336 DISCOURSE ON THE STUDY 



only in a state of uncontrollable intensity were 

 tamed down, as it were, and made to distribute 

 their efficacy over an indefinite time, and to regu- 

 late their action at the will of the operator. It was 

 then soon ascertained that electricity in the act of 

 its passage along conductors, produces a variety of 

 wonderful effects, which had never been previously 

 suspected ; and these of such a nature, as to afford 

 points of contact with several other branches of 

 physical enquiry, and to throw new and unexpected 

 lights on some of the most obscure operations of 

 nature. 



(373.) The history of this grand discovery affords 

 a fine illustration of the advantage to be derived in 

 physical enquiry from a close and careful attention 

 to any phenomenon, however apparently trifling, 

 which may at the moment of observation appear in- 

 explicable on received principles. The convulsive 

 motions of a dead frog in the neighbourhood of an 

 electric discharge, which originally drew Galvani's 

 attention to the subject, had been noticed by others 

 nearly a century before his time, but attracted no 

 further remark than as indicating a peculiar sensi- 

 bility to electrical excitement depending on that 

 remnant of vitality which is not extinguished in the 

 organic frame of an animal by the deprivation of 

 actual life. Galvani was not so satisfied. He ana- 

 lysed the phenomenon ; and in investigating all the 

 circumstances connected with it was led to the ob- 

 servation of a peculiar electrical excitement which 

 took place when a circuit was formed of three dis- 

 tinct parts, a muscle, a nerve, and a metallic con- 

 ductor, each placed in contact with the other two, 



