294 MECHANICAL ELECTRICITY. 



was the result. Thus it is seen, that with the same 

 heat developed in each case, by the mechanical 

 arrangement, is given an immediate current, 

 which heat will not give current at all by the 

 thermo Electric process, and it is therefore evi- 

 dent that thermo and mechanical Electricity are 

 not derived from the same source. 



These experiments appear very decisive. The 

 fact of the current invariably pursuing the course 

 of that in electro motion, or contact of dissimilar 

 metals, in all cases where metals illustrative of 

 this phenomenon are employed, speaks in favour 

 of the dissimilarity of the source of these two 

 modifications. 



It is also to be remarked here, that if mecha- 

 nical Electricity were the result of the heat 

 applied to the extremity of the metal, the friction 

 of flat surfaces, which is known to produce much 

 more heat than simply cutting or turning with 

 a sharp edge, would produce the greatest deflec- 

 tion of the needle ; but by this means it is found, 

 that none, or scarcely any current is developed, 

 even with a disc of Bismuth. (See 22, 23.) 



Exp. 46. Is mechanical or thermo Electricity 



