AMENDMENT NO. 1 TO

   1
                                                                       Exhibit 4

                                 AMENDMENT NO. 1

                                       TO

                                RIGHTS AGREEMENT

       THIS AMENDMENT NO. 1 TO RIGHTS AGREEMENT ("Amendment No. 1"), dated as of
May 11, 1999, is entered into by and between AMETEK, Inc. (formerly known as
Ametek Aerospace Products, Inc.), a Delaware corporation (the "Company"), and
American Stock Transfer & Trust Company (the "Rights Agent").

       WHEREAS, the Company and the Rights Agent are parties to that certain
Rights Agreement dated as of June 2, 1997 (the "Rights Agreement");

       WHEREAS, the Rights Agreement contains terms restricting the ability of
the Board of Directors of the Company to redeem the Rights issued thereunder
under certain circumstances;

       WHEREAS, the Board of Directors of the Company has determined that it is
in the best interests of the Company and its stockholders to amend the Rights
Agreement as set forth herein to address certain developments in law; and

       WHEREAS, pursuant to Section 27 of the Rights Agreement, the Rights
Agreement may be amended as set forth herein without approval of the holders of
the Rights;

       NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein set forth, the Company and the Rights Agent hereby agree as
follows:

1.     Definitions. Capitalized terms used in this Amendment No. 1 and not
       otherwise defined herein shall have the meanings ascribed thereto in the
       Rights Agreement.

2.     Amendment of Rights Agreement. Section 23(c) of the Rights Agreement is
       hereby deleted in its entirety. 

3.     Other Terms Unchanged. Except as amended by this Amendment No. 1, the
       Rights Agreement shall remain in full force and effect.

4.     Governing Law. This Amendment No. 1 shall be deemed to be a contract made
       under the laws of the State of Delaware and for all purposes shall be
       governed by and construed in accordance with the laws of such State
       applicable to contracts made and to be performed entirely within such
       State.

                                       
   2

5.     Counterparts. This Amendment No. 1 may be executed in any number of
       counterparts and each of such counterparts shall for all purposes be
       deemed to be an original, and all such counterparts shall together
       constitute but one and the same instrument.

6.     Descriptive Headings. Descriptive headings of the several Sections of
       this Amendment No. 1 are inserted for convenience only and shall not
       control or affect the meaning or construction of any of the provisions
       hereof.


       IN WITNESS WHEREOF, the parties hereto have caused this Amendment No. 1
to be duly executed and their respective corporate seals to be hereunto affixed
and attested, all as of the day and year first above written.

Attest:                                                AMETEK, INC.


                                 
                                                   
By:     /s/ Xxxxx X. Xxxxxxxx                          By:       /s/ Xxxx X. Xxxxxxxxx
   -------------------------------------                  ------------------------------
        Name:   Xxxxx X. Xxxxxxxx                           Name: Xxxx X. Xxxxxxxxx
        Title:  Corporate Counsel &                         Title: Executive Vice President -
                Secretary                                   Chief Financial Officer

Attest:                                                AMERICAN STOCK TRANSFER
                                                           & TRUST COMPANY

By:    /s/  Xxxxx Xxxxxx                               By:    /s/  Xxxxxxx X. Xxxxxx
    -------------------------------------                 ------------------------
        Name:   Xxxxx Xxxxxx                                  Name: Xxxxxxx X. Xxxxxx
        Title:  Assistant Secretary                           Title: Vice President