THE ELECTRICAL CIRCUIT. 535 



cedented strength. The writers of fifty years ago, how- 

 ever, find in the supposed storing or accumulating pro- 

 perties of the contrivance its chief value, and for that 

 cause assign to it a high place among the great electrical 

 inventions. From the modern point of view the historical 

 importance accorded to the L,eyden jar or condenser seems 

 disproportionate when the relatively minor part which it 

 plays in existing applications of electricity is recalled; but, 

 on the other hand, the immediate reason for the great pro- 

 moting influence which it exerted upon electrical progress 

 at the time of its advent is not found wholly in the mag- 

 nifying power and the accumulating property of the con- 

 trivance. As ensuing events soon showed this influence 

 rests, and perhaps chiefly rests, upon the fact that by 

 means of the L,eyden jar came the first recognition of an 

 electrical circuit. 



The discharge of the electric machine, like that of the 

 rubbed glass tube, had hitherto been delivered from the 

 globe either directly to the object to be electrified or to a 

 metal prime conductor (usually a suspended gun barrel), 

 and thence to the object the latter being insulated on a 

 pitch cake or by suspension on silk strings. Because the 

 Dantzic philosophers had supposed that the Leyden jar 

 would act in the same way, they regarded it as a failure 

 when, on being merely laid on the table, it refused to 

 driver its spark to an object brought near to it. As 

 soon, however, as Gralath and others understood that the 

 charged jar must rest in one hand, while the other touched 

 the ball upon the end of its inserted wire, the recognition 

 of a circuitous path, to which the electricity of the jar was 

 confined, was complete. That path included both the jar 

 and the human body. When, for the holding hand, a 

 metal pan in which the jar rested, or a chain enwrapping 

 the jar, was substituted, communicating by wire with the 

 ball, then the path became a metallic circuit, and the sup- 

 posed influence of the human body per se was eliminated. 

 In that path the electricity seemed to be present, and not 



