642 THE APPLICATIONS OF PHYSICAL FORCES. [BOOK v. 



We will describe one more very ingenious electric clock (Fig. 

 422), which, like the preceding, may be made, if desired, to go alone, 

 or to serve as regulating clock for a series of dials electrically 

 connected with it. It is due to a clockmaker of Neufchatel, M. Hipp. 



We must first describe the mechanism of the regulator. It is 

 composed of minute wheel work, to which the motion is communi- 

 cated by the oscillations of a pendulum. So long as the oscillations 

 of the pendulum have a sufficient amplitude, the electricity is not 



FIG. 421 Robert Houdin's electric clock. 



called into play. If, on the contrary, the amplitude diminishes 

 the current acts through the attraction of the poles of an electro- 

 magnet, and an impulse given to the pendulum impresses on it the 

 required motion, and keeps up the regularity of its oscillation in 

 the following way. 



The electro-magnet E, Fig. 423, is firmly fixed below the 

 pendulum, so that the line of its poles is a little on one side of 

 the rod in its vertical position. The pendulum carries an armature 



