, mailed by registered or certified mail
(postage prepaid, return receipt requested) to the parties at the following
addresses or sent by electronic transmission to the telecopier number specified
below:

          (a) If to any of the Acquiror Companies, to:

              Halliburton Company
              3600 Lincoln Plaza
              500 North Akard
              Dallas, Texas 75201-3391
              Attention:     Lester L. Coleman
                             Executive Vice President and General Counsel
              Telecopier No.:  (214) 978-2658

              with a copy to:

              Vinson & Elkins L.L.P.
              First City Tower
              1001 Fannin
              Houston, Texas  77002-6760
              Attention:  William E. Joor III
              Telecopier No.:  (713) 758-2346

          (b) If to the Company, to:

              NUMAR Corporation
              508 Lapp Road
              Malvern, Pennsylvania 19355
              Attention:     Edward P. Delson
                             Senior Vice President and Chief Financial Officer
              Telecopier No.: (610) 644-8131

                                     -51-
<PAGE>
 
              with a copy to:

              Drinker Biddle & Reath LLP
              1000 Westlakes Drive
              Suite 300
              Berwyn, Pennsylvania 19312
              Attention:  Walter Mostek, Jr.
              Telecopier No.:  610/993-8585

or to such other address or telecopier number as any party may, from time to
time, designate in a written notice given in a like manner.  Notice given by
telecopier shall be deemed delivered on the day the sender receives telecopier
confirmation that such notice was received at the telecopier number of the
addressee.  Notice given by mail as set out above shall be deemed delivered
three days after the date the same is postmarked.

      SECTION 10.03 Headings.  The headings contained in this Plan are for
                    --------                                              
reference purposes only and shall not affect in any way the meaning or
interpretation of this Plan.

      SECTION 10.04 Severability.  If any term or other provision of this Plan
                    ------------                                              
is invalid, illegal or incapable of being enforced by any rule of law or public
policy, all other conditions and provisions of this Plan shall nevertheless
remain in full force and effect so long as the economic or legal substance of
the transactions contemplated hereby is not affected in any manner materially
adverse to any party.  Upon such determination that any term or other provision
is invalid, illegal or incapable of being enforced, the parties hereto shall
negotiate in good faith to modify this Plan so as to effect the original intent
of the parties as closely as possible in an acceptable manner to the end that
transactions contemplated hereby are fulfilled to the extent possible.

      SECTION 10.05 Entire Agreement.  This Plan (together with the Annexes, the
                    ----------------                                            
Company's Disclosure Letter and the Acquiror's Disclosure Letter) constitutes
the entire agreement of the parties, and, except for the Confidentiality
Agreement which shall remain in full force and effect, supersedes all prior
agreements and undertakings, both written and oral, among the parties, with
respect to the subject matter hereof.

      SECTION 10.06 Assignment.  This Plan shall not be assigned by operation of
                    ----------                                                  
Law or otherwise.

      SECTION 10.07 Parties in Interest.  This Plan shall be binding upon and
                    -------------------                                      
inure solely to the benefit of each party hereto, and nothing in this Plan,
express or implied, other than Section 7.10 which is intended also to benefit
the directors and officers of the Company therein referenced, is intended to or
shall confer upon any other Person any right, benefit or remedy of any nature
whatsoever under or by reason of this Plan.

                                     -52-
<PAGE>
 
      SECTION 10.08 Failure or Indulgence Not Waiver;  Remedies Cumulative.  No
                    ------------------------------------------------------     
failure or delay on the part of any party hereto in the exercise of any right
hereunder shall impair such right or be construed to be a waiver of, or
acquiescence in, any breach of any representation, warranty or agreement herein,
nor shall any single or partial exercise of any such right preclude other or
further exercise thereof or of any other right.  All rights and remedies
existing under this Plan are cumulative to, and not exclusive to, and not
exclusive of, any rights or remedies otherwise available.

      SECTION 10.09 Governing Law.  This Plan shall be governed by, and
                    -------------                                      
construed in accordance with, the Laws of the State of Texas, regardless of the
Laws that might otherwise govern under applicable principles of conflicts of
law; provided, however, that any matter involving the internal corporate affairs
of the Company shall be governed by the provisions of the PBCL and that any
matter involving the internal corporate affairs of the Acquiror or Newco shall
be governed by the provisions of the DGCL.

      SECTION 10.10 Specific Performance.  The parties hereby acknowledge and
                    ---------------------                                    
agree that the failure of any party to this Plan to perform its agreements and
covenants hereunder, including its failure to take all actions as are necessary
on its part to the consummation of the Merger, will cause irreparable injury to
the other parties to this Plan for which damages, even if available, will not be
an adequate remedy.  Accordingly, each of the parties hereto hereby consents to
the granting of equitable relief (including specific performance and injunctive
relief) by any court of competent jurisdiction to enforce any party's
obligations hereunder. The parties further agree to waive any requirement for
the securing or posting of any bond in connection with the obtaining of any such
equitable relief and that this Section is without prejudice to any other rights
that the parties hereto may have for any failure to perform this Plan.

      SECTION 10.11 Counterparts.  This Plan may be executed in multiple
                    ------------                                        
counterparts, and by the different parties hereto in separate counterparts, each
of which when executed shall be deemed to be an original but all of which taken
together shall constitute one and the same agreement.

                                     -53-
<PAGE>
 
     IN WITNESS WHEREOF, each of the parties hereto has caused this Plan to be
executed as of the date first written above by their respective officers
thereunto duly authorized.

                                        HALLIBURTON COMPANY



                                        By:_____________________________________
                                        Name:
                                        Title:


                                        HALLIBURTON M. S. CORP.



                                        By:_____________________________________
                                        Name:
                                        Title:


                                        NUMAR CORPORATION



                                        By:_____________________________________
                                        Name:
                                        Title:

                                     -54-
<PAGE>
 
                                                                         ANNEX A


                           SCHEDULE OF DEFINED TERMS

     The following terms when used in the Plan shall have the meanings set forth
below unless the context shall otherwise require:

     "Acquiror" shall mean Halliburton Company, a Delaware corporation, and its
successors from time to time.

     "Acquiror Common Stock" shall mean the common stock, par value $2.50 per
share, of the Acquiror.

     "Acquiror Companies" shall have the meaning ascribed to such term in the
first paragraph of this Plan.

     "Acquiror Representatives" shall have the meaning ascribed to such term in
Section 6.04.

     "Acquiror Restricted Stock" shall mean Acquiror Common Stock issued in
restricted stock awards pursuant to the Halliburton Company 1993 Stock and Long-
Term Incentive Plan or the Halliburton Company Restricted Stock Plan for Non-
Employee Directors and subject to the restrictions provided therein.

     "Acquiror Stock Options" shall mean stock options granted pursuant to the
Acquiror Stock Plans.

     "Acquiror Stock Plans" shall mean the Halliburton Company 1993 Stock and
Long-Term Incentive Plan and the Halliburton Company Restricted Stock Plan for
Non-Employee Directors and the Landmark Graphics Corporation 1984 Incentive
Stock Option Plan, the Landmark Graphics Corporation 1985 Incentive Stock Option
Plan, the Landmark Graphics Corporation 1987 Nonqualified Stock Option Plan, the
Landmark Graphics Corporation 1989 Flexible Stock Option Plan, the Landmark
Graphics Corporation Directors' Stock Option Plan, the Landmark Graphics
Corporation Consultants' Stock Option Plan, the Landmark Graphics Corporation
1990 Employee Stock Option Plan and the Landmark Graphics Corporation 1994
Flexible Incentive Plan.

     "Acquiror's Audited Consolidated Financial Statements" shall mean the
consolidated balance sheets of the Acquiror and its Subsidiaries as of December
31, 1995 and December 31, 1996 and the related consolidated statements of
operations and cash flows for the fiscal years ended December 31, 1994, 1995 and
1996, together with the notes thereto, all as audited by Arthur Andersen LLP,
independent accountants, under their report with respect thereto dated January
22, 1997 and included in the Acquiror's Annual Report on Form 10-K for the year
ended December 31, 1996 filed with the Commission.

                                      A-1
<PAGE>
 
     "Acquiror's Consolidated Balance Sheet" shall mean the consolidated balance
sheet of the Acquiror as of December 31, 1996 included in the Acquiror's Audited
Consolidated Financial Statements.

     "Acquiror's Consolidated Financial Statements" shall mean the Acquiror's
Audited Consolidated Financial Statements and the Acquiror's Unaudited
Consolidated Financial Statements.

     "Acquiror's Disclosure Letter" shall mean a letter of even date herewith
delivered by the Acquiror to the Company with the execution of the Plan, which,
among other things, shall identify exceptions to the Acquiror's representations
and warranties contained in Article V by specific section and subsection
references.
 
     "Acquiror's Rights Agreement" shall mean the Restated Rights Agreement
dated December 1, 1996 between Halliburton Company and ChaseMellon Shareholder
Services, L.L.C., as Rights Agent.

     "Acquiror's Unaudited Consolidated Financial Statements" shall mean the
unaudited consolidated balance sheet of the Acquiror and its Subsidiaries as of
March 31, 1997 and the related consolidated statements of operations and cash
flows for the fiscal quarters ended March 31, 1996 and March 31, 1997, together
with the notes thereto, included in the Acquiror's Quarterly Report on Form 10-Q
for the quarter ended March 31, 1997 filed with the Commission.
 
     "Affiliate" shall, with respect to any Person, mean any other Person that
controls, is controlled by or is under common control with the former.

     "Articles of Merger" shall have the meaning ascribed to such term in
Section 1926 of the PBCL.

     "Authorization" shall mean any and all permits, licenses, authorizations,
orders, certificates, registrations or other approvals granted by any
Governmental Authority.

     "Benefit Plans" shall mean, with respect to a specified Person,  any
employee pension benefit plan (whether or not insured), as defined in Section
3(2) of ERISA, any employee welfare benefit plan (whether or not insured) as
defined in Section 3(1) of ERISA, any plans that would be employee pension
benefit plans or employee welfare benefit plans if they were subject to ERISA,
such as foreign plans and plans for directors, any stock bonus, stock ownership,
stock option, stock purchase, stock appreciation rights, phantom stock or other
stock plan (whether qualified or nonqualified), and any bonus or incentive
compensation plan sponsored, maintained, or contributed to by the specified
Person or any of its Subsidiaries for the benefit of any of the present or
former directors, officers, employees, agents, consultants or other similar
representatives providing services to or for the specified Person or any of its
Subsidiaries in connection with such services or any such plans which have been
so sponsored, maintained, or 

                                      A-2
<PAGE>
 
contributed to within six years prior to the date of this Plan; provided,
however, that such term shall not include (a) routine employment policies and
procedures developed and applied in the ordinary course of business and
consistent with past practice, including wage, vacation, holiday and sick or
other leave policies, (b) workers compensation insurance and (c) directors and
officers liability insurance.
 
     "Business Day" means any day other than a day on which banks in the State
of Texas or the Commonwealth of Pennsylvania are authorized or obligated to be
closed;
 
     "Certificate of Merger" shall have the meaning ascribed to such term in
Section 252 of the DGCL.
 
     "Closing" shall mean a meeting, which shall be held in accordance with
Section 3.03, of representatives of the parties to the Plan at which, among
other things, all documents deemed necessary by the parties to the Plan to
evidence the fulfillment or waiver of all conditions precedent to the
consummation of the transactions contemplated by the Plan are executed and
delivered.

     "Closing Date" shall mean the date of the Closing as determined pursuant to
Section 3.03.
 
     "Code" shall mean the Internal Revenue Code of 1986, as amended, and the
rules and regulations promulgated thereunder.

     "Common Stock Exchange Ratio" shall mean the ratio of conversion of Company
Common Stock into Acquiror Common Stock pursuant to the Merger as provided in
Section 3.01(a).

     "Company" shall mean NUMAR Corporation, a Pennsylvania corporation, and its
successors from time to time.

     "Company Common Stock" shall mean the common shares, par value $0.01 per
share, of the Company.

     "Company Option Plans" shall mean the Company's 1994 Stock Incentive Plan,
1995 Employee Stock Purchase Plan and the individual stock option agreements
with the individuals named in Section 4.03(b) of the Company's Disclosure
Letter.

     "Company Proxy Statement" shall have the meaning ascribed to such term in
Section 7.02(a).

     "Company Representatives" shall have the meaning ascribed to such term in
Section 6.03.
 
                                      A-3
<PAGE>
 
     "Company Stock Options" shall mean stock options granted pursuant to the
Company Option Plans.

     "Company Shareholders' Meeting" shall have the meaning ascribed to such
term in Section 7.01.

     "Company Warrants" shall mean those certain warrants to purchase 37,879
shares of Company Common Stock pursuant to the Warrant Agreement between the
Company and MMC/GATX Partnership No. I dated August 16, 1991, as amended by
Amendments Nos. 1, 2 and 3 thereto.

     "Company's Consolidated Balance Sheet" shall mean the consolidated balance
sheet of the Company as of December 31, 1996 included in the Company's Audited
Consolidated Financial Statements.

     "Company's Disclosure Letter" shall mean a letter of even date herewith
delivered by the Company to the Acquiror Companies concurrently with the
execution of the Plan, which, among other things, shall identify exceptions to
the Company's representations and warranties contained in Article IV by specific
section and subsection references.

     "Company's Audited Consolidated Financial Statements" shall mean the
consolidated balance sheets of the Company and its Subsidiaries as of December
31, 1995 and December 31, 1996 and the related consolidated and combined
statements of operations and cash flows for the fiscal years ended December 31,
1994, 1995 and 1996, together with the notes thereto, all as audited by Coopers
& Lybrand LLP, independent accountants, under their report with respect thereto
dated March 4,1997 and included in the Company's Annual Report on Form 10-K for
the year ended December 31, 1996 filed with the Commission.

     "Company's Consolidated Financial Statements" shall mean the Company's
Audited Consolidated Financial Statements and the Company's Unaudited
Consolidated Financial Statements.

     "Company's Unaudited Consolidated Financial Statements" shall mean the
unaudited consolidated balance sheet of the Company and its Subsidiaries as of
March 31, 1997 and the related consolidated statements of operations and cash
flows for the three months periods ended March 31, 1996 and March 31, 1997,
together with the notes thereto, included in the Company's Quarterly Report on
Form 10-Q for the quarter ended March 31, 1997 filed with the Commission.

     "Competing Transaction" shall mean (a) a merger, consolidation, share
exchange, business combination or similar transaction involving the Company or
any of its Significant Subsidiaries; (b) a sale, lease, exchange, transfer or
other disposition of 35% or more of the assets of the Company and its
Subsidiaries, taken as a whole, in a single transaction or series of
transactions; or (c) the acquisition (in the case of a Group, through the
formation of such 

                                      A-4
<PAGE>
 
Group or otherwise) by a Person or Group of beneficial ownership (as such term
is defined in Rule 13d-3 under the Exchange Act) or the right to acquire
beneficial ownership of 35% or more of the outstanding Company Common Stock,
whether by tender offer or exchange offer or otherwise or (d) the acquisition in
any manner, directly or indirectly, of a Material equity interest in any voting
securities of, or a substantial portion of the assets of, the Company or any of
its Significant Subsidiaries, other than the transactions contemplated by this
Plan.
 
     "Confidentiality Agreement" shall mean that certain confidentiality
agreement between the Acquiror and the Company dated May 27, 1997.

     "Constituent Corporations" shall mean the Company and Newco.

     "control" (including the terms "controlled," "controlled by" and "under
common control with") means the possession, directly or indirectly or as trustee
or executor, of the power to direct or cause the direction of the management or
policies of a Person, whether through the ownership of stock or as trustee or
executor, by contract or credit arrangement or otherwise.

     "Court" shall mean any court or arbitration tribunal of the United States,
any foreign country or any domestic or foreign state, and any political
subdivision thereof, and shall include the European Court of Justice.

     "Current Benefit Plans" shall mean Benefit Plans that are sponsored,
maintained, or contributed to by a specified Person or any of its Subsidiaries
as of the date of this Plan.
 
     "DGCL" shall mean the General Corporation Law of the State of Delaware.

     "Dissenters' Shares" shall have the meaning ascribed to such term in
Section 3.01(e).

     "Effective Time" shall mean the date and time of the completion of the
filing of the Articles of Merger with the Secretary of State of the Commonwealth
of Pennsylvania in accordance with Section 2.02.

     "Environmental Law or Laws" shall mean any and all laws, statutes,
ordinances, rules, regulations, or orders of any Governmental Authority
pertaining to health or the environment currently in effect and applicable to a
specified Person and its Subsidiaries, including the Clean Air Act, as amended,
the Comprehensive Environmental, Response, Compensation, and Liability Act of
1980 ("CERCLA"), as amended, the Federal Water Pollution Control Act, as
amended, the Occupational Safety and Health Act of 1970, as amended, the
Resource Conservation and Recovery Act of 1976 ("RCRA"), as amended, the Safe
Drinking Water Act, as amended, the Toxic Substances Control Act, as amended,
the Hazardous & Solid Waste Amendments Act of 1984, as amended, the Superfund
Amendments and Reauthorization Act of 1986, as amended, the Hazardous Materials
Transportation Act, as amended, the Oil Pollution Act of 1990, as amended
("OPA"),  any state or local Laws implementing the foregoing federal Laws, and
all other environmental conservation or protection Laws.  For purposes of the
Plan, the terms 

                                      A-5
<PAGE>
 
"hazardous substance" and "release" have the meanings specified in CERCLA;
provided, however, that, to the extent the Laws of the state or locality in
which the property is located establish a meaning for "hazardous substance" or
"release" that is broader than that specified in either CERCLA, such broader
meaning shall apply, and the term "hazardous substance" shall include all
dehydration and treating wastes, waste (or spilled) oil, and waste (or spilled)
petroleum products, and (to the extent in excess of background levels)
radioactive material, even if such are specifically exempt from classification
as hazardous substances pursuant to CERCLA or RCRA or the analogous statutes of
any jurisdiction applicable to the specified Person or its Subsidiaries or any
of their respective properties or assets.

     "ERISA" shall mean the Employee Retirement Income Security Act of 1974, as
amended, and the Regulations promulgated thereunder.
 
     "Exchange Act" shall mean the Securities Exchange Act of 1934, as amended,
and the Regulations promulgated thereunder.

     "Exchange Agent" shall mean ChaseMellon Shareholder Services, L.L.C.

     "Exchange Fund" shall mean the fund of Acquiror Common Stock, cash in lieu
of fractional share interests and dividends and distributions, if any, with
respect to such shares of Acquiror Common Stock established at the Exchange
Agent pursuant to Section 3.02(a).

     "Expenses" shall mean all reasonable out-of-pocket expenses (including all
fees and expenses of counsel, accountants, investment bankers, experts and
consultants to a party hereto and its Affiliates) incurred by a party or on its
behalf in connection with or related to the authorization, preparation,
negotiation, execution and performance of this Plan, the preparation, printing,
filing and mailing of the Registration Statement and the Company Proxy
Statement, the solicitation of stockholder approvals and all other matters
related to the consummation of the transactions contemplated hereby.
 
     "GAAP" shall mean accounting principles generally accepted in the United
States as in effect from time to time consistently applied by a specified
Person.
 
     "Governmental Authority" shall mean any governmental agency or authority
(other than a Court) of the United States, any foreign country, or any domestic
or foreign state, and any political subdivision thereof, and shall include any
multinational authority having governmental or quasi-governmental powers.
 
     "Group" shall have the meaning accorded to such term as it is defined under
Section 13(d) of the Exchange Act and the Regulations promulgated thereunder.

     "HSR Act" shall mean the Hart-Scott-Rodino Antitrust Improvements Act of
1976, as amended, and the rules and regulations promulgated thereunder.

                                     A-6 
<PAGE>
 
     "IRS" shall mean the Internal Revenue Service.

     "Knowledge" shall mean, with respect to either the Company or the Acquiror,
the actual knowledge of any executive officer of such party.

     "Law" shall mean all laws, statutes, ordinances, rules and regulations of
the United States, any foreign country, or any domestic or foreign state, and
any political subdivision or agency thereof, including all decisions of Courts
having the effect of law in each such jurisdiction.
 
     "Lien" shall mean any mortgage, pledge, security interest, adverse claim,
encumbrance, lien or charge of any kind (including any agreement to give any of
the foregoing), any conditional sale or other title retention agreement, any
lease in the nature thereof or the filing of or agreement to give any financing
statement under the Laws of any jurisdiction.
 
     "Material" shall mean material to the condition (financial and other),
results of operations, business or prospects of a specified Person and its
Subsidiaries, if any, taken as a whole; provided, however, that, as used in this
definition the word "material" shall have the meaning accorded thereto pursuant
to Section 11 of the Securities Act.

     "Material Adverse Effect" shall mean any change or effect that would be
material and adverse to the consolidated business, condition (financial or
otherwise), operations, performance or properties of a specified Person and its
Subsidiaries, if any, taken as a whole; provided, however, that, as used in this
definition the word "material" shall have the meaning accorded thereto pursuant
to Section 11 of the Securities Act.

     "Material Contract" shall mean each contract, lease, indenture, agreement,
arrangement or understanding to which a specified Person or any of its
Subsidiaries is a party or to which any of the assets or operations of such
specified Person or any of its Subsidiaries is subject that is of a type that
would be required to be included as an exhibit to a registration statement on
Form S-1 pursuant, in the case of the Company, to Paragraph (2), (4) or (10) of
Item 601(b) and, in the case of the Acquiror, to Paragraph (10) (other than
clause (iii) thereof) of Item 601(b) of Regulation S-K under the Securities Act
if such a registration statement were to be filed by such Person under the
Securities Act on the date of determination.  Notwithstanding the foregoing,
such term shall, in the case of the Company, include any of  the following
contracts, agreements or commitments, whether oral or written:
 
          (1) Any collective bargaining agreement or other agreement with any
     labor union;

          (2) any agreement, contract or commitment with any other Person, other
     than any agency or representation entered in the ordinary course of
     business, containing any 

                                      A-7
<PAGE>
 
     covenant limiting the freedom of such specified Person or any of its
     Subsidiaries to engage in any line of business or to compete with any other
     Person;

          (3) any partnership, joint venture or profit sharing agreement with
     any Person, which partnership, joint venture or profit sharing agreement
     generated revenues during its most recently completed fiscal year of
     $100,000 or more;

          (4) any employment or consulting agreement, contract or commitment
     between the Company or any of its Subsidiaries and any employee, officer or
     director thereof (i) having more than one year to run from the date hereof,
     (ii) providing for an obligation to pay or accrue compensation of $100,000
     or more per annum or (iii) providing for the payment or accrual of any
     additional compensation upon a change in control of such Person or any of
     its Subsidiaries or upon any termination of such employment or consulting
     relationship following a change in control of such Person or any of its
     Subsidiaries;

          (5) any agency or representation agreement with any Person that is not
     terminable by the Company or one of its Subsidiaries without penalty upon
     not more than one year's notice; and

          (6) any confidentiality agreement, development agreement or license
     agreement relating to the products of the Company or any of its
     Subsidiaries.

     "Merger" shall mean the merger of Newco with an into the Company as
provided in Article II of this Plan.

     "NASD" shall mean the National Association of Securities Dealers, Inc.

     "Newco" shall mean Halliburton M.S. Corp., a Delaware corporation and a
wholly owned Subsidiary of the Acquiror.

     "NYSE" shall mean the New York Stock Exchange, Inc.

     "Order" shall mean any judgment, order or decree of any Court or
Governmental Authority, federal, foreign, state or local.

     "PBCL" shall mean the Business Corporation Law of the Commonwealth of
Pennsylvania.

     "PBGC" shall mean the Pension Benefit Guaranty Corporation.
 
     "Permitted Encumbrances" shall mean the following:

                                      A-8
<PAGE>
 
          (1) liens for taxes, assessments and other governmental charges not
     delinquent or which are currently being contested  in good faith by
     appropriate proceedings; provided that, in the latter case, the specified
     Person or one of its Subsidiaries shall have set aside on its books
     adequate reserves with respect thereto;

          (2) mechanics' and materialmen's liens not filed of record and similar
     charges not delinquent or which are filed of record but are being contested
     in good faith by appropriate proceedings; provided that, in the latter
     case, the specified Person or one of its Subsidiaries shall have set aside
     on its books adequate reserves with respect thereto;

          (3) liens in respect of judgments or awards with respect to which the
     specified Person or one of its Subsidiaries shall in good faith currently
     be prosecuting an appeal or other proceeding for review and with respect to
     which such Person or such Subsidiary shall have secured a stay of execution
     pending such appeal or such proceeding for review; provided that such
     Person or such Subsidiary shall have set aside on its books adequate
     reserves with respect thereto;

          (4) easements, leases, reservations or other rights of others in, or
     minor defects and irregularities in title to, property or assets of a
     specified Person or any of its Subsidiaries; provided that such easements,
     leases, reservations, rights, defects or irregularities do not materially
     impair the use of such property or assets for the purposes for which they
     are held; and

          (5) any lien or privilege vested in any lessor, licensor or permittor
     for rent or other obligations of a specified Person or any of its
     Subsidiaries thereunder so long as the payment of such rent or the
     performance of such obligations is not delinquent.

     "Person" shall mean an individual, partnership, limited liability company,
corporation, joint stock company, trust, estate, joint venture, association or
unincorporated organization, or any other form of business or professional
entity, but shall not include a Court or Governmental Authority.

     "Plan" shall mean the Agreement and Plan of Merger made and entered into as
of June 9, 1997 among Acquiror, Newco and the Company, including any amendments
thereto and each Annex (including this Annex A) and schedule thereto (including
the Acquiror's Disclosure Letter and the Company's Disclosure Letter).

     "Pooling Transaction" shall mean a business combination that is treated for
financial accounting purposes as a "pooling of interests" in accordance with
GAAP and the Regulations of the Commission.

     "Prospectus/Proxy Statement" shall have the meaning ascribed to such term
in Section 7.02(a).

     "Registration Statement" shall have the meaning ascribed to such term in
Section 7.02(a).

                                      A-9
<PAGE>
 
     "Regulation" shall mean any rule or regulation of any Governmental
Authority having the effect of Law or of any rule or regulation of any self-
regulatory organization, such as the NYSE or the NASD.

     "Reports" shall mean, with respect to a specified Person, all reports,
registrations, filings and other documents and instruments required to be filed
by the specified Person or any of its Subsidiaries with any Governmental
Authority (other than the Commission).

     "Representatives" shall mean, collectively, the Company's Representatives
and the Acquiror's Representatives.

     "SEC Reports" shall mean  (1) all Annual Reports on Form 10-K, (2) all
Quarterly Reports on Form 10-Q, (3) all proxy statements relating to meetings of
shareholders (whether annual or special), (4) all Current Reports on Form 8-K
and (5) all other reports, schedules, registration statements or other documents
required to be filed during a specified period by a specified Person with the
Commission pursuant to the Securities Act or the Exchange Act.
 
     "Securities Act" shall mean the Securities Act of 1933, as amended, and the
rules and regulations promulgated thereunder.
 
     "Significant Subsidiary" means any Subsidiary of the Company or Acquiror,
as the case may be, that constitutes a significant subsidiary of such party as
such term is defined in Rule 1-02 of Regulation S-X of the Commission.

     "Stock Option Agreement" shall mean that certain Stock Option Agreement of
even date herewith between the Acquiror and the Company.

     A "Subsidiary" of a specified Person shall be any corporation, partnership,
limited liability company, joint venture or other legal entity of which the
specified Person (either alone or through or together with any other subsidiary)
owns, directly or indirectly, 50% or more of the stock or other equity or
partnership interests the holders of which are generally entitled to vote for
the election of the board of directors or other governing body of such
corporation or other legal entity or of which the specified Person controls the
management.
 
     "Surviving Corporation" shall mean the Company as the corporation surviving
the Merger.
 
     "Tax Returns" shall have the meaning ascribed to such term in Section
4.14(a) of the Plan.

     "Taxes" shall mean all taxes, charges, imposts, tariffs, fees, levies or
other similar assessments or liabilities, including income taxes, ad valorem
taxes, excise taxes, withholding taxes, stamp taxes or other taxes of or with
respect to gross receipts, premiums, real property, personal property, windfall
profits, sales, use, transfers, licensing, employment, payroll and franchises
imposed by or under any Law; and such terms shall include any interest, fines,

                                     A-10
<PAGE>
 
penalties, assessments or additions to tax resulting from, attributable to or
incurred in connection with any such tax or any contest or dispute thereof.

     "Terminated Benefit Plans" shall mean Benefit Plans that were sponsored,
maintained, or contributed to by a specified Person or any of its Subsidiaries
within six years prior to the date of this Plan but which have been terminated
prior to the date of this Plan.

     "Terminating Acquiror Breach" shall have the meaning ascribed to such term
in Section 9.01(c).

     "Terminating Company Breach" shall have the meaning ascribed to such term
in Section 9.01(b).

     "Voting Agreement" shall mean one of those several Voting Agreements of
even date herewith between the Acquiror and certain shareholders of the Company.
 
                                     A-11
<PAGE>
 
                                                                         ANNEX B

                          NUMAR AFFILIATE'S AGREEMENT


Halliburton Company
3600 Lincoln Plaza
500 N. Akard Street
Dallas, Texas  75201-3391

Ladies and Gentlemen:

     The undersigned has been advised that, as of the date hereof, the
undersigned may be deemed to be an "affiliate" of NUMAR Corporation, a
Pennsylvania corporation (the "Company"), as that term is defined in the
Regulations of the Commission under the Securities Act.

     Pursuant to the terms and subject to the conditions of that certain
Agreement and Plan of Merger by and among Halliburton Company, a Delaware
corporation (the "Acquiror"), Halliburton M.S. Corp., a newly formed Delaware
corporation and a wholly owned subsidiary of the Acquiror ("Newco"), and the
Company to be dated as of June 9, 1997 (the "Plan") providing, among other
things, for the merger of Newco with and into the Company (the "Merger"), the
undersigned will be entitled to receive shares of Acquiror Common Stock in
exchange for shares of Company Common Stock owned by the undersigned at the
Effective Time of the Merger as determined pursuant to the Plan.  Capitalized
terms used but not defined herein are defined in Annex A to the Plan and are
used herein with the same meanings as ascribed to them therein.
 
     The undersigned understands that the Merger will be treated for financial
accounting purposes as a "pooling of interests" in accordance with GAAP and that
the staff of the Commission has issued certain guidelines that should be
followed to ensure the application of pooling of interests accounting to the
transaction.
 
     In consideration of the agreements contained herein, the Acquiror's
reliance on this letter in connection with the consummation of the Merger and
for other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, the undersigned hereby represents, warrants and agrees
that the undersigned will not make any sale, transfer or other disposition of
(i) Company Common Stock during the period from the date hereof until the
earlier of the Effective Time and the termination of the Plan (which period, if
the Merger is consummated, will be greater than 30 days), (ii) Acquiror Common
Stock received by the undersigned pursuant to the Merger or otherwise owned by
the undersigned until such time as financial statements that include at least 30
days of combined operations of the Company and the Acquiror after the Merger
shall have been publicly reported, unless the undersigned shall have delivered
to the Acquiror prior to any such sale, transfer or other disposition, a written

                                      B-1
<PAGE>
 
opinion from Arthur Andersen LLP, independent public accountants for the
Acquiror, or a written no-action letter from the accounting staff of the
Commission, in either case in form and substance reasonably satisfactory to the
Acquiror, to the effect that such sale, transfer or other disposition will not
cause the Merger to not to be treated as a "pooling of interests" for financial
accounting purposes in accordance with GAAP and the Regulations of the
Commission or (iii) Acquiror Common Stock received by the undersigned pursuant
to the Merger in violation of the Securities Act or the Regulations thereunder.
The undersigned has been advised that the offering, sale and delivery of the
shares of Acquiror Common Stock pursuant to the Merger will have been registered
with the Commission under the Securities Act on a Registration Statement on Form
S-4.  The undersigned has also been advised, however, that, since the
undersigned may be deemed to be an affiliate of the Company at the time the
Merger is submitted for a vote of the shareholders of the Company, the Acquiror
Common Stock received by the undersigned pursuant to the Merger can be sold by
the undersigned only (i) pursuant to an effective registration statement under
the Securities Act, (ii) in conformity with the volume and other limitations of
Rule 145 promulgated by the Commission under the Securities Act or (iii) in
reliance upon an exemption from registration that is available under the
Securities Act.

     The undersigned also understands that instructions will be given to the
transfer agent for the Acquiror Common Stock with respect to the Acquiror Common
Stock to be received by the undersigned pursuant to the Merger and that there
will be placed on the certificates representing such shares of Acquiror Common
Stock, or any substitutions therefor, a legend stating in substance as follows:

     "These shares were issued in a transaction to which Rule 145 promulgated
     under the Securities Act of 1933, as amended, applies.  These shares may
     only be transferred in accordance with the terms of such Rule and an
     Affiliate's Agreement between the original holder of such shares and
     Halliburton Company, a copy of which agreement is on file at the principal
     offices of Halliburton Company."

     It is understood and agreed that the legend set forth above shall be
removed upon surrender of certificates bearing such legend by delivery of
substitute certificates without such legend if (i) the undersigned shall have
delivered to the Acquiror an opinion of counsel, in form and substance
reasonably satisfactory to the Acquiror, to the effect that (A) the sale or
other disposition of the shares represented by the surrendered certificates may
be effected without registration of the offering, sale and delivery of such
shares under the Securities Act and (B) the shares to be so transferred may be
publicly offered, sold and delivered by the transferee thereof without
compliance with the registration provisions of the Securities Act and (ii) the
other restrictions set forth herein are no longer applicable.

     By its execution hereof, the Acquiror agrees that it will, as long as the
undersigned owns any Acquiror Common Stock to be received by the undersigned
pursuant to the Merger, take all reasonable efforts to make timely filings with
the Commission of all reports required to be filed by it pursuant to the
Exchange Act and will promptly furnish upon written request of the undersigned a
written statement confirming that such reports have been so timely filed.

                                      B-2
<PAGE>
 
     If you are in agreement with the foregoing, please so indicate by signing
below and returning a copy of this letter to the undersigned, at which time this
letter shall become a binding agreement between us.

                                    Very truly yours,


                                    By:___________________________________
                                    Name:
                                    Title:
                                    Date:
                                    Address:
ACCEPTED this ___ day
of June, 1997

Halliburton Company


By:_______________________________
Name:
Title:

                                      B-3
<PAGE>
 
                                                                         ANNEX C

                       HALLIBURTON AFFILIATE'S AGREEMENT


Halliburton Company
3600 Lincoln Plaza
500 N. Akard Street
Dallas, Texas  75201-3391
 
Ladies and Gentlemen:

     The undersigned has been advised that, as of the date hereof, the
undersigned may be deemed to be an "affiliate" of Halliburton Company, a
Delaware corporation (the "Acquiror"), as that term is defined in the
Regulations of the Commission under the Securities Act.

     The undertakings contained in this Affiliate's Agreement are being given by
the undersigned in connection with that certain Agreement and Plan of Merger by
and among the Acquiror, Halliburton M.S. Corp., a newly formed Delaware
corporation and a wholly owned subsidiary of the Acquiror ("Newco"), and NUMAR
Corporation, a Pennsylvania corporation (the "Company"),to be dated as of June
9, 1997 (the "Plan"), providing, among other things, for the merger of Newco
with and into the Company (the "Merger").  Capitalized terms used but not
defined herein are defined in Annex A to the Plan and are used herein with the
same meanings as ascribed to them therein.
 
     The undersigned understands that the Merger will be treated for financial
accounting purposes as a "pooling of interests" in accordance with GAAP and that
the staff of the Commission has issued certain guidelines that should be
followed to ensure the application of pooling of interests accounting to the
transaction.
 
     In consideration of the agreements contained herein, the Acquiror's
reliance on this letter in connection with the consummation of the Merger and
for other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, the undersigned hereby represents, warrants and agrees
that the undersigned will not make any sale, transfer or other disposition of
(i) Company Common Stock during the period from the date hereof until the
earlier of the Effective Time and the termination of the Plan (which period, if
the Merger is consummated, will be greater than 30 days) or (ii) Acquiror Common
Stock owned by the undersigned until such time as financial statements that
include at least 30 days of combined operations of the Company and the Acquiror
after the Merger shall have been publicly reported, unless the undersigned shall
have delivered to the Acquiror prior to any such sale, transfer or other
disposition, a written opinion from Arthur Andersen LLP, independent public
accountants for the Acquiror, or a written no-action letter from the accounting
staff of the Commission, in either case in form and substance reasonably
satisfactory to the Acquiror, to the effect that such sale, transfer or other
disposition will not cause the Merger to not to be treated as a "pooling 

                                      C-1
<PAGE>
 
of interests" for financial accounting purposes in accordance with GAAP and the
Regulations of the Commission.
 
     If you are in agreement with the foregoing, please so indicate by signing
below and returning a copy of this letter to the undersigned, at which time this
letter shall become a binding agreement between us.

                                    Very truly yours,



                                    By:  ____________________________
                                    Name:
                                    Title:
                                    Date:
                                    Address:
ACCEPTED this ___ day
of June, 1997

Halliburton Company


By:  _______________________________
     Name:
     Title:

                                      C-2

<PAGE>
 
                                                                     EXHIBIT 2.B


                            STOCK OPTION AGREEMENT

     STOCK OPTION AGREEMENT (the "Agreement"), dated as of June 9, 1997, by and 
between NUMAR Corporation, a Pennsylvania corporation (the "Company"), and 
Halliburton Company, a Delaware corporation (the "Grantee").

                                   RECITALS

     The Grantee, the Company and Halliburton M.S. Corp., a Delaware corporation
and a wholly owned subsidiary of the Grantee ("Newco") propose to enter into an 
Agreement and Plan of Merger dated as of the date hereof (the "Plan") providing,
among other things, for the merger (the "Merger") of Newco with and into the 
Company which shall be the surviving corporation.

     The Board of Directors of the Company has recommended the approval of the 
Plan by the stockholders of the Company.

     As a condition and inducement to the Grantee's willingness to enter into 
the Plan, the Grantee has requested that the Company agree, and the Company has 
agreed, to grant the Grantee the Option (as defined below).

     NOW, THEREFORE, in consideration of the foregoing and the respective 
representations, warranties, covenants and agreements set forth herein and in 
the Plan, the Company and the Grantee agree as follows:

     1.   Capitalized Terms.  Capitalized terms used but not defined herein are 
defined in the Plan and are used herein with the same meanings as ascribed to
them therein; provided, however, that, as used in this Agreement, "Person" shall
have the meaning specified in Sections 3(a)(9) and 13(d)(3) of the Exchange Act.

     2.   Grant of Option.  Subject to the terms and conditions set forth 
herein, the Company hereby grants to the Grantee an irrevocable option (the 
"Option") to purchase, out of the authorized but unissued Company Common Stock, 
a number of shares equal to up to 15.0% of the shares of Company Common Stock 
outstanding as of the date hereof (as adjusted as set forth herein) (the "Option
Shares"), at a purchase price of $36.00 per Option Share (the "Exercise Price").

     3.   Term.  The Option shall be exercisable and shall remain in full force 
and effect until the earliest to occur of (i) the Effective Time, (ii) the first
anniversary of the receipt by Grantee of written notice from the Company of the 
occurrence of an Exercise Event (as hereinafter defined) or (iii) termination of
the Plan prior to the occurrence of an Exercise Event (the "Option Term"). The
<PAGE>
 
rights and obligations set forth in Sections 7, 8, 9 and 10 shall not terminate 
at the expiration of the Option Term, but shall extend to such time as is 
provided in those Sections.

     4.   Exercise of Option.

          (a)  The Grantee may exercise the Option, in whole or in part, at any 
     time and from time to time during the Option Term following the occurrence
     of an Exercise Event. Notwithstanding the expiration of the Option Term,
     the Grantee shall be entitled to purchase those Option Shares with respect
     to which it has exercised the Option in accordance with the terms hereof
     prior to the expiration of the Option Term.

          (b)  As used herein, an "Exercise Event" shall mean any of the 
     following events:

               (i)    any Person (other than the Grantee or any Affiliate of the
          Grantee) shall have commenced (as such term is defined in Rule 14d-2
          under the Exchange Act) a tender or exchange offer to purchase any
          shares of Company Common Stock such that, upon consummation of such
          offer, such Person would own or control 35% or more of the then
          outstanding Company Common Stock and the Board of Directors of the
          Company, within ten Business Days thereafter, either fails to
          recommend against acceptance of such tender or exchange offer by the
          Company's shareholders or takes no position with respect thereto; or

               (ii)   any Person (other than the Grantee, the Company or any of 
          their Subsidiaries) shall, subsequent to the date of this Agreement,
          acquire beneficial ownership (as such term is defined in Rule 13d-3
          under the Exchange Act) or the right to acquire beneficial
          ownership of, or any Group shall have been formed that beneficially
          owns, or has the right to acquire beneficial ownership (as such term
          is defined in Rule 13d-3 under the Exchange Act) of, (A) 35% or more
          of the then outstanding Company Common Stock and the Plan has failed
          to receive the requisite vote at the Company Shareholders' Meeting or
          (B) 45% or more of the then outstanding Company Common Stock.

          (c)  If the Grantee wishes to exercise the Option, it shall send a 
     written notice (the date of which being herein referred to as the "Notice
     Date") to the Company specifying (i) the total number of Option Shares it
     intends to purchase pursuant to such exercise and (ii) a place and a date
     not earlier than three Business Days not later than 15 Business Days from
     the Notice Date for the closing of such purchase (the "Closing Date");
     provided, however, that, if the closing of the purchase and sale pursuant
     to the Option (the "Closing") cannot be consummated by reason of any
     applicable Law, Regulation or Order, the period of time that otherwise
     would run pursuant to this sentence shall run instead from the date on
     which such restriction on consummation has expired or been terminated; and,
     provided, further, that, without limiting the foregoing, if prior
     notification to, or Authorization of, any Governmental Authority is
     required in connection with such purchase, the Grantee and, if applicable,
     the Company shall promptly file the required notice or application for

                            Stock Option Agreement
                                      -2-

<PAGE>
 
     Authorization and shall expeditiously process the same (and the Company 
     shall cooperate with the Grantee in the filing of any such notice or
     application and the obtaining of any such Authorization), and the period of
     time that otherwise would run pursuant to this sentence shall run instead
     from the date on which, as the case may be, (i) any required notification
     period has expired or been terminated or (ii) such Authorization has been
     obtained and, in either event, any requisite waiting period has passed.

          (d)  Notwithstanding Section 4(c), in no event shall any Closing Date 
     be more than 12 months after the related Notice Date, and, if the Closing
     Date shall not have occurred within 12 months after the related Notice Date
     due to the failure to obtain any required Authorization of a Governmental
     Authority, the exercise of the Option effected on the Notice Date shall be
     deemed to have expired. If (i) the Grantee receives official notice that an
     Authorization of any Governmental Authority required for the purchase of
     Option Shares will not be issued or granted or (ii) a Closing Date shall
     not have occurred within 12 months after the related Notice Date due to the
     failure to obtain any such required Authorization of a Governmental
     Authority, the Grantee shall be entitled to exercise its right as set forth
     in Section 7 or to exercise the Option in connection with the resale of the
     Company Common Stock or other securities pursuant to a registration
     statement as provided in Section 9. The provisions of this Section 4 and
     Section 5 shall apply with appropriate adjustments to any such exercise in
     connection with such a resale.

     5.   Payment and Delivery of Certificates.

          (a)  On each Closing Date, the Grantee shall pay to the Company in 
     immediately available funds by wire transfer to a bank account designated
     by the Company an amount equal to the Exercise Price multiplied by the
     Option Shares to be purchased on such Closing Date.

          (b)  At each Closing, simultaneously with the delivery of immediately 
     available funds as provided in Section 5(a), the Company shall deliver to
     the Grantee a certificate or certificates representing the Option Shares to
     be purchased at such Closing, which Option Shares shall be duly authorized,
     validly issued, fully paid and nonassessable and free and clear of all
     Liens, and Grantee shall deliver to the Company its written agreement that
     the Grantee will not offer to sell or otherwise dispose of such Option
     Shares in violation of applicable Law or the provisions of this Agreement.

          (c)  Certificates for the Option Shares delivered at each Closing 
     shall be endorsed with a restrictive legend that shall read substantially
     as follows:

               THE TRANSFER OF THE STOCK REPRESENTED BY THIS CERTIFICATE IS
               SUBJECT TO RESTRICTIONS ARISING UNDER THE SECURITIES ACT OF
               1933, AS AMENDED, AND PURSUANT TO THE TERMS OF A STOCK
               OPTION AGREEMENT DATED AS OF JUNE 9, 1997. A COPY OF SUCH

                            Stock Option Agreement
                                      -3-
<PAGE>
 
               AGREEMENT WILL BE PROVIDED TO THE HOLDER HEREOF WITHOUT
               CHARGE UPON RECEIPT BY THE COMPANY OF A WRITTEN REQUEST
               THEREFOR.

     A new certificate or certificates evidencing the same number of shares of
     the Company Common Stock will be issued to the Grantee in lieu of the
     certificate bearing the above legend, and such new certificate shall not
     bear such legend, insofar as it applies to the Securities Act, if the
     Grantee shall have delivered to the Company a copy of a letter from the
     staff of the Commission, or an opinion of counsel in form and substance
     reasonably satisfactory to the Company and its counsel, to the effect that
     such legend is not required for purposes of the Securities Act. 

     6.   Adjustment Upon Changes in Capitalization, Etc.

          (a)  In the event of any change in the Company Common Stock by reason 
     of a stock dividend, split-up, combination, recapitalization, exchange of
     shares or similar transaction, the type and number of shares or securities
     subject to the Option, and the Exercise Price therefor, shall be adjusted
     appropriately, and proper provision shall be made in the agreements
     governing such transaction, so that the Grantee shall receive upon exercise
     of the Option the same class and number of outstanding shares or other
     securities or property that Grantee would have received in respect of the
     Company Common Stock if the Option had been exercised immediately prior to
     such event, or the record date therefor, as applicable. If any additional
     shares of Company Common Stock are issued after the date of this Agreement
     (other than pursuant to an event described in the first sentence of this
     Section 6(a)), the number of shares of Company Common Stock then remaining
     subject to the Option shall be adjusted so that, after such issuance of
     additional shares, such number of shares then remaining subject to the
     Option, together with shares theretofore issued pursuant to the Option,
     equals 15.0% of the number of shares of the Company Common Stock then
     issued and outstanding shares of Company Common Stock; provided, however,
     that the number of shares of the Company Common Stock subject to the Option
     shall only be increased to the extent the Company then has available
     authorized but unissued and unreserved shares of the Company Common Stock.

          (b)  If the Company shall enter into an agreement (i) to consolidate, 
     exchange shares or merge with any Person, other than the Grantee or one of
     its subsidiaries, and, in the case of a merger, shall not be the continuing
     or surviving corporation, (ii) to permit any Person, other than the Grantee
     or one of its Subsidiaries, to merge into the Company and the Company shall
     be the continuing or surviving corporation, but, in connection with such
     merger, the then outstanding shares of Company Common Stock shall be
     changed into or exchanged for stock or other securities of the Company or
     any other Person or cash or any other property, or the shares of Company
     Common stock outstanding immediately before such merger shall after such
     merger represent less than 50% of the common shares and common share
     equivalents of the Company outstanding immediately after the merger or
     (iii) to sell, lease or otherwise transfer all or substantially all of its
     assets to any Person, other

                            Stock Option Agreement
                                      -4-
<PAGE>
 
     than the Grantee or one of its Subsidiaries, then, and in each such case,
     the proper provisions shall be made in the agreement governing such
     transaction so that the Option shall, upon the consummation of any such
     transaction and upon the terms and conditions set forth herein, become
     exercisable for the stock, securities, cash or other property that would
     have been received by the Grantee if the Grantee had exercised this Option
     immediately prior to such transaction or the record date for determining
     stockholders entitled to participate therein, as appropriate.

          (c)  The provisions of Sections 7, 8, 9, 10 and 11 shall apply with 
     appropriate adjustments to any securities for which the Option becomes 
     exercisable pursuant to this Section 6.

     7.   Repurchase at the Option of Grantee,

          (a)  At any time during the Option Term, at the request of the Grantee
     made at any time after the first Repurchase Event (as hereinafter defined)
     and ending on the first anniversary thereof (the "Put Period"), the Company
     (or any successor thereto) shall repurchase from the Grantee (i) that
     portion of the Option that then remains unexercised and (ii) all (but not
     less than all) the shares of Company Common Stock purchased by the Grantee
     pursuant hereto and with respect to which the Grantee then has beneficial
     ownership. The date on which the Grantee exercises its rights under this
     Section 7 is referred to as the "Grantee Request Date." Such repurchase
     shall be at an aggregate price (the "Section 7 Repurchase Consideration")
     equal to the sum of:

               (i)    the aggregate exercise price paid (or, in the case of 
          Option Shares with respect to which the Option has been exercised but
          the Closing Date has not occurred, payable) by the Grantee for any
          Option Shares as to which the Option has theretofore been exercised
          and with respect to which the Grantee then has beneficial ownership:

               (ii)   the excess, if any, of the Applicable Price (as defined 
          below), over the Exercise Price (subject to adjustment pursuant to
          Section 6) paid (or, in the case of Option Shares with respect to
          which the Option has been exercised but the Closing Date has not
          occurred, payable) by the Grantee for each Option Share as to which
          the Option has been exercised and with respect to which the Grantee
          then has beneficial ownership, multiplied by the number of such
          shares; and

               (iii)  the excess, if any, of (x) the Applicable Price for each 
          share of Company Common Stock over (y) the Exercise Price (subject to
          adjustment pursuant to Section 6), multiplied by the number of Option
          Shares as to which the Option has not been exercised.

          (b)  If the Grantee exercises its rights under this Section 7, the
     Company shall, within five Business Days after the Grantee Request Date,
     pay the Section 7 Repurchase

                            Stock Option Agreement
                                      -5-
<PAGE>
 
     Consideration to the Grantee in immediately available funds, and the
     Grantee shall surrender to the Company the Option and the certificates
     evidencing the shares of Company Common Stock purchased thereunder with
     respect to which the Grantee then has beneficial ownership, and the Grantee
     shall warrant to the Company that, immediately prior to the repurchase
     thereof pursuant to this Section 7, the Grantee had sole record and
     beneficial ownership of such shares and that such shares were then held
     free and clear of all Liens.

          (c)  For purposes of this Agreement, the "Applicable Price" means the 
     highest of (i) the highest purchase price per share paid pursuant a tender
     or exchange offer made for shares of Company Common Stock after the date
     hereof and on or prior to the Grantee Request Date, (ii) the price per
     share to be paid by any third Person for shares of Company Common Stock, in
     each case pursuant to an agreement for a merger or other business
     combination transaction with the Company entered into on or prior to the
     Grantee Request Date, or (iii) the highest bid price per share of Company
     Common Stock as quoted on The Nasdaq National Market (or if Company Common
     Stock is not quoted on The Nasdaq National Market, the highest bid price
     per share as quoted on any other market comprising a part of The Nasdaq
     Stock Market or, if the shares of Company Common Stock are not quoted
     thereon, on the principal trading market (as defined in Regulation M under
     the Exchange Act) on which such shares are traded as reported by a
     recognized source), during the 60 Business Days preceding the Grantee
     Request Date. If the consideration to be offered, paid or received pursuant
     to either of the foregoing clauses (i) or (ii) shall be other than in cash,
     the value of such consideration shall be determined in good faith by an
     independent nationally recognized investment banking firm selected by the
     Grantee and reasonably acceptable to the Company, which determination shall
     be conclusive for all purposes of this Agreement.

          (d)  As used herein, a "Repurchase Event" means the occurrence of any 
     Exercise Event.

          (e)  Notwithstanding any provision to the contrary in this Agreement, 
     the Grantee may not exercise its rights pursuant to this Section 7 in a
     manner that would result in the cash payment to the Grantee of an aggregate
     amount under this Section 7 of more than $12 million, including the amount,
     if any, paid to the Grantee pursuant to Section 9.05(b) of the Plan;
     provided, however, that nothing in this sentence shall limit the Grantee's
     ability to exercise the Option in accordance with its terms.

     8.   Repurchase at the Option of the Company.

          (a)  Unless the Grantee shall have previously exercised its rights 
     under Section 7, at the request made by the Company at any time during the
     six-month period commencing at the expiration of the Put Period (the "Call
     Period"), the Company may repurchase from the Grantee, and the Grantee
     shall sell to the Company, all (but not less than all) the shares of
     Company Common Stock acquired by the Grantee pursuant hereto and with
     respect to which the Grantee has beneficial ownership at the time of such
     repurchase at a price per

                            Stock Option Agreement
                                      -6-

<PAGE>
 
share equal to the greater of (A) the Current Market Price (as hereinafter
defined) or (B) the Exercise Price per share in respect of the shares so
acquired (such price per share multiplied by the number of shares of Company
Common Stock to be repurchased pursuant to this Section 8 being herein called
the "Section 8 Repurchase Consideration"). The date on which the Company
exercises its rights under this Section 8 is referred to as the "Company Request
Date." Notwithstanding the first sentence of this Section 8(a), the Grantee,
within 30 days following the Company Request Date, may deliver an Offeror's
Notice pursuant to Section 10, in which case the provisions of Section 10 and
not those of this Section 8 shall control (unless the sale to a third Person
contemplated thereby is not consummated). The Company's rights under this
Section 8 shall be suspended (and the Call Period shall be extended accordingly)
during any period when the exercise of such rights would subject the Grantee to
liability pursuant to Section 16(b) of the Exchange Act by reason of the
issuance of the Option, any adjustment pursuant to Section 6 hereof, the
Grantee's purchase of shares of Company Common Stock hereunder or the Grantee's
sale of shares pursuant to Section 7, 8 or 10.

     (b)  If the Company exercises its rights under this Section 8 and the
Grantee does not deliver an Offeror's Notice or, having delivered an Offeror's
Notice, the Grantee does not sell the shares to a third Person pursuant thereto,
the Company shall, within five Business Days after the expiration of the
Grantee's right to deliver an Offeror's Notice or to sell the shares subject to
an Offeror's Notice to a third Person, pay the Section 8 Repurchase
Consideration in immediately available funds, and the Grantee shall surrender to
the Company certificates evidencing the shares of Company Common Stock purchased
hereunder, and the Grantee shall warrant to the Company that, immediately prior
to the repurchase thereof pursuant to this Section 8, the Grantee had sole
record and beneficial ownership of such shares and that such shares were then
held free and clear of all Liens.

     (c)  As used herein, "Current Market Price" means the average closing sales
price per share of Company Common Stock quoted on The Nasdaq National Market (or
if Company Common Stock is not quoted on The Nasdaq National Market, on any
other market comprising a part of The Nasdaq Stock Market or, if the shares of
Company Common Stock are not quoted thereon, on the principal trading market (as
defined in Regulation M under the Exchange Act) on which such shares are traded
as reported by a recognized source) for the ten Business Days preceding the date
of the Company's request for repurchase pursuant to this Section 8.

9.   Registration Rights.

     (a)  The Company shall, if requested by the Grantee at any time and from
time to time within two years of the first exercise of the Option (the
"Registration Period"), as expeditiously as practicable, prepare, file and cause
to be made effective up to two registration statements under the Securities Act
if such registration is necessary or desirable in order to permit the offering,
sale and delivery of any or all shares of Company Common Stock or other
securities that have been acquired by or are issuable to the Grantee upon

                            Stock Option Agreement
                                      -7-
<PAGE>
 
exercise of the Option in accordance with the intended method of sale or other 
disposition stated by the Grantee, including, at the sole discretion of the 
Company, a "shelf" registration statement under Rule 415 under the Securities 
Act or any successor provision, and the Company shall use all reasonable efforts
to qualify such shares or other securities under any applicable state securities
laws. Without the Grantee's prior written consent, no other securities may be 
included in any such registration. The Company shall use all reasonable efforts 
to cause each such registration statement to become effective, to obtain all 
consents or waivers of other parties that are required therefor and to keep such
registration statement effective for such period not in excess of 180 days from 
the day such registration statement first becomes effective as may be reasonably
necessary to effect such sale or other disposition. The obligations of the 
Company hereunder to file a registration statement and to maintain its 
effectiveness may be suspended for one or more periods of time not exceeding 60 
days in the aggregate if the Board of Directors of the Company shall have 
determined in good faith that the filing of such registration or the maintenance
of its effectiveness would require disclosure of nonpublic information that
would materially and adversely affect the Company. For purposes of determining
whether two requests have been made under this Section 9, only requests relating
to a registration statement that has become effective under the Securities Act
and pursuant to which the Grantee has disposed of all shares covered thereby in
the manner contemplated therein shall be counted.

     (b)  The expenses associated with the preparation and filing of any such 
registration statement pursuant to this Section 9 and any sale covered thereby 
(including any fees related to blue sky qualifications and filing fees in 
respect of the National Association of Securities Dealers, Inc.) ("Registration 
Expenses") shall be for the account of the Company except for underwriting 
discounts or commissions or brokers' fees in respect to shares to be sold by the
Grantee and the fees and disbursements of the Grantee's counsel; provided, 
however, that the Company shall not be required to pay for any Registration 
Expenses with respect to such registration if the registration request is 
subsequently withdrawn at the request of the Grantee unless the Grantee agrees 
to forfeit its right to request one registration; and provided further that, if
at the time of such withdrawal the Grantee has learned of a material adverse 
change in the results of operations, condition (financial or other), business or
prospects of the Company from that known to the Grantee at the time of its 
request and has withdrawn the request with reasonable promptness following 
disclosure by the Company of such material adverse change, then the Grantee 
shall not be required to pay any of such expenses and shall retain all remaining
rights to request registration.

     (c)  The Grantee shall provide all information reasonably requested by the 
Company for inclusion in any registration statement to be filed hereunder. If 
during the Registration Period the Company shall propose to register under the 
Securities Act the offering, sale and delivery of Company Common Stock for cash 
for its own account or for any other stockholder of the Company pursuant to a 
firm underwriting, it shall, in addition to the Company's other obligations 
under this Section 9, allow the Grantee the right to 

                            Stock Option Agreement
                                      -8-

<PAGE>
 
     participate in such registration provided that the Grantee participates in
     the underwriting; provided, however, that, if the managing underwriter of
     such offering advises the Company in writing that in its opinion the number
     of shares of Company Common Stock requested to be included in such
     registration exceeds the number that can be sold in such offering, the
     Company shall, after fully including therein all securities to be sold by
     the Company, include the shares requested to be included therein by Grantee
     pro rata (based on the number of shares intended to be included therein)
     with the shares intended to be included therein by Persons other than the
     Company. In connection with any offering, sale and delivery of Company
     Common Stock pursuant to a registration statement effected pursuant to this
     Section 9, the Company and the Grantee shall provide each other and each
     underwriter of the offering with customary representations, warranties and
     covenants, including covenants of indemnification and contribution.

     10.  First Refusal. At any time after the first occurrence of an Exercise 
Event and prior to the second anniversary of the first purchase of shares of 
Company Common Stock pursuant to the Option, if the Grantee shall desire to 
sell, assign, transfer or otherwise dispose of all or any of the Option Shares 
or other securities acquired by it pursuant to the Option, it shall give the 
Company written notice of the proposed transaction (an "Offeror's Notice"), 
identifying the proposed transferee, accompanied by a copy of a binding offer to
purchase such shares or other securities signed by such transferee and setting 
forth the terms of the proposed transaction. An Offeror's Notice shall be deemed
an offer by the Grantee to the Company, which may be accepted, in whole but not 
in part, within ten Business Days of the receipt of such Offeror's Notice, on 
the same terms and conditions and at the same price at which the Grantee is 
proposing to transfer such shares or other securities to such transferee. The 
purchase of any such shares or other securities by the Company shall be settled 
within ten Business Days of the date of the acceptance of the offer and the 
purchase price shall be paid to the Grantee in immediately available funds. If 
the Company shall fail or refuse to purchase all the shares or other securities 
covered by an Offeror's Notice, the Grantee may, within sixty days from the date
of the Offeror's Notice, sell all, but not less than all, of such shares or 
other securities to the proposed transferee at no less than the price specified
and on terms no more favorable than those set forth in the Offeror's Notice; 
provided, however, that the provisions of this sentence shall not limit the 
rights the Grantee may otherwise have if the Company has accepted the offer 
contained in the Offeror's Notice and wrongfully refuses to purchase the shares 
or other securities subject thereto. The requirements of this Section 10 shall 
not apply to (a) any disposition as a result of which the proposed transferee 
would own beneficially not more than 2% of the outstanding voting power of the 
Company, (b) any disposition of Company Common Stock or other securities by a 
Person to whom the Grantee has assigned its rights under the Option with the 
consent of the Company, (c) any sale by means of a public offering registered 
under the Securities Act or (d) any transfer to a wholly owned Subsidiary of the
Grantee which agrees in writing to be bound by the terms hereof.

     11.  Listing. If the Company Common Stock or any other securities then 
subject to the Option are then listed on The Nasdaq National Market (or if 
Company Common Stock is not quoted on The Nasdaq National Market, on any other 
market comprising a part of The Nasdaq Stock Market or, if the shares of Company
Common Stock are not quoted thereon, on another trading market or

                            Stock Option Agreement
                                      -9-
<PAGE>
 
exchange), the Company, upon the occurrence of an Exercise Event, shall promptly
file an application to list on The Nasdaq National Market, such other market 
comprising a part of The Nasdaq Stock Market or such other trading market or 
exchange, as applicable, the shares of the Company Common Stock or other 
securities then subject to the Option and will use all reasonable efforts to 
cause such listing application to be approved as promptly as practicable.

     12.  Replacement of Agreement. Upon receipt by the Company of evidence 
reasonably satisfactory to it of the loss, theft, destruction or mutilation of 
this Agreement, and (in the case of loss, theft or destruction) or reasonably 
satisfactory indemnification, and upon surrender and cancellation of this 
Agreement, if mutilated, the Company will execute and deliver a new Agreement of
like tenor and date. Any such new Agreement shall constitute an additional 
contractual obligation of the Company, whether or not the Agreement so lost, 
stolen, destroyed or mutilated shall at any time be enforceable by anyone.

     13.  Miscellaneous.

          (a)  Expenses. Except as otherwise provided in the Plan or in Sections
     7,8 or 9 hereof, each of the Parties hereto shall bear and pay all costs
     and expenses incurred by it or on its behalf in connection with the
     transactions contemplated hereunder, including fees and expenses of its own
     financial consultants, investment bankers, accountants and counsel.

          (b)  Waiver and Amendment. Any provision of this Agreement may be
     waived at any time by the party that is entitled to the benefits of such
     provision. This Agreement may not be modified, amended, altered or
     supplemented except upon the execution and delivery of a written agreement
     executed by the parties hereto.

          (c)  Entire Agreement; No Third Party Beneficiary; Severability.
     Except as otherwise set forth in the Plan, this Agreement (including the
     Plan and the other documents and instruments referred to herein and
     therein) (i) constitutes the entire agreement and supersedes all prior
     agreements and understandings, both written and oral, between the parties
     with respect to the subject matter hereof and (ii) is not intended to
     confer upon any Person other than the parties hereto any rights or remedies
     hereunder. If any term, provision, covenant or restriction of this
     Agreement is held by a court of competent jurisdiction to be invalid, void
     or unenforceable, the remainder of the terms, provisions, covenants and
     restrictions of this Agreement shall remain in full force and effect and
     shall in no way be affected, impaired or invalidated.

          (d)  Governing Law. This Agreement shall be governed by, and construed
     in accordance with, the Laws of the State of Texas, regardless of the Laws
     that might otherwise govern under applicable principles of conflicts of
     law; provided, however, that any matter involving the internal corporate
     affairs of any party hereto shall be governed by the provisions of the
     PBCL.

                            Stock Option Agreement
                                     -10-
<PAGE>
 
          (e)  Descriptive Headings. The descriptive headings contained herein
     are for convenience or reference only and shall not affect in any way the
     meaning or interpretation of this Agreement.

          (f)  Notices. All notices and other communications hereunder shall be
     in writing and shall be deemed given if delivered personally, telecopied
     (with confirmation) or mailed by registered or certified mail (return
     receipt requested) to the parties at the following addresses (or at such
     other address for a party as shall be specified by like notice):

          If to the Company to:

          NUMAR Corporation
          508 Lapp Road
          Malvern, Pennsylvania 19355
          Attention:   Edward P. Delson
                       Senior Vice President and Chief Financial Officer
          Telecopier No.: (610) 644-8131

               with a copy to:

               Drinker Biddle & Reath LLP
               1000 Westlakes Drive
               Suite 300
               Berwyn, Pennsylvania 19312
               Attention: Walter Mostek, Jr.
               Telecopier No.: (610) 993-8585

          If to Grantee to:

          Halliburton Company
          3600 Lincoln Plaza
          500 North Akard
          Dallas, Texas 75201-3391
          Attention:    Lester L. Coleman
                        Executive Vice President and General Counsel
          Telecopier No.: (214) 978-2658

                            Stock Option Agreement
                                     -11-
<PAGE>
 
               with a copy to:

               Vinson & Elkins L.L.P.
               2300 First City Tower
               1001 Fannin Street
               Houston, Texas 77002-6760
               Attention: William E. Joor III, Esq.
               Telecopier No.: (713) 615-5282

          (g)  Counterparts. This Agreement and any amendments hereto may be 
executed in two counterparts, each of which shall be considered one and the same
agreement and shall become effective when both counterparts have been signed by 
each of the parties and delivered to the other party, it being understood that 
both parties need not execute the same counterpart.

          (h)  Assignment. Neither this Agreement nor any of the rights, 
interests or obligations hereunder or under the Option shall be assigned by 
either of the parties hereto (whether by operation of law or otherwise) without 
the prior written consent of the other party, except that the Grantee may assign
this Agreement to a wholly owned Subsidiary of the Grantee; provided, however, 
that no such assignment shall have the effect of releasing the Grantee from its 
obligations hereunder. Subject to the preceding sentence, this Agreement shall 
be binding upon, inure to the benefit of and be enforceable by the parties and 
their respective successors and assigns.

          (i)  Further Assurances. In the event of any exercise of the Option by
the Grantee, the Company and the Grantee shall execute and deliver all other 
documents and instruments and take all other action that may be reasonably 
necessary in order to consummate the transactions provided for by such exercise.

          (j)  Specific Performance. The parties hereto hereby acknowledge and 
agree that the failure of any party to this Agreement to perform its agreements 
and covenants hereunder will cause irreparable injury to the other party to this
Agreement for which damages, even if available, will not be an adequate remedy. 
Accordingly, each of the parties hereto hereby consents to the granting of 
equitable relief (including specific performance and injunctive relief) by any 
court of competent jurisdiction to enforce any party's obligations hereunder. 
The parties further agree to waive any requirement for the securing or posting 
of any bond in connection with the obtaining of any such equitable relief and 
that this provision is without prejudice to any other rights that the parties 
hereto may have for any failure to perform this Agreement.

                            Stock Option Agreement
                                     -12-
<PAGE>
 
     IN WITNESS WHEREOF, the Company and the Grantee have caused this Stock 
Option Agreement to be signed by their respective officers thereunto duly 
authorized, all as of the day and year first written above.


                                   NUMAR CORPORATION

                                   By: /s/ Dr. Melvin N. Miller
                                      ---------------------------------
                                Name:  Dr. Melvin N. Miller
                                Title: Chairman of the Board of Directors
                                       Chief Executive Officer and President


                                   HALLIBURTON COMPANY


                                   By: /s/ Lester L. Coleman
                                      ---------------------------------
                                Name:  Lester L. Coleman
                                Title: Executive Vice President and
                                       General Counsel


                            STOCK OPTION AGREEMENT
                                     -13-

<PAGE>
 
                                                                     EXHIBIT 2.C

                               VOTING AGREEMENT


     VOTING AGREEMENT ("Agreement") dated as of June 9, 1997, between
Halliburton Company, a Delaware corporation (the "Acquiror"), and Davis Venture
Partners, L.P. (the "Shareholder"), a holder of common shares, par value $0.01
per share, of NUMAR Corporation, a Pennsylvania corporation (the "Company").

                                   RECITALS:

     The Shareholder beneficially owns an aggregate of 700,486 common shares
(together with any additional common shares as to which beneficial ownership is
acquired by any member of the Shareholder Group described below, the "Company
Shares"), par value $0.01 per share ("Company Common Shares"), of the Company.

     The Acquiror is prepared to enter into an Agreement and Plan of Merger with
the Company (the "Plan") providing for the merger of a wholly owned subsidiary
of Acquiror with and into the Company and the conversion in such merger of each
Company Common Share into the number of shares of the Common Stock, par value
$2.50 per share, of the Acquiror set forth in the Plan (the "Merger").

     To facilitate the Merger, the Shareholder is willing to enter into certain
arrangements with respect to the Company Shares.

     NOW, THEREFORE, in consideration of the premises set forth above, the
mutual promises set forth below, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

1.   Shareholder's Support of the Merger. From the date hereof until December
31, 1997, or, if earlier, termination of the Plan:

          (a) Except as contemplated by the Plan or hereby, neither the
     Shareholder nor any Person controlled by the Shareholder, other than the
     Company and its subsidiaries (collectively, the "Shareholder Group"), will,
     directly or indirectly, sell, transfer, pledge or otherwise dispose of, or
     grant a proxy with respect to, any Company Shares to any Person other than
     any member of the Shareholder Group or the Acquiror or its designee, or
     grant an option with respect to any of the Company Shares or enter into any
     other agreement or arrangement with respect to any of the Company Shares.

          (b) The Shareholder agrees that the Shareholder will vote, and will
     cause each member of the Shareholder Group to vote, all Company Shares
     entitled to vote and beneficially owned by such Persons (i) in favor of the
     Merger and (ii), subject to the provisions of paragraph (c) below, against
     any combination proposal or other matter that may
<PAGE>
 
     (in the reasonable opinion of the Acquiror) interfere or be inconsistent
     with the Merger (including without limitation a Competing Transaction).

          (c) The Shareholder agrees that, if requested by the Acquiror in
     writing in order to facilitate the Merger, the Shareholder will not, and
     will cause each member of the Shareholder Group not to, attend or vote any
     Company Shares beneficially owned by any such Person at any annual or
     special meeting of shareholders or execute any written consent of
     shareholders

          (d) Neither the Shareholder nor any other member of the Shareholder
     Group will initiate, solicit or encourage (including by way of furnishing
     information or assistance), or take any other action to facilitate, any
     inquiries or the making of any proposal that constitutes, or that may
     reasonably be expected to lead to, any merger, consolidation, share
     exchange, business combination or similar transaction involving the Company
     or any of its Significant Subsidiaries, a sale, lease, exchange, transfer
     or other disposition of 50% or more of the assets of the Company and its
     subsidiaries, taken as a whole, in a single transaction or series of
     transactions, the acquisition by a Person or Group of beneficial ownership
     or the right to acquire beneficial ownership of 50% or more of the
     outstanding Company Common Shares, whether by tender offer, exchange offer
     or otherwise, or the acquisition in any manner, directly or indirectly, of
     a material equity interest in any voting securities of, or a substantial
     portion of the assets of, the Company or any of its Significant
     Subsidiaries, other than the transactions contemplated by the Plan (a
     "Competing Transaction"), or enter into discussions or negotiate with any
     Person in furtherance of such inquiries or to obtain a Competing
     Transaction, or agree to or endorse any Competing Transaction, or authorize
     or permit any of the officers, directors or employees of the Shareholder or
     any member of the Shareholder Group or any investment banker, financial
     advisor, attorney, accountant or other representative retained by the
     Shareholder or any other member of the Shareholder Group to take any such
     action. The Shareholder shall promptly notify the Acquiror of all relevant
     terms of any such inquiries or proposals received by such Shareholder or
     any other member of the Shareholder Group or by any such officer, director,
     employee, investment banker, financial advisor, attorney, accountant or
     other representative relating to any of such matters and, if such inquiry
     or proposal is in writing, such Shareholder shall deliver or cause to be
     delivered to the Acquiror a copy of such inquiry or proposal.

          (e) The Shareholder hereby consents to the Acquiror's announcement in
     any press release, public filing, advertisement or other document, that the
     Shareholder has entered into this Agreement.

          (f) To the extent inconsistent with the provisions of this Section 1,
     the Shareholder hereby revokes, and will cause each member of the
     Shareholder Group to revoke, any and all proxies with respect to such
     member's Company Common Shares or any other voting securities of the
     Company.
 

                                      -2-
<PAGE>
 
2.   Miscellaneous

     (a) The Shareholder, on the one hand, and the Acquiror, on the other,
acknowledge and agree that irreparable damage would occur if any of the
provisions of this Agreement were not performed in accordance with their
specific terms or were otherwise breached.  It is accordingly agreed that the
parties hereto shall be entitled to an injunction or injunctions to prevent
breaches of the provisions of this Agreement and to enforce specifically the
terms and provisions hereof in any court of the United States or any state
thereof having jurisdiction, in addition to any other remedies to which they may
be entitled at law or equity.

     (b) Descriptive headings are for convenience only and shall not control or
affect the meaning or construction of any provision of this Agreement.

     (c) All notices, consents, requests, instructions, approvals and other
communications provided for herein shall be validly given, made or served, if in
writing and delivered personally, by telecopier (subject to receipt of
electronic confirmation) or sent by registered mail, postage prepaid:

     If to the Acquiror:

         Halliburton Company
         3600 Lincoln Plaza
         500 N. Akard Street
         Dallas, Texas  75201-3391
         Attention: Lester L. Coleman
                    Executive Vice President
                      and General Counsel
         Telecopier No.:  (214) 978-2658

         with a copy to:

                    Vinson & Elkins L.L.P.
                    First City Tower
                    1001 Fannin
                    Houston, Texas  77002-6760
                    Attention:  William E. Joor III
                    Telecopier No.:  (713) 758-2346

                                      -3-
<PAGE>
 
         If to the Shareholder:

               Davis Venture Partners, L.P.
               320 South Boston, Suite 1000
               Tulsa, Oklahoma  74103
               Attention:  Barry M. Davis
               Telecopier No.:  (918) 582-3404

or to such other address or telecopier number as any party may, from time to
time, designate in a written notice given in a like manner.  Notice given by
telecopier shall be deemed delivered on the day the sender receives telecopier
confirmation that such notice was received at the telecopier number of the
addressee.  Notice given by mail as set out above shall be deemed delivered
three days after the date the same is postmarked.

     (d) From and after the termination of this Agreement, the covenants of the
parties set forth herein shall be of no further force or effect and the parties
shall be under no further obligation with respect thereto.

     (e) For purposes of this Agreement, the following terms shall have the
following meanings:

         (i)   Affiliate.  "Affiliate" shall have the meaning ascribed to it in
               ---------                                                       
     Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
     in effect on the date hereof.

         (ii)  Associate.  "Associate" shall have the meaning ascribed to it in
               --------- 
     Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
     in effect on the date hereof.

         (iii) Beneficial Owner.  A person shall be deemed a "beneficial owner"
               ----------------                                                
     of or to have "beneficial ownership" of Company Shares in accordance with
     the interpretations of the term "beneficial ownership" as defined in Rule
     13-d(3) under the Exchange Act, as in effect on the date hereof, provided
     that a person shall be deemed to be the beneficial owner of, and to have
     beneficial ownership of, Company Shares that such Person or any Affiliate
     of such Person has the right to acquire (whether such right is exercisable
     immediately or only after the passage of time) pursuant to any agreement,
     arrangement or understanding or upon the exercise of conversion rights,
     exchange rights, warrant, options or otherwise.

         (iv)  Exchange Act.  "Exchange Act" shall mean the Securities Exchange
               -------------  
     Act of 1934, as amended.

                                      -4-
<PAGE>
 
         (v)   Person.  A "Person" shall mean any individual, firm, corporation,
               ------                                                           
     partnership, trust, limited liability company or other entity.

         (vi)  Significant Subsidiary.  "Significant Subsidiary" shall have the
               ----------------------                                          
     meaning ascribed to it in Rule 1-02 of SEC Regulation S-X as in effect on
     the date hereof.

     (g) The Shareholder hereby represents and warrants to the Acquiror as
follows:  The Shareholder has full power and authority to enter into this
Agreement; neither the execution or delivery of this Agreement nor the
consummation of the transactions contemplated herein will (i) conflict with or
result in a breach, default or violation of (A) any of the terms, provisions or
conditions of the certificate of incorporation or bylaws of any member of the
Shareholder Group or (B) any agreement, proxy, document, instrument, judgment,
decree, order, governmental permit, certificate, license, law, statute, rule or
regulation to which any member of the Shareholder Group is a party or to which
it is subject, (ii) result in the creation of any lien, charge or other
encumbrance on any Company Common Shares or (iii) require any member of the
Shareholder Group to obtain the consent of any private nongovernmental third
party; and no consent, action, approval or authorization of, or registration,
declaration or filing with, any governmental department, commission, agency or
other instrumentality or any other person or entity is required to authorize, or
is otherwise required in connection with, the execution and delivery of this
Agreement (with the exception of an amended Schedule 13D to be filed by the
Shareholder pursuant to the Exchange Act) or the Shareholder's performance of
the terms of this Agreement or the validity or enforceability of this Agreement.

     (h) This Agreement shall be binding upon, and inure to the benefit of, the
parties hereto and their respective heirs, personal representatives, successors,
assigns and Affiliates, but shall not be assignable by either party hereto
without the prior written consent of the other party hereto.

     (i) No party may waive any of the terms or conditions of this Agreement
except by a duly signed writing referring to the specific provision to be
waived.

     (j) This Agreement shall be governed by, and construed in accordance with,
the laws of the State of Texas, regardless of the laws that might otherwise
govern under applicable principles of conflicts of law; provided, however, that
any matter involving the internal corporate affairs of any party hereto shall be
governed by the provisions of the Business Corporation Law of the Commonwealth
of Pennsylvania.

     (k) This Agreement constitutes the entire agreement, and supersedes all
other and prior agreements and understandings, both written and oral, among the
parties hereto and their Affiliates.

                                      -5-
<PAGE>
 
     (l) This Agreement may be executed in two or more counterparts, each of
which shall be deemed an original but all of which shall constitute one and the
same instrument.

                                      -6-
<PAGE>
 
     IN WITNESS WHEREOF, the Shareholder and the Acquiror have each caused this
Agreement to be duly executed by an officer or other Person, thereunto duly
authorized, all as of the day and year first above written.

                                 HALLIBURTON COMPANY


                                 By: /s/ Lester L. Coleman
                                    ------------------------------
                                    Lester L. Coleman
                                    Executive Vice President and General Counsel
 

                                 DAVIS VENTURE PARTNERS, L.P.


                                 By: /s/ Barry M. Davis
                                    ------------------------------      
                                    Barry M. Davis
                                    General Partner
 
 

                                      -7-
<PAGE>
 
                               VOTING AGREEMENT


     VOTING AGREEMENT ("Agreement") dated as of June 9, 1997, between
Halliburton Company, a Delaware corporation (the "Acquiror"), and Melvin N.
Miller (the "Shareholder"), a holder of common shares, par value $0.01 per
share, of NUMAR Corporation, a Pennsylvania corporation (the "Company").

                                   RECITALS:

     The Shareholder beneficially owns an aggregate of 334,143 common shares
(together with any additional common shares as to which beneficial ownership is
acquired by any member of the Shareholder Group described below, the "Company
Shares"), par value $0.01 per share ("Company Common Shares"), of the Company.

     The Acquiror is prepared to enter into an Agreement and Plan of Merger with
the Company (the "Plan") providing for the merger of a wholly owned subsidiary
of Acquiror with and into the Company and the conversion in such merger of each
Company Common Share into the number of shares of the Common Stock, par value
$2.50 per share, of the Acquiror set forth in the Plan (the "Merger").

     To facilitate the Merger, the Shareholder is willing to enter into certain
arrangements with respect to the Company Shares.

     NOW, THEREFORE, in consideration of the premises set forth above, the
mutual promises set forth below, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

1.   Shareholder's Support of the Merger. From the date hereof until December
31, 1997, or, if earlier, termination of the Plan:

          (a) Except as contemplated by the Plan or hereby, neither the
     Shareholder nor any Person controlled by the Shareholder, other than the
     Company and its subsidiaries (collectively, the "Shareholder Group"), will,
     directly or indirectly, sell, transfer, pledge or otherwise dispose of, or
     grant a proxy with respect to, any Company Shares to any Person other than
     any member of the Shareholder Group or the Acquiror or its designee, or
     grant an option with respect to any of the Company Shares or enter into any
     other agreement or arrangement with respect to any of the Company Shares.

          (b) The Shareholder agrees that the Shareholder will vote, and will
     cause each member of the Shareholder Group to vote, all Company Shares
     entitled to vote and beneficially owned by such Persons (i) in favor of the
     Merger and (ii), subject to the provisions of paragraph (c) below, against
     any combination proposal or other matter that may 
<PAGE>
 
     (in the reasonable opinion of the Acquiror) interfere or be inconsistent
     with the Merger (including without limitation a Competing Transaction).

          (c) The Shareholder agrees that, if requested by the Acquiror in
     writing in order to facilitate the Merger, the Shareholder will not, and
     will cause each member of the Shareholder Group not to, attend or vote any
     Company Shares beneficially owned by any such Person at any annual or
     special meeting of shareholders or execute any written consent of
     shareholders

          (d) Neither the Shareholder nor any other member of the Shareholder
     Group will initiate, solicit or encourage (including by way of furnishing
     information or assistance), or take any other action to facilitate, any
     inquiries or the making of any proposal that constitutes, or that may
     reasonably be expected to lead to, any merger, consolidation, share
     exchange, business combination or similar transaction involving the Company
     or any of its Significant Subsidiaries, a sale, lease, exchange, transfer
     or other disposition of 50% or more of the assets of the Company and its
     subsidiaries, taken as a whole, in a single transaction or series of
     transactions, the acquisition by a Person or Group of beneficial ownership
     or the right to acquire beneficial ownership of 50% or more of the
     outstanding Company Common Shares, whether by tender offer, exchange offer
     or otherwise, or the acquisition in any manner, directly or indirectly, of
     a material equity interest in any voting securities of, or a substantial
     portion of the assets of, the Company or any of its Significant
     Subsidiaries, other than the transactions contemplated by the Plan (a
     "Competing Transaction"), or enter into discussions or negotiate with any
     Person in furtherance of such inquiries or to obtain a Competing
     Transaction, or agree to or endorse any Competing Transaction, or authorize
     or permit any of the officers, directors or employees of the Shareholder or
     any member of the Shareholder Group or any investment banker, financial
     advisor, attorney, accountant or other representative retained by the
     Shareholder or any other member of the Shareholder Group to take any such
     action. The Shareholder shall promptly notify the Acquiror of all relevant
     terms of any such inquiries or proposals received by such Shareholder or
     any other member of the Shareholder Group or by any such officer, director,
     employee, investment banker, financial advisor, attorney, accountant or
     other representative relating to any of such matters and, if such inquiry
     or proposal is in writing, such Shareholder shall deliver or cause to be
     delivered to the Acquiror a copy of such inquiry or proposal.

          (e) The Shareholder hereby consents to the Acquiror's announcement in
     any press release, public filing, advertisement or other document, that the
     Shareholder has entered into this Agreement.

          (f) To the extent inconsistent with the provisions of this Section 1,
     the Shareholder hereby revokes, and will cause each member of the
     Shareholder Group to revoke, any and all proxies with respect to such
     member's Company Common Shares or any other voting securities of the
     Company.

                                      -2-
<PAGE>
 
2.   Miscellaneous

     (a) The Shareholder, on the one hand, and the Acquiror, on the other,
acknowledge and agree that irreparable damage would occur if any of the
provisions of this Agreement were not performed in accordance with their
specific terms or were otherwise breached.  It is accordingly agreed that the
parties hereto shall be entitled to an injunction or injunctions to prevent
breaches of the provisions of this Agreement and to enforce specifically the
terms and provisions hereof in any court of the United States or any state
thereof having jurisdiction, in addition to any other remedies to which they may
be entitled at law or equity.

     (b) Descriptive headings are for convenience only and shall not control or
affect the meaning or construction of any provision of this Agreement.

     (c) All notices, consents, requests, instructions, approvals and other
communications provided for herein shall be validly given, made or served, if in
writing and delivered personally, by telecopier (subject to receipt of
electronic confirmation) or sent by registered mail, postage prepaid:

     If to the Acquiror:

         Halliburton Company
         3600 Lincoln Plaza
         500 N. Akard Street
         Dallas, Texas  75201-3391
         Attention: Lester L. Coleman
                    Executive Vice President
                      and General Counsel
         Telecopier No.:  (214) 978-2658

         with a copy to:

               Vinson & Elkins L.L.P.
               First City Tower
               1001 Fannin
               Houston, Texas  77002-6760
               Attention:  William E. Joor III
               Telecopier No.:  (713) 758-2346

                                      -3-
<PAGE>
 
          If to the Shareholder:

               Melvin N. Miller
               c/o NUMAR Corporation
               508 Lapp Road
               Malvern, Pennsylvania  19355
               Telecopier No.:  (610) 644-8131

or to such other address or telecopier number as any party may, from time to
time, designate in a written notice given in a like manner.  Notice given by
telecopier shall be deemed delivered on the day the sender receives telecopier
confirmation that such notice was received at the telecopier number of the
addressee.  Notice given by mail as set out above shall be deemed delivered
three days after the date the same is postmarked.

     (d) From and after the termination of this Agreement, the covenants of the
parties set forth herein shall be of no further force or effect and the parties
shall be under no further obligation with respect thereto.

     (e) For purposes of this Agreement, the following terms shall have the
following meanings:

         (i)    Affiliate.  "Affiliate" shall have the meaning ascribed to it in
                ----------                                                     
Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
in effect on the date hereof.

         (ii)   Associate.  "Associate" shall have the meaning ascribed to it in
                ---------- 
Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
in effect on the date hereof.

         (iii)  Beneficial Owner.  A person shall be deemed a "beneficial owner"
                -----------------                                              
of or to have "beneficial ownership" of Company Shares in accordance with
the interpretations of the term "beneficial ownership" as defined in Rule
13-d(3) under the Exchange Act, as in effect on the date hereof, provided
that a person shall be deemed to be the beneficial owner of, and to have
beneficial ownership of, Company Shares that such Person or any Affiliate
of such Person has the right to acquire (whether such right is exercisable
immediately or only after the passage of time) pursuant to any agreement,
arrangement or understanding or upon the exercise of conversion rights,
exchange rights, warrant, options or otherwise.

         (iv)   Exchange Act.  "Exchange Act" shall mean the Securities Exchange
                ------------- 
Act of 1934, as amended.

         (v)    Person.  A "Person" shall mean any individual, firm, 
                ------   
corporation, partnership, trust, limited liability company or other entity.

                                      -4-
<PAGE>
 
         (vi) Significant Subsidiary.  "Significant Subsidiary" shall have the
              ----------------------                                          
     meaning ascribed to it in Rule 1-02 of SEC Regulation S-X as in effect on
     the date hereof.

     (g) The Shareholder hereby represents and warrants to the Acquiror as
follows:  The Shareholder has full power and authority to enter into this
Agreement; neither the execution or delivery of this Agreement nor the
consummation of the transactions contemplated herein will (i) conflict with or
result in a breach, default or violation of (A) any of the terms, provisions or
conditions of the certificate of incorporation or bylaws of any member of the
Shareholder Group or (B) any agreement, proxy, document, instrument, judgment,
decree, order, governmental permit, certificate, license, law, statute, rule or
regulation to which any member of the Shareholder Group is a party or to which
it is subject, (ii) result in the creation of any lien, charge or other
encumbrance on any Company Common Shares or (iii) require any member of the
Shareholder Group to obtain the consent of any private nongovernmental third
party; and no consent, action, approval or authorization of, or registration,
declaration or filing with, any governmental department, commission, agency or
other instrumentality or any other person or entity is required to authorize, or
is otherwise required in connection with, the execution and delivery of this
Agreement (with the exception of an amended Schedule 13D to be filed by the
Shareholder pursuant to the Exchange Act) or the Shareholder's performance of
the terms of this Agreement or the validity or enforceability of this Agreement.

     (h) This Agreement shall be binding upon, and inure to the benefit of, the
parties hereto and their respective heirs, personal representatives, successors,
assigns and Affiliates, but shall not be assignable by either party hereto
without the prior written consent of the other party hereto.

     (i) No party may waive any of the terms or conditions of this Agreement
except by a duly signed writing referring to the specific provision to be
waived.

     (j) This Agreement shall be governed by, and construed in accordance with,
the laws of the State of Texas, regardless of the laws that might otherwise
govern under applicable principles of conflicts of law; provided, however, that
any matter involving the internal corporate affairs of any party hereto shall be
governed by the provisions of the Business Corporation Law of the Commonwealth
of Pennsylvania.

     (k) This Agreement constitutes the entire agreement, and supersedes all
other and prior agreements and understandings, both written and oral, among the
parties hereto and their Affiliates.

     (l) This Agreement may be executed in two or more counterparts, each of
which shall be deemed an original but all of which shall constitute one and the
same instrument.

                                      -5-
<PAGE>
 
     IN WITNESS WHEREOF, the Shareholder has executed this Agreement and the
Acquiror has caused this Agreement to be duly executed by an officer, thereunto
duly authorized, all as of the day and year first above written.

                                 HALLIBURTON COMPANY


                                 By: /s/ Lester L. Coleman
                                    ----------------------------
                                    Lester L. Coleman
                                    Executive Vice President and General Counsel
 
                                 SHAREHOLDER

                                 /s/ Melvin N. Miller
                                 ------------------------------- 
                                 Melvin N. Miller

                                      -7-
 
<PAGE>
 
                               VOTING AGREEMENT


     VOTING AGREEMENT ("Agreement") dated as of June 9, 1997, between
Halliburton Company, a Delaware corporation (the "Acquiror"), and Barry M. Davis
(the "Shareholder"), a holder of common shares, par value $0.01 per share, of
NUMAR Corporation, a Pennsylvania corporation (the "Company").

                                   RECITALS:

     The Shareholder beneficially owns an aggregate of 723,144 common shares
(together with any additional common shares as to which beneficial ownership is
acquired by any member of the Shareholder Group described below, the "Company
Shares"), par value $0.01 per share ("Company Common Shares"), of the Company.

     The Acquiror is prepared to enter into an Agreement and Plan of Merger with
the Company (the "Plan") providing for the merger of a wholly owned subsidiary
of Acquiror with and into the Company and the conversion in such merger of each
Company Common Share into the number of shares of the Common Stock, par value
$2.50 per share, of the Acquiror set forth in the Plan (the "Merger").

     To facilitate the Merger, the Shareholder is willing to enter into certain
arrangements with respect to the Company Shares.

     NOW, THEREFORE, in consideration of the premises set forth above, the
mutual promises set forth below, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

1.   Shareholder's Support of the Merger.  From the date hereof until
December 31, 1997, or, if earlier, termination of the Plan:

          (a) Except as contemplated by the Plan or hereby, neither the
     Shareholder nor any Person controlled by the Shareholder, other than the
     Company and its subsidiaries (collectively, the "Shareholder Group"), will,
     directly or indirectly, sell, transfer, pledge or otherwise dispose of, or
     grant a proxy with respect to, any Company Shares to any Person other than
     any member of the Shareholder Group or the Acquiror or its designee, or
     grant an option with respect to any of the Company Shares or enter into any
     other agreement or arrangement with respect to any of the Company Shares.

          (b) The Shareholder agrees that the Shareholder will vote, and will
     cause each member of the Shareholder Group to vote, all Company Shares
     entitled to vote and beneficially owned by such Persons (i) in favor of the
     Merger and (ii), subject to the provisions of paragraph (c) below, against
     any combination proposal or other matter that may 
<PAGE>
 
     (in the reasonable opinion of the Acquiror) interfere or be inconsistent
     with the Merger (including without limitation a Competing Transaction).

          (c) The Shareholder agrees that, if requested by the Acquiror in
     writing in order to facilitate the Merger, the Shareholder will not, and
     will cause each member of the Shareholder Group not to, attend or vote any
     Company Shares beneficially owned by any such Person at any annual or
     special meeting of shareholders or execute any written consent of
     shareholders

          (d) Neither the Shareholder nor any other member of the Shareholder
     Group will initiate, solicit or encourage (including by way of furnishing
     information or assistance), or take any other action to facilitate, any
     inquiries or the making of any proposal that constitutes, or that may
     reasonably be expected to lead to, any merger, consolidation, share
     exchange, business combination or similar transaction involving the Company
     or any of its Significant Subsidiaries, a sale, lease, exchange, transfer
     or other disposition of 50% or more of the assets of the Company and its
     subsidiaries, taken as a whole, in a single transaction or series of
     transactions, the acquisition by a Person or Group of beneficial ownership
     or the right to acquire beneficial ownership of 50% or more of the
     outstanding Company Common Shares, whether by tender offer, exchange offer
     or otherwise, or the acquisition in any manner, directly or indirectly, of
     a material equity interest in any voting securities of, or a substantial
     portion of the assets of, the Company or any of its Significant
     Subsidiaries, other than the transactions contemplated by the Plan (a
     "Competing Transaction"), or enter into discussions or negotiate with any
     Person in furtherance of such inquiries or to obtain a Competing
     Transaction, or agree to or endorse any Competing Transaction, or authorize
     or permit any of the officers, directors or employees of the Shareholder or
     any member of the Shareholder Group or any investment banker, financial
     advisor, attorney, accountant or other representative retained by the
     Shareholder or any other member of the Shareholder Group to take any such
     action. The Shareholder shall promptly notify the Acquiror of all relevant
     terms of any such inquiries or proposals received by such Shareholder or
     any other member of the Shareholder Group or by any such officer, director,
     employee, investment banker, financial advisor, attorney, accountant or
     other representative relating to any of such matters and, if such inquiry
     or proposal is in writing, such Shareholder shall deliver or cause to be
     delivered to the Acquiror a copy of such inquiry or proposal.

          (e) The Shareholder hereby consents to the Acquiror's announcement in
     any press release, public filing, advertisement or other document, that the
     Shareholder has entered into this Agreement.

          (f) To the extent inconsistent with the provisions of this Section 1,
     the Shareholder hereby revokes, and will cause each member of the
     Shareholder Group to revoke, any and all proxies with respect to such
     member's Company Common Shares or any other voting securities of the
     Company.

                                      -2-
<PAGE>
 
2.   Miscellaneous

     (a) The Shareholder, on the one hand, and the Acquiror, on the other,
acknowledge and agree that irreparable damage would occur if any of the
provisions of this Agreement were not performed in accordance with their
specific terms or were otherwise breached.  It is accordingly agreed that the
parties hereto shall be entitled to an injunction or injunctions to prevent
breaches of the provisions of this Agreement and to enforce specifically the
terms and provisions hereof in any court of the United States or any state
thereof having jurisdiction, in addition to any other remedies to which they may
be entitled at law or equity.

     (b) Descriptive headings are for convenience only and shall not control or
affect the meaning or construction of any provision of this Agreement.

     (c) All notices, consents, requests, instructions, approvals and other
communications provided for herein shall be validly given, made or served, if in
writing and delivered personally, by telecopier (subject to receipt of
electronic confirmation) or sent by registered mail, postage prepaid:

     If to the Acquiror:

               Halliburton Company
               3600 Lincoln Plaza
               500 N. Akard Street
               Dallas, Texas  75201-3391
               Attention:  Lester L. Coleman
                          Executive Vice President
                              and General Counsel
               Telecopier No.:  (214) 978-2658

               with a copy to:

                    Vinson & Elkins L.L.P.
                    First City Tower
                    1001 Fannin
                    Houston, Texas  77002-6760
                    Attention:  William E. Joor III
                    Telecopier No.:  (713) 758-2346

                                      -3-
<PAGE>
 
     If to the Shareholder:


               Davis Venture Partners, L.P.
               320 South Boston, Suite 1000
               Tulsa, Oklahoma  74103
               Attention: Barry M.Davis 
               Telecopier No.:  (918) 582-3404
 
or to such other address or telecopier number as any party may, from time to
time, designate in a written notice given in a like manner.  Notice given by
telecopier shall be deemed delivered on the day the sender receives telecopier
confirmation that such notice was received at the telecopier number of the
addressee.  Notice given by mail as set out above shall be deemed delivered
three days after the date the same is postmarked.

     (d) From and after the termination of this Agreement, the covenants of the
parties set forth herein shall be of no further force or effect and the parties
shall be under no further obligation with respect thereto.

     (e) For purposes of this Agreement, the following terms shall have the
following meanings:

         (i)   Affiliate.  "Affiliate" shall have the meaning ascribed to it in
               ---------                                                       
     Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
     in effect on the date hereof.

         (ii)  Associate.  "Associate" shall have the meaning ascribed to it in
               ---------
     Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
     in effect on the date hereof.

         (iii) Beneficial Owner.  A person shall be deemed a "beneficial owner"
               ----------------                                                
     of or to have "beneficial ownership" of Company Shares in accordance with
     the interpretations of the term "beneficial ownership" as defined in Rule
     13-d(3) under the Exchange Act, as in effect on the date hereof, provided
     that a person shall be deemed to be the beneficial owner of, and to have
     beneficial ownership of, Company Shares that such Person or any Affiliate
     of such Person has the right to acquire (whether such right is exercisable
     immediately or only after the passage of time) pursuant to any agreement,
     arrangement or understanding or upon the exercise of conversion rights,
     exchange rights, warrant, options or otherwise.

         (iv)  Exchange Act.  "Exchange Act" shall mean the Securities Exchange
               ------------
Act of 1934, as amended.

                                      -4-
<PAGE>
 
         (v)   Person.  A "Person" shall mean any individual, firm, corporation,
               ------                                                           
     partnership, trust, limited liability company or other entity.

         (vi)  Significant Subsidiary.  "Significant Subsidiary" shall have the
               ----------------------                                          
     meaning ascribed to it in Rule 1-02 of SEC Regulation S-X as in effect on
     the date hereof.

     (g) The Shareholder hereby represents and warrants to the Acquiror as
follows:  The Shareholder has full power and authority to enter into this
Agreement; neither the execution or delivery of this Agreement nor the
consummation of the transactions contemplated herein will (i) conflict with or
result in a breach, default or violation of (A) any of the terms, provisions or
conditions of the certificate of incorporation or bylaws of any member of the
Shareholder Group or (B) any agreement, proxy, document, instrument, judgment,
decree, order, governmental permit, certificate, license, law, statute, rule or
regulation to which any member of the Shareholder Group is a party or to which
it is subject, (ii) result in the creation of any lien, charge or other
encumbrance on any Company Common Shares or (iii) require any member of the
Shareholder Group to obtain the consent of any private nongovernmental third
party; and no consent, action, approval or authorization of, or registration,
declaration or filing with, any governmental department, commission, agency or
other instrumentality or any other person or entity is required to authorize, or
is otherwise required in connection with, the execution and delivery of this
Agreement (with the exception of an amended Schedule 13D to be filed by the
Shareholder pursuant to the Exchange Act) or the Shareholder's performance of
the terms of this Agreement or the validity or enforceability of this Agreement.

     (h) This Agreement shall be binding upon, and inure to the benefit of, the
parties hereto and their respective heirs, personal representatives, successors,
assigns and Affiliates, but shall not be assignable by either party hereto
without the prior written consent of the other party hereto.

     (i) No party may waive any of the terms or conditions of this Agreement
except by a duly signed writing referring to the specific provision to be
waived.

     (j) This Agreement shall be governed by, and construed in accordance with,
the laws of the State of Texas, regardless of the laws that might otherwise
govern under applicable principles of conflicts of law; provided, however, that
any matter involving the internal corporate affairs of any party hereto shall be
governed by the provisions of the Business Corporation Law of the Commonwealth
of Pennsylvania.

     (k) This Agreement constitutes the entire agreement, and supersedes all
other and prior agreements and understandings, both written and oral, among the
parties hereto and their Affiliates.

                                      -5-
<PAGE>
 
     (l) This Agreement may be executed in two or more counterparts, each of
which shall be deemed an original but all of which shall constitute one and the
same instrument.

                                      -6-
<PAGE>
 
     IN WITNESS WHEREOF, the Shareholder has executed this Agreement and the
Acquiror has caused this Agreement to be duly executed by an officer, thereunto
duly authorized, all as of the day and year first above written.

                                 HALLIBURTON COMPANY


                                 By:/s/ Lester L. Coleman
                                    ------------------------------
                                    Lester L. Coleman
                                    Executive Vice President and General Counsel
 
                                 SHAREHOLDER

                                 /s/ Barry M. Davis
                                 --------------------------------
                                 Barry M. Davis

                                      -7-
<PAGE>
 
                               VOTING AGREEMENT


     VOTING AGREEMENT ("Agreement") dated as of June 9, 1997, between
Halliburton Company, a Delaware corporation (the "Acquiror"), and Seymour G.
Mandell (the "Shareholder"), a holder of common shares, par value $0.01 per
share, of NUMAR Corporation, a Pennsylvania corporation (the "Company").

                                   RECITALS:

     The Shareholder beneficially owns an aggregate of 174,771 common shares
(together with any additional common shares as to which beneficial ownership is
acquired by any member of the Shareholder Group described below, the "Company
Shares"), par value $0.01 per share ("Company Common Shares"), of the Company.

     The Acquiror is prepared to enter into an Agreement and Plan of Merger with
the Company (the "Plan") providing for the merger of a wholly owned subsidiary
of Acquiror with and into the Company and the conversion in such merger of each
Company Common Share into the number of shares of the Common Stock, par value
$2.50 per share, of the Acquiror set forth in the Plan (the "Merger").

     To facilitate the Merger, the Shareholder is willing to enter into certain
arrangements with respect to the Company Shares.

     NOW, THEREFORE, in consideration of the premises set forth above, the
mutual promises set forth below, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

1.   Shareholder's Support of the Merger. From the date hereof until December
31, 1997, or, if earlier, termination of the Plan:

          (a) Except as contemplated by the Plan or hereby, neither the
     Shareholder nor any Person controlled by the Shareholder, other than the
     Company and its subsidiaries (collectively, the "Shareholder Group"), will,
     directly or indirectly, sell, transfer, pledge or otherwise dispose of, or
     grant a proxy with respect to, any Company Shares to any Person other than
     any member of the Shareholder Group or the Acquiror or its designee, or
     grant an option with respect to any of the Company Shares or enter into any
     other agreement or arrangement with respect to any of the Company Shares.

          (b) The Shareholder agrees that the Shareholder will vote, and will
     cause each member of the Shareholder Group to vote, all Company Shares
     entitled to vote and beneficially owned by such Persons (i) in favor of the
     Merger and (ii), subject to the provisions of paragraph (c) below, against
     any combination proposal or other matter that may
<PAGE>
 
     (in the reasonable opinion of the Acquiror) interfere or be inconsistent
     with the Merger (including without limitation a Competing Transaction).

          (c) The Shareholder agrees that, if requested by the Acquiror in
     writing in order to facilitate the Merger, the Shareholder will not, and
     will cause each member of the Shareholder Group not to, attend or vote any
     Company Shares beneficially owned by any such Person at any annual or
     special meeting of shareholders or execute any written consent of
     shareholders

          (d) Neither the Shareholder nor any other member of the Shareholder
     Group will initiate, solicit or encourage (including by way of furnishing
     information or assistance), or take any other action to facilitate, any
     inquiries or the making of any proposal that constitutes, or that may
     reasonably be expected to lead to, any merger, consolidation, share
     exchange, business combination or similar transaction involving the Company
     or any of its Significant Subsidiaries, a sale, lease, exchange, transfer
     or other disposition of 50% or more of the assets of the Company and its
     subsidiaries, taken as a whole, in a single transaction or series of
     transactions, the acquisition by a Person or Group of beneficial ownership
     or the right to acquire beneficial ownership of 50% or more of the
     outstanding Company Common Shares, whether by tender offer, exchange offer
     or otherwise, or the acquisition in any manner, directly or indirectly, of
     a material equity interest in any voting securities of, or a substantial
     portion of the assets of, the Company or any of its Significant
     Subsidiaries, other than the transactions contemplated by the Plan (a
     "Competing Transaction"), or enter into discussions or negotiate with any
     Person in furtherance of such inquiries or to obtain a Competing
     Transaction, or agree to or endorse any Competing Transaction, or authorize
     or permit any of the officers, directors or employees of the Shareholder or
     any member of the Shareholder Group or any investment banker, financial
     advisor, attorney, accountant or other representative retained by the
     Shareholder or any other member of the Shareholder Group to take any such
     action. The Shareholder shall promptly notify the Acquiror of all relevant
     terms of any such inquiries or proposals received by such Shareholder or
     any other member of the Shareholder Group or by any such officer, director,
     employee, investment banker, financial advisor, attorney, accountant or
     other representative relating to any of such matters and, if such inquiry
     or proposal is in writing, such Shareholder shall deliver or cause to be
     delivered to the Acquiror a copy of such inquiry or proposal.

          (e) The Shareholder hereby consents to the Acquiror's announcement in
     any press release, public filing, advertisement or other document, that the
     Shareholder has entered into this Agreement.

          (f) To the extent inconsistent with the provisions of this Section 1,
     the Shareholder hereby revokes, and will cause each member of the
     Shareholder Group to revoke, any and all proxies with respect to such
     member's Company Common Shares or any other voting securities of the
     Company.
 
                                      -2-
<PAGE>
 
2.   Miscellaneous

     (a) The Shareholder, on the one hand, and the Acquiror, on the other,
acknowledge and agree that irreparable damage would occur if any of the
provisions of this Agreement were not performed in accordance with their
specific terms or were otherwise breached.  It is accordingly agreed that the
parties hereto shall be entitled to an injunction or injunctions to prevent
breaches of the provisions of this Agreement and to enforce specifically the
terms and provisions hereof in any court of the United States or any state
thereof having jurisdiction, in addition to any other remedies to which they may
be entitled at law or equity.

     (b) Descriptive headings are for convenience only and shall not control or
affect the meaning or construction of any provision of this Agreement.

     (c) All notices, consents, requests, instructions, approvals and other
communications provided for herein shall be validly given, made or served, if in
writing and delivered personally, by telecopier (subject to receipt of
electronic confirmation) or sent by registered mail, postage prepaid:

     If to the Acquiror:

               Halliburton Company
               3600 Lincoln Plaza
               500 N. Akard Street
               Dallas, Texas  75201-3391
               Attention:  Lester L. Coleman
                          Executive Vice President
                              and General Counsel
               Telecopier No.:  (214) 978-2658

               with a copy to:

                    Vinson & Elkins L.L.P.
                    First City Tower
                    1001 Fannin
                    Houston, Texas  77002-6760
                    Attention:  William E. Joor III
                    Telecopier No.:  (713) 758-2346

                                      -3-
<PAGE>
 
     If to the Shareholder:

               Melvin N. Miller  
               c/o NUMAR Corporation
               508 Lapp Road
               Malvern, Pennsylvania 19355
               Telecopier No.:  (610) 644-8131
 
or to such other address or telecopier number as any party may, from time to
time, designate in a written notice given in a like manner.  Notice given by
telecopier shall be deemed delivered on the day the sender receives telecopier
confirmation that such notice was received at the telecopier number of the
addressee.  Notice given by mail as set out above shall be deemed delivered
three days after the date the same is postmarked.

     (d) From and after the termination of this Agreement, the covenants of the
parties set forth herein shall be of no further force or effect and the parties
shall be under no further obligation with respect thereto.

     (e) For purposes of this Agreement, the following terms shall have the
following meanings:

         (i)   Affiliate.  "Affiliate" shall have the meaning ascribed to it in
               ---------                                                       
     Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
     in effect on the date hereof.

         (ii)  Associate.  "Associate" shall have the meaning ascribed to it in
               ---------  
     Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
     in effect on the date hereof.

         (iii) Beneficial Owner.  A person shall be deemed a "beneficial owner"
               ----------------                                                
     of or to have "beneficial ownership" of Company Shares in accordance with
     the interpretations of the term "beneficial ownership" as defined in Rule
     13-d(3) under the Exchange Act, as in effect on the date hereof, provided
     that a person shall be deemed to be the beneficial owner of, and to have
     beneficial ownership of, Company Shares that such Person or any Affiliate
     of such Person has the right to acquire (whether such right is exercisable
     immediately or only after the passage of time) pursuant to any agreement,
     arrangement or understanding or upon the exercise of conversion rights,
     exchange rights, warrant, options or otherwise.

         (iv)  Exchange Act.  "Exchange Act" shall mean the Securities Exchange
               ------------
Act of 1934, as amended.

                                      -4-
<PAGE>
 
         (v)   Person.  A "Person" shall mean any individual, firm, corporation,
               ------                                                           
     partnership, trust, limited liability company or other entity.

         (vi)  Significant Subsidiary.  "Significant Subsidiary" shall have the
               ----------------------                                          
     meaning ascribed to it in Rule 1-02 of SEC Regulation S-X as in effect on
     the date hereof.

     (g) The Shareholder hereby represents and warrants to the Acquiror as
follows:  The Shareholder has full power and authority to enter into this
Agreement; neither the execution or delivery of this Agreement nor the
consummation of the transactions contemplated herein will (i) conflict with or
result in a breach, default or violation of (A) any of the terms, provisions or
conditions of the certificate of incorporation or bylaws of any member of the
Shareholder Group or (B) any agreement, proxy, document, instrument, judgment,
decree, order, governmental permit, certificate, license, law, statute, rule or
regulation to which any member of the Shareholder Group is a party or to which
it is subject, (ii) result in the creation of any lien, charge or other
encumbrance on any Company Common Shares or (iii) require any member of the
Shareholder Group to obtain the consent of any private nongovernmental third
party; and no consent, action, approval or authorization of, or registration,
declaration or filing with, any governmental department, commission, agency or
other instrumentality or any other person or entity is required to authorize, or
is otherwise required in connection with, the execution and delivery of this
Agreement (with the exception of an amended Schedule 13D to be filed by the
Shareholder pursuant to the Exchange Act) or the Shareholder's performance of
the terms of this Agreement or the validity or enforceability of this Agreement.

     (h) This Agreement shall be binding upon, and inure to the benefit of, the
parties hereto and their respective heirs, personal representatives, successors,
assigns and Affiliates, but shall not be assignable by either party hereto
without the prior written consent of the other party hereto.

     (i) No party may waive any of the terms or conditions of this Agreement
except by a duly signed writing referring to the specific provision to be
waived.

     (j) This Agreement shall be governed by, and construed in accordance with,
the laws of the State of Texas, regardless of the laws that might otherwise
govern under applicable principles of conflicts of law; provided, however, that
any matter involving the internal corporate affairs of any party hereto shall be
governed by the provisions of the Business Corporation Law of the Commonwealth
of Pennsylvania.

     (k) This Agreement constitutes the entire agreement, and supersedes all
other and prior agreements and understandings, both written and oral, among the
parties hereto and their Affiliates.

                                      -5-
<PAGE>
 
     (l) This Agreement may be executed in two or more counterparts, each of
which shall be deemed an original but all of which shall constitute one and the
same instrument.

                                      -6-
<PAGE>
 
     IN WITNESS WHEREOF, the Shareholder has executed this Agreement and the
Acquiror has caused this Agreement to be duly executed by an officer, thereunto
duly authorized, all as of the day and year first above written.


                                 HALLIBURTON COMPANY


                                 By:/s/ Lester L. Coleman
                                    ------------------------------
                                    Lester L. Coleman
                                    Executive Vice President and General Counsel
 
                                 SHAREHOLDER

                                 /s/ Seymour G. Mandell
                                 ---------------------------------
                                 Seymour G. Mandell

                                      -6-
<PAGE>
 
                               VOTING AGREEMENT


     VOTING AGREEMENT ("Agreement") dated as of June 9, 1997, between
Halliburton Company, a Delaware corporation (the "Acquiror"), and James H.
Simons (the "Shareholder"), a holder of common shares, par value $0.01 per
share, of NUMAR Corporation, a Pennsylvania corporation (the "Company").

                                   RECITALS:

     The Shareholder beneficially owns an aggregate of 13,434 common shares
(together with any additional common shares as to which beneficial ownership is
acquired by any member of the Shareholder Group described below, the "Company
Shares"), par value $0.01 per share ("Company Common Shares"), of the Company.

     The Acquiror is prepared to enter into an Agreement and Plan of Merger with
the Company (the "Plan") providing for the merger of a wholly owned subsidiary
of Acquiror with and into the Company and the conversion in such merger of each
Company Common Share into the number of shares of the Common Stock, par value
$2.50 per share, of the Acquiror set forth in the Plan (the "Merger").

     To facilitate the Merger, the Shareholder is willing to enter into certain
arrangements with respect to the Company Shares.

     NOW, THEREFORE, in consideration of the premises set forth above, the
mutual promises set forth below, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

1.   Shareholder's Support of the Merger. From the date hereof until December
31, 1997, or, if earlier, termination of the Plan:

          (a) Except as contemplated by the Plan or hereby, neither the
     Shareholder nor any Person controlled by the Shareholder, other than the
     Company and its subsidiaries (collectively, the "Shareholder Group"), will,
     directly or indirectly, sell, transfer, pledge or otherwise dispose of, or
     grant a proxy with respect to, any Company Shares to any Person other than
     any member of the Shareholder Group or the Acquiror or its designee, or
     grant an option with respect to any of the Company Shares or enter into any
     other agreement or arrangement with respect to any of the Company Shares.

          (b) The Shareholder agrees that the Shareholder will vote, and will
     cause each member of the Shareholder Group to vote, all Company Shares
     entitled to vote and beneficially owned by such Persons (i) in favor of the
     Merger and (ii), subject to the provisions of paragraph (c) below, against
     any combination proposal or other matter that may 
<PAGE>
 
     (in the reasonable opinion of the Acquiror) interfere or be inconsistent
     with the Merger (including without limitation a Competing Transaction).

          (c) The Shareholder agrees that, if requested by the Acquiror in
     writing in order to facilitate the Merger, the Shareholder will not, and
     will cause each member of the Shareholder Group not to, attend or vote any
     Company Shares beneficially owned by any such Person at any annual or
     special meeting of shareholders or execute any written consent of
     shareholders

          (d) Neither the Shareholder nor any other member of the Shareholder
     Group will initiate, solicit or encourage (including by way of furnishing
     information or assistance), or take any other action to facilitate, any
     inquiries or the making of any proposal that constitutes, or that may
     reasonably be expected to lead to, any merger, consolidation, share
     exchange, business combination or similar transaction involving the Company
     or any of its Significant Subsidiaries, a sale, lease, exchange, transfer
     or other disposition of 50% or more of the assets of the Company and its
     subsidiaries, taken as a whole, in a single transaction or series of
     transactions, the acquisition by a Person or Group of beneficial ownership
     or the right to acquire beneficial ownership of 50% or more of the
     outstanding Company Common Shares, whether by tender offer, exchange offer
     or otherwise, or the acquisition in any manner, directly or indirectly, of
     a material equity interest in any voting securities of, or a substantial
     portion of the assets of, the Company or any of its Significant
     Subsidiaries, other than the transactions contemplated by the Plan (a
     "Competing Transaction"), or enter into discussions or negotiate with any
     Person in furtherance of such inquiries or to obtain a Competing
     Transaction, or agree to or endorse any Competing Transaction, or authorize
     or permit any of the officers, directors or employees of the Shareholder or
     any member of the Shareholder Group or any investment banker, financial
     advisor, attorney, accountant or other representative retained by the
     Shareholder or any other member of the Shareholder Group to take any such
     action. The Shareholder shall promptly notify the Acquiror of all relevant
     terms of any such inquiries or proposals received by such Shareholder or
     any other member of the Shareholder Group or by any such officer, director,
     employee, investment banker, financial advisor, attorney, accountant or
     other representative relating to any of such matters and, if such inquiry
     or proposal is in writing, such Shareholder shall deliver or cause to be
     delivered to the Acquiror a copy of such inquiry or proposal.

          (e) The Shareholder hereby consents to the Acquiror's announcement in
     any press release, public filing, advertisement or other document, that the
     Shareholder has entered into this Agreement.

          (f) To the extent inconsistent with the provisions of this Section 1,
     the Shareholder hereby revokes, and will cause each member of the
     Shareholder Group to revoke, any and all proxies with respect to such
     member's Company Common Shares or any other voting securities of the
     Company.
 
                                      -2-
<PAGE>
 
2.   Miscellaneous

     (a) The Shareholder, on the one hand, and the Acquiror, on the other,
acknowledge and agree that irreparable damage would occur if any of the
provisions of this Agreement were not performed in accordance with their
specific terms or were otherwise breached.  It is accordingly agreed that the
parties hereto shall be entitled to an injunction or injunctions to prevent
breaches of the provisions of this Agreement and to enforce specifically the
terms and provisions hereof in any court of the United States or any state
thereof having jurisdiction, in addition to any other remedies to which they may
be entitled at law or equity.

     (b) Descriptive headings are for convenience only and shall not control or
affect the meaning or construction of any provision of this Agreement.

     (c) All notices, consents, requests, instructions, approvals and other
communications provided for herein shall be validly given, made or served, if in
writing and delivered personally, by telecopier (subject to receipt of
electronic confirmation) or sent by registered mail, postage prepaid:

          If to the Acquiror:

               Halliburton Company
               3600 Lincoln Plaza
               500 N. Akard Street
               Dallas, Texas  75201-3391
               Attention: Lester L. Coleman
                          Executive Vice President
                              and General Counsel
               Telecopier No.:  (214) 978-2658

               with a copy to:

                    Vinson & Elkins L.L.P.
                    First City Tower
                    1001 Fannin
                    Houston, Texas  77002-6760
                    Attention:  William E. Joor III
                    Telecopier No.:  (713) 758-2346

                                      -3-
<PAGE>
 
          If to the Shareholder:

               James H. Simons
               c/o Renaissance Technologies
               800 Third Avenue
               New York, New York  10022
 
or to such other address or telecopier number as any party may, from time to
time, designate in a written notice given in a like manner.  Notice given by
telecopier shall be deemed delivered on the day the sender receives telecopier
confirmation that such notice was received at the telecopier number of the
addressee.  Notice given by mail as set out above shall be deemed delivered
three days after the date the same is postmarked.

     (d) From and after the termination of this Agreement, the covenants of the
parties set forth herein shall be of no further force or effect and the parties
shall be under no further obligation with respect thereto.

     (e) For purposes of this Agreement, the following terms shall have the
following meanings:

         (i)   Affiliate.  "Affiliate" shall have the meaning ascribed to it in
               ----------                                                       
     Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
     in effect on the date hereof.

         (ii)  Associate.  "Associate" shall have the meaning ascribed to it in
               ----------
     Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
     in effect on the date hereof.

         (iii) Beneficial Owner.  A person shall be deemed a "beneficial owner"
               -----------------                                                
     of or to have "beneficial ownership" of Company Shares in accordance with
     the interpretations of the term "beneficial ownership" as defined in Rule
     13-d(3) under the Exchange Act, as in effect on the date hereof, provided
     that a person shall be deemed to be the beneficial owner of, and to have
     beneficial ownership of, Company Shares that such Person or any Affiliate
     of such Person has the right to acquire (whether such right is exercisable
     immediately or only after the passage of time) pursuant to any agreement,
     arrangement or understanding or upon the exercise of conversion rights,
     exchange rights, warrant, options or otherwise.

         (iv)  Exchange Act.  "Exchange Act" shall mean the Securities Exchange
               ------------- 
     Act of 1934, as amended.

         (v)   Person.  A "Person" shall mean any individual, firm, corporation,
               -------                                                         
     partnership, trust, limited liability company or other entity.

                                      -4-
<PAGE>
 
         (vi) Significant Subsidiary.  "Significant Subsidiary" shall have the
              ----------------------                                          
     meaning ascribed to it in Rule 1-02 of SEC Regulation S-X as in effect on
     the date hereof.

     (g) The Shareholder hereby represents and warrants to the Acquiror as
follows:  The Shareholder has full power and authority to enter into this
Agreement; neither the execution or delivery of this Agreement nor the
consummation of the transactions contemplated herein will (i) conflict with or
result in a breach, default or violation of (A) any of the terms, provisions or
conditions of the certificate of incorporation or bylaws of any member of the
Shareholder Group or (B) any agreement, proxy, document, instrument, judgment,
decree, order, governmental permit, certificate, license, law, statute, rule or
regulation to which any member of the Shareholder Group is a party or to which
it is subject, (ii) result in the creation of any lien, charge or other
encumbrance on any Company Common Shares or (iii) require any member of the
Shareholder Group to obtain the consent of any private nongovernmental third
party; and no consent, action, approval or authorization of, or registration,
declaration or filing with, any governmental department, commission, agency or
other instrumentality or any other person or entity is required to authorize, or
is otherwise required in connection with, the execution and delivery of this
Agreement (with the exception of an amended Schedule 13D to be filed by the
Shareholder pursuant to the Exchange Act) or the Shareholder's performance of
the terms of this Agreement or the validity or enforceability of this Agreement.

     (h) This Agreement shall be binding upon, and inure to the benefit of, the
parties hereto and their respective heirs, personal representatives, successors,
assigns and Affiliates, but shall not be assignable by either party hereto
without the prior written consent of the other party hereto.

     (i) No party may waive any of the terms or conditions of this Agreement
except by a duly signed writing referring to the specific provision to be
waived.

     (j) This Agreement shall be governed by, and construed in accordance with,
the laws of the State of Texas, regardless of the laws that might otherwise
govern under applicable principles of conflicts of law; provided, however, that
any matter involving the internal corporate affairs of any party hereto shall be
governed by the provisions of the Business Corporation Law of the Commonwealth
of Pennsylvania.

     (k) This Agreement constitutes the entire agreement, and supersedes all
other and prior agreements and understandings, both written and oral, among the
parties hereto and their Affiliates.

     (l) This Agreement may be executed in two or more counterparts, each of
which shall be deemed an original but all of which shall constitute one and the
same instrument.

                                      -5-
<PAGE>
 
     IN WITNESS WHEREOF, the Shareholder has executed this Agreement and the
Acquiror has caused this Agreement to be duly executed by an officer, thereunto
duly authorized, all as of the day and year first above written.

                                 HALLIBURTON COMPANY


                                 By:/s/ Lester L. Coleman
                                    -----------------------------
                                    Lester L. Coleman
                                    Executive Vice President and General Counsel
 
                                 SHAREHOLDER


                                 /s/ James H. Simons 
                                 --------------------------------
                                 James H. Simons

                                      -6-
 
<PAGE>
 
                               VOTING AGREEMENT


     VOTING AGREEMENT ("Agreement") dated as of June 9, 1997, between
Halliburton Company, a Delaware corporation (the "Acquiror"), and Bermuda Trust
Company Limited, as Trustee of the Lord Jim Trust (the "Shareholder"), a holder
of common shares, par value $0.01 per share, of NUMAR Corporation, a
Pennsylvania corporation (the "Company").

                                   RECITALS:

     The Shareholder beneficially owns an aggregate of 900,000 common shares
(together with any additional common shares as to which beneficial ownership is
acquired by any member of the Shareholder Group described below, the "Company
Shares"), par value $0.01 per share ("Company Common Shares"), of the Company.

     The Acquiror is prepared to enter into an Agreement and Plan of Merger with
the Company (the "Plan") providing for the merger of a wholly owned subsidiary
of Acquiror with and into the Company and the conversion in such merger of each
Company Common Share into the number of shares of the Common Stock, par value
$2.50 per share, of the Acquiror set forth in the Plan (the "Merger").

     To facilitate the Merger, the Shareholder is willing to enter into certain
arrangements with respect to the Company Shares.

     NOW, THEREFORE, in consideration of the premises set forth above, the
mutual promises set forth below, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

1.   Shareholder's Support of the Merger. From the date hereof until December
31, 1997, or, if earlier, termination of the Plan:

          (a) Except as contemplated by the Plan or hereby, neither the
     Shareholder nor any Person controlled by the Shareholder, other than the
     Company and its subsidiaries (collectively, the "Shareholder Group"), will,
     directly or indirectly, sell, transfer, pledge or otherwise dispose of, or
     grant a proxy with respect to, any Company Shares to any Person other than
     any member of the Shareholder Group or the Acquiror or its designee, or
     grant an option with respect to any of the Company Shares or enter into any
     other agreement or arrangement with respect to any of the Company Shares.

          (b) The Shareholder agrees that the Shareholder will vote, and will
     cause each member of the Shareholder Group to vote, all Company Shares
     entitled to vote and beneficially owned by such Persons (i) in favor of the
     Merger and (ii), subject to the provisions of paragraph (c) below, against
     any combination proposal or other matter that may 
<PAGE>
 
     (in the reasonable opinion of the Acquiror) interfere or be inconsistent
     with the Merger (including without limitation a Competing Transaction).

          (c) The Shareholder agrees that, if requested by the Acquiror in
     writing in order to facilitate the Merger, the Shareholder will not, and
     will cause each member of the Shareholder Group not to, attend or vote any
     Company Shares beneficially owned by any such Person at any annual or
     special meeting of shareholders or execute any written consent of
     shareholders

          (d) Neither the Shareholder nor any other member of the Shareholder
     Group will initiate, solicit or encourage (including by way of furnishing
     information or assistance), or take any other action to facilitate, any
     inquiries or the making of any proposal that constitutes, or that may
     reasonably be expected to lead to, any merger, consolidation, share
     exchange, business combination or similar transaction involving the Company
     or any of its Significant Subsidiaries, a sale, lease, exchange, transfer
     or other disposition of 50% or more of the assets of the Company and its
     subsidiaries, taken as a whole, in a single transaction or series of
     transactions, the acquisition by a Person or Group of beneficial ownership
     or the right to acquire beneficial ownership of 50% or more of the
     outstanding Company Common Shares, whether by tender offer, exchange offer
     or otherwise, or the acquisition in any manner, directly or indirectly, of
     a material equity interest in any voting securities of, or a substantial
     portion of the assets of, the Company or any of its Significant
     Subsidiaries, other than the transactions contemplated by the Plan (a
     "Competing Transaction"), or enter into discussions or negotiate with any
     Person in furtherance of such inquiries or to obtain a Competing
     Transaction, or agree to or endorse any Competing Transaction, or authorize
     or permit any of the officers, directors or employees of the Shareholder or
     any member of the Shareholder Group or any investment banker, financial
     advisor, attorney, accountant or other representative retained by the
     Shareholder or any other member of the Shareholder Group to take any such
     action. The Shareholder shall promptly notify the Acquiror of all relevant
     terms of any such inquiries or proposals received by such Shareholder or
     any other member of the Shareholder Group or by any such officer, director,
     employee, investment banker, financial advisor, attorney, accountant or
     other representative relating to any of such matters and, if such inquiry
     or proposal is in writing, such Shareholder shall deliver or cause to be
     delivered to the Acquiror a copy of such inquiry or proposal.

          (e) The Shareholder hereby consents to the Acquiror's announcement in
     any press release, public filing, advertisement or other document, that the
     Shareholder has entered into this Agreement.

          (f) To the extent inconsistent with the provisions of this Section 1,
     the Shareholder hereby revokes, and will cause each member of the
     Shareholder Group to revoke, any and all proxies with respect to such
     member's Company Common Shares or any other voting securities of the
     Company.
 
                                      -2-
<PAGE>
 
2.   Miscellaneous

     (a) The Shareholder, on the one hand, and the Acquiror, on the other,
acknowledge and agree that irreparable damage would occur if any of the
provisions of this Agreement were not performed in accordance with their
specific terms or were otherwise breached.  It is accordingly agreed that the
parties hereto shall be entitled to an injunction or injunctions to prevent
breaches of the provisions of this Agreement and to enforce specifically the
terms and provisions hereof in any court of the United States or any state
thereof having jurisdiction, in addition to any other remedies to which they may
be entitled at law or equity.

     (b) Descriptive headings are for convenience only and shall not control or
affect the meaning or construction of any provision of this Agreement.

     (c) All notices, consents, requests, instructions, approvals and other
communications provided for herein shall be validly given, made or served, if in
writing and delivered personally, by telecopier (subject to receipt of
electronic confirmation) or sent by registered mail, postage prepaid:

          If to the Acquiror:

                   Halliburton Company
                   3600 Lincoln Plaza
                   500 N. Akard Street
                   Dallas, Texas  75201-3391
                   Attention:  Lester L. Coleman
                               Executive Vice President
                                 and General Counsel
                   Telecopier No.:  (214) 978-2658

                   with a copy to:

                           Vinson & Elkins L.L.P.
                           First City Tower
                           1001 Fannin
                           Houston, Texas  77002-6760
                           Attention:  William E. Joor III
                           Telecopier No.:  (713) 758-2346

                                      -3-
<PAGE>
 
          If to the Shareholder:

                  Murdoch & Co.
                  c/o Bank of Bermuda
                  Compass Point
                  9 Bermuda Road
                  Hamilton, Bermuda
                  Attention:  Susan Gibbons
                  Telecopier No.:  (441) 295-9991

or to such other address or telecopier number as any party may, from time to
time, designate in a written notice given in a like manner.  Notice given by
telecopier shall be deemed delivered on the day the sender receives telecopier
confirmation that such notice was received at the telecopier number of the
addressee.  Notice given by mail as set out above shall be deemed delivered
three days after the date the same is postmarked.

     (d) From and after the termination of this Agreement, the covenants of the
parties set forth herein shall be of no further force or effect and the parties
shall be under no further obligation with respect thereto.

     (e) For purposes of this Agreement, the following terms shall have the
following meanings:

         (i) Affiliate.  "Affiliate" shall have the meaning ascribed to it in
             ---------                                                       
     Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
     in effect on the date hereof.

         (ii) Associate.  "Associate" shall have the meaning ascribed to it in
              --------- 
     Rule 12b-2 of the General Rules and Regulations under the Exchange Act, as
     in effect on the date hereof.

          (iii) Beneficial Owner.  A person shall be deemed a "beneficial owner"
                ----------------                                                
     of or to have "beneficial ownership" of Company Shares in accordance with
     the interpretations of the term "beneficial ownership" as defined in Rule
     13-d(3) under the Exchange Act, as in effect on the date hereof, provided
     that a person shall be deemed to be the beneficial owner of, and to have
     beneficial ownership of, Company Shares that such Person or any Affiliate
     of such Person has the right to acquire (whether such right is exercisable
     immediately or only after the passage of time) pursuant to any agreement,
     arrangement or understanding or upon the exercise of conversion rights,
     exchange rights, warrant, options or otherwise.

          (iv) Exchange Act.  "Exchange Act" shall mean the Securities Exchange
               ------------ 
     Act of 1934, as amended.

                                      -4-
<PAGE>
 
          (v)  Person.  A "Person" shall mean any individual, firm, corporation,
               -------                                                         
     partnership, trust, limited liability company or other entity.

          (vi) Significant Subsidiary.  "Significant Subsidiary" shall have the
               -----------------------                                          
     meaning ascribed to it in Rule 1-02 of SEC Regulation S-X as in effect on
     the date hereof.

     (g) The Shareholder hereby represents and warrants to the Acquiror as
follows:  The Shareholder has full power and authority to enter into this
Agreement; neither the execution or delivery of this Agreement nor the
consummation of the transactions contemplated herein will (i) conflict with or
result in a breach, default or violation of (A) any of the terms, provisions or
conditions of the certificate of incorporation or bylaws of any member of the
Shareholder Group or (B) any agreement, proxy, document, instrument, judgment,
decree, order, governmental permit, certificate, license, law, statute, rule or
regulation to which any member of the Shareholder Group is a party or to which
it is subject, (ii) result in the creation of any lien, charge or other
encumbrance on any Company Common Shares or (iii) require any member of the
Shareholder Group to obtain the consent of any private nongovernmental third
party; and no consent, action, approval or authorization of, or registration,
declaration or filing with, any governmental department, commission, agency or
other instrumentality or any other person or entity is required to authorize, or
is otherwise required in connection with, the execution and delivery of this
Agreement (with the exception of an amended Schedule 13D to be filed by the
Shareholder pursuant to the Exchange Act) or the Shareholder's performance of
the terms of this Agreement or the validity or enforceability of this Agreement.

     (h) This Agreement shall be binding upon, and inure to the benefit of, the
parties hereto and their respective heirs, personal representatives, successors,
assigns and Affiliates, but shall not be assignable by either party hereto
without the prior written consent of the other party hereto.

     (i) No party may waive any of the terms or conditions of this Agreement
except by a duly signed writing referring to the specific provision to be
waived.

     (j) This Agreement shall be governed by, and construed in accordance with,
the laws of the State of Texas, regardless of the laws that might otherwise
govern under applicable principles of conflicts of law; provided, however, that
any matter involving the internal corporate affairs of any party hereto shall be
governed by the provisions of the Business Corporation Law of the Commonwealth
of Pennsylvania.

     (k) This Agreement constitutes the entire agreement, and supersedes all
other and prior agreements and understandings, both written and oral, among the
parties hereto and their Affiliates.

                                      -5-
<PAGE>
 
     (l) This Agreement may be executed in two or more counterparts, each of
which shall be deemed an original but all of which shall constitute one and the
same instrument.

                                      -6-
<PAGE>
 
     IN WITNESS WHEREOF, the Shareholder and the Acquiror have each caused this
Agreement to be duly executed by an officer or other Person, thereunto duly
authorized, all as of the day and year first above written.

                                 HALLIBURTON COMPANY


                                 By:/s/ Lester L. Coleman
                                    ------------------------------------------- 
                                    Lester L. Coleman
                                    Executive Vice President and General Counsel
 
                                 BERMUDA TRUST COMPANY LIMITED,
                                    as Trustee of the Lord Jim Trust


                                  By:/s/ Susan E. Gibbons
                                     ------------------------------------------
                                Name:  Susan E. Gibbons
                                Title: Trust Officer

                                     -7- 

<PAGE>
 
<TABLE>
<CAPTION>
 
 
FOR IMMEDIATE RELEASE    CONTACT:      Guy T. Marcus   Edward P. Delson
- -----------------------
<S>                      <C>           <C>             <C>
June 10, 1997            VP-Inv. Rel.  Sr. VP-CFO
Halliburton              NUMAR
                                       (214) 978-2691    (610) 251-0116
</TABLE>
                    HALLIBURTON TO ACQUIRE NUMAR CORPORATION
                    ----------------------------------------

     DALLAS, Texas -- Halliburton Company (NYSE:HAL) and NUMAR Corporation
(NASDAQ:NUMR) today jointly announced that they have signed a definitive
agreement providing for the acquisition of NUMAR by Halliburton in a stock-for-
stock transaction valued at about $360 million, or approximately $39.62 per
NUMAR share, based on Halliburton's closing share price on June 9, 1997.

     Under terms of the agreement, Halliburton will issue 0.4832 of a share of
its common stock for each outstanding share of NUMAR common stock (or 0.9664 of
a share presuming the acquisition closes following Halliburton's previously
announced 2-for-1 common stock split for shareholders of record at the close of
business on the June 26, 1997 record date).  Also, options and warrants of NUMAR
will be converted into Halliburton common stock securities based upon this
exchange ratio.  The acquisition will result in the issuance of approximately
4.4 million shares of Halliburton common stock (approximately 8.8 million shares
following the 2-for-1 stock split).  Approximately 130.9 million shares of
Halliburton common stock will be outstanding following completion of the
acquisition (261.8 million shares following the stock split).
                                    - more -

                                       1
<PAGE>
 
     The proposed merger has received unanimous approval from the boards of
directors of each company, but is subject to the approval of NUMAR's
stockholders and Hart-Scott-Rodino antitrust clearance.  For accounting
purposes, the merger will be structured as a pooling of interests and for
federal income tax purposes as a tax-free exchange to NUMAR shareholders.
NUMAR's directors and other affiliates representing over 25 percent of NUMAR's
shares have agreed to vote in favor of the proposed transaction.  The companies
anticipate completion of the acquisition during the 1997 third quarter.

     Dick Cheney, Halliburton Company's chairman of the board and chief
executive officer, said, "The acquisition of NUMAR is a strategic move
Halliburton is making to strengthen our position in the $3.2 billion formation
evaluation market. NUMAR has established itself as an industry leader with its
proprietary MRIL(R) technology which is fundamentally changing the future
direction of the marketplace.  Halliburton can help NUMAR to accelerate
development, delivery and application of the MRIL technology to benefit
customers by utilizing Halliburton's worldwide infrastructure.  The technology
is currently being applied to a small percentage of wells drilled worldwide, but
future growth opportunities are significant."

     NUMAR designs, manufactures and markets a patented proprietary well logging
device, the Magnetic Resonance Imaging Logging ("MRIL") tool, which
                                    - more -

                                       2
<PAGE>
 
utilizes magnetic resonance imaging ("MRI") technology, to evaluate subsurface
rock formations in newly-drilled oil and gas wells.  The MRIL tool measures
directly in real time at the wellsite the formation porosity, proportion of
fluid in the formation that is free to flow, fluid viscosity and type of
hydrocarbons in the pore space, and derived formation permeability.
Furthermore, these measurements are accomplished without the use of radioactive
sources, which are present in the traditional density and neutron logging tools.

     Halliburton believes the MRIL technology represents a major breakthrough in
wireline logging and that the acquisition of NUMAR will strengthen its position
in logging as the MRIL technology is deployed throughout the global Halliburton
organization.  Over the last two years, Halliburton has been a licensee of NUMAR
and, as a result, has had the opportunity to gain insight into MRIL technology,
including testing the reliability and performance of NUMAR's MRIL tools and to
verify the level of technological acceptance among a broad cross-section of
major customers around the world.

     While modestly dilutive to near-term earnings per share, Halliburton
believes that the transaction will not be dilutive to earnings per share for
1998 as the deployment of further enhancements increases customers acceptance of
MRIL technology.
                                    - more -

                                       3
<PAGE>
 
     NUMAR will operate as a wholly-owned subsidiary of Halliburton Company, and
part of Halliburton's Energy Services business segment.  Following the merger,
NUMAR's management team will remain in place with Dr. Melvin Miller continuing
as president.

     Miller said, "NUMAR is highly ambitious in its goal to provide the source
of real-time data with which oil and gas companies can better determine the
presence of hydrocarbons, the characteristics of rock formations and whether
commercial quantities of oil and gas can be recovered.  We are delighted to join
forces with Halliburton to accelerate and expand the scope and range of MRIL
technology throughout the world."

     NUMAR has distribution agreements with several service companies for the
use of MRIL technology.  The company will continue to honor these agreements.

     NUMAR Corporation was founded in 1983 and maintains its headquarters in
Malvern, Pennsylvania.  The company has about 140 employees and provides the
MRIL service to over 200 oil and gas company customers worldwide.

     Halliburton Company is one of the world's largest diversified energy
services, engineering, maintenance, and construction companies.  Founded in
1919, Halliburton provides a broad range of energy services and products,
industrial and marine engineering and construction services.
                                     # # #

                                       4


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