1911 Encyclopædia Britannica/Pedometer

PEDOMETER (Lat. pes, foot, and Gr. μέτρον, measure), an apparatus in the form of a watch, which, carried on the person of a walker, counts the number of paces he makes, and thus indicates approximately the distance travelled. The ordinary form has a dial-plate marked for yards and miles. The registration is effected by the fall of a heavy pendulum, caused by the percussion of each step. The pendulum is forced back to a horizontal position by a delicate spring, and with each stroke a fine-toothed ratchet-wheel connected with it is moved round a certain length. The ratchet communicates with a train of wheels which work the dial-hands. In using the apparatus a measured mile or other known distance is walked and the indication thereby made on the dial-plate observed. According as it is too great or too small, the stroke of the pendulum is shortened or lengthened by a screw. Obviously the pedometer is little better than an ingenious toy, depending even for rough measurements on the uniformity of pace maintained throughout the journey measured.