_fall rope_ of which is taken up by a geered windlass, operated by a steam engine; the upper block being of course attached to an elevated _shears_ or derick. Vessels, and other bodies, which have been sunk in the ocean, have been sometimes raised by means of airtight sacks, attached to different parts of the object by means of diving bells, been inflated with air, forced down through hollow tubes by pumps, till they thus acquired a buoyancy sufficient for the purpose. The power of buoyancy has also been applied for elevating vessels above water, by placing hollow trunks, filled with water, under the keel of the vessel, and then pumping them out. One of the best methods that has ever yet been proposed for raising vessels to repair, is to place under the keel a horizontal platform, to which is attached four large hollow trunks under its four corners: the trunks to be filled with water, and to have open apertures in the bottom of each. Then by allowing a stream of atmospheric air, to rush by its own expansive force from the reservoirs in which it had been previously compressed, through suitable pipes or hose, into each trunk, the water is expelled through the apertures in the bottom, and the vessel is elevated immediately, and without loss of time. In this case, the reservoirs (iron cylinders) of compressed air, may be recharged by steam or other power, during the process of repairing one vessel, and be thus in readiness for another. A patent has been granted for this invention, but it has not yet been put in operation on a scale of practical use, though the patentee would willingly give the right of the patent to any person or company who should be disposed to construct the apparatus on a large scale. We have recently given a description of Mr. Spencer's plan for elevating vessels, and some other modes have been recently projected, which we may describe in a future number. * * * * * INFORMATION TO PERSONS HAVING BUSINESS TO TRANSACT AT THE PATENT OFFICE. SEC. 1. The existing laws relating to patents are those approved July 4, 1836, March 3, 1837, and March 3, 1839; all former acts having been repealed by the act of 1836.