DRAG SHEETS. The name given to a contrivance for lessening the drift of vessels in heavy gales of wind, for which Mr. Burnett obtained a patent in 1826. The current caused by the action of the wind extends but a few feet below the surface, even in the heaviest gales; and if a body be sunk to a considerable depth it will remain nearly stationary. Dr. Franklin, aware of this fact, recommended vessels encountering adverse gales in the open ocean, instead of lying to, to form a kind of floating anchor by attaching a stout hauser to four bridles from the four corners of a sail, the corners being distended by spars, and then lowering the sail into the sea with sufficient weight to sink it. The effect of it will be considerable in retarding the pro gress of the vessel ast4..aii. Another well-knout, fact is, that any bubbLalice floating upon the water, prevents, in a very great degree, the waves from breaking; and fishermen and sailors who have taken to the boats upon a vessel, frequently make them fast with some scope of rope to a spar, which they throw overboard, which breaks the force of the waves, and allows the boats to ride in comparatively smooth water. Mr. Bumett's invention is a combination of these two plans, as will be perceived from the annexed repre sentation of it. The upper figure represents the drag sheet, viewed a little in perspective; a is a plank hollowed out underneath, so as to form a cavity of sufficient dimensions to receive the remainder of the apparatus when rolled up.
When in use, this plank forms the float for the rest of the apparatus; appended to it, and sunk in the water b, is a circular bar or rod of metal, firmly fixed at the extremities to the float, within the cavity before mentioned; round this bar the upper side of a square piece of sail-cloth c is fastened ; the lowermost side is in like manner secured to another metallic bar or roller d; the ex tremities of d are formed into rings or eyes, which are thereby hung upon hooks attached to the uppermost bar b; a series of eye-books, like the one shown in the margin (at i) sliding upon the rods f are then employed to stretch the can vass c tightly out between them. The frame thus completed, a rope or chain is attached to each corner of it; one from e to g on the one side, and another chain in the same manner on the opposite side; both these pass through a ring h, as represented, which ring is attached to a hanger or cable, that is made fast to the bow of the ship. By this arrangement the heaving of the vessel, or of the drag, by the undulatory motion of the waves, allows the ring to traverse up and down the chains, pre serving thereby the perpendicularity of the drag, and consequently producing the utmost resistance to its pasqage through the water.