BUOY. A floating mark to point out the position of objects beneath the water, as shoals, anchors, &c. ; also any light body used to support in the water another body, whose specific gravity exceeds that of water, as the buoys used to support the swivel rings of mooring chains, &c. The buoys used to mark the position of shoals, and to point out the right channel, are generally large and strong conical casks, made water tight, and are retained in their proper situation by a rope from the apex, made fast to an anchor dropped in the desired spot. These buoys are variously distinguished, either by their colour, or numbers painted on them; also sometimes by small beacons rising from their upper surface. All these buoys are under the superintendence of the Corporation of the Trinity House. Ships' buoys are generally formed as double cones attached at their bases, and are mostly composed of wood ; but these being very liable to sink by leakage, buoys made of plate iron have for some time past been extensively used both in the royal and mercantile navy. They are attached by ropes, termed buoy-ropes, to the anchor, care being taken that the length of the buoy-rope exceeds the depth of water in which the ship is to anchor. Their principal use is for weighing the anchor in cases where the cable has broken or been let go.
BUOY (Life). A buoy intended to support persons who have fallen into the water, until a boat can be dispatched to their assistance. The forms and materials of which life buoys are composed are very numerous. The annexed cut represents a very simple and effectual machine of this kind invented by Mr. Scheffer. Fig. 1 is the machine inflated with air. It is made of skins, without any seam, (by a process of which the inventor retains the secret,) and is perfectly air and water tight ; it is provided with an ingeniously contrived stop-cock, which screws into the hole shown in the engraving, by means of which the machine may be readily inflated by blowing with the month, and its escape afterwards rendered impossible. The buoyancy of the machine is suffi oient to support two persons ; so that a man equipped with one, even if totally unacquainted with swimming, need not hesitate to proceed to the assistance of a person struggling in the water ; and it is put on in a moment, by merely stepping into it, and passing it up to the chest, where it may be worn without inconvenience, or in the least impeding the full action of the limbs. Fig. 2
represents another construction, by which the machine can be more easily put on over the clothes. The following cut represents the air cock. a is the nozzle of the cock, which is screwed into the elastic air vessel ; b an ivory pipe screwed into the barrel, used, when required, as a mouth-piece to inflate the vessel ; when that is effected, the handle d of the plug is turned, so that the hole a of the plug is brought round opposite to the bolt f, when the spiral springg projects the bolt into e, and locks it fast. The hole a is perforated through the plug, so that the locking takes place whether the plug be turned to the right or to the left : thus the cock is secured from being opened by accident, and the escape of the air is prevented. To open the air passage it is necessary to draw and hold back the spnng-bolt with one hand, while the other turns the handle d into the position shown. Another important purpose to which these buoys may be applied is that of floating a rope from a stranded ship, by which means a communication with the shore is more easily established than when it is attempted to convey a rope from the shore to the ship, as the wind and sea assist in the transmission of the rope in the first case, whilst in the latter, they form a serious obstacle to it. Spars and casks are sometimes employed to float the rope, but are much inferior to the present invention, as the lives of the men passing along the floating line are greatly endangered by, their being struck with them. The weight of such apparatus likewise keeps the floats deep in the water, con sequently less exposed to the action of the wind, so that the tide may carry the rope in a wrong direction ; but with Scheffer's buoyant vessels lying on the surface of the sea, the wind would have so powerful an effect as to render the course of the tide immaterial ; the passengers and crew might then with security pass along the rope to the shore. a the air vessel, or float for the rope b, which is suspended by the rings to the bands ccc; d d the water line, or depth at which it lies immersed when the rope is attached.