188G.] NEW YORK ACADEMY OF SCIENCES. 157 



the outer end of the spring is at a point of temporary rest, or is 

 being carried around tiie arbor at the hour as above described. 



By actual experiment, it is found that to obtain a given force 

 at tiie escape-wheel, it is only necessary to apply a power in this 

 manner at the centre arbor equal to less than one-forty-sixth part 

 of that used in the ordinary clock. The train work is thereby 

 shortened one-half, and the friction on the remainder reduced 

 in the proportion above stated. 



Experiments seem to prove that a motor as constructed for 

 this purpose can be run for one year at an expense of less than 

 twenty-five cents. A common clock constructed on this prin- 

 ciple has been found to keep as accurate time as one of the higher 

 grades, with gravity escapements, etc., run by the old methods. 



It may be not unprofitable to give a more detailed explanation 

 of tlie circuit-making and breaking apparatus. 



Tlie electric motor is normally out of circuit, but at stated 

 intervals, by the operation of the clock itself, the circuit is com- 

 pleted, and the motor is thus set in motion. But, to be more 

 exact, we will give a general description of the mechanism em- 

 13loyed in the clock. Upon the centre arbor there is placed a 

 loose 'toggle" or arm, between the hour wheel and the wheel 

 carrying the spring box. At one side of one of the frame plates 

 is secured an insulated spring connector, the free end of which 

 extends to the centre of the frame and is within reach of the 

 " toggle " when the same has been brought to a perpendicular 

 position by means of a pin projecting from the hour Avheel. 

 When the hour wheel has thus brought the "toggle" to an up- 

 right position and in contact with the insulated spring con- 

 nector, the circuit is completed through the motor, which at 

 once commences to rotate the spring box one revolution from 

 left to right, or in the direction that the hands move. The 

 spring-box wheel also carries a projecting pin, but set at a less 

 distance from the axis than the other pin. Now, as the motor 

 continues to rotate the spring-box wheel while the spring con- 

 nector is resting upon the "toggle," it follows that as soon as 

 there has been one revolution of the spring-box wheel, the pro- 

 jecting pin upon the same will press the "toggle" forward and 

 out from under the spring connector, thereby breaking the 

 circuit, and stopping the motor. This arrangement prevents 

 the possibility of the clock's running beyond the regular limit 

 for winding, and prevents the motor, when once set in operation, 

 from performing more than the work required. The operation 

 of the clock causes the circuit to be established, while the motor 

 utilizes its own power to interrupt the circuit. 



[A common clock provided with the Pond winding-apparatus 

 was exhibited.] 



