OF NATURAL PHILOSOPHY. 341 



the curious relations of electricity to heat, as ex- 

 hibited in the phenomena of what has been called 

 thermo-electricity, promise an ample supply of new 

 information. 



(378.) Among the remarkable effects of electricity 

 disclosed by the researches of Galvani and Volta, 

 perhaps the most so consisted in its influence on 

 the nervous system of animals. The origin of mus- 

 cular motion is one of those profound mysteries of 

 nature which we can scarcely venture to hope will 

 ever be fully explained. Physiologists, however, 

 had long entertained a general conception of the 

 conveyance of some subtle fluid or spirit from the 

 brain to the muscles of animals along the nerves ; 

 and the discovery of the rapid transmission of elec- 

 tricity along conductors, with the violent effects 

 produced by shocks, transmitted through the body, 

 on the nervous system, would very naturally lead to 

 the idea that this nervous fluid, if it had any real 

 existence, might be no other than the electrical 

 But until the discoveries of Galvani and Volta, this 

 could only be looked upon as a vague conjecture. 

 The character of a vera causa was wanting to give it 

 any degree of rational plausibility, since no reason 

 could be imagined for the disturbance of the electrical 

 equilibrium in the animal frame, composed as it is 

 entirely of conductors, or rather, it seemed contrary 

 to the then known laws of electrical communication 

 to suppose any such. Yet one strange and surpris- 

 ing phenomenon might be adduced indicative of the 

 possibility of such disturbance, viz. the powerful 

 shock given by the torpedo and other fishes of the 

 same kind, which presented so many analogies with 

 z 3 



