1855.] on tJte Currents of the Ley den Battery. 135 



precisely equal to tliat used in the former instance, raised the plati- 

 num wire to a high state of incandescence, and indeed could be 

 made to destroy it altogether. 



When a primary and a secondary spiral are placed opposite to 

 each other, a peculiar reaction of the secondary upon the primary 

 is observed. If the ends of a secondary (50 feet long) be connected 

 by a thick wire, the effect upon the primary current is the same as 

 when the ends of the secondary remain wholly unconnected. If 

 the ends of the secondary be joined by a long thin platinum wire, 

 the reaction of the secondary is such as to enfeeble the primary. 

 This enfeeblement increases up to a certain limit as the resistance is 

 increased, from which forwards it diminishes until it becomes insen- 

 sible. This would appear to prove that to react upon the primary 

 the secondary requires to be retarded ; and that the greater the 

 amount of the retardation, up to a certain limit, the greater is the 

 enfeeblement. But by increasing the resistance we diminish the 

 strength of the secondary, and when a certain limit is attained, this 

 diminution is first compensated for by the influence of retardation, 

 from which point forwards with every increase of the resistance, the 

 enfeeblement of the primary is diminished. A primary current 

 which fuses a certain length of platinum wire where the ends of the 

 secondary are disunited, or where they are united by a thick wire, 

 fails to do so when they are united with a thin wire. Biit if, instead 

 of a thin wire, a body of much greater resistance, a column of water 

 for example, be introduced, the platinum wire is fused as before. 



[J. T.] 



