166 Dr. Faraday's Experimental Researches in Electricity. 



discharge of a voltaic battery is known to all as the most 

 beautiful light that man can produce by art. 



281. That these effects may be almost infinitely varied, 

 some being exalted whilst others are diminished, is universally 

 acknowledged; and yet without any doubt of the identity of 

 character of the voltaic currents thus made to differ in their 

 effect. The beautiful explication of these variations afforded 

 by Cavendish's theory of quantity and intensity requires no 

 support at present, as it is not understood to be doubted. 



282. In consequence of the comparisons that will hereafter 

 arise between wires carrying voltaic and ordinary electricities, 

 and also because of certain views of the condition of a wire or 

 any other conducting substance connecting the poles of a vol- 

 taic apparatus, it will be necessary to give some definite view 

 of what is called the voltaic current, in contradistinction to any 

 supposed peculiar state of arrangement, not progressive, which 

 the wire or the electricity within it may be supposed to as- 

 sume. If two voltaic troughs PN, P'N', fig. 1. be symmetri- 



Fig. 1. 



Ky_K. .:\ T \ . 



N 



ST 



cally arranged and insulated, and the ends NP' connected by 

 a wire, over which a magnetic needle is suspended, the wire 

 will exert no effect over the needle; but immediately that the 

 ends PN' are connected by another wire, the needle will be 

 deflected, and will remain so as long as the circuit is complete. 

 Now if the troughs merely act by causing a peculiar arrange- 

 ment in the wire either of its particles or its electricity, that 

 arrangement constituting its electrical and magnetic state, 

 then the wire NP' should be in a similar state of arrangement 

 before P and N' were connected, to what it is afterwards, and 

 should have deflected the needle, although less powerfully, 

 perhaps to one half the extent which would result when the 

 communication is complete throughout. But if the magnetic 

 effects depend upon a current, then it is evident why they 

 could not be produced in any degree before the circuit was 

 complete ; because prior to that no current could exist. 



283. By current, I mean anything progressive, whether it 

 be a fluid of electricity, or two fluids moving in opposite di- 

 rections, or merely vibrations, or, speaking still more ge- 



