THE ELECTEICAL EXPERIMENTS OF HENRY CAVENDISH. 615 



ferent experiments 1-08, 1'03, 0'976 and 1, and he finally concludes that 

 the resistance is as the first power of the velocity, thus anticipating Ohm's 

 Law. 



The general accuracy of these results is the more remarkable when we 

 consider the method by which they were obtained, forty years before the 

 invention of the galvanometer. 



Every comparison of two resistances was made by Cavendish by connecting 

 one end of each resistance-tube with the external coatings of a set of equally 

 charged Leyden jars and touching the jars in succession with a piece of metal 

 held in one hand, while with a piece of metal in the other hand he touched 

 alternately the ends of the two resistances. He thus compared the sensation 

 of the shock felt when the one or the other resistance in addition to the 

 resistance of his body was placed in the path of the discharge. His results 

 therefore are derived from the comparison of the sensations produced by an 

 enormous number of shocks passed through his own body. 



The skill which he thus acquired in the discrimination of shocks was so 

 great that he is probably accurate even when he tells us that the shock 

 when taken through a long thin copper wire wound on a large reel was 

 sensibly greater than when taken direct. The experiment is certainly worth 

 repeating, to determine whether the intensification of the physiological effect 

 on account of the oscillatory character of the discharge through a coil would 

 in any case compensate for the weakening effect of the resistance of the coil. 

 But I have not hitherto succeeded in obtaining this result. Indeed on com- 

 paring the shock through two coils of equal resistance, one of which had far 

 more self-induction than the other, I found the shock sensibly feebler through 

 the coil of large self-induction. 



