490 . . MEMORIAL, OP JOSEPH HENRY. . 



could not read German, and Ohm's papers were first published in 

 'English in Taylor's ScientiJiG Memoirs, vol. ii, London, 1 841. . From 

 the very manner in which Henry worked at his problems and 

 viewed the results of his experimenting it is evident that, at that 

 date, he had no knowledge of Ohm's law ; otherwise, he would not 

 have been so astonished at the results when his 'intensity magnet" 

 was connected with his "intensity battery." , . 



Henry, now in possession of the powerful magnets of his own 

 creation, turned his thoughts to the uses to which he might put 

 these instruments as aids in making other discoveries. He began 

 with work on a problem which had baffled many able men before 

 him. He tried to do the reverse of what he had already done. He 

 had made his great magnet by the action of the electric current, he 

 now tried to obtain an electric current from the magnetism of his 

 great magnet, — and he succeeded. 



It is not generally known or appreciated that Henry and Faraday 

 independently discovered the means of producing the electric current 

 and the electric spark from a magnet. Tyndall, in speaking of this 

 great discovery of Faraday's, says; "I cannot help thinking while 

 I dwell upon them that this discovery of magneto-electricity is the 

 greatest experimental result ever obtained by an investigator. It 

 is the Mont Blanc of Faraday's own achievements. He always 

 worked at great elevations, but higher than this he never subse- 

 quently attained." 



The history of Henry's connection with this notable discovery is, 

 I think, best given in Henry's own words, which I take from 

 Silliman's Journal of July, 1832. Referring to Faraday's discov- 

 ery, he says: "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 paf ts of his researches 

 in electricity, namely, volta-electric induction and magneto-electric 

 induction. - - - If a wire, connected at "both extremities with 



