STRIKING APPARATUS. The principal function of a clock. according to the media•val conception, was that it should be a reliable instrument for automatically calling out the hours, particularly the hours for devotion. This conception of the clock is shown in the word itself, which orig inally meant 'bell'—a meaning which has been retained in the French word rloche. A strik ing apparatus was therefore. early invented, and it is interesting to note that the striking mech anism of De Vick's clock is similar to that used in some modern timepieces. A striking clock contains one or more extra trains of wheels to control the striker. In De Vick's clock twelve pins projected from the wheel on which the hand was attached. At each hour one of these pins. by pushing a lever, released the striking-train. which lifted the hammer that strikes the bell. The number of strokes was determined by the position of the notches around the edge of a locking-plate, which held the lever controlling the striking-train. These notches were so placed that at one o'clock the catch in the lever entered a notch as soon as one blow had been struck. At two o'clock there was a longer space before the notch was reached, so that the bell was struck twice; at three o'clock the bell struck three times before the train was locked.
and so on. The chief objection to this striking ap paratus is that it is thrown out of order and strikes wrong every time the clock happens to run down.
The rack and snail Or pealing meeka nisi)! has been used for two centuries. It is a peculiar and intricate piece of mechanism. In or dinary clocks, the impelling power is a weight sim ilar to that which moves the time-measu•ing met-It :Mb:1n itself; but the pressure of this weight on the striking machinery is only permitted to come into play at stated periods in course of the workings of the timekeeping apparatus—viz. at the completion of every hour; when the minute wheel, which revolves once in an hour, and car ries the minute-hand of the clock along with it, brings it into action by the temporary release of a catch or detent, permitting the weight wound up on the cylinder of the striking apparatus to run down a little, in doing which the ham mer is forced into action, so as to strike the bell.
Whether the strokes shall be one or many is de termined principally by two pieces of mechanism, one called a 'snail,' from its form or outline, with twelve steps, and the other a 'rack,' with twelve teeth. The time during which the strik ing-weight is allo•cd to descend varies accord ing to the turning of the twelve steps of the snail on its axis, and the position of the twelve teeth of the rack at different, hours of the day, being sometimes only long enough to permit one blow to be given by the hammer on the bell, and at another time long enough for twelve such blows.
It is not known when the alarm or when the striking mechanism of the clock was first ap plied. The alarm was adopted for the use of the priesthood. to arouse them to their morning de votions. The first striking clock probably an nounced the hour by a single blow, as they still do, to avoid noise in churches. During the seven teenth century there existed a great taste for striking clocks, and hence a great variety of them. Several of Tompion's clocks not only struck the quarters on eight bells, but also the hour after each quarter: at 12 o'clock 44 blows were struck, and between 12 and 1 no fewer than 113. Many struck the hour twice, like that of Saint Clement Danes, in the Strand, London. Before the fifteenth century chimes had been in troduced. (See CHIMES; also an article in the Journal of the Society of Arts (London, March 29, 1901), on "Clocks, Carillons, and Bells.")