Exhibit 24.2 POWER OF ATTORNEY I, Herbert D. Simons, hereby authorize and appoint Louis G. Baldwin as my attorney-in-fact to sign on my behalf individually and in my capacity as a Director of Cross Timbers Oil Company all amendments and post-effective amendments to Registration Statement No. 333-56983, and any related registration statement filed pursuant to Rule 462(b) under the Securities Act of 1933 and all amendments and post-effective amendments thereto, as such attorney-in-fact may deem necessary or appropriate. Dated October 5, 2000 /s/ HERBERT D. SIMONS --------------------------------- Herbert D. Simons