256 BULLETIN OF THE 



exertions to the duties of exposition and instruction; and during 

 Dr. Torrey's visit to Europe in 1833, at the Doctor's request 

 Professor Henry filled ad interim his chair of Chemistry, Miner- 

 alogy, and Geology. These occupations left him no leisure for 

 the pursuit of original research. He subsequently gave lectures 

 on Astronomy, and also on Architecture. 



In 1834, Henry constructed for the Laboratory of his College 

 an original form of Galvanic Battery; so arranged as to bring 

 into action any desired number of elements, from a single pair to 

 eighty-eight. Each zinc plate 9 inches wide and 12 inches 

 deep was surrounded by a copper case open at top and bottom, 

 and giving thus one and a half square feet of efficient surface. 

 Eleven of these in eleven separate cells, formed a sub-battery; 

 and eight of these were grouped together by means of adjustable 

 conductors, so as to form from the whole a single battery. By 

 means of a crank and windlass shaft in proper connection, any 

 one or more of the eight sub-batteries could be immersed or dis- 

 engaged, and if desired, a single cell could alone be charged. By 

 another arrangement of adjustable conductors, all the zinc plates 

 could be directly connected together, and all the copper plates 

 together, after the plan of Dr. Hare's " calorimotor" battery ; 

 thus giving the "quantity" effect due to a single element of 132 

 square feet of zinc surface, or of any smaller area desired. As 

 the author remarks concerning its various arrangements, "they 

 have been adopted in most cases after several experiments and 

 much personal labor." A detailed account of this battery was 

 given in a communication read January 16th 1835, before the 

 American Philosophical Society (of which he had recently been 

 elected a member), and was published in its Transactions.* 



Meanwhile he had been engaged in his brief intervals of relaxa- 

 tion from his exacting professional cares during the past year, in 

 repeating and extending his interesting observations (commenced 

 at Albany in 1832), on the remarkable intensifying inJiuence of a 

 long conductor, and especially of a spiral one, when interposed 

 in a galvanic circuit of a single pair, or a battery of low " inten- 

 sity." A verbal communication on this curious form of "induc- 

 tion," was made to the Society on the same occasion as the 

 description of his battery, and was illustrated by experiments 

 exhibited before the Society. 



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

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

 ing actions of a single galvanic element giving a "quantity" cur- 

 rent, and of a series of elements giving an "intensity" current :f 

 thus entirely confirming the results obtained by Henry more than 

 three years previously. 



* Trans. Am. Philox. Soc. vol. V. new series, art. iv. pp. 217-222. 

 t J'hil. Trans. Royal Soc. June 5, 1834, vol. cxxiv. art. 990-994, pp. 

 445, 446. Experimental Researches in Electricity, vol. i. pp. 301, 302. 



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