Exhibit 23

                    Consent of Independent Public Accountants

     As independent public  accountants,  we hereby consent to the incorporation
by reference of our reports dated  February 16, 1999 (except with respect to the
matter discussed in Note 18, as to which the date is March 1, 1999), included in
or incorporated by reference into Thermo Instrument Systems Inc.'s Annual Report
on Form 10-K for the year ended January 2, 1999,  into the Company's  previously
filed Registration Statements as follows: Registration Statement No. 33-14980 on
Form  S-8,  Registration  Statement  No.  33-16461  on  Form  S-8,  Registration
Statement No.  33-14974 on Form S-8, Post  Effective  Amendment to  Registration
Statement on Form S-4 No.  33-32579-02 on Form S-8,  Registration  Statement No.
33-33577  on  Form  S-8,  Registration  Statement  No.  33-36221  on  Form  S-8,
Registration  Statement  No.  33-37866 on Form S-8,  Registration  Statement No.
33-42270  on  Form  S-3,  Registration  Statement  No.  33-69526  on  Form  S-3,
Registration  Statement  No.  33-65275 on Form S-8,  Registration  Statement No.
33-37559 on Form S-8,  Registration  Statement  No.  333-02163  on Form S-3, and
Registration Statement No. 333-17707 on Form S-3.


                                                           Arthur Andersen LLP



Boston, Massachusetts
March 18, 1999