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                                                                     EXHIBIT 4.2


                            CERTIFICATE OF AMENDMENT
                                       OF
                      RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                            BAKER HUGHES INCORPORATED


         Baker Hughes Incorporated (the "Corporation"), a corporation duly
organized and existing under the General Corporation Law of the State of
Delaware (the "DGCL"), does hereby certify that:

         FIRST: Article FOURTH of the Corporation's Restated Certificate of
Incorporation is amended to read in its entirety as follows:

         "The total number of shares of stock which the Corporation shall have
         the authority to issue is 765,000,000 shares of capital stock
         consisting of 15,000,000 shares of preferred stock, par value $1.00 per
         share (the "Preferred Stock"), and 750,000,000 shares of common stock,
         par value $1.00 per share (the "Common Stock")."

         SECOND: The foregoing amendment to the Corporation's Restated
Certificate of Incorporation was unanimously adopted by the Corporation's Board
of Directors at a meeting duly called and held on March 3, 1999 and by the
holders of a majority of the outstanding shares of the Corporation's capital
stock at a meeting duly called and held on April 28, 1999, all in accordance
with the provisions of Section 242 of the DGCL.

         IN WITNESS WHEREOF, the undersigned has caused this Certificate to be
executed in its name and on its behalf by its duly authorized officer on this
3rd day of May, 1999.

                                        BAKER HUGHES INCORPORATED


                                        By: /s/ LINDA J. SMITH
                                            ------------------------------------
                                            Linda J. Smith
                                            Secretary