EXHIBIT 2

              AMENDMENT NO. 2 TO ASSET AND STOCK PURCHASE AGREEMENT

             This Amendment No. 2 to the Asset and Stock Purchase
        Agreement dated as of March 1, 1995, as previously amended (the
        "Agreement"), between Fisons plc, a company organized under the
        laws of England (the "Seller"), Thermo Instrument Systems Inc., a
        corporation organized under the laws of Delaware, U.S.A. (the
        "Buyer"), and Thermo Electron Corporation, a corporation
        organized under the laws of Delaware, U.S.A. (the "Parent"), is
        made as of the 1st day of November, 1995.  The Buyer and the
        Parent are sometimes collectively referred to herein as the
        "Thermo Parties".  Terms used but not otherwise defined herein
        shall have the meanings ascribed to them in the Agreement.

             WHEREAS, the parties acknowledge that certain conditions to
        closing of the transactions contemplated by the Agreement will
        not be satisfied unless the Thermo Parties and the Seller make
        certain undertakings with respect to the operation and sale of
        certain product lines included within the Business, including
        those described on Exhibit A attached hereto; and

             WHEREAS, to address the concerns of the U.S. Federal Trade
        Commission (the "FTC"), the Parent and the Seller intend to enter
        into a consent order (the "Consent Order") with the FTC and an
        Agreement to Hold Separate (the "Hold Separate") under which the
        Parent will agree, inter alia, to hold certain product lines,
        including those described on Exhibit A, separate from the
        remainder of the Business and the other businesses of the Thermo
        Parties and to sell such product lines to an unaffiliated third
        party within a certain period of time after the Closing; and

             WHEREAS, to address the concerns of the United Kingdom
        Director General of Fair Trading ("OFT") and the German
        Bundeskartellamt (the "FCO"), the Thermo Parties and the Seller
        may make similar undertakings with respect to certain product
        lines included in the Business (collectively, the "European
        Undertakings"); and

             WHEREAS, compliance by the Thermo Parties with the Consent
        Order and with the European Undertakings and the operation of the
        product lines subject to the Consent Order and the European
        Undertakings by the Thermo Parties prior to their sale may result
        in costs to the Thermo Parties that would not have been incurred
        if such product lines had been treated, instead, as Excluded
        Assets; and

             WHEREAS, the parties desire to put the Thermo Parties, to
        the extent possible, in the same position they would have been in
        had such product lines been treated as Excluded Assets, had the
        Purchase Price been reduced by the value of such product lines,
PAGE



        and had the Thermo Parties not been required to comply with the
        Consent Order and the European Undertakings;

             NOW, THEREFORE, the parties agree as follows:

             1.   Operation of Excluded Product Lines.

                  (a)  Sale of Excluded Product Lines.  The Seller and
        the Thermo Parties shall cooperate in the process of (i) defining
        (to the extent not specified in Exhibit A) the assets and
        liabilities that comprise the Excluded Product Lines (as such
        term is defined in Section 2(c) of this Amendment) and allocating
        employees to the Excluded Product Lines, (ii) preparing one or
        more selling memoranda and other documents necessary to provide
        prospective purchasers with information about the Excluded
        Product Lines, (iii) locating prospective purchasers and
        discussing  the Excluded Product Lines with prospective
        purchasers, (iv) facilitating due diligence review of the
        Excluded Product Lines by prospective purchasers, (v) negotiating
        purchase and sale agreements with prospective purchasers and (vi)
        conveying the assets and liabilities of the Excluded Product
        Lines to purchasers and otherwise facilitating an orderly
        transfer of the Excluded Product Lines to the purchasers thereof.
        Notwithstanding anything to the contrary in Exhibit A, the
        parties agree that the following employees (the "Excluded Product
        Line Employees") will be allocated to the Excluded Product Lines:
        (A) any employees whose responsibilities involve primarily the
        support of the Excluded Product Lines and (B) a percentage of the
        administrative (including, without limitation, clerical, human
        resources and accounting) employees at any Shared Building (as
        defined in Section 1(d)) equal to the ratio of the revenues
        generated from sales of Excluded Product Line products from such
        Shared Building to the revenues generated from sales of all
        products from such Shared Building.

             Notwithstanding the foregoing, the parties agree and
        acknowledge that the Seller shall bear primary responsibility for
        the sale of the Excluded Product Lines.  In furtherance of, but
        without limiting, the foregoing, the Seller shall be responsible,
        at its expense, for drafting and negotiating purchase and sale
        agreements with prospective purchasers, preparing exhibits and
        schedules to such agreements, providing representations and
        warranties and indemnifications to such purchasers, ensuring
        compliance of such transactions with applicable laws and
        preparing any periodic reports relating to compliance with the
        Consent Order, the Hold Separate or the European Undertakings
        that are required to be submitted to the FTC under the Consent
        Order or to the OFT or FCO under the European Undertakings,
        including applications for divestiture.  Such reports shall be
        provided to Buyer in sufficient time that Buyer has a reasonable
        opportunity to review and comment thereon prior to the time they
        are to be submitted.  The Thermo Parties shall have no liability
        or obligation to any purchaser of the Excluded Product Lines


                                        2PAGE



        except for the obligations of the Thermo Parties described in the
        first sentence of this Section 1(a) or to the extent such
        liability results from the gross negligence or willful misconduct
        of the Thermo Parties, their employees, agents or
        representatives.

             All consideration paid by purchasers of the Excluded Product
        Lines shall be paid directly to the Buyer at the closing of any
        sale of Excluded Product Lines.  Within five days after all of
        the Excluded Product Lines have been sold, the Seller shall pay
        to the Buyer interest from the Closing Date at the rate of the
        one-month London Interbank Offered Rate in effect from time to
        time as reported in The Wall Street Journal ("LIBOR") plus 1% on
        the Excluded Product Line Value (as such term is defined in
        Section 2(c) of this Amendment) as reduced from time to time upon
        the sale of Excluded Product Lines and the receipt by the Buyer
        of the cash proceeds from such sales as described in the
        preceding sentence.  Interest shall be computed for all purposes
        of this Amendment and the Agreement on a daily basis, with a year
        being deemed to represent 365 days.

                  (b)  Management of Excluded Product Lines.  The
        Excluded Product Lines shall be managed and operated as provided
        in the Hold Separate and the European Undertakings by the Manager
        and Management Committee ("Manager" and "Management Committee"
        being used herein as defined in the Hold Separate.)  Each of
        Seller and the Thermo Parties will direct their respective
        representatives on the Management Committee to act so that the
        Excluded Product Lines comply with applicable laws during the
        period they are subject to the Hold Separate; however, as the
        party controlling the Management Committee, the Seller shall be
        responsible for ensuring such compliance.  The Thermo Parties
        shall be provided promptly with any financial, tax or other
        information regarding the Excluded Product Lines as either of the
        Thermo Parties shall reasonably request, subject to any
        limitations on access to such information set forth in the
        Consent Order, the Hold Separate or the European Undertakings.  

                  (c)  Intellectual Property.  The parties acknowledge
        that there may be certain Intellectual Property that is used in
        the operation of both the Business other than the business of the
        Excluded Product Lines (the "Retained Businesses") and the
        business of the Excluded Product Lines ("Shared Intellectual
        Property").  Title to any such Shared Intellectual Property shall
         be retained by the Buyer and shall not be transferred to any
        purchaser of the Excluded Product Lines.  However, Buyer shall
        grant a license to any purchaser of Excluded Product Lines to use
        any Shared Intellectual Property used by such Excluded Product
        Lines, but only to the extent the Buyer has the legal right to
        grant such a license.  Any such license, to the extent legally
        possible, shall be perpetual, royalty-free and non-exclusive,
        shall be transferable only to those of such purchaser's
        suppliers, distributors or representatives who must obtain such a


                                        3PAGE


        license to legally make or sell products on behalf of such
        purchasers or those of such purchaser's customers who must obtain
        such a license to legally use such purchaser's products or to a
        subsequent purchaser of a business of the Excluded Product Lines,
        and shall be on such other terms and conditions as shall be
        reasonably acceptable to the Buyer.  Notwithstanding the
        foregoing, neither of the Thermo Parties shall be obligated to
        make any payment to any third parties or incur any out-of-pocket
        expenses to grant any such license unless the Thermo Party is
        reimbursed for such expense.  No such license shall apply to
        improvements to Shared Intellectual Property developed by Buyer
        after the Closing and the Thermo Parties will not have a license
        over or title to such improvements developed by the purchaser or
        in the operation of the business of the Excluded Product Lines
        after the Closing.

                  (d)  Ownership for Tax Purposes.  The Thermo Parties
        and the Seller agree that, notwithstanding the Consent Order, the
        Hold Separate or European Undertakings and any provision of the
        Agreement or this Amendment, the Thermo Parties shall for Tax
        purposes be treated as the legal owners of, and legally liable
        for Taxes with respect to, each of the Excluded Product Lines
        until the Thermo Parties have sold such Excluded Product Lines,
        unless the Thermo Parties shall have received a binding written
        determination by the applicable Taxing authorities, or shall have
        received an actual refund of Taxes paid, based upon a
        determination by the applicable Taxing authorities that the
        Thermo Parties are not legal owners of, and are not legally
        liable for Taxes with respect to, such Excluded Product Lines.

        `    2.   Indemnification.

                  (a)  By the Seller.  Notwithstanding anything to the
        contrary in the Agreement, including, without limitation, Section
        11.3 thereof, the Seller shall indemnify the Thermo Parties for
        all (i) Divestiture Costs (as defined in subparagraph (c) below),
        (ii) Negative Cashflow (as defined in subparagraph (c) below),
        (iii) Sale Price Shortfall (as defined in subparagraph (c)
        below), (iv) Excluded Product Line Taxes (as defined in
        subparagraph (c) below) except to the extent otherwise
        indemnified under this Section 2(a), (v) Excluded Product Line
        Losses (as defined in subparagraph (c) below), (vi) any Losses
        resulting from any failure by the Seller to comply with the
        Consent Order, the Hold Separate or the European Undertakings or
        from the failure of the Excluded Product Lines to be managed or
        operated in a manner that complies with the Consent Order, the
        Hold Separate or the European Undertakings or (vii) any
        Transaction Taxes or VAT applicable to the sale of the Excluded
        Product Lines to the Buyer under the Agreement.

                  (b)  By the Thermo Parties.  The Thermo Parties,
        jointly and severally, shall pay the Seller an amount equal to
        (i) Positive Cashflow (as defined in subparagraph (c) below),


                                        4PAGE



        (ii) 50% of all Sale Price Excess (as defined in subparagraph (c)
        below), (iii) Seller's Disposition Costs ( as defined in
        subparagraph (c) below), but only up to an amount equal to the
        excess of the Sale Price over the Excluded Product Line Value,
        (iv) Excluded Product Line Tax Benefits (as defined in
        subparagraph (c) below) except to the extent otherwise
        indemnified under this Section 2(b), and (v) any Losses resulting
        from any failure by the Thermo Parties to comply with the Consent
        Order, the Hold Separate or the European Undertakings.

                  (c)  Definitions.

                  (i)  "Divestiture Costs"  means, except to the extent
             otherwise paid or reimbursed to the Thermo Parties, (A) the
             reasonable fees and expenses of any legal, tax, accounting
             or other advisors retained by the Thermo Parties, and the
             out-of-pocket expenses reasonably incurred by employees of
             the Thermo Parties, incurred in connection with selling the
             Excluded Product Lines or complying with any aspect of the
             Consent Order, the Hold Separate or the European
             Undertakings relating to the ownership, operation,
             maintenance or disposition of the Excluded Product Lines,
             (B) the fees and expenses of any trustee or other third
             party that the Thermo Parties are required under the Consent
             Order or the European Undertakings to retain for purposes of
             operating or selling the Excluded Product Lines, (C) the
             out-of-pocket expenses reasonably incurred by any employees
             of the Thermo Parties in providing corporate services
             (including, without limitation, legal, tax, accounting,
             treasury, and risk management services) to or for the
             benefit of the Excluded Product Lines, (D) Transaction
             Taxes, VAT, filing fees and similar costs relating to the
             disposition of the Excluded Product Lines, (E) any
             Redundancy Costs (as defined below), (F) any Licensing Costs
             (as defined below) and (F) the costs and expenses of any
             lessors or sublessors (and their advisors, including
             applicable VAT) in connection with obtaining the consents of
             any such lessors or sublessors to the assignment of any
             leases relating to properties occupied by the Excluded
             Product Lines upon the sale of the Excluded Product Lines as
             contemplated hereby, but only to the extent such costs and
             expenses are billed to the Thermo Parties.  Other fees and
             expenses relating to the Agreement and the closing of the
             transactions contemplated thereby, including the negotiation
             of this Amendment, the Consent Order, the Hold Separate and
             the European Undertakings, shall be paid in accordance with
             Section 13.3 of the Agreement.  It is understood that Seller
             is taking primary responsibility for the sale of the
             Excluded Product Lines and therefore the fees and expenses
             of the Thermo Parties relating to any such sale and
             described in clause (A) above should be limited to any
             necessary review of the legal, financial or other impact of
             such sale on the Thermo Parties.


                                        5PAGE



                  (ii)  "Negative Cashflow"  means any cash invested in
             or loaned or advanced to any of the operations of the
             Excluded Product Lines by the Thermo Parties during the
             Interim Period (as defined below) except for any such
             investments, loans or advancements that are repaid prior to
             the end of the Interim Period.

                  (iii) "Excluded Product Line Taxes" means any and all
             losses, liabilities, obligations, damages, impositions,
             assessments, judgments, settlements, costs and expenses
             (including reasonable attorneys', accountants' and experts'
             fees and expenses and any applicable assessments of interest
             and penalties) with respect to the Tax liability of the
             Thermo Parties attributable to acquiring, owning, holding,
             operating or selling all or any part of the Excluded Product
             Lines related to any Tax period ending on or before the
             later of December 31, 1999 or the date upon which all of the
             Excluded Product Lines have been sold.  Excluded Product
             Line Taxes shall not include any Taxes actually or
             anticipated to be paid, incurred or accrued with respect to
             any taxable year ending after the later of December 31, 1999
             or the date upon which all of the Excluded Product Lines
             have been sold. The amount of Excluded Product Line Taxes
             shall be determined by computing (A) the amount of Taxes
             actually paid by the Thermo Parties and their affiliates
             (including the Excluded Product Lines), minus (B) the amount
             of Tax liability of the Thermo Parties and their affiliates
             determined as if the Thermo Parties had never acquired the
             Excluded Product Lines.  The amount of Excluded Product Line
             Taxes shall in no case be less than zero.

                  (iv)  "Excluded Product Line Losses"  means any Losses
             resulting from any Third Party Claim incurred by the Thermo
             Parties that arise from or relate to the ownership or
             operation of the Excluded Product Lines at any time, whether
             before or after the Closing Date, except to the extent such
             Losses result from the gross negligence or willful
             misconduct of the Thermo Parties, or their employees, agents
             or representatives.

                  (v)  "Excluded Product Line Tax Benefits" means any
             refunds of Taxes paid or the amount of the decrease, if any,
             in the amount of the Tax liability of the Thermo Parties and
             their affiliates attributable to acquiring, owning, holding,
             operating or selling all or any part of the Excluded Product
             Lines with respect to any Tax period ending on or before the
             later of December 31, 1999 or the date upon which all of the
             Excluded Product Lines have been sold.  Excluded Product
             Line Tax Benefits shall not include any reduction in Tax
             liability (or refunds) actually or anticipated to be
             received with respect to any taxable year ending after the
             later of December 31, 1999 or the date upon which all of the



                                        6PAGE


             Excluded Product Lines have been sold. The amount of
             Excluded Product Line Tax Benefits shall be determined by
             computing (A) the amount of tax liability of the Thermo
             Parties and their affiliates determined as if the Thermo
             Parties had never acquired the Excluded Product Lines minus
             (B) the amount of taxes actually paid by the Thermo Parties
             and their affiliates (including the Excluded Product Lines).
             The amount of the Excluded Product Line Tax Benefits will in
             no case be less than zero.

                  (vi)  "Sale Price Shortfall" means the amount by which
             the Excluded Product Line Value exceeds the aggregate cash
             purchase price actually received by the Buyer at the
             closing(s) for all of the Excluded Product Lines (the "Sale
             Price").  Neither non-cash consideration nor any deferred
             consideration will be included in the calculation of Sale
             Price.

                  (vii)  "Sale Price Excess"  means the amount by which
             the Sale Price exceeds the sum of (A) the Excluded Product
             Line Value plus (B) Seller's Disposition Costs.  Neither
             non-cash consideration nor any deferred consideration will
             be included in the calculation of Sale Price.

                  (viii)  "Positive Cashflow"  means any cash
             distributed, loaned or advanced from the businesses of the
             Excluded Product Lines to the Thermo Parties or their
             respective subsidiaries or affiliates other than the
             businesses of the Excluded Product Lines, except for any
             such loans or advances that are repaid by the Thermo Parties
             prior to the end of the Interim Period.

                  (ix)  "Seller's Disposition Costs" means the reasonable
             fees and expenses of any legal, tax, accounting, investment
             banking or other advisors retained by the Seller in
             connection with the sale of the Excluded Product Lines, and
             the reasonable out-of-pocket expenses incurred by employees
             of the Seller in connection with the sale of the Excluded
             Product Lines.  Other fees and expenses relating to the
             Agreement and the closing of the transaction contemplated
             thereby, including the negotiation of this Amendment, the
             Consent Order, the Hold Separate and the European
             Undertakings, shall be paid in accordance with Section 13.3
             of the Agreement.

                  (x)  "Excluded Product Lines" means the product lines
             described on Exhibit A attached hereto and any other product
             lines included within the Business, the divestiture of which
             is required by the FTC, OFT or FCO as a condition to the
             approval by any of such entities of the transactions
             contemplated by the Agreement.




                                        7PAGE



                  (xi) "Excluded Product Line Value" means

                  [Information ommitted, subject to request for
             confidential treatment.]

                  (xii)     "Redundancy Costs" means the costs of
             terminating the employment of any Excluded Product Line
             Employees that are not offered employment by the purchaser
             of the Excluded Product Line with which such Excluded
             Product Line Employees are associated.

                  (xiii)    "Licensing Costs" means the out-of-pocket
             costs incurred by the Thermo Parties as a result of any
             requirement under the Consent Order, the Hold Separate or
             the European Undertakings that the Thermo Parties (A)
             license to any third party any technology relating to a
             product included within the Retained Businesses, or (B)
             supply any such product to any third party on prescribed
             terms, except to the extent such costs are permitted to be
             recovered by the Thermo Parties under such license or supply
             arrangements.

                  (d)  Procedures for Indemnification.

                  (i)  The Seller shall indemnify the Thermo Parties for
             Divestiture Costs on a monthly basis within 30 days after
             receipt of a reasonably detailed description of the
             Divestiture Costs for which indemnification is sought.
             Seller shall provide to the Thermo Parties a reasonably
             detailed description of the Seller's Disposition Costs
             within 30 business days after completion of the sale of all
             of the Excluded Product Lines.

                  (ii)  The Seller shall indemnify the Buyer for any Sale
             Price Shortfall, or the Thermo Parties shall pay the Seller
             50% of any Sale Price Excess, as the case may be, and, to
             the extent provided in Section 2(b) of this Amendment, the
             Thermo Parties shall indemnify the Seller for Seller's
             Disposition Costs, within 30 business days after the last to
             occur of the Seller's receipt of the description of cash
             flow referred to in clause (iii) below, the Thermo Parties'
             receipt of the description of Seller's Disposition Costs
             referred to in clause (i) above and completion of the sale
             of all of the Excluded Product Lines.

                  (iii)  Within 40 business days after completion of the
             sale of all of the Excluded Product Lines, the Thermo
             Parties shall provide the Seller with a reasonably detailed
             description of any Negative Cashflow or Positive Cashflow.
             If the Positive Cashflow exceeds the Negative Cashflow, such
             description shall be accompanied by payment of such excess
             to the Seller.  If the Negative Cashflow exceeds the
             Positive Cashflow, the Seller shall pay the amount of such


                                        8PAGE



             excess to the Buyer within 30 days after receipt of such
             description.

                  (iv) Claims for indemnification for Excluded Product
             Line Taxes shall be made within 90 days of the filing of the
             Tax Return or amended Tax Return or payment of Tax, to which
             such claim relates.  Such claims shall be accompanied by a
             reasonably detailed description of the Excluded Product Line
             Taxes that are the subject of the claim for indemnification.
             In addition, for each taxable year beginning with the
             taxable year in which the Closing occurs and each subsequent
             taxable year ending on or before the later of December 31,
             1999 or December 31 of the year in which all of the Excluded
             Product Lines have been sold, the Buyer shall, no later than
             90 days after the filing of the Buyer's United States
             federal income Tax return for such taxable year, provide to
             the Seller a reasonably detailed description of all known
             Excluded Product Line Taxes and Excluded Product Line Tax
             Benefits with respect to that taxable year.  If such
             description shows Excluded Product Line Tax Benefits that
             exceed Excluded Product Line Taxes, such description shall
             be accompanied by payment of such excess to the Seller.  If
             such description shows Excluded Product Line Taxes in excess
             of Excluded Product Line Tax Benefits, the Seller shall pay
             the amount of such excess to the Buyer within 30 days after
             receipt of such description.  In either case, appropriate
             adjustment to the payment due shall be made to reflect any
             indemnification already made with respect to Excluded
             Product Line Taxes shown on such description (such as for
             estimated tax payments previously made and indemnified).

                  (v)  Any indemnification sought by the Thermo Parties
             for Excluded Product Line Losses shall follow the procedure
             set forth in Section 11.4 of the Agreement.

                  (vi) The Seller shall indemnify the Thermo Parties for
             the amounts referred to under clause (vii) of Section 2(a)
             above within 15 days after receipt of a reasonably detailed
             description of the amount and the basis for such
             indemnification and evidence of payment.

                  (vii)  As used in this Amendment the terms "Sale Price
             Shortfall" and "Sale Price Excess" exclude non-cash and
             deferred consideration in their calculation.  However, any
             such consideration that is received by the Thermo Parties
             and is thereafter reduced to cash after completion of the
             sale of all of the Excluded Product Lines shall be added to
             the Sale Price, and the Sale Price Shortfall, Sale Price
             Excess and Seller's Disposition Costs shall be recalculated
             accordingly.  Amounts owed to the Seller pursuant to Section
             2 of this Amendment after such recalculation shall be paid
             within 10 days of such recalculation.



                                        9PAGE



                  (e)  Settlement of Disputes.  Failure of the Seller to
        notify the Buyer in reasonable detail of any objection with
        respect to any description received as provided in subparagraph
        (d) above within 30 days after receipt of such description shall
        constitute acceptance thereof, whereupon all amounts shown
        therein to be due to the Thermo Parties shall be deemed to have
        been agreed to by the Seller.  If the Seller objects to any such
        descriptions within such 30-day period, the parties shall use
        good faith efforts to resolve any such objections.  However, if
        the parties cannot reach a resolution within 30 days after the
        Buyer has received notice of Seller's objection, the parties
        shall submit the dispute to the Neutral Auditors, the decision of
        which shall be binding upon the parties.  The parties shall share
        equally the fees and expenses of the Neutral Auditors.  The
        parties agree that nothing in this Section (2)(e) shall entitle
        the Seller to examine the books and records relating to the Taxes
        of the Thermo Parties and their affiliates, other than books and
        records relating solely to the Taxes of the Excluded Product
        Lines.  The parties further agree that the Neutral Auditors shall
        be permitted to examine the books and records relating to the
        books and records of the Thermo Parties only insofar as they
        relate to a dispute to be resolved under this Section 2(e), and
        only if the Neutral Auditors provide assurance reasonably
        acceptable to the Thermo Parties that the Neutral Auditors will
        preserve the confidentiality of all information regarding the
        Thermo Parties.

                  (f)  Survival of Indemnity.  The indemnification
        obligations of the parties under this Section 2 shall survive
        indefinitely.

                  (g)  Security.  To secure the obligations of the Seller
        pursuant to Sections 1(a) and 2(a) of this Amendment, at the
        Closing the Seller shall place cash in an amount equal to the
        Excluded Product Line Value in a collateral trust account at
        Chemical Bank and shall grant the Buyer a security interest in
        the proceeds of such account pursuant to a pledge and collateral
        trust agreement in the form attached hereto as Exhibit B.

                  (h)  All indemnification payments under the Agreement
        and this Amendment shall be deemed adjustments to the Purchase
        Price.

             3.   Adjustment of Purchase Price.

                  (a)  The last sentence of Section 2.1 of the Agreement
        is amended by replacing "138,000,000" British pounds sterling
        each place it appears by a figure that equals the Net Book Value
        of the Retained Businesses as of the December 31, 1994 balance
        sheet, assuming that the Retained Businesses consist of the
        Business other than the Excluded Product Lines described on
        Exhibit A.  Such figure is currently estimated to be 108.5
        million British pounds sterling, but the parties shall determine
        a precise figure in good faith.  If the Excluded

                                       10PAGE



        Product Lines include product lines in addition to those
        described on Exhibit A, such figure shall be recalculated to
        reflect the resulting change in composition of the Retained
        Businesses.

                  (b)  Section 4.1 of the Agreement is amended to read in
        its entirety as follows:

             "4.1 Post-Closing Adjustment.  The Purchase Price shall be
             subject to adjustment after the Closing Date as follows:

                  (a)  Within 60 days after the Closing Date, the Seller
             shall prepare and deliver to the Buyer a balance sheet as of
             the Closing Date, which shall reflect the assets and
             liabilities of the Retained Businesses (the "Draft Closing
             Balance Sheet").  The Draft Closing Balance Sheet shall not
             include assets or liabilities that are not Assets, Company
             Assets, Assumed Liabilities or Company Liabilities.  The
             Seller shall prepare the Draft Closing Balance Sheet in
             accordance with English generally accepted accounting
             principles ("GAAP") and the Accounting Principles and in
             such detail as the Buyer shall reasonably request.  The
             Draft Closing Balance Sheet shall include appropriate
             accruals for (x) liabilities of the Retained Businesses
             incurred prior to the Closing Date but for which invoices
             have not been received as of the Closing Date and (y)
             prepayments in respect of the Retained Businesses.

                  (b)  The Buyer shall deliver to the Seller within 60
             days after receiving the Draft Closing Balance Sheet a
             detailed statement describing its objections (if any)
             thereto. Failure of the Buyer so to object to the Draft
             Closing Balance Sheet shall constitute acceptance thereof,
             whereupon the Draft Closing Balance Sheet shall be deemed to
             be the "Closing Balance Sheet"The Buyer and the Seller shall
             use reasonable efforts to resolve any such objections, but
             if they do not reach a final resolution within 30 days after
             the Seller has received the statement of objections, the
             Buyer and the Seller shall select an accounting firm
             mutually acceptable to them (the "Neutral Auditors") to
             resolve any remaining objections.  If the Buyer and the
             Seller are unable to agree on the choice of Neutral
             Auditors, they shall select as Neutral Auditors an
             internationally-recognized accounting firm by lot (after
             excluding their respective regular independent accounting
             firms).  The Draft Closing Balance Sheet shall be adjusted
             by the Neutral Auditors only to conform to GAAP and the
             Accounting Principles and, as so adjusted, shall be the
             Closing Balance Sheet.  Such determination by the Neutral
             Auditors shall be conclusive and binding upon the Buyer and
             the Seller, absent fraud or manifest error.




                                       11PAGE


                  (c)  During the preparation of the Draft Closing
             Balance Sheet by the Seller and the period of any dispute
             referred to above, the Buyer shall promptly disclose to the
             Seller, the Seller's independent accountants and, if
             applicable, the Neutral Auditors all relevant facts and
             information, give them full access to books, records,
             facilities and employees of the Retained Businesses and
             cooperate fully with the Seller, the Seller's accountants
             and, if applicable, the Neutral Auditors in order to prepare
             the Draft Closing Balance Sheet or the Closing Balance
             Sheet, as the case may be;  provided, however, that any such
             access shall be allowed only in such manner as not to
             interfere unreasonably with the operation of the Retained
             Businesses.

                  (d)  The Buyer and the Seller shall share equally the
             fees and expenses of the Neutral Auditors. 

                  (e)  If the Net Book Value (as defined below) as shown
             on the Closing Balance Sheet is less than the Interim Net
             Book Value, the Seller shall pay to the Buyer, by wire
             transfer or other delivery of immediately available funds,
             within three business days after the date on which the
             Closing Balance Sheet is finally determined pursuant to this
             Section 4.1, an amount equal to such deficiency (plus
             interest thereon from the Closing Date at the interest rate
             equal to 1% above LIBOR).  "Net Book Value" shall mean the
             excess of the combined tangible Assets and Company Assets
             (and for the avoidance of doubt shall include accounts
             receivable, cash, bank balances and similar assets) of the
             Retained Businesses over the combined Assumed Liabilities
             and Company Liabilities of the Retained Businesses.

                  (f)  If the Net Book Value as shown on the Closing
             Balance Sheet exceeds the Interim Net Book Value, the Buyer
             shall pay to the Seller, by wire transfer or other delivery
             of immediately available funds, within three business days
             after the date on which the Closing Balance Sheet is finally
             determined pursuant to this Section 4.1, an amount equal to
             such excess (plus interest thereon from the Closing Date at
             the interest rate equal to 1% above LIBOR). 

             4.   Allocation of Purchase Price.  Notwithstanding Section
        4.2 of the Agreement, the portion of the Purchase Price allocated
        to the Assets and the Shares that comprise the Excluded Product
        Lines shall equal the Excluded Product Line Value.

             5.   Transition Period for Foreign Retirement Plans.  For
        Continuing Employees who are Excluded Product Line Employees and
        who are located outside of the U.S., the Foreign Transition
        Period (as defined in Section 7.7(a) of the Agreement) shall not
        equal one year, but shall equal the period commencing on the
        Closing Date through the date upon which all of the Excluded


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        Product Lines are sold by the Buyer to one or more unaffiliated
        third parties in accordance with the Consent Order (the "Sale
        Date").  

             6.   Health Insurance for U.K. Employees.  The maximum
        period during which the Seller shall be required, at the Buyer's
        election, to allow U.K. Employees to participate in the Seller's
        private health insurance scheme pursuant to Section 7.7(b)(vi) of
        the Agreement, shall be extended to the Sale Date for any
        Excluded Product Line Employees that are U.K. Employees.

             7.   Assignment.  Notwithstanding anything to the contrary
        in the Agreement, the Buyer may assign some or all of its rights
        and obligations under the Agreement to one or more third parties
        other than the Thermo Parties that acquire some or all of the
        Excluded Product Lines, to the extent such rights and obligations
        relate to such Excluded Product Lines.  To the extent such
        obligations are so assigned, neither the Buyer nor the Parent
        shall have any further obligation to the Seller with respect
        thereto, and the Seller will look only to the assignee for the
        performance thereof.

             8.   Modifications to Indemnification Provisions.  Section
        11.3(a) of the Agreement shall apply only to Losses that do not
        relate to the Excluded Product Lines, and each reference to
        "Losses" therein shall refer only to such Losses.  The
        Indemnification Threshold shall be reduced from 2,000,000 British
        pounds sterling to the product of (i) 2,000,000 British pounds
        sterling and (ii) the ratio of the Purchase Price less the
        Excluded Product Line Value to the Purchase Price.  The Minimum
        Claim Amount shall be reduced from 100,000 British pounds
        sterling to the product of (i) 100,000 British pounds sterling
        and (ii) the ratio of the Purchase Price less the Excluded
        Product Line Value to the Purchase Price.  Section 11.3(a)(ii)
        shall be amended to read in its entirety as follows:

             "(ii) The Indemnitor shall not be required to indemnify the
             Indemnitee for any Losses which, when added to the aggregate
             amount of all other Losses indemnifiable under this Section
             11, exceed in the aggregate one-half of the amount equal to
             the Purchase Price minus the Excluded Product Line Value."

             9.   Modification of Best Efforts Clause.  The following
        sentence shall be added as the second sentence of Section 7.3:

             "For purposes of clause (ii) of the preceding sentence and
        Section 13.11 hereof, "best efforts" shall include entering into
        arrangements with competition regulatory authorities that
        contemplate the divestiture by the Buyer of the Excluded Product
        Lines and the management of the Excluded Product Lines prior to
        such divestiture by the Seller."

             10.  Certain Employment Arrangements.   Notwithstanding
        anything to the contrary in the Agreement, the Thermo Parties

                                       13PAGE



        shall not assume any obligations whatsoever of the Seller or any
        other Asset Seller or any Company (including under any employment
        agreement, severance agreement or benefit or welfare plan of any
        kind, or under applicable law) with respect to the employment of
        David Richardson, the principal executive officer of the
        Business, or the termination of such employment, and the Seller
        shall indemnify the Thermo Parties against any costs or expenses
        incurred as a result of any such obligations.  The Seller shall
        use its best efforts to retain Mr. Richardson in the employment
        of the Business up to the Closing Date and terminate the
        employment of Mr. Richardson prior to the Closing.  If the Thermo
        Parties elect to offer employment to Mr. Richardson as of the
        Closing Date, such employment shall be deemed to be a new
        employment relationship and shall not cause the Thermo Parties to
        assume any liabilities with respect to Mr. Richardson's
        employment or termination by the Seller prior to the Closing.
         
             11.  Extension of Termination Date.  The Termination Date
        shall be extended to March 31, 1996.

             12.  Conflicts.  In the event of any conflict between the
        terms of this Amendment and any other term of the Agreement, the
        terms of this Amendment shall be controlling.

             13.  No Further Amendments.  Except as amended heretofore
        and hereby, the Agreement shall remain in full force and effect,
        enforceable in accordance with its terms.

             IN WITNESS WHEREOF, the parties have caused this Agreement
        to be executed on the day and year first written above.

                                      THERMO INSTRUMENT SYSTEMS INC.


                                      By:  Jonathan W. Painter
                                         Name:  Jonathan W. Painter
                                         Title:  Treasurer

                                      THERMO ELECTRON CORPORATION


                                      By:  Peter G. Pantazelos
                                         Name:  Peter G. Pantazelos
                                         Title:  Executive Vice President

                                      FISONS PLC


                                      By:  John H. Bailey
                                      Name:  John H. Bailey
                                      Title:  Corporate Development
                                              Director



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