V. CLOCKS AND SUNDIALS. 



417 



thereby giving motion to the pendulum, and maintaining it in vibration. The 

 connexions between the batteries and motor and sympathetic clock pendulums 

 with the position of magnets are shown in Fig. A. 



3rd. The sympathetic pendulum is also made with an ordinary ball or bob, 

 carrying a single bar magnet passing into small coils of wire fixed to the case 

 and placed in circuit with motor clock, as shown in the square case. 



4th. To admit of a pendulum vibrating seconds being introduced within 

 the limits of the usual office round clock-case, two small coiis, one below and 

 the other above the point of suspension, are used, having double magnets 

 placed for each coil, through both of which the currents from the motor clock 

 are passed. 



This form of pendulum requires a more powerful battery to sustain its 

 motion, and has less momentum than the long pendulums, 'its construction 

 is shown in the circular case, and in Fig. B. 



5th. An arrangement to enable a pendulum vibrating half seconds to bea 

 seconds is shown in Fig. C. 



40075. 



Dd 



