Truss Frames for Bridges.—C. & T. W. Pratt, of Newton, Mass., have applied for an extension of the patent granted to them on the 4th April, 1844, for the above invention. The petition is to be heard on the 22d of March next, at the Patent Office. Hay Presses.—Joseph Eaton, administrator, applies for an extension of the patent of Charles F.. Paine, deceased, for a hay press, granted April 25, 1844. The petition is to be heard on the 19th of April next, at the Patent Office. Loch Gate.--Henry McCarty, of Pittsburgh, Pa., has applied for the extension of his patent for "suspending, opening and closing lock gates," which expires on the 16th of March next. Persons opposing these extensions are required to file in the Patent Office their objections specially set forth in writing, at least twenty days before the day of hearing : all testimony filed by either party, to be used at the said hearing, must be taken and transmitted in accordance with the rules of the Office which will be furnished on application.