S*cr. XXXlil. VOLTA-ELECTllHJ INDUCTION. 3^3 



as the contacts were made or broken, but neither chem- 

 ical action nor any other electric effects were obtained. 

 A deviation of the needle of the galvanometer took place 

 when common magnets were employed instead of the 

 Voltaic current; so that the magnetic and electric 

 fluids are identical in their effects in this experiment. 

 Again, when a helix formed of 220 feet of copper wire, 

 into which a cylinder of soft iron was introduced, was 

 placed between the north and south poles of two bar 

 magnets, and connected with the galvanometer by means 

 of wires from each extremity, as often as the magnets 

 were brought into contact with the iron cylinder, it be- 

 came magnetic by induction, and produced a deflection 

 in the needle of the galvanometer. On continuing the 

 contact, the needle resumed its natural position, and 

 when the contact was broken, deflection took place in 

 the opposite direction ; when the magnetic contacts 

 were reversed, the deflection was reversed also. With 

 strong magnets, so powerful was the action, that the 

 needle of the galvanometer whirled round several times 

 successively ; and similar effects were produced by the 

 mere approximation or removal of the heb'x to the poles 

 of the magnets. Thus it was proved that magnets pro- 

 duce the veiy same effects on the galvanometer that 

 electricity does. Though at that time no chemical de- 

 composition was effected by these momentary currents 

 which emanate from the magnets, they agitated the 

 limbs of a frog ; and Dr. Faraday justly observes, that 

 "an agent which is conducted along metallic wires in 

 the manner described, which, while so passing, pos- 

 sesses the peculiar magnetic actions and force of a cur- 

 rent of electricity, which can agitate and convulse the 

 limbs of a frog, and which finally can produce a spark 

 by its discharge through charcoal, can only be electri- 

 city." Hence it appears that electrical currents are 

 evolved by magnets, which produce the same phenomena 

 with the electrical currents from the Voltaic battery : 

 they however differ materially in this respect that 

 time is required for the exercise of the magnetico-elec- 

 trie induction, whereas Volta-electric induction is in- 

 stantaneous. 



After Dr. Faraday had proved the identity of the 



