1835] WRITINGS OF JOSEPH HENRY. 89 



APPENDIX TO THE ABOVE — ACTION OF A SPIRAL CONDUCTOR. 

 (Silliman's Am. Journal of Science, July, 1835, vol. xxviii, pp. 329-331.) 



To Prof. Silliman. 



Sir : With this I send you a copy of a paper communi- 

 cated by me to the American Philosophical Society, on the 

 influence of a spiral conductor in increasing the intensity 

 of electricity from a galvanic arrangement of a single pair. 

 As the part of the Transactions which contains the paper has 

 not yet been distributed, I regret that I am not at liberty 

 to request you to insert the article for more general diffu- 

 sion in your valuable Journal. An abstract however of the 

 principal facts was ordered to be published, and appeared 

 in the March number of the Franklin Journal. A copy 

 was also sent by Prof. Bache for insertion in the American 

 Journal ; but as it did not appear in the last number, you 

 will confer a favor by inserting it in the next.* 



Should you wish to repeat the experiments, you will find 

 them most interestingly exhibited with one of Dr. Hare's " cal- 

 orimotors." If a galvanic current of very low intensity from 

 this instrument be transmitted through a spiral conductor 

 formed of copper ribbon about one inch wide, from sixty to 

 one hundred feet long, well covered with silk, and the several 

 spires closely wound on each other, the "calorimotor" will be 

 almost converted into a " deflagrator." One end of the con- 

 ductor being attached to a pole of the battery, and the other 

 brought in contact with or rubbed along the edge of a plate 

 of metal attached to the other pole, a vivid deflagration 

 will be produced, even when the plates are immersed in a 

 mixture containing not more than one part of acid to five 

 hundred parts of water. 



If a copper cylinder of about two inches in diameter and 

 four or five inches long, to serve as a handle, be attached to 

 each end of the spiral b}^ an intervening piece of copper 

 wire and these cylinders grasped with moistened hands, a 

 series of shocks will be felt when one end of the conductor 



* [Then mislaid, but now inserted ; as above. — Ed.'^ 



