346 Experimental Researches in Electricity. 



placed Faraday in the position of a general advancing into 

 a new region, and leaving a strong post unsubdued in his 

 rear, by which the integrity of his movements would have 

 been destroyed, and the prospects of his ultimate success 

 rendered unsatisfactory, because uncertain. In a spirit of 

 the soundest policy, however, he delayed his advance until 

 the obstacle in question had been satisfactorily removed 

 from his path, and of the means adopted by him to this end, 

 we may now proceed to give a rapid sketch. 



The various phenomena exhibited by Electricity may, for 

 the purpose of comparison, be arranged with two divisions ; 

 namely, those connected with electricity of tension, or what 

 we may venture to call, statical electricity, and those con- 

 nected with electricity in motion, or dynamical electricity. 

 The effects of the first, at rest, are either attraction or re- 

 pulsion at sensible distances; of the second, 1st evolution 

 of heat ; 2nd magnetism ; 3rd chemical decomposition ; 

 4th physiological effects ; 5th spark. The mode of pro- 

 ceeding adopted by Faraday was to compare electricities 

 from different sources by their power of producing these 

 effects, and in the event of identity of effect being establish- 

 ed, he was, of course, warranted in inferring identity of 

 cause. 



The first step was to ascertain in how far voltaic electri- 

 city corresponded in its effects to the standard above ad- 

 verted to, and as it is well known that the discharge of 

 ordinary electricity through air by means of points, its 

 transmission through highly rarefied air, and also through 

 heated air, as for instance a flame, are effects due to its 

 state of high tension, similar effects were sought for with 

 voltaic electricity under the same circumstances ; the deflec- 

 tion of the galvanometer, or the occurrence of chemical de- 

 composition being employed as the tests of the passage of 

 the electricity. On endeavouring, however, to procure indi- 

 cations of a discharge by means of very fine points carefully 



