402 



obliterated, the absolute maximum occurring during the night. 

 In six hours, namely, from 7 a. m. to 1 p. m., the increase 

 amounted to nineteen degrees. 



Michael Donovan, Esq., read a continuation of his paper 

 " on the supposed identity of the agent in the phenomena of 

 ordinary electricity, voltaic electricity, electro-magnetism^ 

 magneto-electricity, and thermo-electricity." 



After briefly noticing the circumstances of the discovery 

 of galvanism, the author remarked, that as soon as even a few 

 of the facts were discovered, an hypothesis was invented to 

 account for them ; they were at once attributed to the agency 

 of an animal electricity secreted by the brain, of which the 

 muscles are the depositories, and the nerves the conductors. 

 Volta admitted that the agent is electricity, but maintained 

 that it is generated by the contact of the conductors concerned ; 

 the contraction being produced by the restoration of the equi- 

 librium throngh the animal. Hundreds of facts have been 

 since discovered, but, wonderful to say, the hypothesis in- 

 vented before they were known has been adhered to, and is 

 still used for their explanation. 



The vast difference of properties observable in electric and 

 voltaic phenomena has been conceived to be explicable on the 

 supposition that in the former the quantity of electricity is 

 small, and the intensity great, while in the latter the quantity 

 is great and the intensity low. Several quotations from autho- 

 rities were adduced to this effect, and also with a view of 

 determining the exact meaning oi quantity -Andi intensity. 



It was then argued, that the efficiency of great quantity, 

 at a low intensity, to account for the difference between com- 

 mon and voltaic electricity, has been received upon grounds 

 which have not been sufficiently canvassed ; that we know 

 nothing of quantity of electricity but by its intensity ; that 

 the two terms represent ideas which are inseparable; that in- 

 tensity is the only significant condition of electricity of which 



