THERMO PROCESS SYSTEMS INC.

                             Secured Promissory Note
                             Waltham, Massachusetts
                                                                         
                                    
        $28,000,000                                As of January 29, 1995


             For value received, THERMO PROCESS SYSTEMS INC., a Delaware
        corporation (the "Company"), hereby promises to pay to the order
        of Nord Est S.A., or assigns (hereinafter referred to as the
        "Payee"), the principal sum of twenty-eight million dollars
        ($28,000,000) or such part thereof as then remains unpaid,
        without interest, except as set forth below, and net of any
        withholding obligation that may apply under applicable law.  The
        principal amount hereof shall be payable $13,935,000 on February
        15, 1998 and $14,065,000 on May 15, 1998.  Principal and
        interest, if any, shall be payable in lawful money of the United
        States of America, in immediately available funds, at the
        principal office of the Payee or at such other place as the Payee
        may designate from time to time in writing to the Company.  This
        Note may be prepaid at any time or from time to time, in whole or
        in part, without any premium or penalty.  

             This Note is the Note referred to in that certain Stock
        Purchase and Sale Agreement effective as of the date hereof among
        Payee, the Company and certain members of the management of Elson
        T. Killam Associates Inc., a New Jersey corporation (the
        "Agreement"), and is secured by the deposit of U.S. Treasury
        securities as provided for in that certain Pledge Agreement
        effective as of the date hereof between the Company and the
        Payee.

             The then unpaid principal amount of this Note shall be and
        become immediately due and payable without notice or demand, at
        the option of the Payee, upon the occurrence of any of the
        following events (an "Event of Default"):

                  (a)  the failure of the Company to pay when due the
             principal amount hereof;

                  (b)  any representation or warranty made to the Payee
             by the Company in the Agreement shall prove to have been
             false or misleading in any material respect as of the date
             hereof;

                  (c)  the failure of the Company to pay its debts as
             they become due, the insolvency of the Company, the filing
             against the Company of any petition under the U.S.
             Bankruptcy Code (or the filing of any similar petition under
             the insolvency law of any jurisdiction) which filing is not
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             dismissed within 60 days thereafter, the filing by the
             Company of any petition under the U.S. Bankruptcy Code (or
             the filing by the Company of any similar petition under the
             insolvency law of any jurisdiction), or the making by the
             Company 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 Company;

                  (d)  the sale by the Company of all or substantially
             all of its assets (other than to Thermo Electron Corporation
             ("Thermo Electron") or to a subsidiary of Thermo Electron in
             a transaction in which Thermo Electron guarantees the
             payment of this Note);

                  (e)  the merger or consolidation of the Company with or
             into any other corporation (other than Thermo Electron or a
             subsidiary of Thermo Electron) in a transaction in which the
             Company is not the surviving entity;

                  (f)  the issuance of any writ of attachment, by trustee
             process or otherwise, or any restraining order or injunction
             not removed, repealed or dismissed within 60 days of
             issuance, against or affecting the person or property of the
             Company or any liability or obligation of the Company to the
             holder hereof; and

                  (f)  the suspension of the transaction of the usual
        business of the Company.

             Any amount that remains unpaid when due under this Note
        shall bear interest, from and after such due date through the
        date on which such amount is paid, at a rate per annum equal to
        the rate of interest announced from time to time by The First
        National Bank of Boston at its head office in Boston,
        Massachusetts as its "base rate" plus 3%.  In case any payment
        herein provided for shall not be paid when due, the Company
        further promises to pay all costs of collection, including all
        reasonable attorneys' fees.

             No delay or omission on the part of the Payee in exercising
        any right hereunder shall operate as a waiver of such right or of
        any other right of the Payee, 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 Company
        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 Company hereby assents to any indulgence and any
        extension of time for payment of any indebtedness evidenced
        hereby granted or permitted by the Payee.  The Company waives
        trial by jury and the right to interpose any counterclaim or
        setoff of any kind whatsoever.
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             The Company hereby irrevocably and unconditionally consents
        to submit to the exclusive jurisdiction of the courts of the
        State of New Jersey and of the United States of America located
        in or having jurisdiction over Millburn, New Jersey, for any
        actions, suits or proceedings arising out of or relating to this
        Note (and agrees not to commence any action, suit or proceeding
        relating thereto except in such courts), and further agrees that
        service of any process, summons, notice or document in accordance
        with the provisions of Section 6.1 of the Agreement shall be
        effective service of process for any action, suit or proceeding
        brought against the Company in any such court.  The Company
        hereby irrevocably and unconditionally waives any objection to
        the laying of venue of any action, suit or proceeding arising out
        of this Note in the courts of the State of New Jersey or of the
        United States of America located in or having jurisdiction over
        Millburn, New Jersey, and hereby further irrevocably and
        unconditionally waives and agrees not to plead or claim in any
        such court that any such action, suit or proceeding brought in
        any such court has been brought in an inconvenient forum.
          
             This Note shall be governed by and construed in accordance
        with, the laws of the Commonwealth of Massachusetts and shall
        have the effect of a sealed instrument.


                                      THERMO PROCESS SYSTEMS INC.

                                      By: /s/ John P. Appleton

                                      Printed Name: John P. Appleton

                                      Title: President

        [Corporate Seal]

        Attest:

        /s/ Sandra L. Lambert
        Sandra L. Lambert