Experimental Researches in Electricity, 7 



and well charged. When the contact was made, there was a 

 sudden and very slight effect at the galvanometer, and also 

 a similar slight effect when the contact with the battery 

 was broken. But whilst the voltaic current was continuing to 

 pass through the one helix, no galvanometrical appearances 

 nor any effect like induction upon the other helix could 

 be perceived, although the active power of the battery 

 was proved to be great, by its heating the whole of its 

 own helix, and by the brilliancy of the discharge when made 

 through charcoal." The results caused by this experiment 

 proved in Faraday's hands the clue to the electrical laba- 

 rynth in which he had been wandering so long in com- 

 parative darkness; and he rapidly traversed the field of 

 discovery now opening around him. He found by varying the 

 form of the preceding experiment that it was sufficient to ex- 

 hibit proofs of induction, if he merely moved the induci- 

 ble in front of the inducing wire, since as the former 

 was made to approach to, or recede from the latter, so the 

 galvanometer was affected, indicating on the approximation 

 of the wires an induced current in a contrary direction 

 to the inducing current, while on their recession the two 

 currents had the same direction. Efforts were then made to 

 exhibit in it like effects to the preceding, with wires convey- 

 ing charges of common electricity, but without any satisfac- 

 tory result, in consequence of the instantaneous discharge of 

 the current rendering it impossible to separate the effects 

 due to its commencement from the equal and contrary 

 effects due to its close. Time enters as a necessary element 

 with the induction of voltaic currents ; but in discharges of 

 common electricity, this element cannot be commanded. 

 The peculiar action to which we have now alluded, has been 

 termed by Faraday volta-electric induction. 



We formerly, in briefly adverting to the Amperian theory 

 of magnetism, stated that a voltaic current, circulating in 

 a wire of a peculiar form, namely that of a vertical, spiral, or 



