BUOY is also a piece of wood, or cork, sometimes an empty cask, well closed, swimming on the surface of the water, and fastened, by a chain or cord, to a large stone, piece of broken cannon, or the like, serving to mark the dangerous places near a coast, as rocks, shoals, wrecks of vessels, anchors, &c.
There are sometimes, instead of buoys, pieces of wood placed in form of masts, in conspicuous places; and sometimes large trees are planted in a particular manner, in number two at least, to be taken in a right line, the one hiding the other, so as the two may appear to the eye no more than one.