NEW EFFECTS OF INDUCED ELECTRICITY. 399 



demand of time indicates the probable limit to the increase of 

 power to which I have above alluded. 



It is very curious to see the absorption, so to speak, of 

 voltaic power by the Leyden battery; when the maximum 

 effect for a given Leyden jar has been passed, the contact- 

 breaker shows by its sparks the unabsorbed induced electricity 

 which now appears in the primary wire ; an additional jar 

 acts as a safety-valve to the contact-breaker, and utilises the 

 power, and so on. 



It is a question of some interest why a jar charged in the 

 ordinary way by temporary contact of the terminals of a 

 secondary coil will only receive a very slight charge, and give 

 a discharge of scarcely measurable length, yet, when perma- 

 nently connected with the terminals, will give a long and 

 powerful discharge. The following is the best theory I can 

 offer : At the moment of the inductive action or wave of elec- 

 tricity the same wire which is affected by the electric impulse 

 is unable to conduct it back again, and thus to discharge the 

 jar ; while, when the jar is attempted to be charged in the 

 ordinary way, the contact, however apparently of short dura- 

 tion, lasts longer than the single impulse of electricity, and so 

 the coil in great part discharges the jar. Some such state of 

 the wire as that I have suggested must exist at the moment of 

 an induced current, as otherwise the wire would discharge 

 itself, or, in other words, would never receive a charge or state 

 of opposite electricity of great tension at its extremities. At one 

 time I considered the explanation to be, that at the moment 

 of breaking contact a portion of the induced electricity flies off 

 across the discharging interval in the form of a spark, and thus 

 enables the jar to discharge itself, just as the voltaic arc will 

 pass across the path of an electric spark, though it will not 

 pass through a measurable distance of interposed air without 

 the spark. This theory, however, does not satisfactorily explain 

 the great increase in the charge of the Leyden phial in the 

 above experiments, as compared with the charge by contact. 



3rd. It must be borne in mjnd that each coating of the 

 Leyden phial must be connected with each terminal ; the jar 

 is not, as many have tried the experiment, to be interposed in 

 the secondary circuit. 



