ADDRESS OF PROF. A. M. MAYER. 493 



communication to the Royal Society of Edinburgh. My result is 

 therefore entirely independent of his, and was undoubtedly obtained 

 by a different process." 



A few words now will place Henry in his proper and just relation 

 to these important discoveries. We have seen that all the informa- 

 tion he had received about Faraday's discovery was the account of 

 Faraday's production of magneto-electricity by the sudden insertion 

 of a magnet into a helix and by its sudden withdrawal therefrom. 

 This is the experiment described in section No. 39 of Faraday's 

 paper of November, 1 831 . Henry's experiment is entirely different, 

 and certainly was entirely original with him, but it is essentially 

 Faraday's experiment described in sections 27, 28, 29, 30 and 31 of 

 the same paper, and is the first in the order of those which Faraday 

 gives of his various methods of evolving electricity from magnetism. 

 Of this experiment Henry had no knowledge when he obtained the 

 electric current from the magnet, no more than he had of the other 

 experiment in which Faraday moved a permanent steel magnet in a 

 helix. Thus it clearly appears that though Henry cannot be placed 

 on record as the first discoverer of the magneto-electric current, yet 

 it 6an be claimed that he stands alone as its second independent 

 discoverer. 



As to* the production of the electric spark from the magneto- 

 electric current, both Henry and Forbes were anticipated by Faraday, 

 who describes an experiment, which in all essentials is the same as 

 Henry's, in section No. 32 of the same paper of November, 1831. 



I may have been somewhat tedious in these long quotations and 

 minute narrations of dates, but my object is to place Henry before 

 you as a discoverer and make you appreciate him, and that justly; — 

 not to ask too much for him, for that would injure his fair name. 



Henry's next discovery was that of the induction of a current on 

 itself, or of the "extra current," as it is sometimes called. Here 

 he had the good luck to anticipate Faraday by nearly two years and 

 a half in the observation of the fundamental facts of this discovery, 

 Henry publishing his observations in July, 1832, while Faraday's 

 first appear in the Philosophical Magazine for November, 1834. 

 Therefore, to Henry should be given the honor of having made the 

 first observations of these phenomena; but not in opposition to any 



