EXHIBIT 10.10
                         THERMO INSTRUMENT SYSTEMS INC.
                     RESTATED STOCK HOLDING ASSISTANCE PLAN

        SECTION 1.   Purpose.

             The purpose of this Plan is to benefit Thermo Instrument
        Systems Inc. (the "Company") and its stockholders by encouraging
        Key Employees to acquire and maintain share ownership in the
        Company, by increasing such employees' proprietary interest in
        promoting the growth and performance of the Company and its
        subsidiaries and by providing for the implementation of the Stock
        Holding Policy.  

        SECTION 2.     Definitions.

             The following terms, when used in the Plan, shall have the
        meanings set forth below:

             Committee:   The Human Resources Committee of the Board of
        Directors of the Company as appointed from time to time.

             Common Stock:   The common stock of the Company and any
        successor thereto.

             Company:   Thermo Instrument Systems Inc., a Delaware
        corporation.

             Stock Holding Policy:   The Stock Holding Policy of the
        Company, as adopted by the Committee and as in effect from time
        to time.

             Key Employee:   Any employee of the Company or any of its
        subsidiaries, including any officer or member of the Board of
        Directors who is also an employee, as designated by the
        Committee, and who, in the judgment of the Committee, will be in
        a position to contribute significantly to the attainment of the
        Company's strategic goals and long-term growth and prosperity.

             Loans:   Loans extended to Key Employees by the Company
        pursuant to this Plan.

             Plan:   The Thermo Instrument Systems Inc. Stock Holding
        Assistance Plan, as amended from time to time.

        SECTION 3.     Administration.

             The Plan and the Stock Holding Policy shall be administered
        by the Committee, which shall have authority to interpret the
        Plan and the Stock Holding Policy and, subject to their
        provisions, to prescribe, amend and rescind any rules and
        regulations and to make all other determinations necessary or
        desirable for the administration thereof.  The Committee's
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        interpretations and decisions with regard to the Plan and the
        Stock Holding Policy and such rules and regulations as may be
        established thereunder shall be final and conclusive.  The
        Committee may correct any defect or supply any omission or
        reconcile any inconsistency in the Plan or the Stock Holding
        Policy, or in any Loan in the manner and to the extent the
        Committee deems desirable to carry it into effect.  No member of
        the Committee shall be liable for any action or omission in
        connection with the Plan or the Stock Holding Policy that is made
        in good faith.

        SECTION 4.     Loans and Loan Limits.

             The Committee has determined that the provision of Loans
        from time to time to Key Employees in such amounts as to cause
        such Key Employees to comply with the Stock Holding Policy is, in
        the judgment of the Committee, reasonably expected to benefit the
        Company and authorizes the Company to extend Loans from time to
        time to Key Employees in such amounts as may be requested by such
        Key Employees in order to comply with the Stock Holding Policy.
        Such Loans may be used solely for the purpose of acquiring Common
        Stock (other than upon the exercise of stock options or under
        employee stock purchase plans) in open market transactions or
        from the Company.

             Each Loan shall be full recourse and evidenced by a
        non-interest bearing promissory note substantially in the form
        attached hereto as Exhibit A (the "Note") and maturing in
        accordance with the provisions of Section 6 hereof, and
        containing such other terms and conditions, which are not
        inconsistent with the provisions of the Plan and the Stock
        Holding Policy, as the Committee shall determine in its sole and
        absolute discretion.

        SECTION 5.     Federal Income Tax Treatment of Loans.

             For federal income tax purposes, interest on Loans shall be
        imputed on any interest free Loan extended under the Plan.  A Key
        Employee shall be deemed to have paid the imputed interest to the
        Company and the Company shall be deemed to have paid said imputed
        interest back to the Key Employee as additional compensation.
        The deemed interest payment shall be taxable to the Company as
        income, and may be deductible to the Key Employee to the extent
        allowable under the rules relating to investment interest.  The
        deemed compensation payment to the Key Employee shall be taxable
        to the employee and deductible to the Company, but shall also be
        subject to employment taxes such as FICA and FUTA.

        SECTION 6.     Maturity of Loans.

             Each Loan to a Key Employee hereunder shall be due and
        payable on demand by the Company.  If no such demand is made,
        then each Loan shall mature and the principal thereof shall
        become due and payable on the fifth anniversary of the date of
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        the Loan, provided that the Committee may, in its sole and
        absolute discretion, authorize such other maturity and repayment
        schedule as the Committee may determine.  Each Loan shall also
        become immediately due and payable in full, without demand, upon
        the occurrence of any of the events set forth in the Note;
        provided that the Committee may, in its sole and absolute
        discretion, authorize an extension of the time for repayment of a
        Loan upon such terms and conditions as the Committee may
        determine.

        SECTION 7.     Amendment and Termination of the Plan.

             The Committee may from time to time alter or amend the Plan
        or the Stock Holding Policy in any respect, or terminate the Plan
        or the Stock Holding Policy at any time.  No such amendment or
        termination, however, shall alter or otherwise affect the terms
        and conditions of any Loan then outstanding to Key Employee
        without such Key Employee's written consent, except as otherwise
        provided herein or in the promissory note evidencing such Loan.

        SECTION 8.     Miscellaneous Provisions.

             (a)  No employee or other person shall have any claim or
        right to receive a Loan under the Plan, and no employee shall
        have any right to be retained in the employ of the Company due to
        his or her participation in the Plan.

             (b)  No Loan shall be made hereunder unless counsel for the
        Company shall be satisfied that such Loan will be in compliance
        with applicable federal, state and local laws.

             (c)  The expenses of the Plan shall be borne by the Company.

             (d)  The Plan shall be unfunded, and the Company shall not
        be required to establish any special or separate fund or to make
        any other segregation of assets to assure the making of any Loan
        under the Plan.

             (e)  Except as otherwise provided in Section 7 hereof, by
        accepting any Loan under the Plan, each Key Employee shall be
        conclusively deemed to have indicated his acceptance and
        ratification of, and consent to, any action taken under the Plan
        or the Stock Holding Policy by the Company, the Board of
        Directors of the Company or the Committee.

             (f)  The appropriate officers of the Company shall cause to
        be filed any reports, returns or other information regarding
        Loans hereunder, as may be required by any applicable statute,
        rule or regulation.

        SECTION 9.     Effective Date.

             The Plan and the Stock Holding Policy shall become effective
        upon approval and adoption by the Committee.
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                               EXHIBIT A TO STOCK HOLDING ASSISTANCE PLAN


                         THERMO INSTRUMENT SYSTEMS INC.

                                 Promissory Note



        $_________                                                       
                                                Dated:____________


             For value  received, ________________,  an individual  whose
        residence is located at _______________________ (the "Employee"),
        hereby promises to  pay to  Thermo Instrument  Systems Inc.  (the
        "Company"), or assigns, ON DEMAND, but  in any case on or  before
        [insert date which is the fifth anniversary of date of  issuance]
        (the "Maturity  Date"),  the principal  sum  of [loan  amount  in
        words] ($_______), or such part  thereof as then remains  unpaid,
        without interest.  Principal shall be payable in lawful money  of
        the United States of America, in immediately available funds,  at
        the principal office of the Company or at such other place as the
        Company may  designate  from  time  to time  in  writing  to  the
        Employee. 

             Unless the Company has already made a demand for payment  in
        full of this Note,  the Employee agrees to  repay to the  Company
        from the Employee's annual cash incentive compensation  (referred
        to as  bonus), beginning  with the  first such  bonus payment  to
        occur after the date of  this Note and on  each of the next  four
        bonus payment dates  occurring prior to  the Maturity Date,  such
        amount as may be designated by the Company. Any amount  remaining
        unpaid under this Note shall be  due and payable on the  Maturity
        Date.

             This Note may be prepaid at  any time or from time to  time,
        in whole  or  in part,  without  any  premium or  penalty.    The
        Employee acknowledges and agrees that the Company has advanced to
        the Employee the principal  amount of this  Note pursuant to  the
        Company's Stock Holding Assistance Plan,  and that all terms  and
        conditions of such Plan are incorporated herein by reference.  

             The unpaid principal amount of this Note shall be and become
        immediately due  and payable  without notice  or demand,  at  the
        option of  the  Company,  upon  the  occurrence  of  any  of  the
        following events:

                  (a)  the termination of the Employee's employment  with
             the Company, with or without cause, for any reason or for no
             reason;

                  (b)  the death or disability of the Employee;
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                  (c)  the failure  of the  Employee to  pay his  or  her
             debts as they  become due, the  insolvency of the  Employee,
             the filing by or against the Employee of any petition  under
             the United  States Bankruptcy  Code (or  the filing  of  any
             similar  petition   under   the  insolvency   law   of   any
             jurisdiction),  or  the  making   by  the  Employee  of   an
             assignment or trust mortgage for the benefit of creditors or
             the appointment of  a receiver, custodian  or similar  agent
             with respect  to,  or  the  taking by  any  such  person  of
             possession of, any property of the Employee; or

                  (d)  the issuance of any writ of attachment, by trustee
             process or otherwise, or any restraining order or injunction
             not removed, repealed or  dismissed within thirty (30)  days
             of issuance, against or affecting the person or property  of
             the Employee or any liability or obligation of the  Employee
             to the Company.

             In case any payment  herein provided for  shall not be  paid
        when due,  the Employee  further  promises to  pay all  costs  of
        collection, including all reasonable attorneys' fees.

             No  delay  or  omission  on  the  part  of  the  Company  in
        exercising any right hereunder shall operate as a waiver of  such
        right or of any other right of the Company, nor shall any  delay,
        omission or waiver  on any  one occasion be  deemed a  bar to  or
        waiver of the  same or any  other right on  any future  occasion.
        The  Employee  hereby  waives  presentment,  demand,  notice   of
        prepayment,  protest  and  all  other  demands  and  notices   in
        connection with the delivery, acceptance, performance, default or
        enforcement of this Note.  The undersigned hereby assents to  any
        indulgence  and  any  extension  of  time  for  payment  of   any
        indebtedness  evidenced  hereby  granted  or  permitted  by   the
        Company.  

             This Note  has been  made pursuant  to the  Company's  Stock
        Holding Assistance Plan and shall be governed by and construed in
        accordance with, such Plan and the laws of the State of  Delaware
        and shall have the effect of a sealed instrument.


                                      _______________________________

                                      Employee Name: _________________


        ________________________
        Witness