ON MATTER AND FORCE. 55 



through copper, of travelling at the rate of 

 nearly three hundred thousand miles a second, 

 or, like light through the interstellar sether, 

 at two hundred thousand miles a second. 



The researches of Helmholtz* show that the 

 rate of passage of that motion through the 

 particles of matter in a nerve which gives rise 

 to sensation or to motion is only between 

 twenty-eight and thirty-three feet in a second; 



So late as 1866, Professor Bain, in a lecture 

 at the Eoyal Institution on the Correlation of 

 Force in its Bearing on Mind, speaks " of a 

 certain flow of the influence circulating through 

 the nerves." 



Another very remarkable vital fluid was con- 

 sidered to be a chemical agent, an element- 

 ary principle, or highly-attenuated substance, 

 which, among its other singular and remark- 

 able properties, had that of imparting to the 

 constituent matters of the animal frame new 

 chemical affinities between it and the surround- 

 ing elements, and thereby protecting the living 

 fibre from dissolution, or giving them other 

 properties which, without this vitalisation, they 

 would not possess. 



* Appendix I. 



