74 WRITINGS OF JOSEPH HENRY. [1832 



has at length been found by Mr. Faraday of the Royal In- 

 stitution. It states that he has established the general fact, 

 that when a piece of metal is moved in any direction, in 

 front of a magnetic pole, electrical currents are developed in 

 the metal, which pass in a direction at right angles to its own 

 motion, and also that the application of this principle affords 

 a complete and satisfactory explanation of the phenomena 

 of magnetic rotation. No detail is given of the experiments, 

 and it is somewhat surprising that results so interesting, and 

 which certainly form a new era in the history of electricity 

 and magnetism, should not have been more fully described 

 before this time in some of the English publications; the 

 only mention I have found of them is the following short 

 account from the Annals of Philosophy for April, under the 

 head of Proceedings of the Royal Institution : 



" Feb. 17. — Mr. Faraday gave an account of the first two 

 parts of his researches in electricity ; namely, Volta-electric 

 induction and magneto-electric induction. If two wires, A 

 and B, be placed side by side, but not in contact, and a Vol- 

 taic current be passed through A, there is instantly a cur- 

 rent produced by induction in B, in the opposite direction. 

 Although the principal current in A be continued, still the 

 secondary current in B is not found to accompany it, for it 

 ceases after the first moment, but when the principal cur- 

 rent is stopped then there is a second current produced in 

 B, in the opposite direction to that of the first produced by 

 the inductive action, or in the same direction as that of the 

 principal current. 



" If a wire, connected at both extremities with a galvanom- 

 eter, be coiled in the form of a helix around a magnet, no 

 current of electricity takes place in it. This is an experi- 

 ment which has been made by various persons hundreds of 

 times, in the hope of evolving electricity from magnetism, 

 and as in other cases in which the wishes of the experi- 

 menter and the facts are opposed to each other, has given 

 rise to very conflicting conclusions. But if the magnet be 

 withdrawn from or introduced into such a helix, a current 

 of electricity is produced whilst the magnet is in motion, and is 

 rendered evident by the deflection of the galvanometer. If a 

 single wire be passed by a magnetic pole, a current of electri- 

 city is induced through it which can be rendered sensible."* 



♦[Phil. Mag. ; and Annals of Philosophy; April, 1832: vol. xi, p. 300.] 



