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                                                                    EXHIBIT 10.4

                                AMENDMENT NO. 1
                                      TO
                           OYO GEOSPACE CORPORATION
                      1997 KEY EMPLOYEE STOCK OPTION PLAN



                                 FEBRUARY 2, 1998



     This Amendment amends the OYO Geospace Corporation 1997 Key Employee Stock
Option Plan (the "Plan") as follows:

     1.     Section 4.3 of the Plan is amended to read in its entirety as
follows:

     "  4.3 RESTRICTIONS ON TRANSFERABILITY OF STOCK AWARDS AND OPTIONS.  (a)
     Except as set forth in this Section 4.3, Options shall not be transferable
     by the Employee other than by will or under the laws of decent and
     distribution, and shall be exercisable, during the Employee's lifetime,
     only by him.  Any attempt to transfer a Stock Award other than pursuant to
     the terms of the Plan and the Restricted Stock Agreement shall entitle the
     Committee to terminate that Stock Award and all rights of that Employee to
     the Restricted Stock included therein.

          (b) The Committee may, in its discretion, permit an Employee to
     transfer all or any part of an Option, or may grant an Option with terms
     that expressly permit all or any part of that Option to be transferred by
     the Employee, in either case to (i) the spouse, children or grandchildren
     of the Employee ("Immediate Family Members"), (ii) a trust or trusts for
     the exclusive benefit of one or more of the Employee's Immediate Family
     Members, or (iii) a partnership or other legal entity in which only the
     Employee's Immediate Family Members have equity or ownership interests
     (collectively, "Permitted Transferees"); provided that (x) there may be no
     consideration for any such transfer and (y) subsequent transfers of Options
     so transferred (other than transfers by will or under the laws of decent
     and distribution, transfers back to the Employee to whom the Option was
     originally granted and transfers to other Permitted Transferees of such
     Employee) shall be void.

          (c) Following the transfer of any Option pursuant to paragraph (b)
     above, that Option shall continue to have the same terms and provisions and
     be subject to the same restrictions as were applicable immediately before
     that transfer, except that references in this Plan and in the Option
     Agreement applicable to such Option shall be deemed to be references to the
     Permitted Transferee or Permitted Transferees; provided that any provision
     of Section 5.6 that would have been triggered by the termination, death,
     retirement or disability of the Employee to whom the Option was originally
     granted will continue to be triggered by the termination, death, retirement
     or disability of such Employee."

     2.     Section 4.6 of the Plan is amended to read in its entirety as
follows:
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     "  4.6 ELECTION UNDER SECTION 83(B) OF THE CODE.  If any Employee exercises
     the election permitted under Section 83(b) of the Code, that Employee
     shall, within ten days of making the election, (i) notify the Committee
     that he has made the election and (ii) pay to the Company, in immediately
     available funds, an amount equal to the additional amount, if any, that the
     Company will be required to withhold under applicable tax law as a result
     of such election.  If the Employee fails to make such payment or otherwise
     provide for such payment, then the Company shall be entitled to deduct such
     sums from other compensation payable to such Employee or the Committee
     shall be entitled to rescind the Stock Award subject to such election."