a close empty cask, or a block of wood or cork, fastened by a rope to an anchor, and floating on the water, to show where the anchor is situated. Buoys are of various kinds: as can-buoys, in the form of a cone; nun-buoys, which swell in the middle, and taper to a point at each end; cable-buoys, empty casks, employed to buoy up the cable in rocky anchorage. Buoys are also used to indicate the position of rocks and shoals, or to mark a channel.

The life-buoy, of which there are various kinds, is used to throw overboard to preserve a person from drowning. The kind now commonly used in the navy consists of two hollow copper vessels connected together, between which there is fixed a hollow pole, with a port-fire fixed to its top. This apparatus, which is properly ballasted, is suspended so as to be ready for use at a moment's notice; and it is so contrived that by the act of letting it off the port-fire is ignited; thus enabling the person in the water to discern the buoy in the darkest night.