EXHIBIT 10.37

                            UNCONDITIONAL GUARANTY



             For and in consideration of the loan by SILICON VALLEY
        BANK ("Bank") to TYTRONICS INCORPORATED ("Borrower"), which
        loan is made pursuant to a Loan and Security Agreement of even
        date herewith between Borrower and Bank (the "Agreement"), the
        undersigned guarantor ("Guarantor") hereby unconditionally and
        irrevocably guarantees the prompt and complete payment of all
        amounts that Borrower owes to Bank and performance by Borrower
        of the Agreement and any other agreements between Borrower and
        Bank, as amended from time to time (collectively referred to
        as the "Agreements"), in strict accordance with their
        respective terms.

             1.   If Borrower does not perform its obligations in
        strict accordance with the Agreements, Guarantor shall
        immediately pay all amounts due thereunder (including, without
        limitation, all principal, interest, and fees) and otherwise
        to proceed to complete the same and satisfy all of Borrower's
        obligations under the Agreements.

             2.   The obligations hereunder are independent of the
        obligations of Borrower, and a separate action or actions may
        be brought and prosecuted against Guarantor whether action is
        brought against Borrower or whether Borrower be joined in any
        such action or actions.  Guarantor waives the benefit of any
        statute of limitations affecting its liability hereunder or
        the enforcement thereof, to the extent permitted by law.
        Guarantor's liability under this Guaranty is not conditioned
        or contingent upon the genuineness, validity, regularity or
        enforceability of the Agreements.

             3.   Guarantor authorizes Bank, without notice or demand
        and without affecting its liability hereunder, from time to
        time to (a) renew, extend, or otherwise change the terms of
        the Agreements or any part thereof; (b) take and hold security
        for the payment of this Guaranty or the Agreements, and
        exchange, enforce, waive and release any such security; and
        (c) apply such security and direct the order or manner of sale
        thereof as Bank in its sole discretion may determine.

             4.   Guarantor waives any right to require Bank to (a)
        proceed against Borrower or any other person; (b) proceed
        against or exhaust any security held from Borrower; or (c)
        pursue any other remedy in Bank's power whatsoever.  Bank may,
        at its election, exercise or decline or fail to exercise any
        right or remedy it may have against Borrower or any security
        held by Bank, including without limitation the right to
        foreclose upon any such security by judicial or nonjudicial
        sale, without affecting or impairing in any way the liability
        of Guarantor hereunder.  Guarantor waives any defense arising
        by reason of any disability<PAGE>




        or other defense of Borrower or by reason of the cessation
        from any cause whatsoever of the liability of Borrower.
        Guarantor waives any setoff, defense or counterclaim that
        Borrower may have against Bank.  Guarantor waives any defense
        arising out of the absence, impairment or loss of any right of
        reimbursement or subrogation or any other rights against
        Borrower.  Until all of the amounts that Borrower owes to Bank
        have been paid in full, Guarantor shall have no right of
        subrogation or reimbursement for claims arising out of or in
        connection with this Guaranty, contribution or other rights
        against Borrower, and Guarantor waives any right to enforce
        any remedy that Bank now has or may hereafter have against
        Borrower.  Guarantor waives all rights to participate in any
        security now or hereafter held by Bank.  Guarantor waives all
        presentments, demands for performance, notices of
        nonperformance, protests, notices of protest, notices of
        dishonor, and notices of acceptance of this Guaranty and of
        the existence, creation, or incurring of new or additional
        indebtedness.  Guarantor assumes the responsibility for being
        and keeping itself informed of the financial condition of
        Borrower and of all other circumstances bearing upon the risk
        of nonpayment of any indebtedness or nonperformance of any
        obligation of Borrower, warrants to Bank that it will keep so
        informed, and agrees that absent a request for particular
        information by Guarantor, Bank shall have no duty to advise
        Guarantor of information known to Bank regarding such
        condition or any such circumstances.

             5.   Guarantor acknowledges that, to the extent Guarantor
        has or may have certain rights of subrogation or reimbursement
        against Borrower for claims arising out of this Guaranty,
        those rights may be impaired or destroyed if Bank elects to
        proceed against any real property security of Borrower by non-
        judicial foreclosure.  That impairment or destruction could,
        under certain judicial cases and based on equitable principles
        of estoppel, give rise to a defense by Guarantor against its
        obligations under this Guaranty.  Guarantor waives that
        defense and any others arising from Bank's election to pursue
        non-judicial foreclosure.

             6.   If Borrower becomes insolvent or is adjudicated
        bankrupt or files a petition for reorganization, arrangement,
        composition or similar relief under any present or future
        provision of the United States Bankruptcy Code, or if such a
        petition is filed against Borrower, and in any such proceeding
        some or all of any indebtedness or obligations under the
        Agreements are terminated or rejected or any obligation of
        Borrower is modified or abrogated, or if Borrower's
        obligations are otherwise avoided for any reason, Guarantor
        agrees that Guarantor's liability hereunder shall not thereby
        be affected or modified and such liability shall continue in
        full force and effect as if no such action or proceeding had
        occurred.  This Guaranty shall continue to be effective or be
        reinstated, as the case may be, if any payment must be
        returned by Bank upon the insolvency, bankruptcy or
        reorganization of Borrower, Guarantor, any other guarantor, or
        otherwise, as though such payment had not been made.

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             7.   Any indebtedness of Borrower now or hereafter held
        by Guarantor is hereby subordinated to any indebtedness of
        Borrower to Bank; and such indebtedness of Borrower to
        Guarantor shall be collected, enforced and received by
        Guarantor as trustee for Bank and be paid over to Bank on
        account of the indebtedness of Borrower to Bank but without
        reducing or affecting in any manner the liability of Guarantor
        under the other provisions of this Guaranty.

             8.   Guarantor agrees to pay a reasonable attorneys' fee
        and all other costs and expenses which may be incurred by Bank
        in the enforcement of this Guaranty.  No terms or provisions
        of this Guaranty may be changed, waived, revoked or amended
        without Lender's prior written consent.  Should any provision
        of this Guaranty be determined by a court of competent
        jurisdiction to be unenforceable, all of the other provisions
        shall remain effective.  This Guaranty embodies the entire
        agreement among the parties hereto with respect to the matters
        set forth herein, and supersedes all prior agreements among
        the parties with respect to the matters set forth herein.  No
        course of prior dealing among the parties, no usage of trade,
        and no parol or extrinsic evidence of any nature shall be used
        to supplement, modify or vary any of the terms hereof.  There
        are no conditions to the full effectiveness of this Guaranty.
        Bank may assign this Guaranty without in any way affecting
        Guarantor's liability under it.  This Guaranty shall inure to
        the benefit of Bank and its successors and assigns.  This
        Guaranty is in addition to the guaranties of any other
        guarantors and any and all other guaranties of Borrower's
        indebtedness or liabilities to Bank.

             9.   Guarantor represents and warrants to Bank that (i)
        Guarantor has taken all necessary and appropriate action to
        authorize the execution, delivery and performance of this
        guaranty, (ii) execution, delivery and performance of this
        Guaranty do not conflict with or result in a breach of or
        constitute a default under Guarantor's Articles of
        Incorporation or Bylaws or other organizational documents or
        agreements to which it is party or by which it is bound, and
        (iii) this Guaranty constitutes a valid and binding
        obligation, enforceable against Guarantor in accordance with
        its terms.

             10.  Guarantor covenants and agrees that Guarantor shall
        do all of the following:

                  10.1 Guarantor shall maintain its corporate
        existence, remain in good standing in _______________, and
        continue to qualify in each jurisdiction in which the failure
        to so qualify could have a material adverse effect on the
        financial condition, operations or business of Guarantor.
        Guarantor shall maintain in force all licenses, approvals and
        agreement, the loss of which could have a material adverse
        effect on its financial condition, operations or business.

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                  10.2 Guarantor shall comply with all statutes, laws,
        ordinances, directives, orders, and government rules and
        regulations to which it is subject if non-compliance with such
        laws could adversely affect the financial condition,
        operations or business of Guarantor.

                  10.3 At any time and from time to time Guarantor
        shall execute and deliver such further instruments and take
        such further action as may reasonably be requested by Bank to
        effect the purposes of this Agreement.

             11.  This Guaranty shall be governed by the laws of the
        Commonwealth of Massachusetts, without regard to conflicts of
        laws principles.  GUARANTOR WAIVES ANY RIGHT TO A JURY TRIAL
        OF ANY CLAIM OR CAUSE OF ACTION BASED UPON OR ARISING OUT OF
        THIS GUARANTY OR ANY OF THE TRANSACTIONS CONTEMPLATED THEREIN,
        INCLUDING CONTRACT CLAIMS, TORT CLAIMS, BREACH OF DUTY CLAIMS,
        AND ALL OTHER COMMON LAW OR STATUTORY CLAIMS.  Guarantor
        submits to the exclusive jurisdiction of the state and federal
        courts of the Commonwealth of Massachusetts.

             IN WITNESS WHEREOF, the undersigned Guarantor has
        executed this Guaranty as of this ____ day of July, 1997.


                                           HOLOMETRIX, INC.

                                           By:    //JOHN E. WOLFE// 

                                           Name:  John E. Wolfe     

                                           Title: President         























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