CAPSTAN (Fr. cabestan, probably from a derivative of Lat. capistrum, a halter, from capere, to hold), an apparatus largely used on ships for moving heavy weights and by various methods for the application of power. Con structed on the mechanical principle of the wheel and axle, its axis, unlike that of the windlass, is vertical. The capstan may be oper ated either by steam power or by means of a lever set in its socket and worked by horses or pushed by hand, the last method usually re quiring several men. When used elsewhere than on shipboard, the capstan generally has some specific name. Thus, when employed for raising coal from pits it is commonly called a gin; if worked by horses, it is known as a whim-gin. Capstans were formerly made of wood, but are now almost universally of iron. The upright barrel of a capstan is constructed around a spindle. The barrel is sometimes smooth, and sometimes for increase of friction has, running up and down its surface, ribs or ridges called whelps. In the capstan-head or
drum-head, surmounting the barrel are holes for the levers or capstan-bars used to revolve the barrel. Being smaller at its centre than at the top or bottom end, the barrel has a curve from above and below, whereby a rope wound by working the capstan slips toward the concave part so formed. By this device a length of rope may be compactly and securely wound and kept in place for repeated use. On the circumference of a pawl-head at the bottom of the barrel are pivoted pawls which catch a pawl-rim or ratchet-ring fastened to the plat form or floor on which the capstan is fixed. There are various other devices for increasing friction, the prevention of slipping and reverse operation of the mechanism.