DISCOUESE OF W. B. TAYLOR. 241 



although by no means in the same high degree." With continuous 

 straight wire of the same length, he obtained a similar effect, "yet 

 not so bright as that from the helix." " When a short wire is used, 

 all these effects disappear;" although there is undoubtedly a greater 

 " quantity " of electric current in the shorter wire ; thus giving " the 

 strange result of a diminished spark and shock from the strong 

 current, and increased effects from the weak one." * 



While Henry derived only satisfaction from these extended 

 verifications of his own observations, by one whom he had accus- 

 tomed himself to look up to with admiration and regard, Dr. A. 

 Dallas Bache, his attached friend, then Professor of Natural 

 Philosophy in the University of Pennsylvania, more jealous than 

 himself of his scientific fame, strongly urged and insisted that he 

 should immediately publish an account of his later researches. 

 Henry accordingly sent to the American Philosophical Society a 

 memoir (comprising the details of his recent verbal communication) 

 " On the Influence of a Spiral Conductor in increasing the Inten- 

 sity of Electricity from a galvanic arrangement of a Single pair, 

 etc.," which was read before the Society, February 6th, 1835. 



After citing his former paper of July, 1832, the writer remarks 

 that he had been able during the past year to extend his experi- 

 ments on the curious phenomenon. "These though not so complete 

 as I could wish, are now presented to the Society with the belief 

 that they will be interesting at this time on account of the recent 

 publication of Mr. Faraday on the same subject." He then 

 relates that employing a single pair of his battery (comprising one 

 and a half square feet of zinc surface), he found as in his earlier 

 experiment in 1832, that the poles being connected by a piece of 

 copper bell-wire five inches long, no spark was given on making or 

 breaking contact. Fifteen feet of interposed wire gave a very 

 feeble spark; and with successive additions of fifteen feet, the effect 

 increased until with 120 feet the maximum spark appeared to be 

 reached, and beyond this there was no perceptible increase; while 

 with double this length (or 240 feet) there seemed to be a diminu- 



*Phil. Trans. Roy. Soc. Jan. 29, 1835, vol. cxxv. articles 1061-1067, and 1073, pp. 41-45. 

 Experimental Researches in Electricity, vol. i. pp. 324-328. This memoir did not reach 

 this country, of course, till a year later. 



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