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                                                                Exhibit  (a)(19)

                                  June 30, 2000



                      NOTICE OF MERGER AND APPRAISAL RIGHTS



TO THE FORMER STOCKHOLDERS OF THERMO INSTRUMENT SYSTEMS INC.:


         In accordance with Section 262 of the General Corporation Law of the
State of Delaware (the "DGCL"), you are hereby notified that earlier today,
Thermo Instrument Systems Inc., a Delaware corporation (the "Company") was
merged (the "Merger") with and into Thermo Electron Corporation, a Delaware
corporation ("Thermo Electron"), pursuant to Section 253 of the DGCL. The Merger
became effective on June 30, 2000 (the "Effective Date") and Thermo Electron was
the surviving corporation in the Merger. Pursuant to the Merger, each share of
common stock of the Company outstanding at the effective time of the Merger
(other than shares held by Thermo Electron or stockholders exercising
dissenters' rights and shares held in the Company's treasury) converted into the
right to receive 0.85 shares of common stock, $1.00 par value per share, of
Thermo Electron and cash in lieu of fractional shares of Thermo Electron common
stock.

         In accordance with Section 262 of the DGCL, you are hereby notified
that the record holders of shares of common stock of the Company (the "Shares")
at the effective time of the Merger (the "Former Stockholders") are entitled to
have their Shares appraised by the Court of Chancery of the State of Delaware
and to receive payment of the fair value of such Shares together with a fair
rate of interest, if any, as determined by such court. The fair value as
determined by the Delaware court is exclusive of any element of value arising
from the accomplishment or expectation of the Merger. The following is a summary
of certain of the provisions of Section 262 of the DGCL and is qualified in its
entirety by reference to the full text of Section 262, a copy of which is
attached to this notice as EXHIBIT A.

         Any Former Stockholder has the right, within 20 days after the date of
mailing of this notice, to demand in writing from Thermo Electron an appraisal
of their Shares. Such demand will be sufficient if it reasonably informs Thermo
Electron of the identity of the Former Stockholder and that the Former
Stockholder intends to demand an appraisal of the fair value of their Shares.
Failure to make such a timely demand would foreclose a Former Stockholder's
right to appraisal.

         Only a holder of record of Shares at the time of the Merger is entitled
to assert appraisal rights for the Shares registered in that holder's name. A
demand for appraisal should be executed by or on behalf of the holder of record
fully and correctly, as the holder's name appears on the stock certificates.
Holders of Shares who hold their shares in brokerage accounts or other nominee
forms and wish to exercise appraisal rights should consult with their brokers to
determine the appropriate procedures for the making of a demand for appraisal by
such nominee. All written demands for appraisal of the Shares should be sent or
delivered to Sandra L. Lambert, Secretary, Thermo Electron Corporation, 81 Wyman
Street, P.O. Box 9046, Waltham, Massachusetts 02454-9046, so as to be received
within the 20 days after the mailing of this notice.


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         If the Shares are owned of record in a fiduciary capacity, such as by a
trustee, guardian or custodian, execution of the demand should be made in that
capacity, and if the Shares are owned of record by more than one person, as in a
joint tenancy or tenancy in common, the demand should be executed by or on
behalf of all joint owners. An authorized agent, including one or more joint
owners, may execute a demand for appraisal on behalf of a holder of record;
however, the agent must identify the record owner or owners and expressly
disclose the fact that, in executing the demand, the agent is agent for such
owner or owners.

         A record holder such as a broker holding Shares as nominee for several
beneficial owners may exercise appraisal rights with respect to the Shares held
for one or more beneficial owners while not exercising such rights with respect
to the Shares held for other beneficial owners; in such case, the written demand
should set forth the number of Shares as to which appraisal is sought and where
no number of shares is expressly mentioned the demand will be presumed to cover
all Shares held in the name of the record owner.

         Within 120 calendar days after the Effective Date of the Merger, Thermo
Electron, or any Former Stockholder entitled to appraisal rights under Section
262 of the DGCL and who has complied with the foregoing procedures, may file a
petition in the Delaware Court of Chancery demanding a determination of the fair
value of the Shares of all such Former Stockholders. Thermo Electron is not
under any obligation, and has no present intention, to file a petition with
respect to the appraisal of the fair value of the Shares. Accordingly, it is the
obligation of the Former Stockholders to initiate all necessary action to
perfect their appraisal rights within the time prescribed in Section 262 of the
DGCL.

         Within 120 calendar days after the Effective Date of the Merger, any
Former Stockholder who has complied with the requirements for exercise of
appraisal rights will be entitled, upon written request, to receive from Thermo
Electron a statement setting forth the aggregate number of Shares with respect
to which demands for appraisal have been received and the aggregate number of
holders of such Shares. Such statement must be mailed within 10 calendar days
after a written request therefor has been received by Thermo Electron or within
10 calendar days after the expiration of the period for the delivery of demands
for appraisal, whichever is later.

         If a petition for an appraisal is timely filed, after a hearing on such
petition, the Delaware Court of Chancery will determine the Former Stockholders
entitled to appraisal rights and will appraise the fair value of the Shares,
exclusive of any element of value arising from the accomplishment or expectation
of the Merger, together with a fair rate of interest, if any, to be paid upon
the amount determined to be the fair value. Holders considering seeking
appraisal should be aware that the fair value of their Shares as determined
under Section 262 could be more than, the same as or less than the Merger
consideration of 0.85 shares of Thermo Electron common stock per Share that they
would otherwise receive if they did not seek appraisal of their Shares. The
Delaware Supreme Court has stated that "proof of value by any techniques or
methods that are generally considered acceptable in the financial community and
otherwise admissible in court" should be considered in the appraisal
proceedings. In addition, Delaware courts have decided that the statutory
appraisal remedy, depending on factual circumstances, may or may not be a
dissenter's exclusive remedy. The Court will also determine the amount of
interest, if any, to be paid upon the amounts to be received by persons whose
Shares been appraised. The costs of the action may be determined by the Court
and taxed upon the parties as the Court deems equitable. The Court may also
order that all or a portion of the expenses



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incurred by any holder of Shares in connection with an appraisal, including,
without limitation, reasonable attorneys' fees and the fees and expenses of
experts used in the appraisal proceeding, be charged pro rata against the value
of all the Shares entitled to appraisal.

         The Court may require Former Stockholders who have demanded an
appraisal and who hold Shares represented by certificates to submit their
certificates for Shares to the Court for notation thereon of the pendency of the
appraisal proceedings. If any Former Stockholder fails to comply with such
direction, the Court may dismiss the proceedings as to such Former Stockholder.

         Any Former Stockholder who has duly demanded an appraisal in compliance
with Section 262 of the DGCL will not be entitled to vote the Shares subject to
such demand for any purpose or to be entitled to the payment of dividends or
other distributions on those shares (except dividends or other distributions
payable to holders of record of Shares as of a date prior to the Effective Date
of the Merger).

         If any Former Stockholder who demands appraisal of Shares under Section
262 of the DGCL fails to perfect, or effectively withdraws or loses, the right
to appraisal, as provided in the DGCL, the Shares of such holder will be
converted into the right to receive the Merger consideration of 0.85 shares of
Thermo Electron common stock per Share, without interest. A Former Stockholder
will fail to perfect, or effectively lose, the right to appraisal if no petition
is filed within 120 calendar days after the Effective Date of the Merger. A
Former Stockholder may withdraw a demand for appraisal by delivering to Thermo
Electron a written withdrawal of the demand for appraisal and acceptance of the
Merger, except that any such attempt to withdraw made more than 60 calendar days
after the Effective Date of the Merger will require the written approval of
Thermo Electron. Once a petition for appraisal has been filed, such appraisal
proceeding may not be dismissed as to any Former Stockholder without the
approval of the Court.

         The foregoing summary does not purport to be a complete statement of
the procedures to be followed by Former Stockholders desiring to exercise their
dissenting appraisal rights and is qualified in its entirety by express
reference to the Section 262 of the DGCL, the full text of which is attached
hereto as EXHIBIT A. Former Stockholders are urged to read EXHIBIT A in its
entirety since failure to comply with the procedures set forth therein will
result in the loss of appraisal rights.



                           THERMO ELECTRON CORPORATION


                           SANDRA L. LAMBERT
                           Secretary


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                                    EXHIBIT A

               SECTION 262 OF THE DELAWARE GENERAL CORPORATION LAW

262. APPRAISAL RIGHTS.

         (a) Any stockholder of a corporation of this State who holds shares of
stock on the date of the making of a demand pursuant to subsection (d) of this
section with respect to such shares, who continuously holds such shares through
the effective date of the merger or consolidation, who has otherwise complied
with subsection (d) of this section and who has neither voted in favor of the
merger or consolidation nor consented thereto in writing pursuant to ss.228 of
this title shall be entitled to an appraisal by the Court of Chancery of the
fair value of the stockholder's shares of stock under the circumstances
described in subsections (b) and (c) of this section. As used in this section,
the word "stockholder" means a holder of record of stock in a stock corporation
and also a member of record of a nonstock corporation; the words "stock" and
"share" mean and include what is ordinarily meant by those words and also
membership or membership interest of a member of a nonstock corporation; and the
words "depository receipt" mean a receipt or other instrument issued by a
depository representing an interest in one or more shares, or fractions thereof,
solely of stock of a corporation, which stock is deposited with the depository.

         (b) Appraisal rights shall be available for the shares of any class or
series of stock of a constituent corporation in a merger or consolidation to be
effected pursuant to ss.251 (other than a merger effected pursuant to ss.251 (g)
of this title), ss.252, ss.254, ss.257, ss.258, ss.263 or ss.264 of this title:

                  (1) Provided, however, that no appraisal rights under this
         section shall be available for the shares of any class or series of
         stock, which stock, or depository receipts in respect thereof, at the
         record date fixed to determine the stockholders entitled to receive
         notice of and to vote at the meeting of stockholders to act upon the
         agreement of merger or consolidation, were either (i) listed on a
         national securities exchange or designated as a national market system
         security on an interdealer quotation system by the National Association
         of Securities Dealers, Inc. or (ii) held of record by more than 2,000
         holders; and further provided that no appraisal rights shall be
         available for any shares of stock of the constituent corporation
         surviving a merger if the merger did not require for its approval the
         vote of the stockholders of the surviving corporation as provided in
         subsection (f) of ss.251 of this title.

                  (2) Notwithstanding paragraph (1) of this subsection,
         appraisal rights under this section shall be available for the shares
         of any class or series of stock of a constituent corporation if the
         holders thereof are required by the terms of an agreement of merger or
         consolidation pursuant to ss.ss.251, 252, 254, 257, 258, 263 and 264 of
         this title to accept for such stock anything except:

                           a. Shares of stock of the corporation surviving or
                  resulting from such merger or consolidation, or depository
                  receipts in respect thereof;



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                           b. Shares of stock of any other corporation, or
                  depository receipts in respect thereof, which shares of stock
                  (or depository receipts in respect thereof) or depository
                  receipts at the effective date of the merger or consolidation
                  will be either listed on a national securities exchange or
                  designated as a national market system security on an
                  interdealer quotation system by the National Association of
                  Securities Dealers, Inc. or held of record by more than 2,000
                  holders;

                           c. Cash in lieu of fractional shares or fractional
                  depository receipts described in the foregoing subparagraphs
                  a. and b. of this paragraph; or

                           d. Any combination of the shares of stock, depository
                  receipts and cash in lieu of fractional shares or fractional
                  depository receipts described in the foregoing subparagraphs
                  a., b. and c. of this paragraph.

                  (3) In the event all of the stock of a subsidiary Delaware
         corporation party to a merger effected under ss.253 of this title is
         not owned by the parent corporation immediately prior to the merger,
         appraisal rights shall be available for the shares of the subsidiary
         Delaware corporation.

         (c) Any corporation may provide in its certificate of incorporation
that appraisal rights under this section shall be available for the shares of
any class or series of its stock as a result of an amendment to its certificate
of incorporation, any merger or consolidation in which the corporation is a
constituent corporation or the sale of all or substantially all of the assets of
the corporation. If the certificate of incorporation contains such a provision,
the procedures of this section, including those set forth in subsections (d) and
(e) of this section, shall apply as nearly as is practicable.

         (d)      Appraisal rights shall be perfected as follows:

                  (1) If a proposed merger or consolidation for which appraisal
         rights are provided under this section is to be submitted for approval
         at a meeting of stockholders, the corporation, not less than 20 days
         prior to the meeting, shall notify each of its stockholders who was
         such on the record date for such meeting with respect to shares for
         which appraisal rights are available pursuant to subsections (b) or (c)
         hereof that appraisal rights are available for any or all of the shares
         of the constituent corporations, and shall include in such notice a
         copy of this section. Each stockholder electing to demand the appraisal
         of such stockholder's shares shall deliver to the corporation, before
         the taking of the vote on the merger or consolidation, a written demand
         for appraisal of such stockholder's shares. Such demand will be
         sufficient if it reasonably informs the corporation of the identity of
         the stockholder and that the stockholder intends thereby to demand the
         appraisal of such stockholder's shares. A proxy or vote against the
         merger or consolidation shall not constitute such a demand. A
         stockholder electing to take such action must do so by a separate
         written demand as herein provided. Within 10 days after the effective
         date of such merger or consolidation, the surviving or resulting
         corporation shall notify each stockholder of each constituent
         corporation who has complied with this subsection and has not voted in
         favor of or consented to the merger or consolidation of the date that
         the merger or consolidation has become effective; or



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                  (2) If the merger or consolidation was approved pursuant to
         ss.228 or ss.253 of this title, each constituent corporation, either
         before the effective date of the merger or consolidation or within ten
         days thereafter, shall notify each of the holders of any class or
         series of stock of such constituent corporation who are entitled to
         appraisal rights of the approval of the merger or consolidation and
         that appraisal rights are available for any or all shares of such class
         or series of stock of such constituent corporation, and shall include
         in such notice a copy of this section; provided that, if the notice is
         given on or after the effective date of the merger or consolidation,
         such notice shall be given by the surviving or resulting corporation to
         all such holders of any class or series of stock of a constituent
         corporation that are entitled to appraisal rights. Such notice may,
         and, if given on or after the effective date of the merger or
         consolidation, shall, also notify such stockholders of the effective
         date of the merger or consolidation. Any stockholder entitled to
         appraisal rights may, within 20 days after the date of mailing of such
         notice, demand in writing from the surviving or resulting corporation
         the appraisal of such holder's shares. Such demand will be sufficient
         if it reasonably informs the corporation of the identity of the
         stockholder and that the stockholder intends thereby to demand the
         appraisal of such holder's shares. If such notice did not notify
         stockholders of the effective date of the merger or consolidation,
         either (i) each such constituent corporation shall send a second notice
         before the effective date of the merger or consolidation notifying each
         of the holders of any class or series of stock of such constituent
         corporation that are entitled to appraisal rights of the effective date
         of the merger or consolidation or (ii) the surviving or resulting
         corporation shall send such a second notice to all such holders on or
         within 10 days after such effective date; provided, however, that if
         such second notice is sent more than 20 days following the sending of
         the first notice, such second notice need only be sent to each
         stockholder who is entitled to appraisal rights and who has demanded
         appraisal of such holder's shares in accordance with this subsection.
         An affidavit of the secretary or assistant secretary or of the transfer
         agent of the corporation that is required to give either notice that
         such notice has been given shall, in the absence of fraud, be prima
         facie evidence of the facts stated therein. For purposes of determining
         the stockholders entitled to receive either notice, each constituent
         corporation may fix, in advance, a record date that shall be not more
         than 10 days prior to the date the notice is given, provided, that if
         the notice is given on or after the effective date of the merger or
         consolidation, the record date shall be such effective date. If no
         record date is fixed and the notice is given prior to the effective
         date, the record date shall be the close of business on the day next
         preceding the day on which the notice is given.

         (e) Within 120 days after the effective date of the merger or
consolidation, the surviving or resulting corporation or any stockholder who has
complied with subsections (a) and (d) hereof and who is otherwise entitled to
appraisal rights, may file a petition in the Court of Chancery demanding a
determination of the value of the stock of all such stockholders.
Notwithstanding the foregoing, at any time within 60 days after the effective
date of the merger or consolidation, any stockholder shall have the right to
withdraw such stockholder's demand for appraisal and to accept the terms offered
upon the merger or consolidation. Within 120 days after the effective date of
the merger or consolidation, any stockholder who has complied with the
requirements of subsections (a) and (d) hereof, upon written request, shall be
entitled to receive from the corporation surviving the merger or resulting from
the consolidation a statement setting forth the aggregate number of shares not
voted in favor of the merger or consolidation and with respect to which demands
for appraisal have been received and the aggregate number of holders



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of such shares. Such written statement shall be mailed to the stockholder within
10 days after such stockholder's written request for such a statement is
received by the surviving or resulting corporation or within 10 days after
expiration of the period for delivery of demands for appraisal under subsection
(d) hereof, whichever is later.

         (f) Upon the filing of any such petition by a stockholder, service of a
copy thereof shall be made upon the surviving or resulting corporation, which
shall within 20 days after such service file in the office of the Register in
Chancery in which the petition was filed a duly verified list containing the
names and addresses of all stockholders who have demanded payment for their
shares and with whom agreements as to the value of their shares have not been
reached by the surviving or resulting corporation. If the petition shall be
filed, by the surviving or resulting corporation, the petition shall be
accompanied by such a duly verified list. The Register in Chancery, if so
ordered by the Court, shall give notice of the time and place fixed for the
hearing of such petition by registered or certified mail to the surviving or
resulting corporation and to the stockholders shown on the list at the addresses
therein stated. Such notice shall also be given by or more publications at least
week before the day of the hearing, in a newspaper of general circulation
published in the City of Wilmington, Delaware or such publication as the Court
deems advisable. The forms of the notices by mail and by publication shall be
approved by the Court, and the costs thereof shall be borne by the surviving or
resulting corporation.

         (g) At the hearing on such petition, the Court shall determine the
stockholders who have complied with this section and who have become entitled to
appraisal rights. The Court may require the stockholders who have demanded an
appraisal for their shares and who hold stock represented by certificates to
submit their certificates of stock to the Register in Chancery for notation
thereon of the pendency of the appraisal proceedings; and if any stockholder
fails to comply with such direction, the Court may dismiss the proceedings as to
such stockholder.

         (h) After determining the stockholders entitled to an appraisal, the
Court shall appraise the shares, determining their fair value exclusive of any
element of value arising from the accomplishment or expectation of the merger or
consolidation, together with a fair rate of interest, if any, to be paid upon
the amount determined to be the fair value. In determining such fair value, the
Court shall take into account all relevant factors. In determining the fair rate
of interest, the Court may consider all relevant factors, including the rate of
interest which the surviving or resulting corporation would have had to pay to
borrow money during the pendency of the proceeding. Upon application by the
surviving or resulting corporation or by any stockholder entitled to participate
in the appraisal proceeding, the Court may, in its discretion, permit discovery
or other pretrial proceedings and may proceed to trial upon the appraisal prior
to the final determination of the stockholder entitled to an appraisal. Any
stockholder whose name appears on the list filed by the surviving or resulting
corporation pursuant to subsection (f) of this section and who has submitted
such stockholder's certificates of stock to the Register in Chancery, if such is
required, may participate fully in all proceedings until it is finally
determined that such stockholder is not entitled to appraisal rights under this
section.

         (i) The Court shall direct the payment of the fair value of the shares,
together with interest, if any, by the surviving or resulting corporation to the
stockholders entitled thereto. Interest may be simple or compound, as the Court
may direct. Payment shall be so made to each such stockholder, in the case of
holders of uncertificated stock forthwith, and the case of holders of shares
represented by certificates upon the surrender to the corporation of the
certificates



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representing such stock. The Court's decree may be enforced as other decrees in
the Court of Chancery may be enforced, whether such surviving or resulting
corporation be a corporation of this State or of any state.

         (j) The costs of the proceeding may be determined by the Court and
taxed upon the parties as the Court deems equitable in the circumstances. Upon
application of a stockholder, the Court may order all or a portion of the
expenses incurred by any stockholder in connection with the appraisal
proceeding, including, without limitation, reasonable attorney's fees and the
fees and expenses of experts, to be charged pro rata against the value of all
the shares entitled to an appraisal.

         (k) From and after the effective date of the merger or consolidation,
no stockholder who has demanded appraisal rights as provided in subsection (d)
of this section shall be entitled to vote such stock for any purpose or to
receive payment of dividends or other distributions on the stock (except
dividends or other distributions payable to stockholders of record at a date
which is prior to the effective date of the merger or consolidation); provided,
however, that if no petition for an appraisal shall be filed within the time
provided in subsection (e) of this section, or if such stockholder shall deliver
to the surviving or resulting corporation a written withdrawal of such
stockholder's demand for an appraisal and an acceptance of the merger or
consolidation, either within 60 days after the effective date of the merger or
consolidation as provided in subsection (e) of this section or thereafter with
the written approval of the corporation, then the right of such stockholder to
an appraisal shall cease. Notwithstanding the foregoing, no appraisal proceeding
in the Court of Chancery shall be dismissed as to any stockholder without the
approval of the Court, and such approval may be conditioned upon such terms as
the Court deems just.

         (l) The shares of the surviving or resulting corporation to which the
shares of such objecting stockholders would have been converted had they
assented to the merger or consolidation shall have the status of authorized and
unissued shares of the surviving or resulting corporation. (Last amended by Ch.
339, L. `98, eff. 7-1-98.)



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