134 
an account of these anomalies in electrical induction and the re- 
sults of his investigation of them. While, with the larger needles 
subjected to the magnetizing helix, the polarity was always con- 
formable 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. In these researches not less than a 
thousand needles were magnetized in the testing helices. This per- 
plexing phenomenon was finally cleared up by the important dis- 
covery that an electrical equilibrium was not instantaneously effected 
by the spark, but that it was attained only after several oscillations 
of the flow. 
Ina recent lecture before the Royal Institution of Great Britain, 
Dr. Oliver Lodge says, in speaking of the oscillatory character of a 
Leyden jar discharge: * ‘‘ It was first clearly realized and distinctly 
stated by that excellent experimentalist, Joseph Henry, of Wash- 
ington, a man not wholly unlike Faraday in his mode of work, 
though doubtless possessing to a less degree that astonishing insight 
into intricate and obscure phenomena; wanting also in Faraday’s 
circumstantial advantages. This great man arrived at a conviction 
that the Leyden jar discharge was oscillatory by studying the singu- 
lar phenomena attending the magnetization of steel needles by a 
Leyden jar discharge, first observed in 1824 by Savary. Fine 
needles when taken out of the magnetizing helices were found to 
be not always magnetized in the right direction, and the subject is 
referred to in German works as ‘anomalous magnetization.’ It is 
not the magnetization which is anomalous, but the currents which 
have no simple direction ; and we find in a memoir published by 
Henry in 1842 the following words: 
*¢ «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 magnetism, was, after consider- 
able study, satisfactorily referred by the author to an action of the 
discharge of the Leyden jar which had never before been recognized. 
The discharge, whatever may be its nature, is not correctly repre- 
sented (employing for simplicity the theory of Franklin) by the sin- 
gie transfer of an imponderable fluid from one side of the jar to 
the other ; the phenomenon requires us to admit the existence of 
a principal discharge in one direction and then several reflex actions 
backwards and forwards, each more feeble than the preceding, until 
* Modern Views of Electricity, p. 369, London and New York, 1889. 
