EXHIBIT 4.2 Joint Officers' Certificate of Thermo Instrument Systems Inc. and Thermo Electron Corporation Pursuant to Section 301 of the Indenture Identified Below The undersigned, Melissa F. Riordan and Sandra Lambert, as the Treasurer and Corporate Secretary, respectively, of Thermo Instrument Systems Inc. (the "Company"), acting pursuant to authorizations contained in resolutions, copies of which are delivered herewith, duly adopted on July 17, 1997 and January 13, 1998 by the Board of Directors of the Company and on January 15, 1998 by the Pricing Committee thereof, and the undersigned, Melissa F. Riordan and Sandra Lambert, as the Treasurer and the Corporate Secretary, respectively, of Thermo Electron Corporation ("Thermo Electron" or the "Guarantor"), acting pursuant to authorizations contained in resolutions, copies of which are delivered herewith, duly adopted on July 17, 1997 and January 13, 1998 by the Board of Directors of the Guarantor, do hereby authorize, adopt and approve the following terms for a series (the "Series") of the Company's debt securities (the "Securities") to be issued under a Subordinated Indenture dated as of January 15, 1998 (the "Indenture"), from the Company, as issuer, and Thermo Electron, as guarantor, to Bankers Trust Company, as Trustee, pursuant to the Registration Statement on Form S-3 (Nos. 333-32031 and 333-32031-01) under the Securities Act of 1933, as amended. Terms used herein without definition shall have the meanings ascribed to such terms in the Indenture. Article and Section references are to the Indenture. - -------------------------------------------------------------------------------------------------------- Section The title or designation of the 4% Convertible Subordinated Debentures due 301 (1) Securities and the series in which the 2005 (the "Debentures"). Securities shall be included: - -------------------------------------------------------------------------------------------------------- -2- - -------------------------------------------------------------------------------------------------------- Section Any limit upon the aggregate principal $250,000,000 aggregate principal amount 301 (2) amount of the Securities of such title or designation or the Securities of such series which may be authenticated and delivered under the Indenture (except for Securities authenticated and delivered upon registration or transfer of, or in exchange for, or in lieu of, other Securities of such series pursuant to Section 304, 305, 306, 905 or 1107 of the Indenture, upon repayment in part of any Security of such series pursuant to Article Fifteen, or upon surrender in part of any Security for conversion or exchange into other securities pursuant to its terms, or pursuant to the terms of such Securities): - -------------------------------------------------------------------------------------------------------- Section If the Securities are to be issuable as The Debentures are to be issued as both 301 (3) Registered Securities, as Bearer Registered Debentures and as Bearer Debentures. Securities or alternatively as Bearer Securities and Registered Securities, and Bearer Debentures are to be issued with Coupons whether the Bearer Securities are to be attached (except for the temporary global Bearer issuable with Coupons, without Coupons or Debenture). (Section 201) both, and any restrictions applicable to the offer, sale or delivery of the Bearer Restrictions on the offer, sale and delivery of Securities and the terms, if any, upon Bearer Debentures are as set forth in the which Bearer Securities may be exchanged Indenture. (Section 304) for Registered Securities and vice versa: Bearer Debentures may be exchanged for Registered Debentures as set forth in the Indenture. (Section 305) Registered Debentures may not be exchanged for Bearer Debentures. (Section 305) - -------------------------------------------------------------------------------------------------------- -3- - -------------------------------------------------------------------------------------------------------- Section If any of the Securities are to be Registered Debentures are to be issued solely in 301 (4) issuable in global form, when any of such permanent global form (except as otherwise Securities are to be issuable in global specified in Section 305). The Depository for form and (i) whether such Securities are the Registered Debentures is the Depository to be issued in temporary or permanent Trust Company. Registered Debentures shall be global form or both, (ii) the extent to registered in the name of the Depository or its which, or the manner in which, any nominee (except as otherwise specified in interest payment or Additional Amounts on Section 305). Beneficial owners of interests in a global Security on an Interest Payment the permanent global Registered Debenture may Date will be paid and the manner in which not exchange such interest for Debentures, any principal of or premium, if any, on except as specified in Section 305. The original any global Security will be paid, (iii) issuance date for the Debentures is January 21, whether beneficial owners of interests in 1998. any such global Security may exchange such interests for Securities of the same Bearer Debentures shall be initially issued in series and of like tenor and of any temporary global form, to be delivered to and authorized form and denomination, and the held by Bankers Trust Company, London office, as circumstances under which any such the Common Depository. On and after the exchanges may occur, if other than in the Exchange Date, which is the date 40 days after manner specified in Section 305 of the the first closing date relating to the sale Indenture, (iv) the name of the of the Debentures, the temporary global Bearer Depository or the U.S. Depository, as the Debenture shall be exchangeable for Definitive case may be, with respect to any global Debentures as provided in the Indenture. Other Security, (v) the name of the Common exchanges shall be as set forth in the Indenture. Depository, if applicable, and (vi) the Exchange Date, if applicable: Payments of interest and Additional Amounts, if any, on an Interest Payment Date and payments of principal and premium, if any, shall be made to the registered holder of a global Debenture as provided in the Indenture. In the case of a temporary global Bearer Debenture, no interest payments or other payments thereon will be made until such temporary global Bearer Debenture is exchanged for definitive Debentures as provided in the Indenture. - -------------------------------------------------------------------------------------------------------- Section If any of the Securities are to be Bearer Debentures and Registered Debentures in 301 (5) issuable as Bearer Securities or in global form shall be dated the date of original global form, the date as of which any issuance of the Debentures. All other such Bearer Security or global Security Debentures shall be dated the date of their shall be dated (if other than the date of authentication. original issuance of the first of such Securities to be issued): - -------------------------------------------------------------------------------------------------------- -4- - -------------------------------------------------------------------------------------------------------- Section If any of the Securities are to be Not applicable. 301 (6) issuable as Bearer Securities, whether interest in respect of any portion of a temporary Bearer Security in global form payable in respect of an Interest Payment Date therefor prior to the Exchange Date, shall be paid to any clearing organization with respect to the portion of such temporary Bearer Security held for its account and, in such event, the terms and conditions (including any certification requirements) upon which any such interest payment received by a clearing organization will be credited to the Persons entitled to interest payable on such Interest Payment Date, if other than as provided in Section 304 of the Indenture: - -------------------------------------------------------------------------------------------------------- Section The date or dates, or the method or The Stated Maturity of the principal of the 301 (7) methods, if any, by which the date or Debentures is January 15, 2005. dates shall be determined on which the principal of the Securities is payable: - -------------------------------------------------------------------------------------------------------- Section The rate or rates at which the Securities The Debentures shall bear interest at the per 301 (8) shall bear interest, if any, or the annum rate of 4%. Interest shall accrue from method or methods, if any, by which such the date of original issuance of the Debentures. rate or rates are to be determined; the The Interest Payment Dates for the Debentures date or dates, if any, from which such shall be January 15 and July 15 in each year, interest shall accrue or the method or commencing July 15, 1998. The Regular Record Dates methods, if any, by which such date or for the interest payable on such Interest dates are to be determined; the Interest Payment Dates are January 1 and July 1, Payment Dates, if any, on which such respectively. Additional Amounts shall be interest shall be payable and the Regular payable on the Debentures as set forth in the Record Date, if any, for the interest Indenture. payable on Registered Securities on any Interest Payment Date; whether and under what circumstances Additional Amounts on such Securities or any of them shall be payable; the notice, if any, to Holders regarding the determination of interest on a floating rate Security and the manner of giving such notice, and the basis upon which interest shall be calculated if other than that of a 360-day year of twelve 30-day months: - -------------------------------------------------------------------------------------------------------- -5- - -------------------------------------------------------------------------------------------------------- Section If in addition to or other than the The Borough of Manhattan, The City of New York, 301 (9) Borough of Manhattan, The City of New in the case of Registered Debentures, and York (or, in the case of Bearer London, England and Luxembourg, in the case of Securities, except as otherwise provided Bearer Debentures, shall be the places where in the Indenture, London, England), the principal of, any premium and interest on or any place or places where the principal of, Additional Amounts with respect to such any premium and interest on or any Debentures shall be payable, any of such Additional Amounts with respect to such Debentures may be surrendered for registration Securities shall be payable, any of such of transfer and exchange, any of such Debentures Securities may be surrendered for may be surrendered for transfer, exchange or registration of transfer and exchange, conversion in the circumstances described herein any of such Securities may be surrendered and in the Indenture, and notices or demands to for transfer, exchange or conversion in or upon the Company or the Guarantor in respect the circumstances described herein and of such Debentures and the Indenture may be in the Indenture, and notices or demands served. to or upon the Company or the Guarantor in respect of such Securities and the Indenture may be served: Principal, premium (if any), interest payments and Additional Amounts with respect to a global Debenture will be paid in the manner set forth in the Indenture. - -------------------------------------------------------------------------------------------------------- Section Whether any of the Securities are to be The Debentures may be redeemed, at the option of 301 (10) redeemable at the option of the Company the Company, in whole or in part at any time on and, if so, the date or dates on which, or after January 15, 2001, on the Redemption Date, the period or periods within which, the upon notice as described in the Indenture, at price or prices at which and the other the Redemption Price; provided, however, that terms and conditions upon which the the Debentures may also be so redeemed on or Securities may be redeemed, in whole or before January 15, 2001, on the Redemption Date, in part, at the option of the Company in the event of certain changes in United States and, if other than by a Company Board taxation as set forth in the Indenture. Resolution, the manner in which any election by the Company to redeem the The Redemption Price shall be equal to 100% of Securities shall be evidenced: the principal amount of the Debentures, together with accrued interest to the date fixed for redemption, and any Additional Amounts then payable. (Section 1102) - -------------------------------------------------------------------------------------------------------- -6- - -------------------------------------------------------------------------------------------------------- Section If the Company is obligated to redeem or The Debentures are subject to repayment at the 301 (11) purchase any of the Securities pursuant option of the Holder on the Repayment Date at to any sinking fund or analogous the Repayment Price upon the occurrence of a provision or at the option of any Holder Repayment Event. (Section 1502) thereof and, if so, the date or dates on which, the period or periods within The Repayment Notice shall be given as set forth which, the price or prices at which and in the Indenture. (Section 1503) the other terms and conditions upon which the Securities shall be redeemed or Once a Holder of a Debenture shall deliver a purchased, in whole or in part, pursuant Debenture with the Option to Elect Repayment to such obligation, and any provisions duly completed and executed, such election to be for the remarketing of the Securities so repaid shall be irrevocable. (Section 1504) redeemed or purchased: The terms Repayment Date, Repayment Price and Repayment Event shall have the meanings set forth in the Indenture. (Section 1502) - -------------------------------------------------------------------------------------------------------- Section The denominations in which any of the None, except that the global Registered 301 (12) Securities that are Registered Securities Debenture held by the Depository and the shall be issuable if other than temporary global Bearer Debenture held by the denominations of $1,000 and any integral Common Depository (or by a custodian or multiple thereof, and the denominations depository therefor) shall be in such principal in which any of the Securities that are amount as the officer(s) manually executing the Bearer Securities shall be issuable if same shall approve, their manual execution other than the denominations of $1,000 thereof to be conclusive evidence of such and $10,000: approval. - -------------------------------------------------------------------------------------------------------- Section If other than the principal amount Not applicable. 301 (13) thereof, the portion of the principal amount of any of the Securities that shall be payable upon declaration of acceleration of the Maturity thereof pursuant to Section 502 of the Indenture or the method by which such portion is to be determined: - -------------------------------------------------------------------------------------------------------- -7- - -------------------------------------------------------------------------------------------------------- Section If the amount of payments of principal Not applicable. 301 (14) of, any premium or interest on or any Additional Amounts with respect to the Securities may be determined with reference to an index, indices, formula or other method or methods (which index, indices, formula or method or methods may be based, without limitation, on one or more currencies, commodities, equity indices or other indices), and, if so, the terms and conditions upon which and the manner in which such amounts shall be determined and paid or payable: - -------------------------------------------------------------------------------------------------------- Section Any deletions from, modifications of or Not applicable. 301 (15) additions to the Events of Default or covenants of the Company with respect to any of the Securities, whether or not such Events of Default or covenants are consistent with the Events of Default or covenants set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section If either or both of Section 402(2) Not applicable. 301 (16) relating to defeasance or Section 402(3) relating to covenant defeasance, as set forth in the Indenture, shall be applicable to the Securities, or any covenants in addition to those specified in Section 402(3) of the Indenture relating to the Securities which shall be subject to covenant defeasance, and any deletions from, or modifications or additions to, the provisions of Article Four of the Indenture in respect of the Securities shall apply: - -------------------------------------------------------------------------------------------------------- -8- - -------------------------------------------------------------------------------------------------------- Section The terms, if any, on which the The Debentures shall be convertible into shares 301 (17) Securities may be converted into or of Common Stock of the Company from the date of exchanged for other securities of the the issuance thereof (except that the temporary Company: global Bearer Debenture shall not be so convertible) as provided in the Indenture, at an initial Conversion Price (subject to adjustment as provided in the Indenture) of $35.65 per share. The Company may not substitute cash or other securities in lieu of the Common Stock to be delivered upon conversion of the Debentures. - -------------------------------------------------------------------------------------------------------- Section If any of the Securities are to be As set forth or provided in the Indenture. 301 (18) issuable in global form and are to be issuable in definitive form (whether upon original issue or upon exchange of a temporary Security) only upon receipt of certain certificates or other documents or satisfaction of other conditions, then the form and terms of such certificates, documents or conditions: - -------------------------------------------------------------------------------------------------------- Section If there is more than one Trustee, the The Trustee is: 301 (19) identity of the Trustee and, if not the Trustee, the identity of each Security Bankers Trust Company Registrar, Paying Agent, Conversion Agent Four Albany Street or Authenticating Agent with respect to 4th Floor such Securities: New York, NY 10006 The Trustee shall initially be the Security Registrar, one of the Authenticating Agents, the Conversion Agent and the Paying Agent with respect to the Debentures. - -------------------------------------------------------------------------------------------------------- -9- - -------------------------------------------------------------------------------------------------------- Section The subordination provisions with respect The Debentures shall rank pari passu with the 301 (20) to the Securities and Guarantees if other following outstanding obligations of the than as set forth in Article Seventeen or Company: none. Eighteen, respectively, of the Indenture: The obligations represented by the Guarantees shall rank pari passu with the following outstanding obligations of the Guarantor: (i) obligations with respect to its 4 1/4% Convertible Subordinated Debentures due 2003, (ii) subordinated guarantee of the 4 5/8% Convertible Subordinated Debentures due 2003 issued by Thermo TerraTech Inc., the 3 3/4% Convertible Subordinated Debentures due 2000 issued by Thermo Voltek Corp., the 4 7/8% Convertible Subordinated Debentures due 2000 issued by Thermo Remediation Inc., the 5% Convertible Subordinated Debentures due 2000 issued by ThermoQuest Corporation, the 5% Convertible Subordinated Debentures due 2000 issued by Thermo Optek Corporation, the Non-Interest Bearing Convertible Subordinated Debentures due 2001 and the 4 7/8% Convertible Subordinated Debentures due 2004 issued by Thermo Ecotek Corporation, the Non-Interest Bearing Convertible Subordinated Debentures due 2003 issued by Thermedics Inc., the 4 3/4% Convertible Subordinated Debentures due 2004 issued by Thermo Cardiosystems Inc., the 4 1/2% Convertible Subordinated Debentures due 2004 issued by Thermo Fibertek Inc., the 4 3/8% Convertible Subordinated Debentures due 2004 issued by ThermoLase Corporation and the 3 1/4% Convertible Subordinated Debentures due 2007 issued by ThermoTrex Corporation, and (iii) obligations with respect to its subordinated guarantee of the obligations to redeem the common stock of ThermoLyte Corporation, Thermo Fibergen Inc. and ThermoLase Corporation. In addition to the Senior Indebtedness set forth or described in the Indenture, Senior Indebtedness shall include, without limitation, the indebtedness represented by the following outstanding obligations of the Company: none. In addition to the Senior Guarantor Indebtedness set forth or described in the Indenture, Senior Guarantor Indebtedness shall include, without limitation, the indebtedness represented by the following outstanding obligations of the Guarantor: none. - -------------------------------------------------------------------------------------------------------- -10- - -------------------------------------------------------------------------------------------------------- Section Any other terms of the Securities and any The form of the definitive Registered Debentures 301 (21) deletions from or modifications or is attached to this Certificate as Exhibit A. additions to the Indenture in respect of The form of the Registered Debentures in global the Securities (which terms shall not be form is attached to this Certificate as Exhibit inconsistent with the provisions of the B. The forms of the definitive Bearer Indenture, except as permitted by Section Debentures and Coupons are attached to this 901 thereof): Certificate as Exhibit C. The form of the temporary Bearer Debenture in global form is attached to this Certificate as Exhibit D. - -------------------------------------------------------------------------------------------------------- Section Definition of Business Day, if other than Not applicable. 101 as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- - -------------------------------------------------------------------------------------------------------- Section Definition of United States, if other Not applicable. 101 than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- - -------------------------------------------------------------------------------------------------------- Section The extent to which an Indexed Security Not applicable. 101 is deemed Outstanding, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section Whether an Opinion of Counsel may not be Not applicable. 101 given by an employee of the Company or Guarantor: - -------------------------------------------------------------------------------------------------------- Section Whether actions by Holders may not be Not applicable. 104 taken by proxy: - -------------------------------------------------------------------------------------------------------- Section Whether notice of any event given to Not applicable. 106 Holders shall be in a manner different than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section Payment or conversion on a day other than Not applicable. 114 a Business Day, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- -11- - -------------------------------------------------------------------------------------------------------- Section Whether the Securities are issued with or The Debentures are guaranteed on a subordinated 202 without Guarantees: basis by Thermo Electron, as provided in the Indenture. - -------------------------------------------------------------------------------------------------------- Section Whether the Securities initially shall be Not applicable. 204 issued in other than global form: - -------------------------------------------------------------------------------------------------------- Section Whether payment of principal of, any Not applicable. 204 premium and (except for temporary global Bearer Securities) interest on, and any Additional Amounts in respect of, any temporary or permanent global Security shall be made to a Person or Persons other than the Person or Persons specified therein: - -------------------------------------------------------------------------------------------------------- Section The Persons whom the Trustee or any agent Notwithstanding the provisions of Section 308 204 of the Company or the Trustee shall treat and except as provided in the penultimate as the Holder of the principal amount of paragraph of Section 204, the Company, the the temporary global Bearer Security: Trustee or any agent of the Company and the Trustee shall treat the Common Depository as the Holder of the principal amount of the temporary global Bearer Security. - -------------------------------------------------------------------------------------------------------- Section Whether temporary Securities (other than The temporary Debentures, until so exchanged for 304(b) temporary global Bearer Securities), Definitive Debentures of such series, will be until exchanged for Definitive Securities entitled to the same benefits under the of such series, will be entitled to the Indenture as Definitive Debentures of such same benefits under the Indenture as series. Definitive Securities of such series: - -------------------------------------------------------------------------------------------------------- Section Whether temporary global Bearer Temporary global Bearer Debentures shall in all 304(c) Securities shall have the same rights and respects be entitled to the same rights and benefits as definitive Bearer Securities: benefits as definitive Bearer Debentures, except that Euroclear, Cedel or the beneficial owner, as applicable, must exchange the temporary global Bearer Debenture for definitive Debentures before interest payments or other payments thereon are collected or conversion rights exercised. - -------------------------------------------------------------------------------------------------------- -12- - -------------------------------------------------------------------------------------------------------- Section The terms on which a permanent global Not applicable. 305 Registered Security shall be exchangeable for definitive Securities, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section The terms under which holders of Not applicable. 305 definitive Registered Securities and Bearer Securities may exchange such interest for securities in global form, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section The terms on which interest on Bearer Not applicable. 306 Securities shall be paid without presentation and surrender of the applicable Coupon, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section The person or persons to receive payments Not applicable. 307(a) with respect to Registered Securities, if other than the registered holder (including DTC) thereof on the Regular Record Date: - -------------------------------------------------------------------------------------------------------- Section Manner in which payments of interest Not applicable. 307(a) shall be made if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section The terms on which a Bearer Security may Not applicable. 307(a) be exchanged for a Registered Security after a Regular Record Date and before an Interest Payment Date, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section Circumstances under which payments on a Not applicable. 307(a), Bearer Security may be paid in the United 1002 States, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section Method of paying interest, by check or Not applicable. 307(a) wire transfer or both, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- -13- - -------------------------------------------------------------------------------------------------------- Section The terms on which Defaulted Interest Not applicable. 307(b) shall be paid with respect to Registered Securities, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section Whether Securities or Coupons shall be Not applicable. 309 authenticated in lieu of or in exchange for any Securities or Coupons canceled as provided in Section 309 of the Indenture, except as expressly permitted by or pursuant to the Indenture: - -------------------------------------------------------------------------------------------------------- Section Qualifications for an Authenticating Not applicable. 612 Agent, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section Dates upon which the Company and the Not applicable. 701(1) Guarantor will furnish names and addresses of Holders, if other than as set forth in the Indenture: - -------------------------------------------------------------------------------------------------------- Section Whether the Company shall be required to The Company shall not be required to deposit 1105 deposit with the Trustee the accrued with the Trustee the accrued interest on and any interest on and any Additional Amounts Additional Amounts with respect to Debentures with respect to Securities being redeemed being redeemed if the Redemption Date shall be if the Redemption Date shall be an an Interest Payment Date. Interest Payment Date: - -------------------------------------------------------------------------------------------------------- Section Whether installments of interest on Not applicable. 1106 Bearer Securities whose Stated Maturity is on or prior to the Redemption Date shall be payable other than upon the presentation and surrender of the Coupons for such interest: - -------------------------------------------------------------------------------------------------------- Section Whether installments of interest on Not applicable. 1106 Registered Securities whose Stated Maturity is on or prior to the Redemption Date shall be payable to the Holders of such Securities registered as such at the close of business on the Regular Record Date: - -------------------------------------------------------------------------------------------------------- -14- - -------------------------------------------------------------------------------------------------------- Issue price to public of Securities of One hundred percent (100%) of the principal the Series: amount of the Debentures. - -------------------------------------------------------------------------------------------------------- Underwriters' commission or discount as a 2 1/4 percent (2 1/4%) percentage of the principal amount of Securities of the Series to be issued: - -------------------------------------------------------------------------------------------------------- REMAINDER OF PAGE INTENTIONALLY LEFT BLANK -15- IN WITNESS WHEREOF, the undersigned have executed this Certificate on behalf of the Company and Thermo Electron. THERMO INSTRUMENT SYSTEMS INC. By: /s/ Melissa F. Riordan _______________________________________ Name: Melissa F. Riordan Title Treasurer By: /s/ Sandra Lambert _______________________________________ Name: Sandra Lambert Title: Corporate Secretary THERMO ELECTRON CORPORATION By: /s/ Melissa F. Riordan _______________________________________ Name: Melissa F. Riordan Title: Treasurer By: /s/ Sandra Lambert _______________________________________ Name: Sandra Lambert Title: Corporate Secretary Dated as of January 15, 1998 EXHIBIT A (FORM OF FACE OF REGISTERED SECURITIES) THERMO INSTRUMENT SYSTEMS INC. (Incorporated in the State of Delaware) 4% CONVERTIBLE SUBORDINATED DEBENTURE DUE JANUARY 15, 2005 GUARANTEED ON A SUBORDINATED BASIS BY THERMO ELECTRON CORPORATION (Incorporated in the State of Delaware) No. R- __________ Cusip: 883559AE6 __________ Thermo Instrument Systems Inc., a Delaware corporation (herein referred to as the "Company," which term includes any successor corporation under the Indenture referred to on the reverse hereof), for value received, hereby promises to pay to ____________________ or registered assigns the principal sum of _______ Dollars plus any premium, if any, on January 15, 2005 (the "Stated Maturity") upon the presentation and surrender hereof or, at the option of the Company, in whole or in part at any time on or after January 15, 2001, upon notice as described in the Indenture and to pay interest thereon from January 21, 1998 or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually in arrears on January 15 and July 15 in each year (each, an "Interest Payment Date"), commencing July 15, 1998, at the rate of 4% per annum, and Additional Amounts, if any, until the principal hereof is paid or duly provided for. The interest and Additional Amounts, if any, so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Holder in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be the January 1 or July 1 (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date at the Office or Agency of the Company maintained for such purpose; provided, however, that such interest may be paid, at the Company's option, by mailing a check to such Holder at its registered address or by transfer of funds to an account maintained by such Holder within the United States. Any such interest not so punctually paid or duly provided for shall forthwith cease to be payable to the Holder on such Regular Record Date, and may be paid to the Holder in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of Securities of this series not less than 10 days prior to such Special Record Date, or may be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Securities of this series may be listed, and upon such notice as may be required by such exchange, all as more fully provided in the Indenture. Interest will be computed on the basis of a 360-day year of twelve 30-day months. All payments hereunder shall be made in United States Dollars. Reference is hereby made to the further provisions of this Security set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place. Unless the Certificate of Authentication hereon has been executed by the Trustee by manual signature of one of its authorized signatories, this Security shall not be entitled to any benefit under the Indenture, or be valid or obligatory for any purpose. -2- IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed under its facsimile corporate seal. Dated: January __, 1998 THERMO INSTRUMENT SYSTEMS INC. By:_______________________ Attest: [Name] [Title] _____________________________ Secretary [SEAL] CERTIFICATE OF AUTHENTICATION This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture. BANKERS TRUST COMPANY, as Trustee By: ____________________________ Authorized Officer -3- (FORM OF REVERSE OF REGISTERED SECURITIES) THERMO INSTRUMENT SYSTEMS INC. This Security is one of a duly authorized issue of securities of the Company (herein called the "Securities"), issued and to be issued in one or more series under an Indenture, dated as of January 15, 1998 (herein called the "Indenture") by the Company, as issuer, and Thermo Electron Corporation, as guarantor (herein called the "Guarantor," which term includes any successor corporation under the Indenture), to Bankers Trust Company, as Trustee (herein called the "Trustee," which term includes any successor trustee under the Indenture with respect to the series of which this Security is a part), to which Indenture and all indentures supplemental thereto reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Company, the Guarantor, the Trustee and the Holders of the Securities and any Coupons appertaining thereto, and of the terms upon which the Securities are, and are to be, authenticated and delivered. This Security is one of the duly authorized series of Securities designated on the face hereof and the aggregate principal amount of the Securities to be issued under such series is limited to $250,000,000 (except for Securities authenticated and delivered upon transfer of, or in exchange for, or in lieu of other Securities). The Guarantor has unconditionally guaranteed on a subordinated basis the payment of principal, premium, if any, and interest on the Securities. The Holders of the Securities will be entitled to the benefits of, be bound by, and be deemed to have notice of, all of the provisions of the Indenture. A copy of the Indenture is on file and may be inspected at the office of the Paying Agents appointed by the Company. All terms used in this Security which are defined in the Indenture shall have the meanings assigned to them in the Indenture. The Securities are issuable as bearer securities (the "Bearer Securities"), with interest Coupons attached, in the denominations of U.S. $1,000 and U.S. $10,000, and as registered securities (the "Registered Securities"), without Coupons, in denominations of U.S. $1,000 and integral multiples thereof, except as otherwise provided in or pursuant to the Indenture. The Registered Securities, and transfers thereof, shall be registered as provided in the Indenture. The holder of any Bearer Security or any Coupon appertaining thereto and the registered holder of a Registered Security shall (to the fullest extent permitted by applicable law) be treated at all times, by all persons and for all purposes as the absolute owner of such Security or Coupon, as the case may be, regardless of any notice of ownership, theft or loss or of any writing thereon. Bearer Securities may be exchanged for Registered Securities as set forth in the Indenture. Registered Securities may not be exchanged for Bearer Securities. The Securities are general, unsecured obligations of the Company, subordinated in right of payment to the prior payment in full of all existing and future Senior Indebtedness of the Company to the extent set forth in Article Seventeen of the Indenture. There are no restrictions herein on other indebtedness or securities which may be incurred or issued by the Company or the Guarantor. Additional Amounts shall be payable on the Securities as set forth in the Indenture. -4- If an Event of Default, as defined in the Indenture, shall occur and be continuing, the principal of the Securities of this series may be declared due and payable in the manner and with the effect provided in the Indenture. Subject to the terms of the Indenture, the Securities are convertible at any time prior to Maturity at an initial Conversion Price of $35.65 per share, subject to adjustment as provided in the Indenture. Accrued interest from the immediately preceding Interest Payment Date until the Conversion Date will be paid within five Business Days after the Conversion Date. In case this Security, or a portion thereof, is called for redemption, or is delivered for repayment, the conversion right in respect of this Security or a portion thereof so called and delivered shall expire on the close of business on the fifth Business Day preceding the Redemption Date or the second Business Day preceding a repayment on the Repayment Date, as the case may be, unless the Company defaults in making the payment due upon redemption or repayment, as the case may be. To convert this Security, the Holder must surrender this Security, duly endorsed or assigned to the Company, at any applicable Place of Conversion, accompanied by a duly signed conversion notice. Bearer Securities surrendered for conversion must be surrendered together with all Coupons appertaining thereto that mature after the Conversion Date, except as otherwise provided in the Indenture. The Securities are subject to redemption at any time on or after January 15, 2001, as a whole or in part, at the option of the Company, at a Redemption Price equal to 100% of the principal amount, together in the case of any such redemption with accrued interest to the Redemption Date as provided in the Indenture. Notice of redemption will be given to Holders of Securities, not less than 20 nor more than 60 days prior to the Redemption Date, all as provided in the Indenture. Subject to the terms of the Indenture, if as a result of a Tax Law Change the Company has or will become obligated to pay to the Holder of any Tax Affected Security Additional Amounts, and such obligation cannot be avoided by the Company taking reasonable measures available to it, then the Company may, at its option, redeem the Tax Affected Securities as a whole, but not in part, upon not less than 20 nor more than 60 days' notice to the Holders prior to the Redemption Date therefor, at a Redemption Price equal to 100% of the principal amount plus interest accrued to the Redemption Date, and any Additional Amounts then payable. Subject to the terms of the Indenture, the Securities are subject to repayment at the option of the Holder thereof, in whole or in part, on the Repayment Date, if the Common Stock (or other equity securities into which this Security is then convertible) is neither listed for trading on a United States national securities exchange, the Nasdaq National Market nor approved for trading on an established automated over-the-counter trading market in the United States. In such event, the Securities shall be repaid at a price equal to the principal amount hereof, plus accrued interest and Additional Amounts, if any. The Holders of Securities of this series desiring to be repaid must deliver (1) this Security with the "Option to Elect Repayment" duly signed and completed, or (2) such other documentation as may be provided by the Indenture, to the Trustee at the Place of Payment not earlier than 60 days nor later than 30 days prior to the Repayment Date. Bearer Securities must be surrendered together with all Coupons appertaining thereto that mature after the Repayment Date, except as otherwise provided in the Indenture. -5- In the event of redemption, exchange, repayment or conversion of this Security in part only, a new Security or Securities for the unredeemed, unexchanged, unrepaid or unconverted portion hereof shall be issued in the name of the Holder hereof upon the cancellation hereof as set forth in the Indenture. The Place of Payment, place of registration of transfer and exchange and the Place of Conversion for the Registered Securities and the Guarantees endorsed thereon, shall be the Borough of Manhattan, The City of New York, and the Corporate Trust Office of the Trustee shall be the Company's and the Guarantor's Office or Agency in the Borough of Manhattan, The City of New York for such purpose. The Places of Payment and Places of Conversion for the Bearer Securities and the Guarantees endorsed thereon, shall be London, England and Luxembourg, and the offices of the Trustee in London and Luxembourg shall be the Offices or Agencies for such purpose and the offices of the Trustee in London and Luxembourg shall be the Company's and the Guarantor's Paying Agent in London and Luxembourg, respectively. The Trustee initially shall be the Security Registrar, one of the Authenticating Agents, the Paying Agent and the Conversion Agent. The Trustee presently has its Corporate Trust Office at Four Albany Street, 4th Floor, New York, NY 10006, its Office in London at 1 Appold Street, Broadgate, London, EC2A 2HE, England, and its Office in Luxembourg at 14 Boulevard F.D. Roosevelt, L-2450 Luxembourg. The Company and the Guarantor may subsequently appoint an Office or Agency in addition to or other than the Borough of Manhattan, The City of New York with respect to the Registered Securities and London, England and Luxembourg with respect to the Bearer Securities. The Indenture permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the Guarantor and the rights of the Holders of the Securities under the Indenture at any time by the Company, the Guarantor and the Trustee with the consent of the Holders of not less than a majority of the aggregate principal amount of all Securities issued under the Indenture at the time Outstanding and affected thereby. The Indenture also contains provisions permitting the Holders of not less than a majority of the aggregate principal amount of the Outstanding Securities, on behalf of the Holders of all such Securities, to waive compliance by the Company and the Guarantor with certain provisions of the Indenture. Furthermore, provisions in the Indenture permit the Holders of not less than a majority of the aggregate principal amount, in certain instances, of the Outstanding Securities of any series to waive, on behalf of all of the Holders of Securities of such series, certain past defaults under the Indenture and their consequences. Any such consent or waiver by the Holder of this Security shall be conclusive and binding upon such Holder and upon all future Holders of this Security and other Securities issued upon the registration of transfer hereof or in exchange herefor or in lieu hereof, whether or not notation of such consent or waiver is made upon this Security. No reference herein to the Indenture and no provision of this Security or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional (except as to the specific subordination provisions contained in Article Seventeen of the Indenture), to -6- pay the principal of, premium, if any, interest and Additional Amounts, if any, on this Security at the times, places and rates, and in the coin or currency, herein prescribed. No service charge shall be made for any registration of transfer or exchange, but the Company may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith. The Indenture and the Securities shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts applicable to agreements made and to be performed entirely in such Commonwealth except that the rights, protections, obligations, indemnities and immunities of the Trustee under the Indenture and the Securities shall be governed by the laws of the State of New York, without regard to the principles of conflicts of laws of either state. -7- GUARANTEE For value received, Thermo Electron Corporation, a corporation organized under the laws of the State of Delaware (herein called the "Guarantor," which term includes any successor corporation under the Indenture referred to in the Security upon which this Guarantee is endorsed), hereby unconditionally guarantees to the Holder of the Security upon which this Guarantee is endorsed and to the Trustee on behalf of the Trustee and such Holder the due and punctual payment of the principal of, premium, if any, and interest and Additional Amounts, if any, on such Security, any other amount due and payable pursuant to the terms of the Indenture and the due and punctual payment of the sinking fund or analogous payments referred to therein if any, when and as the same shall become due and payable, whether at the Stated Maturity, by declaration of acceleration, call for redemption, repayment at the option of the Holder or otherwise, according to the terms thereof and of the Indenture. In case of the failure of Thermo Instrument Systems Inc., a corporation organized under the laws of Delaware (herein called the "Company," which term includes any successor corporation under such Indenture), punctually to make any such payment of principal, premium, if any, or interest or Additional Amounts, if any, the Guarantor hereby agrees to cause any such payment to be made punctually when and as the same shall become due and payable, whether at the Stated Maturity or by declaration of acceleration, call for redemption, repayment at the option of the Holder or otherwise, and as if such payment were made by the Company. The Guarantor hereby agrees that its obligations hereunder shall be as if it were principal debtor and not merely surety, and shall be absolute and unconditional (except as to the specific subordination provisions contained in Article Eighteen of the Indenture), irrespective of, and shall be unaffected by, any invalidity, subordination, irregularity or unenforceability of such Security or such Indenture, any failure to enforce the provisions of such Security or such Indenture, or any waiver, modification or indulgence granted to the Company with respect thereto, by the Holder of such Security or the Trustee or any other circumstance which may otherwise constitute a legal or equitable discharge of a surety or guarantor. The Guarantor hereby waives the benefits of diligence, presentment, demand of payment, filing of claims with a court in the event of merger, insolvency or bankruptcy of the Company, any right to require a proceeding first against the Company, protest or notice with respect to such Security or the indebtedness evidenced thereby and all demands whatsoever, and covenants that this Guarantee will not be discharged except by strict and complete performance of the obligations contained in such Security and this Guarantee. The Guarantor hereby agrees that, in the event of a default in payment of principal of, premium, if any, and interest, and Additional Amounts, if any, on such Security, or default in any sinking fund or analogous payment referred to therein, legal proceedings may be instituted by the Trustee on behalf of, or by, the Holder of such Security, on the terms and conditions set forth in the Indenture, directly against the Guarantor to enforce this Guarantee without first proceeding against the Company. The Guarantor shall be subrogated to all rights of the Holder of such Security and the Trustee against the Company in respect of any amounts paid to such Holder by the Guarantor on account of such Security pursuant to the provisions of this Guarantee or the Indenture; provided, however, that the -------- ------- Guarantor shall not be entitled to enforce, or to receive any payments arising -8- out of or based upon, such right of subrogation until the principal of, premium, if any, and interest and Additional Amounts, if any, on all Securities issued under such Indenture shall have been paid in full. Claims under this Guarantee are, to the extent provided in the Indenture, subject in right of payment to the prior payment in full of all Senior Guarantor Indebtedness, and this Guarantee is issued subject to the provisions of the Indenture with respect thereto. Each Holder of a Security upon which this Guarantee is endorsed, by accepting the same, (a) agrees to and shall be bound by such provisions, (b) authorizes and directs the Trustee on his behalf to take such action as may be necessary or appropriate to effectuate the subordination so provided and (c) appoints the Trustee his, her or its attorney-in-fact for any and all such purposes. No reference herein to such Indenture and no provision of this Guarantee or of such Indenture shall alter or impair the guarantee of the Guarantor, which is absolute and unconditional (except as to the specific subordination provisions contained in Article Eighteen of the Indenture), of the due and punctual payment of principal, premium (if any), and interest and Additional Amounts, if any, on the Security upon which this Guarantee is endorsed. This Guarantee shall not be valid or obligatory for any purpose until the certificate of authentication of the Security upon which this Guarantee is endorsed shall have been manually executed by or on behalf of the Trustee under such Indenture. All terms used in this Guarantee which are defined in such Indenture shall have the meanings assigned to them in such Indenture. This Guarantee shall be deemed to be a contract made under the laws of the Commonwealth of Massachusetts, and for all purposes shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts. IN WITNESS WHEREOF, the Guarantor has caused this Guarantee to be duly executed under its corporate seal and dated the date on the face hereof. THERMO ELECTRON CORPORATION Attest:______________________________ By: ________________________________ Title: _____________________________ -9- This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture. Dated: _______________________ BANKERS TRUST COMPANY, as Trustee By: __________________________ Authorized Officer -10- TRANSFER NOTICE FOR VALUE RECEIVED, the undersigned Holder hereby sell(s), assign(s) and transfer(s) unto______________________________________________________________ ______________________________________________________________________________ whose taxpayer identification number is _____________________ and whose address including postal/zip code is _____________________________________ the within Security and all rights thereunder, hereby irrevocably constituting and appointing _____________________________ attorney-in-fact to transfer said Security on the books of the Security Registrar with full power of substitution in the premises. Dated:___________________ Name:______________________ By:________________________ Title:_____________________ NOTICE: The signature of the Holder to this assignment must correspond with the name as written upon the face of the within instrument in every particular, without enlargement or any change whatsoever. SIGNATURE GUARANTEED ___________________________ -11- CONVERSION NOTICE The undersigned Holder of this Security hereby irrevocably exercises the option to convert this Security, or any portion of the principal amount hereof (which is an integral multiple of U.S. $1,000 below designated), into shares of Common Stock in accordance with the terms of the Indenture referred to in this Security, and directs that such shares, together with a check in payment for any fractional share and any Securities representing any unconverted principal amount hereof, be delivered to and be registered in the name of the undersigned unless a different name has been indicated below. If shares or Securities are to be registered in the name of a Person other than the undersigned, the undersigned will pay all transfer taxes payable with respect thereto. Dated:------------------------------ --------------------------------- Signature [MUST BE GUARANTEED IF STOCK OR SECURITIES ARE TO BE ISSUED IN A NAME OTHER THAN THE REGISTERED HOLDER OF THE SECURITY] - ------------------------------------ Name - ------------------------------------ Address - ------------------------------------ Social Security or other Taxpayer Identification Number, if any -12- If shares or Registered Securities are to If only a portion of the be registered in the name of a Person Securities is to be converted, other than the Holder, print such please please indicate: Person's name and address: 1. Principal amount to be converted: U.S. $___________________ _______________________________ 2. Principal amount and Name denomination of Registered Securities representing unconverted principal amount to be issued. _______________________________ Address Amount: U.S.$_________________ _______________________________ Social Security or other Taxpayer Denominations: Identification Number, if any U.S.$__________ (any integral multiple of U.S. $1,000) _______________________________ -13- OPTION TO ELECT REPAYMENT UPON A REPAYMENT EVENT To: Thermo Instrument Systems Inc. The undersigned owner of this Security hereby acknowledges receipt of a notice from Thermo Instrument Systems Inc.(the "Company") as to the occurrence of a Repayment Event with respect to the Common Stock of the Company and requests and instructs the Company to repay the entire principal amount of this Security, or the portion thereof (which is $1,000 or an integral multiple thereof) below designated, in accordance with the terms of the Indenture referred to in this Security at the Repayment Price (or the relevant percentage thereof), together with accrued interest to such date (except if the Repayment Date shall be an Interest Payment Date), to the holder hereof. Dated: ________________________ _______________________________ Signature*(s) Name: _______________________ Address:_____________________ _____________________ [* Signature Guarantee Required] Principal amount to be repaid (if less than all): $__________ NOTICE: If this Security is issued in registered form, the above signatures of the holder(s) hereof must correspond with the name as it appears in the Security in every particular without alteration or enlargement or any change whatever. ____________________________ Social Security or Other Taxpayer Identification Number -14- EXHIBIT B (FORM OF FACE OF REGISTERED GLOBAL SECURITIES) Unless this Security is presented by an authorized representative of The Depository Trust Company ("DTC"), 55 Water Street, New York, New York to the issuer or its agent for registration of transfer, exchange or payment, and such Security issued is registered in the name of CEDE & CO., or such other name as requested by an authorized representative of DTC, ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL, since the registered owner hereof, CEDE & CO., has an interest herein. Unless and until this Security is exchanged in whole or in part for Securities in certificated form, this Security may not be transferred except as a whole by DTC to a nominee thereof or by a nominee thereof to DTC or another nominee of DTC or by DTC or any such nominee to a successor of DTC or a nominee of such successor. THERMO INSTRUMENT SYSTEMS INC. (Incorporated in the State of Delaware) 4% CONVERTIBLE SUBORDINATED GLOBAL DEBENTURE DUE JANUARY 15, 2005 GUARANTEED ON A SUBORDINATED BASIS BY THERMO ELECTRON CORPORATION (Incorporated in the State of Delaware) No. R-________________ Cusip: 883559AE6 ________________ Thermo Instrument Systems Inc., a Delaware corporation (herein referred to as the "Company," which term includes any successor corporation under the Indenture referred to on the reverse hereof), for value received, hereby promises to pay to Cede & Co. or registered assigns the principal sum of _______ Dollars (or any other amounts as are endorsed on the Schedule of Adjustments hereto) plus any premium, if any, on January 15, 2005 (the "Stated Maturity") upon the presentation and surrender hereof or, at the option of the Company, in whole or in part at any time on or after January 15, 2001, upon notice as described in the Indenture and to pay interest thereon from January 21, 1998 or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually in arrears on January 15 and July 15 in each year (each, an "Interest Payment Date"), commencing July 15, 1998, at the rate of 4% per annum, and Additional Amounts, if any, until the principal hereof is paid or duly provided for. The interest and Additional Amounts, if any, so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Holder in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be the January 1 or July 1 (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date at the Office or Agency of the Company maintained for such purpose; provided, however, that such interest may be paid, at the Company's -------- ------- option, by mailing a check to such Holder at its registered address or by transfer of funds to an account maintained by such Holder within the United States. Any such interest not so punctually paid or duly provided for shall forthwith cease to be payable to the Holder on such Regular Record Date, and may be paid to the Holder in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of Securities of this series not less than 10 days prior to such Special Record Date, or may be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Securities of this series may be listed, and upon such notice as may be required by such exchange, all as more fully provided in the Indenture. Interest will be computed on the basis of a 360-day year of twelve 30-day months. All payments hereunder shall be made in United States Dollars. Subject to the applicable provisions of the Indenture, the aggregate principal amount represented by this global Security may be decreased to reflect exchanges or partial conversions, redemptions or repayments, by endorsing the Schedule of Adjustments hereto, and the principal amount hereof shall be deemed to be decreased for all purposes by the amount so exchanged, converted, redeemed or repaid, as applicable. Reference is hereby made to the further provisions of this Security set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place. Unless the Certificate of Authentication hereon has been executed by the Trustee by manual signature of one of its authorized signatories, this Security shall not be entitled to any benefit under the Indenture, or be valid or obligatory for any purpose. -2- IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed under its facsimile corporate seal. Dated: January __, 1998 THERMO INSTRUMENT SYSTEMS INC. By:_______________________ Attest: [Name] [Title] _______________________________ Secretary [SEAL] CERTIFICATE OF AUTHENTICATION This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture. BANKERS TRUST COMPANY, as Trustee By:________________________ Authorized Officer -3- (FORM OF REVERSE OF REGISTERED GLOBAL SECURITIES) THERMO INSTRUMENT SYSTEMS INC. This Security is one of a duly authorized issue of securities of the Company (herein called the "Securities"), issued and to be issued in one or more series under an Indenture, dated as of January 15, 1998 (herein called the "Indenture") by the Company, as issuer, and Thermo Electron Corporation, as guarantor (herein called the "Guarantor," which term includes any successor corporation under the Indenture), to Bankers Trust Company, as Trustee (herein called the "Trustee," which term includes any successor trustee under the Indenture with respect to the series of which this Security is a part), to which Indenture and all indentures supplemental thereto reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Company, the Guarantor, the Trustee and the Holders of the Securities and any Coupons appertaining thereto, and of the terms upon which the Securities are, and are to be, authenticated and delivered. This Security is one of the duly authorized series of Securities designated on the face hereof and the aggregate principal amount of the Securities to be issued under such series is limited to $250,000,000 (except for Securities authenticated and delivered upon transfer of, or in exchange for, or in lieu of other Securities). The Guarantor has unconditionally guaranteed on a subordinated basis the payment of principal, premium, if any, and interest on the Securities. The Holders of the Securities will be entitled to the benefits of, be bound by, and be deemed to have notice of, all of the provisions of the Indenture. A copy of the Indenture is on file and may be inspected at the office of the Paying Agents appointed by the Company. All terms used in this Security which are defined in the Indenture shall have the meanings assigned to them in the Indenture. The Securities are issuable as bearer securities (the "Bearer Securities"), with interest Coupons attached, in the denominations of U.S. $1,000 and U.S. $10,000, and as registered securities (the "Registered Securities"), without Coupons, in denominations of U.S. $1,000 and integral multiples thereof, except as otherwise provided in or pursuant to the Indenture. The Registered Securities, and transfers thereof, shall be registered as provided in the Indenture. The holder of any Bearer Security or any Coupon appertaining thereto and the registered holder of a Registered Security shall (to the fullest extent permitted by applicable law) be treated at all times, by all persons and for all purposes as the absolute owner of such Security or Coupon, as the case may be, regardless of any notice of ownership, theft or loss or of any writing thereon. Bearer Securities may be exchanged for Registered Securities as set forth in the Indenture. Registered Securities may not be exchanged for Bearer Securities. The Securities are general, unsecured obligations of the Company, subordinated in right of payment to the prior payment in full of all existing and future Senior Indebtedness of the Company to the extent set forth in Article Seventeen of the Indenture. There are no restrictions herein on other indebtedness or securities which may be incurred or issued by the Company or the Guarantor. Additional Amounts shall be payable on the Securities as set forth in the Indenture. -4- If an Event of Default, as defined in the Indenture, shall occur and be continuing, the principal of the Securities of this series may be declared due and payable in the manner and with the effect provided in the Indenture. Subject to the terms of the Indenture, the Securities are convertible at any time prior to Maturity at an initial Conversion Price of $35.65 per share, subject to adjustment as provided in the Indenture. Accrued interest from the immediately preceding Interest Payment Date until the Conversion Date will be paid within five Business Days after the Conversion Date. In case this Security, or a portion thereof, is called for redemption, or is delivered for repayment, the conversion right in respect of this Security or a portion thereof so called and delivered shall expire on the close of business on the fifth Business Day preceding the Redemption Date or the second Business Day preceding a repayment on the Repayment Date, as the case may be, unless the Company defaults in making the payment due upon redemption or repayment, as the case may be. To convert this Security, the Holder must surrender this Security, duly endorsed or assigned to the Company, at any applicable Place of Conversion, accompanied by a duly signed conversion notice. Bearer Securities surrendered for conversion must be surrendered together with all Coupons appertaining thereto that mature after the Conversion Date, except as otherwise provided in the Indenture. The Securities are subject to redemption at any time on or after January 15, 2001, as a whole or in part, at the option of the Company, at a Redemption Price equal to 100% of the principal amount, together in the case of any such redemption with accrued interest to the Redemption Date as provided in the Indenture. Notice of redemption will be given to Holders of Securities, not less than 20 nor more than 60 days prior to the Redemption Date, all as provided in the Indenture. Subject to the terms of the Indenture, if as a result of a Tax Law Change the Company has or will become obligated to pay to the Holder of any Tax Affected Security Additional Amounts, and such obligation cannot be avoided by the Company taking reasonable measures available to it, then the Company may, at its option, redeem the Tax Affected Securities as a whole, but not in part, upon not less than 20 nor more than 60 days' notice to the Holders prior to the Redemption Date therefor, at a Redemption Price equal to 100% of the principal amount plus interest accrued to the Redemption Date, and any Additional Amounts then payable. Subject to the terms of the Indenture, the Securities are subject to repayment at the option of the Holder thereof, in whole or in part, on the Repayment Date, if the Common Stock (or other equity securities into which this Security is then convertible) is neither listed for trading on a United States national securities exchange, the Nasdaq National Market nor approved for trading on an established automated over-the-counter trading market in the United States. In such event, the Securities shall be repaid at a price equal to the principal amount hereof, plus accrued interest and Additional Amounts, if any. The Holders of Securities of this series desiring to be repaid must deliver (1) this Security with the "Option to Elect Repayment" duly signed and completed, or (2) such other documentation as may be provided by the Indenture, to the Trustee at the Place of Payment not earlier than 60 days nor later than 30 days prior to the Repayment Date. Bearer -5- Securities must be surrendered together with all Coupons appertaining thereto that mature after the Repayment Date, except as otherwise provided in the Indenture. The Place of Payment, place of registration of transfer and exchange and the Place of Conversion for the Registered Securities and the Guarantees endorsed thereon, shall be the Borough of Manhattan, The City of New York, and the Corporate Trust Office of the Trustee shall be the Company's and the Guarantor's Office or Agency in the Borough of Manhattan, The City of New York for such purpose. The Places of Payment and Places of Conversion for the Bearer Securities and the Guarantees endorsed thereon, shall be London, England and Luxembourg, and the offices of the Trustee in London and Luxembourg shall be the Offices or Agencies for such purpose and the offices of the Trustee in London and Luxembourg shall be the Company's and the Guarantor's Paying Agent in London and Luxembourg, respectively. The Trustee initially shall be the Security Registrar, one of the Authenticating Agents, the Paying Agent and the Conversion Agent. The Trustee presently has its Corporate Trust Office at Four Albany Street, 4th Floor, New York, NY 10006, its Office in London at 1 Appold Street, Broadgate, London, EC2A 2HE, England, and its Office in Luxembourg at 14 Boulevard F.D. Roosevelt, L-2450 Luxembourg. The Company and the Guarantor may subsequently appoint an Office or Agency in addition to or other than the Borough of Manhattan, The City of New York with respect to the Registered Securities and London, England and Luxembourg with respect to the Bearer Securities. The Indenture permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the Guarantor and the rights of the Holders of the Securities under the Indenture at any time by the Company, the Guarantor and the Trustee with the consent of the Holders of not less than a majority of the aggregate principal amount of all Securities issued under the Indenture at the time Outstanding and affected thereby. The Indenture also contains provisions permitting the Holders of not less than a majority of the aggregate principal amount of the Outstanding Securities, on behalf of the Holders of all such Securities, to waive compliance by the Company and the Guarantor with certain provisions of the Indenture. Furthermore, provisions in the Indenture permit the Holders of not less than a majority of the aggregate principal amount, in certain instances, of the Outstanding Securities of any series to waive, on behalf of all of the Holders of Securities of such series, certain past defaults under the Indenture and their consequences. Any such consent or waiver by the Holder of this Security shall be conclusive and binding upon such Holder and upon all future Holders of this Security and other Securities issued upon the registration of transfer hereof or in exchange herefor or in lieu hereof, whether or not notation of such consent or waiver is made upon this Security. No reference herein to the Indenture and no provision of this Security or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional (except as to the specific subordination provisions contained in Article Seventeen of the Indenture), to pay the principal of, premium, if any, interest and Additional Amounts, if any, on this Security at the times, places and rates, and in the coin or currency, herein prescribed. -6- No service charge shall be made for any registration of transfer or exchange, but the Company may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith. The Indenture and the Securities shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts applicable to agreements made and to be performed entirely in such Commonwealth except that the rights, protections, obligations, indemnities and immunities of the Trustee under the Indenture and the Securities shall be governed by the laws of the State of New York, without regard to the principles of conflicts of laws of either state. -7- SCHEDULE OF ADJUSTMENTS Remaining Notation Principal principal amount made on amount following such behalf of the Date made adjustment adjustment Trustee - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ----------------- - -------------- -------------------- ------------- ------------------ - ------------------------------------------------------------------------------- -8- GUARANTEE For value received, Thermo Electron Corporation, a corporation organized under the laws of the State of Delaware (herein called the "Guarantor," which term includes any successor corporation under the Indenture referred to in the Security upon which this Guarantee is endorsed), hereby unconditionally guarantees to the Holder of the Security upon which this Guarantee is endorsed and to the Trustee on behalf of the Trustee and such Holder the due and punctual payment of the principal of, premium, if any, and interest and Additional Amounts, if any, on such Security, any other amount due and payable pursuant to the terms of the Indenture and the due and punctual payment of the sinking fund or analogous payments referred to therein if any, when and as the same shall become due and payable, whether at the Stated Maturity, by declaration of acceleration, call for redemption, repayment at the option of the Holder or otherwise, according to the terms thereof and of the Indenture. In case of the failure of Thermo Instrument Systems Inc., a corporation organized under the laws of Delaware (herein called the "Company," which term includes any successor corporation under such Indenture), punctually to make any such payment of principal, premium, if any, or interest or Additional Amounts, if any, the Guarantor hereby agrees to cause any such payment to be made punctually when and as the same shall become due and payable, whether at the Stated Maturity or by declaration of acceleration, call for redemption, repayment at the option of the Holder or otherwise, and as if such payment were made by the Company. The Guarantor hereby agrees that its obligations hereunder shall be as if it were principal debtor and not merely surety, and shall be absolute and unconditional (except as to the specific subordination provisions contained in Article Eighteen of the Indenture), irrespective of, and shall be unaffected by, any invalidity, subordination, irregularity or unenforceability of such Security or such Indenture, any failure to enforce the provisions of such Security or such Indenture, or any waiver, modification or indulgence granted to the Company with respect thereto, by the Holder of such Security or the Trustee or any other circumstance which may otherwise constitute a legal or equitable discharge of a surety or guarantor. The Guarantor hereby waives the benefits of diligence, presentment, demand of payment, filing of claims with a court in the event of merger, insolvency or bankruptcy of the Company, any right to require a proceeding first against the Company, protest or notice with respect to such Security or the indebtedness evidenced thereby and all demands whatsoever, and covenants that this Guarantee will not be discharged except by strict and complete performance of the obligations contained in such Security and this Guarantee. The Guarantor hereby agrees that, in the event of a default in payment of principal of, premium, if any, and interest, and Additional Amounts, if any, on such Security, or default in any sinking fund or analogous payment referred to therein, legal proceedings may be instituted by the Trustee on behalf of, or by, the Holder of such Security, on the terms and conditions set forth in the Indenture, directly against the Guarantor to enforce this Guarantee without first proceeding against the Company. The Guarantor shall be subrogated to all rights of the Holder of such Security and the Trustee against the Company in respect of any amounts paid to such Holder by the Guarantor on account of such Security pursuant to the provisions of this Guarantee or the Indenture; provided, however, that the -------- ------- Guarantor shall not be entitled to enforce, or to receive any payments arising -9- out of or based upon, such right of subrogation until the principal of, premium, if any, and interest and Additional Amounts, if any, on all Securities issued under such Indenture shall have been paid in full. Claims under this Guarantee are, to the extent provided in the Indenture, subject in right of payment to the prior payment in full of all Senior Guarantor Indebtedness, and this Guarantee is issued subject to the provisions of the Indenture with respect thereto. Each Holder of a Security upon which this Guarantee is endorsed, by accepting the same, (a) agrees to and shall be bound by such provisions, (b) authorizes and directs the Trustee on his behalf to take such action as may be necessary or appropriate to effectuate the subordination so provided and (c) appoints the Trustee his, her or its attorney-in-fact for any and all such purposes. No reference herein to such Indenture and no provision of this Guarantee or of such Indenture shall alter or impair the guarantee of the Guarantor, which is absolute and unconditional (except as to the specific subordination provisions contained in Article Eighteen of the Indenture), of the due and punctual payment of principal, premium (if any), and interest and Additional Amounts, if any, on the Security upon which this Guarantee is endorsed. This Guarantee shall not be valid or obligatory for any purpose until the certificate of authentication of the Security upon which this Guarantee is endorsed shall have been manually executed by or on behalf of the Trustee under such Indenture. All terms used in this Guarantee which are defined in such Indenture shall have the meanings assigned to them in such Indenture. This Guarantee shall be deemed to be a contract made under the laws of the Commonwealth of Massachusetts, and for all purposes shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts. IN WITNESS WHEREOF, the Guarantor has caused this Guarantee to be duly executed under its corporate seal and dated the date on the face hereof. THERMO ELECTRON CORPORATION Attest:______________________________ By: _____________________________ Title: __________________________ -10- This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture. Dated: _______________________ BANKERS TRUST COMPANY, as Trustee By: ______________________________ Authorized Officer -11- TRANSFER NOTICE FOR VALUE RECEIVED, the undersigned Holder hereby sell(s), assign(s) and transfer(s) unto ______________________________________________________________ whose taxpayer identification number is _____________________ and whose address including postal/zip code is _____________________________________ the within Security and all rights thereunder, hereby irrevocably constituting and appointing _____________________________ attorney-in-fact to transfer said Security on the books of the Security Registrar with full power of substitution in the premises. Dated: __________________________ Name: ____________________________ By: ______________________________ Title: ___________________________ NOTICE: The signature of the Holder to this assignment must correspond with the name as written upon the face of the within instrument in every particular, without enlargement or any change whatsoever. SIGNATURE GUARANTEED ____________________________________ -12- CONVERSION NOTICE The undersigned Holder of this Security hereby irrevocably exercises the option to convert this Security, or any portion of the principal amount hereof (which is an integral multiple of U.S. $1,000 below designated), into shares of Common Stock in accordance with the terms of the Indenture referred to in this Security, and directs that such shares, together with a check in payment for any fractional share and any Securities representing any unconverted principal amount hereof, be delivered to and be registered in the name of the undersigned unless a different name has been indicated below. If shares or Securities are to be registered in the name of a Person other than the undersigned, the undersigned will pay all transfer taxes payable with respect thereto. Dated: ___________________________ ___________________________________ Signature [MUST BE GUARANTEED IF STOCK OR SECURITIES ARE TO BE ISSUED IN A NAME OTHER THAN THE REGISTERED HOLDER OF THE SECURITY] ____________________________________ Name ____________________________________ Address ____________________________________ Social Security or other Taxpayer Identification Number, if any -13- If shares or Registered Securities are If only a portion of the Securities to be registered in the name of a Person is to be converted, please indicate: other than the Holder, please print such Person's name and address: 1. Principal amount to be converted: U.S. $___________________ _______________________________ 2. Principal amount and denomination Name of Registered Securities representing unconverted principal amount to be issued. _______________________________ Address Amount: U.S.$_________________ _______________________________ Social Security or other Taxpayer Denominations: Identification Number, if any U.S.$__________ (any integral multiple of U.S. $1,000) _______________________________ OPTION TO ELECT REPAYMENT UPON A REPAYMENT EVENT To: Thermo Instrument Systems Inc. The undersigned owner of this Security hereby acknowledges receipt of a notice from Thermo Instrument Systems Inc.(the "Company") as to the occurrence of a Repayment Event with respect to the Common Stock of the Company and requests and instructs the Company to repay the entire principal amount of this Security, or the portion thereof (which is $1,000 or an integral multiple thereof) below designated, in accordance with the terms of the Indenture referred to in this Security at the Repayment Price (or the relevant percentage thereof), together with accrued interest to such date (except if the Repayment Date shall be an Interest Payment Date), to the holder hereof. Dated: ________________________ _______________________________ Signature*(s) -14- Name: ___________________________ Address:_________________________ ______________________________ [* Signature Guarantee Required] Principal amount to be repaid (if less than all): $__________________ NOTICE: If this Security is issued in registered form, the above signatures of the holder(s) hereof must correspond with the name as it appears in the Security in every particular without alteration or enlargement or any change whatever. _______________________________ Social Security or Other Taxpayer Identification Number -15- EXHIBIT C FORM OF CONVERTIBLE SUBORDINATED BEARER SECURITY [Face of Security] ANY UNITED STATES PERSON WHO HOLDS THIS SECURITY WILL BE SUBJECT TO LIMITATIONS UNDER THE UNITED STATES INCOME TAX LAWS, INCLUDING THE LIMITATIONS PROVIDED IN SECTIONS 165(j) AND 1287(a) OF THE UNITED STATES INTERNAL REVENUE CODE. THERMO INSTRUMENT SYSTEMS INC. (INCORPORATED IN THE STATE OF DELAWARE) 4% CONVERTIBLE SUBORDINATED DEBENTURE DUE JANUARY 15, 2005 GUARANTEED ON A SUBORDINATED BASIS BY THERMO ELECTRON CORPORATION (INCORPORATED IN THE STATE OF DELAWARE) NO. ____________ $____________ Thermo Instrument Systems Inc., a Delaware corporation (herein referred to as the "Company," which term includes any successor corporation under the Indenture referred to on the reverse hereof), for value received, hereby promises to pay to bearer upon presentation and surrender hereof the principal sum of $_______ United States Dollars plus any premium, if any, on January 15, 2005 (the "Stated Maturity") or, at the option of the Company, in whole or in part at any time on or after January 15, 2001, upon notice as described in the Indenture and to pay interest thereon from January 21, 1998 or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually in arrears on January 15 and July 15 in each year (each, an "Interest Payment Date"), commencing July 15, 1998, at the rate of 4% per annum, and Additional Amounts, if any, until the principal hereof is paid or duly provided for. The interest and Additional Amounts, if any, so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Holder surrendering the appropriate Coupon appertaining hereto. Interest will be computed on the basis of a 360-day year of twelve 30-day months. Such payments (including premium, if any) shall be made in United States Dollars. The Company shall maintain, subject to any laws or regulations applicable thereto, an Office or Agency in a Place of Payment that is located outside the United States where this Security and any Coupons appertaining hereto, and Guarantees with respect hereto, may be presented and surrendered for payment. Subject to the right of the Company (limited as provided in the Indenture) to change the location of any Office or Agency, the Place of Payment and Place of Conversion with respect to this Security shall be either at the London office of Bankers Trust Company located at 1 Appold Street, Broadgate, London, EC2A 2HE, England, at Bankers Trust Luxembourg, S.A. located at 14 Boulevard, F.D. Roosevelt, L-2450 Luxembourg or at such other Offices or Agencies outside the United States as the Company may designate. Such payments shall be made by United States Dollar check drawn on a bank in the City of New York, or (at the option of the Company with the consent of the Paying Agent) by transfer to a United States Dollar account maintained by the Holder at a bank located outside the United States. Interest on this Security shall be paid only at an Office or Agency located outside the United States and, in the case of interest due on or before Maturity, only upon presentation and surrender at such an Office or Agency of the applicable interest Coupons hereto attached as they severally mature. No payment on this Security or any Coupon will be made at the Corporate Trust Office of the Trustee or any other Paying Agent maintained by the Company in the United States, nor will any payment be made by transfer to an account in the United States, except as may be permitted by United States tax laws and regulations in effect at the time of such payment without detriment to the Company. Notwithstanding the foregoing, payment of this Security and Coupons may be made at the Corporate Trust Office of the Trustee in the City of New York if full payment at all Paying Agents outside the United States is illegal or effectively precluded by exchange controls or other similar restrictions. Reference is hereby made to the further provisions of this Security set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place. Unless the Certificate of Authentication hereon has been executed by the Trustee by manual signature of one of its authorized signatories, this Security shall not be entitled to any benefit under the indenture, or be valid or obligatory for any purpose. -2- IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed under its facsimile corporate seal. Dated: January __, 1998 THERMO INSTRUMENT SYSTEMS INC. By:_______________________ Attest: Name Title _______________________________ Secretary [SEAL] CERTIFICATE OF AUTHENTICATION This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture. BANKERS TRUST COMPANY, As Trustee BY:_____________________________ Authorized Officer -3- (FORM OF FACE OF COUPON ON BEARER SECURITIES) ANY UNITED STATES PERSON WHO HOLDS THIS SECURITY WILL BE SUBJECT TO LIMITATIONS UNDER THE UNITED STATES INCOME TAX LAWS, INCLUDING THE LIMITATIONS PROVIDED IN SECTIONS 165(j) AND 1287(a) OF THE UNITED STATES INTERNAL REVENUE CODE. THERMO INSTRUMENT SYSTEMS INC. (Incorporated in the State of Delaware) 4% CONVERTIBLE SUBORDINATED DEBENTURE DUE 2005 No: _____________ U.S.$____________ Due: Unless the Security to which this Coupon appertains shall have been called for redemption or presented for repayment prior to the due date hereof and payment thereof duly provided for or shall have been converted, Thermo Instrument Systems Inc. (herein called the "Company") shall, subject to and in accordance with the terms and conditions of the Bearer Security and the Indenture dated as of January 15, 1998 by the Company, as issuer, and Thermo Electron Corporation, as guarantor, to Bankers Trust Company, as Trustee, pay to the bearer, on the date set forth herein upon surrender hereof, the amount shown hereon (together with any Additional Amounts in respect thereof which the Company may be required to pay according to the terms of said Indenture) at the offices of the Paying Agent set out on the reverse hereof or at such other places outside the United States as the Company may determine from time to time, by United States Dollar check drawn on a bank in the City of New York, or (at the option of the Company with the consent of the Paying Agent) by transfer to a United States Dollar account maintained by the bearer at a bank outside the United States, being one-half year's interest then payable on said Security. THERMO INSTRUMENT SYSTEMS INC. By:___________________________ Name: Title: Attest: __________________________ -4- [Reverse of Coupon] Bankers Trust Company Bankers Trust Luxembourg, S.A. 1 Appold Street 14 Boulevard, F.D. Roosevelt Broadgate, London EC2A 2HE L-2450 Luxembourg England -5- (FORM OF REVERSE OF BEARER SECURITIES) THERMO INSTRUMENT SYSTEMS INC. This Security is one of a duly authorized issue of securities of the Company (herein called the "Securities"), issued and to be issued in one or more series under an Indenture, dated as of January 15, 1998 (herein called the "Indenture") by the Company, as issuer, and Thermo Electron Corporation, as guarantor (herein called the "Guarantor," which term includes any successor corporation under the Indenture), to Bankers Trust Company, as Trustee (herein called the "Trustee," which term includes any successor trustee under the Indenture with respect to the series of which this Security is a part), to which Indenture and all indentures supplemental thereto reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Company, the Guarantor, the Trustee and the Holders of the Securities and any Coupons appertaining thereto, and of the terms upon which the Securities are, and are to be, authenticated and delivered. This Security is one of the duly authorized series of Securities designated on the face hereof and the aggregate principal amount of the Securities to be issued under such series is limited to $250,000,000 (except for Securities authenticated and delivered upon transfer of, or in exchange for, or in lieu of other Securities). The Guarantor has unconditionally guaranteed on a subordinated basis the payment of principal, premium, if any, and interest on the Securities. The Holders of the Securities will be entitled to the benefits of, be bound by, and be deemed to have notice of, all of the provisions of the Indenture. A copy of the Indenture is on file and may be inspected at the office of the Paying Agent appointed by the Company. All terms used in this Security which are defined in the Indenture shall have the meanings assigned to them in the Indenture. The Securities are issuable as bearer securities (the "Bearer Securities"), with interest Coupons attached, in the denominations of U.S. $1,000 AND U.S. $10,000, and as registered securities (the "Registered Securities"), without Coupons, in denominations of U.S. $1,000 and integral multiples thereof, except as otherwise provided in or pursuant to the Indenture. The Registered Securities, and transfers thereof, shall be registered as provided in the Indenture. The holder of any Bearer Security or any Coupon appertaining thereto and the registered holder of a Registered Security shall (to the fullest extent permitted by applicable law) be treated at all times, by all persons and for all purposes as the absolute owner of such Security or Coupon, as the case may be, regardless of any notice of ownership, theft or loss or of any writing thereon. Bearer Securities may be exchanged for Registered Securities as set forth in the Indenture. Registered Securities may not be exchanged for Bearer Securities. The Securities are general, unsecured obligations of the Company, subordinated in right of payment to the prior payment in full of all existing and future Senior Indebtedness of the Company to the extent set forth in Article Seventeen of the Indenture. There are no restrictions herein on other indebtedness or securities which may be incurred or issued by the Company or the Guarantor. The Securities have been approved for listing on the American Stock Exchange (the "AMEX"). Contracts for Securities traded on the AMEX must be settled in Registered Securities. Additional Amounts shall be payable on the Securities as set forth in the Indenture. -6- If an Event of Default, as defined in the indenture, shall occur and be continuing, the principal of the Securities of this series may be declared due and payable in the manner and with the effect provided in the Indenture. Subject to the terms of the Indenture, the Securities are convertible at any time prior to Maturity at an initial Conversion Price of $35.65 per share, subject to adjustment as provided in the Indenture. Accrued interest from the immediately preceding Interest Payment Date until the Conversion Date will be paid within five Business Days after the Conversion Date. In case this Security, or a portion thereof, is called for redemption, or is delivered for repayment, the conversion right in respect of this Security or a portion thereof so called and delivered shall expire on the close of business on the fifth Business Day preceding the Redemption Date or the second Business Day preceding a repayment on the Repayment Date, as the case may be, unless the Company defaults in making the payment due upon redemption or repayment, as the case may be. To convert this Security, the Holder must surrender this Security, duly endorsed or assigned to the company, at any applicable place of conversion, accompanied by a duly signed conversion notice. Bearer Securities surrendered for conversion must be surrendered together with all Coupons appertaining thereto that mature after the Conversion Date, except as otherwise provided in the Indenture. The Securities are subject to redemption at any time on or after January 15, 2001, as a whole or in part, at the option of the Company, at a Redemption Price equal to 100% of the principal amount, together in the case of any such redemption with accrued interest to the Redemption Date as provided in the Indenture. Notice of redemption will be given to Holders of Securities, not less than 20 nor more than 60 days prior to the Redemption Date, all as provided in the Indenture. Subject to the terms of the indenture, if as a result of a Tax Law Change the Company has or will become obligated to pay to the Holder of any Tax Affected Security Additional Amounts, and such obligation cannot be avoided by the Company taking reasonable measures available to it, then the Company may, at its option, redeem the Tax Affected Securities as a whole, but not in part, upon not less than 20 nor more than 60 days' notice to the Holders prior to the Redemption Date therefor, at a Redemption Price equal to 100% of the principal amount plus interest accrued to the Redemption Date, and any Additional Amounts then payable. Subject to the terms of the Indenture, the Securities are subject to repayment at the option of the Holder thereof, in whole or in part, on the Repayment Date, if the Common Stock (or other equity securities into which this Security is then convertible) is neither listed for trading on a United States national securities exchange, the Nasdaq National Market nor approved for trading on an established automated over-the-counter trading market in the United States. In such event, the Securities shall be repaid at a price equal to the principal amount hereof, plus accrued interest -7- and Additional Amounts, if any. The Holders of Securities of this series desiring to be repaid must deliver (1) this Security with the "Option to Elect Repayment" duly signed and completed, or (2) such other documentation as may be provided by the Indenture, to the Trustee at the Place of Payment not earlier than 60 days nor later than 30 days prior to the Repayment Date. Bearer Securities must be surrendered together with all Coupons appertaining thereto that mature after the Repayment Date, except as otherwise provided in the Indenture. In the event of redemption, exchange, repayment or conversion of this Security in part only, a new Security or Securities for the unredeemed, unexchanged, unrepaid or unconverted portion hereof shall be issued to the Holder hereof upon the cancellation hereof as set forth in the Indenture. The Place of Payment, place of registration of transfer and exchange and the Place of Conversion for the Registered Securities and the Guarantees endorsed thereon, shall be the Borough of Manhattan, The City of New York, and the Corporate Trust Office of the Trustee shall be the Company's and the Guarantor's Office or Agency in the Borough of Manhattan, The City of New York for such purpose. The Places of Payment and Places of Conversion for the Bearer Securities and the Guarantees endorsed thereon, shall be London, England and Luxembourg, and the offices of the Trustee in London and Luxembourg shall be the Offices or Agencies for such purpose and the offices of the Trustee in London and Luxembourg shall be the Company's and the Guarantor's Paying Agent in London and Luxembourg, respectively. The Trustee initially shall be the Security Registrar, one of the Authenticating Agents, the Paying Agent and the Conversion Agent. The Trustee presently has its Corporate Trust Office at Four Albany Street, 4th floor, New York, NY 10006, its Office in London at 1 Appold Street, Broadgate, London, EC2A 2HE, England and its Office in Luxembourg at 14 Boulevard, F.D. Roosevelt, L- 2450 Luxembourg. The Company and the Guarantor may subsequently appoint an Office or Agency in addition to or other than the Borough of Manhattan, The City of New York with respect to the Registered Securities and London, England and Luxembourg with respect to the Bearer Securities. The Indenture permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the Guarantor and the rights of the Holders of the Securities under the Indenture at any time by the Company, the Guarantor and the Trustee with the consent of the Holders of not less than a majority of the aggregate principal amount of all Securities issued under the Indenture at the time Outstanding and affected thereby. The Indenture also contains provisions permitting the Holders of not less than a majority of the aggregate principal amount of the Outstanding Securities, on behalf of the Holders of all such Securities, to waive compliance by the Company or the Guarantor with certain provisions of the Indenture. Furthermore, provisions in the Indenture permit the Holders of not less than a majority of the aggregate principal amount, in certain instances, of the Outstanding Securities of any series to waive, on behalf of all of the Holders of Securities of such series, certain past defaults under the Indenture and their consequences. Any such consent or waiver by the Holder of this Security shall be conclusive and binding upon such Holder and upon all future Holders of this Security and other Securities issued upon the registration of transfer -8- hereof or in exchange herefor or in lieu hereof, whether or not notation of such consent or waiver is made upon this Security. No reference herein to the indenture and no provision of this Security or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional (except as to the specific subordination provisions contained in Article Seventeen of the Indenture), to pay the principal of, premium, if any, interest and Additional Amounts, if any, on this Security at the times, places and rates, and in the coin or currency, herein prescribed. No service charge shall be made for any registration of transfer or exchange, but the Company may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith. The Indenture and the Securities shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts applicable to agreements made and to be performed entirely in such Commonwealth except that the rights, protections, obligations, indemnities and immunities of the Trustee under the Indenture and the Securities shall be governed by the laws of the State of New York, without regard to the principles of conflicts of laws of either state. -9- GUARANTEE For value received, Thermo Electron Corporation, a corporation organized under the laws of the State of Delaware (herein called the "Guarantor," which --------- term includes any successor corporation under the Indenture referred to in the Security upon which this Guarantee is endorsed), hereby unconditionally guarantees to the Holder of the Security upon which this Guarantee is endorsed and to the Trustee on behalf of the Trustee and such Holder the due and punctual payment of the principal of, premium, if any, and interest and Additional Amounts, if any, on such Security, any other amount due and payable pursuant to the terms of the Indenture and the due and punctual payment of the sinking fund or analogous payments referred to therein if any, when and as the same shall become due and payable, whether at the Stated Maturity, by declaration of acceleration, call for redemption, repayment at the option of the Holder or otherwise, according to the terms thereof and of the Indenture. In case of the failure of Thermo Instrument Systems Inc., a corporation organized under the laws of Delaware (herein called the "Company," which term includes any successor ------- corporation under such Indenture), punctually to make any such payment of principal, premium, if any, or interest or Additional Amounts, if any, the Guarantor hereby agrees to cause any such payment to be made punctually when and as the same shall become due and payable, whether at the Stated Maturity or by declaration of acceleration, call for redemption, repayment at the option of the Holder or otherwise, and as if such payment were made by the Company. The Guarantor hereby agrees that its obligations hereunder shall be as if it were principal debtor and not merely surety, and shall be absolute and unconditional (except as to the specific subordination provisions contained in Article Eighteen of the Indenture), irrespective of, and shall be unaffected by, any invalidity, subordination, irregularity or unenforceability of such Security or such Indenture, any failure to enforce the provisions of such Security or such Indenture, or any waiver, modification or indulgence granted to the Company with respect thereto, by the Holder of such Security or the Trustee or any other circumstance which may otherwise constitute a legal or equitable discharge of a surety or guarantor. The Guarantor hereby waives the benefits of diligence, presentment, demand of payment, filing of claims with a court in the event of merger, insolvency or bankruptcy of the Company, any right to require a proceeding first against the Company, protest or notice with respect to such Security or the indebtedness evidenced thereby and all demands whatsoever, and covenants that this Guarantee will not be discharged except by strict and complete performance of the obligations contained in such Security and this Guarantee. The Guarantor hereby agrees that, in the event of a default in payment of principal of, premium, if any, and interest, and Additional Amounts, if any, on such Security, or default in any sinking fund or analogous payment referred to therein, legal proceedings may be instituted by the Trustee on behalf of, or by, the Holder of such Security, on the terms and conditions set forth in the Indenture, directly against the Guarantor to enforce this Guarantee without first proceeding against the Company. The Guarantor shall be subrogated to all rights of the Holder of such Security and the Trustee against the Company in respect of any amounts paid to such Holder by the Guarantor on account of such Security pursuant to the provisions of this Guarantee or the Indenture; provided, however, that the -------- ------- Guarantor shall not be entitled to enforce, or to receive any payments arising -10- out of or based upon, such right of subrogation until the principal of, premium, if any, and interest and Additional Amounts, if any, on all Securities issued under such Indenture shall have been paid in full. Claims under this Guarantee are, to the extent provided in the Indenture, subject in right of payment to the prior payment in full of all Senior Guarantor Indebtedness, and this Guarantee is issued subject to the provisions of the Indenture with respect thereto. Each Holder of a Security upon which this Guarantee is endorsed, by accepting the same, (a) agrees to and shall be bound by such provisions, (b) authorizes and directs the Trustee on his behalf to take such action as may be necessary or appropriate to effectuate the subordination so provided and (c) appoints the Trustee his, her or its attorney-in-fact for any and all such purposes. No reference herein to such Indenture and no provision of this Guarantee or of such Indenture shall alter or impair the guarantee of the Guarantor, which is absolute and unconditional (except as to the specific subordination provisions contained in Article Eighteen of the Indenture), of the due and punctual payment of principal, premium (if any), and interest and Additional Amounts, if any, on the Security upon which this Guarantee is endorsed. This Guarantee shall not be valid or obligatory for any purpose until the certificate of authentication of the Security upon which this Guarantee is endorsed shall have been manually executed by or on behalf of the Trustee under such Indenture. All terms used in this Guarantee which are defined in such Indenture shall have the meanings assigned to them in such Indenture. This Guarantee shall be deemed to be a contract made under the laws of the Commonwealth of Massachusetts, and for all purposes shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts. IN WITNESS WHEREOF, the Guarantor has caused this Guarantee to be duly executed under its corporate seal and dated the date on the face hereof. THERMO ELECTRON CORPORATION Attest:_______________________ By:________________________________ Title: ____________________________ -11- This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture. BANKERS TRUST COMPANY, as Trustee By: ______________________________ Authorized Officer -12- CONVERSION NOTICE The undersigned Holder of this Security hereby irrevocably exercises the option to convert this Security, or any portion of the principal amount hereof (which is an integral multiple of U.S. $1,000 below designated) into shares of Common Stock in accordance with the terms of the Indenture referred to in this Security and directs that such shares, together with a check in payment for any fractional share and any Securities representing any unconverted principal amount hereof, be delivered to the undersigned unless a different name has been indicated below. The address for payment of any such check must be outside the United States. If shares are to be registered in the name of a Person other than the undersigned, the undersigned will pay all transfer taxes payable with respect thereto. Dated: __________________ ______________________________ Signature If shares are to be registered in the name of HOLDER and delivered to a Person other than the Holder, please print such Person's name and Please print name and address address: of Holder _____________________________________ _________________________________ Name Name _____________________________________ _________________________________ Address Address _____________________________________ _________________________________ _____________________________________ _________________________________ _____________________________________ _________________________________ Social Security or other Taxpayer Social Security or other Taxpayer Identification Number, if any Identification Number, if any -13- Name and address (outside the United If only a portion of the Securities States) to where any check referred is to be converted, please indicate: to in the first paragraph of this Conversion Notice should be mailed: 1. Principal amount to be converted: U.S. $______________ ______________________________________ 2. Principal amount and denomination Name of Bearer Securities representing unconverted principal amount to be issued: ______________________________________ Amount: U.S. $_________________ Address Denominations: U.S. $________________ (any integral multiple of U.S. $1,000) -14- OPTION TO ELECT REPAYMENT UPON A REPAYMENT EVENT To: Thermo Instrument Systems Inc. The undersigned owner of this Security hereby acknowledges receipt of a notice from Thermo Instrument Systems Inc. (the "Company") as to the occurrence of a Repayment Event with respect to the Common Stock of the Company and requests and instructs the Company to repay the entire principal amount of this Security, or the portion thereof (which is $1,000 or an integral multiple thereof) below designated, in accordance with the terms of the Indenture referred to in this Security at the Repayment Price (or the relevant percentage thereof), together with accrued interest to such date (except if the Repayment Date shall be an Interest Payment Date), to the holder hereof. Dated: ________________________ ________________________________ Signature Name: __________________________ Address:_________________________ _________________________ Principal amount to be repaid (if less than all): $__________ _____________________________ Social Security or Other Taxpayer Identification Number -15- EXHIBIT D ANY UNITED STATES PERSON WHO HOLDS THIS SECURITY WILL BE SUBJECT TO LIMITATIONS UNDER THE UNITED STATES INCOME TAX LAWS, INCLUDING THE LIMITATIONS PROVIDED IN SECTION 165(j) AND 1287(a) OF THE UNITED STATES INTERNAL REVENUE CODE. THIS SECURITY IS A TEMPORARY GLOBAL SECURITY, WITHOUT COUPONS OR CONVERSION RIGHTS, EXCHANGEABLE FOR DEFINITIVE BEARER SECURITIES WITH INTEREST COUPONS OR REGISTERED SECURITIES WITHOUT INTEREST COUPONS. THE RIGHTS ATTACHING TO THIS GLOBAL SECURITY, AND THE CONDITIONS AND PROCEDURES GOVERNING ITS EXCHANGE FOR DEFINITIVE SECURITIES, ARE AS SPECIFIED IN THE INDENTURE (AS DEFINED HEREIN). NEITHER THE HOLDER NOR THE BENEFICIAL OWNERS OF THIS GLOBAL SECURITY SHALL BE ENTITLED TO RECEIVE PAYMENT OF INTEREST OR ANY PAYMENTS HEREON EXCEPT PURSUANT TO THE PROVISIONS HEREOF. THERMO INSTRUMENT SYSTEMS INC. (Incorporated in the State of Delaware) 4% CONVERTIBLE SUBORDINATED DEBENTURE DUE 2005 GUARANTEED ON A SUBORDINATED BASIS BY THERMO ELECTRON CORPORATION (Incorporated in the State of Delaware) TEMPORARY GLOBAL BEARER DEBENTURE Thermo Instrument Systems Inc., a Delaware corporation (herein referred to as the "Company", which term includes any successor corporation under the Indenture referred to below), for value received, hereby promises to pay to bearer upon presentation and surrender of this global Security the principal sum of $____________ United States Dollars plus any premium, if any, on January 15, 2005 and to pay interest thereon from January 21, 1998 or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually in arrears on January 15 and July 15 in each year, commencing July 15, 1998, at the rate of 4% per annum, and Additional Amounts, if any, until the principal hereof is paid or duly provided for; provided, however, that interest, Additional Amounts, if any, and any other payments on this global Security shall be payable only after the issuance of the definitive Securities for which this global Security is exchangeable and, in the case of definitive Securities in bearer form, only upon presentation and surrender (at an Office or Agency located outside the United States, except as otherwise provided in the Indenture referred to below) of the appropriate Coupons appertaining thereto. This global Security is one of a duly authorized issue of Securities of the Company designated as specified in the title hereof, issued and to be issued in one or more series under the Indenture, dated as of January 15, 1998 (the "Indenture") by the Company and Thermo Electron Corporation, as guarantor, to Bankers Trust Company, as Trustee (the "Trustee", which term includes any successor Trustee under the Indenture). This global Security is a temporary security and is exchangeable in whole or from time to time in part without charge upon request of the Holder hereof for definitive Securities in bearer form, with interest Coupons attached, commencing on the date 40 days after the later of (i) the first closing date relating to the sale of the Securities or (ii) the date of the closing relating to the sale of the Securities acquired pursuant to the exercise of the over-allotment option granted by the Company to the Underwriters, upon certification, in the forms set forth as Exhibits D and E of the Indenture for such purpose, that the beneficial owner or owners of this global Security (or, if such exchange is only for a part of this global Security, of such part) are not United States persons or other persons who have purchased such Security for resale to United States persons. Definitive Securities in bearer form to be delivered in exchange for any part of this global Security shall be delivered only outside of the United States. This global Security will be exchangeable for definitive Securities in registered form at any time without the certification requirements set forth above; provided that such exchange is permitted by the rules and procedures then in effect of Cedel and Euroclear, and provided, further, that if and so long as Securities in registered form are represented solely by a permanent global Security in registered form, this global Security will only be exchangeable for an interest in the permanent global Security in registered form as set forth in the Indenture. Until exchanged in full for definitive Securities, this global Security shall in all respects be entitled to the same benefits under, and subject to the same terms and conditions of, the Indenture as definitive Securities authenticated and delivered thereunder, except that neither the Holder hereof nor the beneficial owners of this global Security shall be entitled to receive payment of interest or any other payments hereon, except as provided above, or to convert this global Security into shares of Common Stock of the Company or any other security, cash or other property. THIS GLOBAL SECURITY SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS, UNITED STATES OF AMERICA, EXCEPT THAT THE RIGHTS, PROTECTIONS, OBLIGATIONS, INDEMNITIES, AND IMMUNITIES OF THE TRUSTEE UNDER THIS GLOBAL SECURITY AND THE INDENTURE SHALL BE GOVERNED BY THE LAWS OF THE STATE OF NEW YORK, WITHOUT REGARD TO THE PRINCIPLES OF CONFLICTS OF LAWS OF EITHER STATE. All terms used in this global Security which are defined in the Indenture shall have the meanings assigned to them in the Indenture. Unless the certificate of authentication hereon has been manually executed by an authorized signatory of the Trustee, this global Security shall not be entitled to any benefit under the Indenture or valid or obligatory for any purpose. -2- IN WITNESS WHEREOF, the Company has caused this global Security to be duly executed under its facsimile corporate seal. Dated: January __, 1998 THERMO INSTRUMENT SYSTEMS INC. By: ----------------------------------------- Name: Title: Attest: - -------------------------- Secretary [SEAL] -3- CERTIFICATE OF AUTHENTICATION This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture. BANKERS TRUST COMPANY, as Trustee By: ------------------------- Authorized Officer -4- GUARANTEE For value received, Thermo Electron Corporation, a corporation organized under the laws of the State of Delaware (herein called the "Guarantor," which term includes any successor corporation under this Indenture referred to in the Security upon which this Guarantee is endorsed), hereby unconditionally guarantees to the Holder of the Security upon which this Guarantee is endorsed and to the Trustee on behalf of the Trustee and such Holder the due and punctual payment of the principal of, premium, if any, and interest and Additional Amounts, if any, on such Security, any other amount due and payable pursuant to the terms of the Indenture and the due and punctual payment of the sinking fund or analogous payments referred to therein if any, when and as the same shall become due and payable, whether at the Stated Maturity, by declaration of acceleration, call for redemption, repayment at the option of the Holder or otherwise, according to the terms thereof and of the Indenture. In case of the failure of Thermo Instrument Systems Inc., a corporation organized under the laws of Delaware (herein called the "Company," which term includes any successor corporation under such Indenture), punctually to make any such payment of principal, premium, if any, or interest or Additional Amounts, if any, the Guarantor hereby agrees to cause any such payment to be made punctually when and as the same shall become due and payable, whether at the Stated Maturity or by declaration of acceleration, call for redemption, repayment at the option of the Holder or otherwise, and as if such payment were made by the Company. The Guarantor hereby agrees that its obligations hereunder shall be as if it were principal debtor and not merely surety, and shall be absolute and unconditional (except as to the specific subordination provisions contained in Article Eighteen of the Indenture), irrespective of, and shall be unaffected by, any invalidity, subordination, irregularity or unenforceability of such Security or such Indenture, any failure to enforce the provisions of such Security or such Indenture, or any waiver, modification or indulgence granted to the Company with respect thereto, by the Holder of such Security or the Trustee or any other circumstance which may otherwise constitute a legal or equitable discharge of a surety or guarantor. The Guarantor hereby waives the benefits of diligence, presentment, demand of payment, filing of claims with a court in the event of merger, insolvency or bankruptcy of the Company, any right to require a proceeding first against the Company, protest or notice with respect to such Security or the indebtedness evidenced thereby and all demands whatsoever, and covenants that this Guarantee will not be discharged except by strict and complete performance of the obligations contained in such Security and this Guarantee. The Guarantor hereby agrees that, in the event of a default in payment of principal of, premium, if any, and interest, and Additional Amounts, if any, on such Security, or default in any sinking fund or analogous payment referred to therein, legal proceedings may be instituted by the Trustee on behalf of, or by, the Holder of such Security, on the terms and conditions set forth in the Indenture, directly against the Guarantor to enforce this Guarantee without first proceeding against the Company. The Guarantor shall be subrogated to all rights of the Holder of such Security and the Trustee against the Company in respect of any amounts paid to such Holder by the Guarantor on account of such Security pursuant to the provisions of this Guarantee or the Indenture; provided, however, that the -------- ------- Guarantor shall not be entitled to enforce, or to receive any payments arising -5- out of or based upon, such right of subrogation until the principal of, premium, if any, and interest and Additional Amounts, if any, on all Securities issued under such Indenture shall have been paid in full. Claims under this Guarantee are, to the extent provided in the Indenture, subject in right of payment to the prior payment in full of all Senior Guarantor Indebtedness, and this Guarantee is issued subject to the provisions of the Indenture with respect thereto. Each Holder of a Security upon which this Guarantee is endorsed, by accepting the same, (a) agrees to and shall be bound by such provisions, (b) authorizes and directs the Trustee on his behalf to take such action as may be necessary or appropriate to effectuate the subordination so provided and (c) appoints the Trustee his, her or its attorney-in-fact for any and all such purposes. No reference herein to such Indenture and no provision of this Guarantee or of such Indenture shall alter or impair the guarantee of the Guarantor, which is absolute and unconditional (except as to the specific subordination provisions contained in Article Eighteen of the Indenture), of the due and punctual payment of principal, premium (if any), and interest and Additional Amounts, if any, on the Security upon which this Guarantee is endorsed. This Guarantee shall not be valid or obligatory for any purpose until the certificate of authentication of the Security upon which this Guarantee is endorsed shall have been manually executed by or on behalf of the Trustee under such Indenture. All terms used in this Guarantee which are defined in such Indenture shall have the meanings assigned to them in such Indenture. This Guarantee shall be deemed to be a contract made under the laws of the Commonwealth of Massachusetts, and for all purposes shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts. IN WITNESS WHEREOF, the Guarantor has caused this Guarantee to be duly executed under its corporate seal and dated the date on the face hereof. THERMO ELECTRON CORPORATION Attest:______________________________ By: ________________________________ Title: _____________________________ -6-