240 MEMORIAL OF JOSEPH HENRY. 



Faraday in his "eighth series of Researches" (read before the 

 Royal Society June 5th, 1834), pointed out very fully the differing 

 actions of a single galvanic element giving a "quantity" current, 

 and of a series of elements giving an " intensity " current : * thus 

 entirely confirming the results obtained by Henry more than three 

 years previously. 



In the Philosophical Magazine for November, 1834, appeared a 

 paper by Faraday, "On a peculiar condition of electric and 

 magneto-electric Induction :" in which he notices as a remarkable 

 fact, that while a short circuit wire from a single galvanic element, 

 gives little or no visible spark, a long conductor gives a very sen- 

 sible spark. "If the connecting wire be much lengthened, then 

 the spark is much increased." f In his interesting research, Faraday 

 appears to have entirely overlooked Henry's earlier labors in the 

 same field; as contrary to his usual custom, he makes no allusion 

 to the same results having been obtained, and published in Silliman's 

 Journal two years and a half before. ;f 



These observations were made by Faraday the subject of his 

 "ninth series of Researches," in a communication "On the influence 

 by induction of an electric current on itself:" read before the Royal 

 Society January 29th, 1835. In this paper he states: "The inquiry 

 arose out of a fact communicated to me by Mr. Jenkin, which is 

 as follows: If an ordinary wire of short length be used as the 

 medium of communication between two plates of an electro-motor 

 consisting of a single pair of metals, no management will enable 

 the experimenter to obtain an electric shock from this wire : but if 

 the wire which surrounds an electro-magnet be used, a shock is felt 

 each time the contact with the electro-motor is broken." Having 

 varied the experiment, Faraday adds : " There was no sensible spark 

 on making contact, but on breaking contact there was a very large 

 and bright spark, with considerable combustion of the mercury." 

 He found a similar result with the wire helix alone, without its 

 magnetic core. "The power of producing these phenomena exists 

 therefore in the simple helix, as well as in the electro-magnet, 



*Phll. Trans. Roy. Soc. June 5, 1834, vol. cxxiv. arts. 990-994, pp. 455, 456. Experi- 

 mental Researches in Electricity, vol. i. pp. 301, 302. 



f L. & E. Philosoph. Mag. Nov. 1834, vol. v. pp. 351, 352. 



t Silliman's Am. Jour. Sci. July, 1832, vol. xxii. p. 408, above quoted. 



