135 
the equilibrium is obtained. All the facts are shown to be in ac- 
cordance with this hypothesis, and a ready explanation is afforded 
by it of a number of phenomena which are to be found in the older 
works on electricity, but which have until this time remained unex- 
plained.’ ’’ * 
Dr. Lodge continues: ‘‘If this were an isolated passage it might 
be nothing more than a lucky guess. But it is not. The conclu- 
sion is one at which he arrives after a laborious repetition and seri- 
ous study of the facts, and he keeps the idea constantly before him 
when once grasped and uses it in all the rest of his researches on 
the subject. The facts studied by Henry do, in my opinion, sup- 
port his conclusion, and if I am right in this, it follows that he is 
the original discoverer of the oscillatory character of a spark, 
although he does not attempt to state its theory. That was first 
done, and completely done, in 1853, by Sir William Thomson ; 
and the progress of experiment by Feddersen, Helmholtz, Schiller 
and others has done nothing but substantiate it.’’ + 
These investigations of Henry established the fact that ‘‘ in every 
case of the electrostatic discharge the testing needles were really 
subjected to an oscillating alternation of currents and consequently 
to successive partial demagnetizations and remagnetizations.’’ He 
at once made use of this singular reflux of current to explain the 
apparent change in the inductive action caused by distance. If 
‘«the primitive discharge wave be in excess of the magnetic capacity 
of the needle in a given position, the return wave might be just suf- 
ficient to completely reverse its polarity and the diminished succeed- 
ing wave insufficient to restore it to its former condition ; while at a 
greater distance the primitive wave might beso far reduced as to just 
magnetize the needle fully, and the second wave, being still more en- 
feebled, would only partially demagnetize it, leaving still a portion 
of the original polarity ; and so for the following diminished oscil- 
lations.’’ f 
‘‘Qne more extract I must make from that same memoir by 
Henry,”’ says Dr. Lodge, ‘‘ and it isa most interesting one ; it shows 
how near he was or might have been to obtaining some of the results 
of Hertz; though, if he had obtained them, neither he nor any other 
experimentalist could possibly have divined their real significance. 
* Proceedings Amer. Philos. Soc., Vol. ii, p. 193, June 17, 1842. 
+ Modern Views of Electricity, p. 370, London and New York, 1889. 
}W. B. Taylor, loc. cit., p. 255. 
