Exhibit 10.70

                                Richard F. Syron
                               394 Hammond Street
                       Chestnut Hill, Massachusetts 02467

December 12, 2003

Board of Directors
Thermo Electron Corporation
81 Wyman Street
Waltham, Massachusetts  02451

Re:  Resignation

Ladies and Gentlemen:

Effective  as of December  31,  2003,  I hereby  resign my position as Executive
Chairman  and member of the Board of Directors  of Thermo  Electron  Corporation
("Thermo")  and from each and every other  office or position I now have or hold
in Thermo and any and all affiliates of Thermo.

Our agreement  regarding my  resignation  is governed by my Amended and Restated
Employment  Agreement  dated  November  21,  2002  (the  "Agreement")  except as
otherwise provided by this letter.  First, Thermo waives the provision under the
Agreement that requires 30 days prior written notice of my resignation.  Second,
Thermo agrees,  as such amount is finally  determined by the Board of Directors,
to pay my annual  cash  incentive  award  for 2003 at the same  time that  other
senior  executives  are paid  their  annual  cash  incentive  awards as if I had
remained  employed by Thermo through the date of such payment.  Third, by way of
clarification  of certain  provisions  of the  Agreement,  (a) my salary and all
employee  benefits shall,  except as expressly set forth herein, be discontinued
as of the close of business on December 31, 2003,  (b) all vested stock  options
(as set forth on Schedule A hereto) shall remain  exercisable  through March 30,
2004,  and (c) all vested stock units (as set forth on Schedule A hereto)  shall
be paid out as soon as practicable  after December 31, 2003.  Fourth,  all other
provisions of the Agreement that survive the termination of my employment,  such
as the non-compete provision, shall survive in accordance with their terms.

Sincerely,


/s/ Richard F. Syron
-------------------------------
Richard F. Syron


Agreed and accepted this 12th day of December, 2003

THERMO ELECTRON CORPORATION


By:     Seth H. Hoogasian
        -----------------------
        Vice President, General Counsel and Secretary
<PAGE>


                                                   Schedule A

Restricted Stock that are Forfeited Upon Termination
--------------------------------------------------------------------------------
                  ---------------  ---------------  --------------  -----------
  Date of              Vesting         Stock          Cash Paid        Number
   Grant                Date                                         of Shares
----------------- ---------------  ---------------  --------------  -----------
  6/1/2002             6/1/2005         TMO              $0.00          5,461
----------------- ---------------  ---------------  --------------  -----------
  6/1/2001             6/1/2004         TMO              $0.00          3,560
----------------- ---------------  ---------------  --------------  -----------
                                      Kadant             $0.00            218
----------------- ---------------  ---------------  --------------  -----------
                                      Viasys             $0.00            520
----------------- ---------------  ---------------  --------------  -----------
Restricted Stock that Vests Upon Termination
--------------------------------------------------------------------------------
                  ---------------  ---------------  --------------  -----------
  Date of              Vesting         Stock          Cash Paid        Number
   Grant                Date                                         of Shares
----------------- ---------------  ---------------  --------------  -----------
  6/1/2002             6/1/2005         TMO              $0.00          5,462
----------------- ---------------  ---------------  --------------  -----------
  6/1/2001             6/1/2004         TMO              $0.00          3,560
----------------- ---------------  ---------------  --------------  -----------
                                      Kadant             $0.00            218
----------------- ---------------  ---------------  --------------  -----------
                                      Viasys             $0.00            520
----------------- ---------------  ---------------  --------------  -----------

Restricted Stock Units that are Forfeited Upon Termination
--------------------------------------------------------------------------------
                  ---------------  ---------------  --------------  -----------
  Date of              Vesting         Stock          Cash Paid        Number
   Grant                Date                                         of Shares
----------------- ---------------  ---------------  --------------  -----------
11/21/2002           11/21/2004         TMO              $0.00         33,333
----------------- ---------------  ---------------  --------------  -----------
11/21/2002           11/21/2005         TMO              $0.00         33,334
----------------- ---------------  ---------------  --------------  -----------

Vested Stock Units to be Paid Following Termination
--------------------------------------------------------------------------------
                  ---------------  ---------------  --------------  -----------
  Date of              Vesting         Stock          Cash Paid       Number
    Grant               Date                                        of Shares
----------------- ---------------  ---------------  --------------  -----------
11/21/2002                              TMO              $0.00        111,845
----------------- ---------------  ---------------  --------------  -----------
11/21/2002           11/21/2003         TMO              $0.00         33,333
----------------- ---------------  ---------------  --------------  -----------

Unvested TMO Options that are Forfeited Upon Termination
--------------------------------------------------------------------------------
                  ---------------  ---------------  --------------  -----------
  Date of               Vesting        Type            Exercise        Number
    Grant               Date                             Price       of Shares
----------------- ---------------  ---------------  --------------  -----------
 9/24/1997              various         n/a             $33.88          4,652
----------------- ---------------  ---------------  --------------  -----------
 3/14/2001            3/14/2004         n/a             $22.47        100,790
----------------- ---------------  ---------------  --------------  -----------
 3/15/2002            3/15/2004         n/a             $20.27         43,333
----------------- ---------------  ---------------  --------------  -----------
 3/15/2002            3/15/2005         n/a             $20.27         43,334
----------------- ---------------  ---------------  --------------  -----------
11/21/2002           11/21/2005         n/a             $19.67        173,316
----------------- ---------------  ---------------  --------------  -----------
11/21/2002           11/21/2006         n/a             $19.67        173,316
----------------- ---------------  ---------------  --------------  -----------
11/21/2002           11/21/2007         n/a             $19.67        173,368
----------------- ---------------  ---------------  --------------  -----------
TMO Options that Vest Upon Termination,
and Expire 90 Days Following Termination
--------------------------------------------------------------------------------
                  ---------------  ---------------  --------------  -----------
  Date of               Vesting        Type            Exercise        Number
    Grant               Date                             Price       of Shares
----------------- ---------------  ---------------  --------------  -----------
 3/15/2002            3/15/2004         NQO             $20.27         43,333
----------------- ---------------  ---------------  --------------  -----------
 3/15/2002            3/15/2005         NQO             $20.27         43,334
----------------- ---------------  ---------------  --------------  -----------

Vested TMO Options that Expire 90 Days Following Termination *
--------------------------------------------------------------------------------
                  ---------------  ---------------  --------------  -----------
  Date of               Vesting        Type            Exercise        Number
    Grant               Date                             Price       of Shares
----------------- ---------------  ---------------  --------------  -----------
 9/24/1997              various         n/a             $33.88          6,976
----------------- ---------------  ---------------  --------------  -----------
                                        NQO             $16.43        977,055
----------------- ---------------  ---------------  --------------  -----------
                                        NQO             $18.27        348,886
----------------- ---------------  ---------------  --------------  -----------
 3/14/2001            3/14/2002         NQO            $22.47         100,789
----------------- ---------------  ---------------  --------------  -----------
 3/14/2001            3/14/2003         NQO             $22.47        100,789
----------------- ---------------  ---------------  --------------  -----------
 3/15/2002            3/15/2003         NQO             $20.27         86,666
----------------- ---------------  ---------------  --------------  -----------