DISCOURSE OF W. B. TAYLOR. 255 



Oscillation of Electrical Discharge. In June, 1842, he presented a 

 communication to the Society recounting an investigation of some 

 anomalies in ordinary electrical induction. While with the larger 

 needles ("No. 3 and No. 4") subjected to the magnetizing helix, the 

 polarity was always conformable to the direction of the discharge, 

 he found that when very fine needles were employed, an increase in 

 the force of the electricity produced changes of polarity. About a 

 thousand needles were magnetized in the testing helices in these 

 researches. 



This puzzling phenomenon was finally cleared up by the important 

 discovery that an electrical equilibrium was not instantaneously 

 effected by the spark, but that it was attained only after several 

 oscillations of the flow. "The discharge whatever may be its 

 nature, is not correctly represented by the single transfer 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 pre- 

 ceding, until the equilibrium is obtained."* In every case therefore 

 of the electrostatic discharge, the testing needles were really sub- 

 jected to an oscillating alternation of currents, and consequently to 

 successive partial de-magnetizations and re-magnetizations. The 

 complications produced by this residual action, satisfactorily ex- 

 plained for the first time, the discordant results obtained by different 

 investigators. This singular reflux of current was ingeniously ap- 

 plied by Henry to explain the apparent change of inductive current 

 with differing distances. Should the primitive discharge wave be 

 in excess of the magnetic capacity of the needle at a given position, 

 the return wave might be just sufficient to completely reverse its 

 polarity, and the diminished succeeding wave insufficient to restore 

 it to its former condition ; while at a greater distance, the primitive 

 wave might be so far reduced as to just magnetize the needle fully, 



* Proceedings Am. Phil. Soc. June 17, 1842, vol. ii. pp. 193-196. Prof. HERMANN L. 

 F. HELMHOLTZ sc^ne five years later (In 1847), but quite Independently, suggested 

 "a backward and forward motion between the coatings" when the Leydeii jar is 

 discharged. (Scientific Memoirs, edited by Dr. J. Tyndall, 1853, vol. i. p. 143.) And still 

 five years later (in 1852) Sir WILLIAM THOMSON made the same independent conjec- 

 ture. (L. E. D. Phil. Mag. June, 1853, vol. v. pp. 400, 401.) To FELIX SAVARY however 

 is due the credit of having first advanced the hypothesis of electrical oscillations, 

 as early as 1827. See "Supplement," NOTE F. 



