131 



metallic plates, or the strength of the exciting liquid ; to 

 ohtain intensity, we must increase the number of the plates, 

 and join them together in series or sequence ; thus the first 

 zinc is joined to the second copper plate, the second zinc 

 to the third copper, and so on, until we multiply the pairs 

 sufficiently to obtain the desired intensity. 



The first kind of battery I used, was such a series of 

 copper and zinc plates, excited by a solution of sulphate of 

 copper, (which has been fully explained in my pamphlet on the 

 subject,) but this arrangement was afterwards improved by 

 substituting iron for the copper plates, as I discovered that 

 iron was superior to copper if the battery was to be in action 

 for some time ; the cause of this phenomena, which at first 

 sight appeared at variance with our received notions of elec- 

 trical science, will be found fully explained by me in the 

 Philosophical Magazine for June, 1841. This iron battery 

 was filled up without the intervening cells that are commonly 

 employed, such an arrangement being cheap and easy of 

 management, but it had the defect of diminishing the inten- 

 sity of the electric current, and was therefore not very 

 applicable to situations where it was necessary that the 

 battery should be far removed from the rock. 



Since this I have contrived a battery, which is now brought, 

 for the first time, before the scientific world ; and that now 

 shown to you has been made expressly for this Society. 

 There is no doubt that for the purpose of firing gunpowder 

 and other such momentary actions, it will be found far more 

 powerful than any hitherto made, simply because we avail 

 ourselves of the intense current of electricity always deve- 

 loped at the first instant of the immersion of the plates into 

 the exciting solution. This battery consists of twelve copper 

 cylinders 2\ inches in diameter, and 10 inches long, closed at 

 both ends ; a cylinder of zinc is fixed into each of these 

 copper tubes, and being only 6 inches long, extends from the 



