122 ELEMENTS OF STATIC ELECTRICITY. 



twelve times the inductive energy which it had at the 

 beginning of the first; and this energy continues to 

 increase, and react on the carriers, at the same rate as 

 before. And as the plate makes about five revolutions 

 per second, the rate of increase on any tin-foil inductor 

 is about sixty increments per second. 



But as the charge spreads from the tin-foil inductors 

 over the paper inductors and adjacent parts of the sta- 

 tionary plate; and from the carriers over adjacent parts 

 of the revolving plate, each point on each plate, within 

 the charged areas, becomes a center of direct and induct- 

 ive action in the same manner as the metal inductors and 

 carriers. So that even an infinitesimal charge is increased 

 in a few seconds to the full capacity of the machine. 



HOLTZ AND TOPLER MACHINES COMPARED. Since 



the chief difference between the Holtz and Topler con- 

 sists in the latter being self-inciting, the mode of action 

 is essentially the same in each. 



The Holtz may receive its initial charge from a fric- 

 tional machine, an electrophorus, or any similar, exter- 

 nal source : but the usual method of charging is by 

 means of a piece of ebonite, electrified by the fur of a 

 cat-skin. 



The electrified ebonite is held in contact with one of 

 the paper inductors on the stationary plate, which is 

 thus charged ; a portion of the charge being commu- 

 nicated to the revolving plate through the points which 

 project into the windows; and this plate is made to 

 rotate rapidly, so that the charge is soon multiplied to 

 the full capacity of the machine, if the atmospheric con- 

 ditions are favorable; and the ebonite is then removed. 



It will thus be seen that the initial charge in both 

 machines is produced by friction and multiplied by 



