1842] WRITINGS OF JOSEPH HENRY. 201 



wire through which the discharge of a Leyden battery is 

 passed, they are magnetized in different directions, and that 

 by constantly increasing the discharge through a spiral, 

 several reversions of the polarity of the contained needles 

 are obtained. 



It was therefore very important before attempting further 

 advances in the discovery of the laws of the phenomena, 

 that the results obtained by M. Savary should be carefully 

 studied; and accordingly the first experiments of the new 

 series relate to the repetition of them. The author first 

 attempted to obtain them by using needles of a larger size, 

 Nos. 3, and 4, such as he had generally employed in all 

 his previous experiments; but although nearly a thous- 

 and needles were magnetized in the course of the experi- 

 ments, he did not succeed in getting a single change in the 

 polarity. The needles were always magnetized in a direc- 

 tion conformable to the direction of the electrical discharge. 

 When however very fine needles were employed he did 

 obtain several changes in the polarity in the case of the 

 spiral, by merely increasing the quantity of the electricity, 

 while the direction of the discharge remained the same. 



This anomaly which has remained so long unexplained, 

 and which at first sight appears at variance with all our 

 theoretical ideas of the connection of electricity and mag- 

 netism, was after considerable study satisfactorily referred 

 by the author to an action of the discharge of the Leyden 

 jar which had never before been recognized. The dis- 

 charge, whatever may be its nature, is not correctly repre- 

 sented (employing for simplicity the theory of Franklin) by 

 the single transfer of an imponderable fluid from one side 

 of the jar to the other; the phenomena require us to admit 

 the existence of a principal discharge in one direction, and then 

 several reflex actions backward and forward, each more feeble than 

 the preceding, until the equilibrium is obtained. All the facts 

 are shown to be in accordance with this hypothesis, and a 

 ready explanation is aff'orded by it of a number of phenom- 

 ena which are to be found in the older works on electricity, 

 but whicli have until this time remained unexplained. 



