CHAP, vi.] ELECTRIC HOROLOGY. 643 



at A, which at each oscillation passes at a very short distance 

 from the poles (about twice the thickness of a piece of paper). 

 Below its end is fixed a tongue, p, or little steel plate, which is 

 jointed to a horizontal axis, about which it can move freely, and 

 is terminated by a knife edge. 



This tongue goes to and fro with each oscillation of the pendulum, 

 and slides, without pressing, on a raised bar with two notches, called 

 the detainer, and which is supported by a spring, and communicating 

 by one of its extremities with the negative pole of the battery. Wh en 

 the oscillation of the pendulum is of sufficient amplitude, the tongue 

 passes over the detainer, but if the motion is relaxed it stops in the 

 position marked in the figure, and at the commencement of the 

 returning oscillation conies to a stop against one of the notches ; 

 if the detainer could not then be lowered, the pendulum would 

 stop, but the spring which carries the detainer yields, contact is 

 made with the termination of the other wire of the battery, and the 

 circuit is closed. The electro-magnet being energized, the armature of 

 the pendulum is attracted, and this attraction giving the necessary 

 impulse for the maintenance of the pendulum's motion at the following 

 oscillation, everything is re-established in the original order, and it is 

 only when a new impulse becomes necessary that the electricity is 

 called into play. 



The time which elapses between two successive impulses depends 

 on the force of the pile. It has been called by M. Hipp the 

 duration of impulse. It may be several minutes or only a few 

 seconds. With one Leclanche element, a regulator of this system 

 will go for several months. 



We now come to the mechanism of distribution, which com- 

 municates the time of this regulating clock to any number of indicators 

 connected electrically with it and with the battery. 



The ratchet-wheel R, having 60 teeth, and which at each oscillation 

 of the pendulum moves one second, carries on its axis a metal ray or 

 branch I, which makes one turn per minute, like the ratchet-wheel, 

 and which touches at any given moment one, two, or more of the 

 tongues attached at c c to the line-wires one current per minute is 

 thus thrown into each indicator, whose mechanism works under its 

 influence. Since this mechanism, which we cannot describe here, 

 requires a periodic change in the direction of the current, the regulator 



T T 



