TRANSVERSE FORCES OF THE CURRENT. 165 



only as an approximation, I have seen no reason as yet to alter, and it is confirmed 

 generally by the experiments and results of M. Pouillet *. According to Mr. Wheat- 

 stone's experiments the influence or effects of the current would appear at a distance 

 of 576,000 miles in a second-}-. We have, therefore, in this view of the matter, on the 

 one hand, an enormous quantity of power equal to a most destructive thunder storm 

 appearing instantly at the distance of 576,000 miles from its source, and on the other, 

 a quiet effect, in producing which the power had taken an hour and a half to travel 

 through the tenth of an inch : yet these are the equivalents to each other, being effects 

 observed at the sections of one and the same current (1634.). 



1653. It is time that I should call attention to the lateral or transverse forces of 

 the current. The great things which have been achieved by Oersted, Arago, Ampere, 

 Davy, De la Rive, and others, and the high degree of simplification which has been 

 introduced into their arrangement by the theory of Ampere, have not only done their 

 full service in advancing most rapidly this branch of knowledge, but have secured to 

 it such attention that there is no necessity for urging on its pursuit. I refer of course 

 to magnetic action and its relations ; but though this is the only recognised lateral 

 action of the current, there is great reason for believing that others exist and would 

 by their discovery reward a close search for them (951.). 



1654. The magnetic or transverse action of the current seems to be in a most ex- 

 traordinary degree independent of those variations or modes of action which it pre- 

 sents directly in its course; it consequently is of the more value to us, as it gives us 

 a higher relation of the power than any that might have varied with each mode of 

 discharge. This discharge, whether it be by conduction through a wire with infinite 

 velocity (1652.), or by electrolyzation with its corresponding and exceeding slow mo- 

 tion (1651.), or by spark, and probably even by convection, produces a transverse 

 magnetic action always the same in kind and direction. 



1655. It has been shown by several experimenters, that whilst the discharge is of the 

 same kind the amount of lateral or magnetic force is very constant (366. 367. 368. 

 376.). But when we wish to compare discharge of different kinds, for the important 

 purpose of ascertaining whether the same amount of current will in its differ emt forms 

 produce the same amount of transverse action, we find the data very imperfect. 

 Davy noticed, that when the electric current was passing through an aqueous solution 

 it affected a magnetic needlej, and Dr. Ritchie says, that the current in the electro- 

 lyte is as magnetic as that in a metallic wire§, and has made water revolve round a 

 magnet as a wire carrying the current would revolve. 



1656. Disruptive discharge produces its magnetic effects: a strong spark, passed 



* Becqtjerbl, Traitd de I'Electricite, v, p. 278. f Philosophical Transactions, 1834, p. 589. 



: Philosophical Transactions, 1821, p. 426. § Ibid. 1832, p. 294. 



