OF ARTS AND SCIENCES. 251 



In those and all the remaining experiments the period of the 

 galvanometer was 45.1 seconds. Unless otherwise stated, the meas- 

 urements were taken by discharging through the galvanometer. 

 Measurements marked with a star (*) were taken by charging the 

 condenser through the galvanometer. 



The following table of capacities was determined by comparing the 

 condensers with Elliot Brothers' standard microfarad No. 72 by the 

 throws of the needle of a ballistic galvanometer. 



TABLE OF CAPACITIES. 



None of these condensers has an electromotive force of its own. 



With a poor condenser, the value of the throw obtained by 

 charging through the galvanometer differs widely from that obtained 

 by discharging. With four typical condensers, Nos. 9, 10, and 14 and 

 15, I compared the two throws. The time of charge was 0.2 sec. 

 In the first column is given the throw produced by the charge. As 

 soon as the needle was brought to rest, the condenser was discharged 

 through the same galvanometer, and the throw noted in the second 

 column. The per cent loss and the intervening time occupy the third 

 and fourth columns respectively. 



