ESCAPEMENT

the general contrivance in a timepiece by which the pre ure of the wheels (which move always in one direction) and the vibratory motion of the pendulum or balance-wheel are accommodated the one to the other. By this contrivance the wheelwork is made to communicate an impulse to the regulating Zz 1, Dead-beat or repose escapement. The pallets are concentric with the axis @, and thus while a tooth is against the pallet the wheel is stationary. 2, Recoil escapement. The pallets are not concentric to axis a, and therefore a slight recoil of the wheel takes place after the escape of a tooth (whence the name escapement). When the pallets leave a tooth, the teeth slide along their surfaces, giving an impulse to the pendulum. Lettering for 1 and 2: The anchor H L K is made to oscillate on the axis a by the pendulum. The teeth of the escapement-wheel A come alternately against the outer surface of the pallet K and the inner surface of the pallet H. 3, Chronometer escapement. As the balance rotates in the direction of the arrow, the tooth V pre es the spring against the lever, thus pre ing aside the lever and removing the detent from the tooth of the wheel. As the balance returns, V pre es aside and pa es the spring without moving the lever, which then reste against the stop E. power (which in a clock is the pendulum and ina watch the balance-wheel), so as to restore to it the small portion of force which it loses in every vibration, in consequence of friction and ESCALATOR, moving stairway. It | the resistance of the air. The leading 218 ESCAR requisite of a good escapement is that the impulse communicated to the pendulum or balance-wheel shall be invariable, notwithstanding any irregularity or foulne in the train of wheels. Various kinds of escapements have been contrived, some of which are shown in the accompanying figure. See CLOCK; WATCH.