ELECTRIC GENERATORS. 121 



of the machine in like proportion. A film of moisture, 

 settling on the plates, will often so reduce the insula- 

 tion, that the slight initial charge by the action of the 

 brushes is conducted over the damp surface as fast as 

 it is generated ; so that no difference of potential, and 

 consequently no permanent charge, can occur. And as 

 the machine is much more sensitive to such influences 

 than the operator, the latter is often puzzled to know 

 why it will not generate. The simple and effectual 

 remedy, in all such cases, is to dry it. This may be 

 done by a fire, a kerosene lamp, a hot iron, or by 

 the sun's heat, though artificial heat is generally more 

 effectual. 



Warm days, before or after rain, when the atmos- 

 phere is loaded with moisture, are the most unfavorable. 

 At such times the plates should not only be dried, but 

 warmed, as moisture will continue to be deposited so 

 long as they are colder than the air. 



The electric conditions in upper rooms, other things 

 being equal, are more favorable to the operation of the 

 machine than in those on the ground floor. 



MULTIPLICATION or THE CHARGE. The multipli- 

 cation of the initial charge proceeds with great rapidity. 

 During the first revolution of the plate A, each tin-foil 

 inductor receives six direct charges from the contact of 

 its connecting brush with each of the six carriers: and 

 also six inductive charges of equal amount, as each 

 charged carrier passes it. So that at the end of the 

 first revolution, it has accumulated twelve charges ; and, 

 during that revolution, it has reacted inductively on each 

 passing carrier with this constantly increasing energy, 

 increasing the energy of the carrier in like proportion. 



At the beginning of the second revolution, it has 



