416 



SEC. 11. ASTRONOMY. 



These consist of 



1st. An ordinary clock, requiring periodical winding, to serve as a normal 

 or motor clock for the system. 



Wires from the reverse poles of two galvanic batteries are connected with 

 slender insulated springs, so placed that the peudulum in vibrating touches 

 each alternately, and transmits through the pendulum rod reverse currents to 

 the line wire and subsidiary clocks. 



This arrangement may be seen through the glass sides of the clock-case, 

 and in Fig. A. 



2nd. Electro-sympathetic clock. The pendulum consists of a coil of insu- 

 lated copper wire. Within the coil (which forms the ball or bob) a double 

 cluster of magnets, having their similar poles slightly separated, is fixed to 

 the casing of the clock. The currents from the motor clock passing through 

 the wire coil cause it to be alternately attracted and repelled by the magnets, 



fig. B. 



