TREADMILL. A machine where the weight of men or animals acting on a series of treads or steps is employed to furnish power. The treads are so arranged on a cylinder or in an endless band that as a step is carried back under the weight of the operating man or animal, the latter is forced to move forward to the next in order to keep his footing. The most general application of this machine has been to farming machinery, where horses and clogs are used to supply the motive power. Such machines are employed for cutting hay or stalks, grinding and threshing grain, sawing wood, and in the case of the smaller machines for churning and similar light work. The endless band formed by the treads is inclined and is connected with a fly-wheel, to which the machinery to be operated is connected by belting. The term treadmill is most generally applied, however, to a device for carrying out a sentence of a prisoner to hard labor, which was formerly in general use in prisons in Great Britain. It consists of a wheel
in the form of a long, hollow cylinder, with steps around its circumference and a hand rail above the wheel, so that a prisoner may support him self while treading the steps and thus working the wheel. The proper resistance may be created by means of weights, or the motive power thus created may be utilized to grind grain, etc. The physical exercise is severe, and the use of this form of prison discipline has been generally abolished. The crank, a small wheel with paddles, which revolves in a box partially filled with sand or gravel, has been generally substi tuted where unproductive bard labor is neces sary. The number of revolutions of both a tread wheel and a crank may he recorded by a dial, and a prisoner's labor thus regulated according to his physical condition. Neither device is in use in the United States.