Oscillatory Discharges. 25 



Now, as y and - /r represent the resistance per unit of 



length of two wires, one of them wound into a spiral, the 

 other drawn out into a straight line, we may write, denoting 

 them for brevity's sake by p and p' respectively . 



p n r n 



p' n r ' ' n' 



We may say also that the quotient 



represents the ratio between the resistance of a wire wound 

 into a spiral and the resistance of the same wire drawn into 

 a straight line for discharges of period r. 



24. Before undertaking the experiments for determining 

 this ratio, w T e made up our minds to test whether the calori- 

 metric method, as used by us, was adequate for affording 

 reliable indications. 



There may, in fact, arise the suspicion that within the toluol 

 dielectric viscosity phenomena may take place, these pheno- 

 mena, owing to the heat they evolve in the insulator, being- 

 capable of disguising to a considerable degree the evolution 

 of heat in the spiral due to the Joule effect. 



But two series of measurements made with special calori- 

 meters perfectly warranted our rejecting this suspicion. 



The first series, performed with two calorimeters in which 

 the spiral and the wire were immersed in air, gave results 

 identical with those obtained with toluol calorimeters. 



The second series was made with a calorimeter of the 

 usual form, where in the place of the spiral there was 

 immersed in toluol a condenser made up of two cylin- 

 drical armatures. Having placed this calorimeter in parallel 

 with one of the spirals traversed by the discharge, we 

 w r ere not able to ascertain in it any sensible evolution of 

 heat. 



On the other hand, the objection could be raised that, as a 

 rule, the displacement of the toluol meniscus, in addition to 

 its depending upon the amount of heat evolved in the wire. 

 will depend upon the rate of this amount being given off to 

 the surrounding medium ; since in the case of a calorimeter 

 containing a rectilinear wire the radiating surface is greater 

 than in the case of a calorimeter containing the same wire 

 w r ound into a spiral, one would expect that on this account 



