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On the Diamagnetic Force. - Q7 
tending to deflect the bar; and if two other poles of the same 
name, but of opposite names to the former two, be caused to act 
upon the bar the force of deflexion ought to be increased. 
this form the experiment was made before the Section. Four 
magnets were made use of; the two poles to the left were of the 
same name, and the two to the right were of the opposite quality. 
The result completely coincided with the author’s anticipations, 
and the bar was promptly deflected. 
hese experiments, without any exception, are all corroborative 
of the view, that diamagnetic bodies possess a polarity opposed 
to that of magnetic bodies,—but they do not prove that the phys- 
ical theory of Weber is correct. Indeed, it is scarcely possible 
that this theory can stand in opposition to the experimental evi- 
dence which can be brought to bear against it. One consequence 
of this truly beautiful theory is, that when the particles of a dia- 
magnetic body are caused to approach each other, the effect of 
their approximation will be to enfeeble the magnetic action along 
the line of approach. his view is opposed by the most direct 
experiments, which prove that the approximation of diamagnetic 
os ota has an effect precisely opposite to that deduced from the 
theory. a 
Prof. W. Tomson remarked, that as early as the year 1847 he 
C idge and Dublin Mathematical 
ures the inductive capacity of the substance, has positive values 
for all ferromagnetics, and negative values for all diamagnetics. 
Since the time when that Paper had been published, he never 
1, as it appears, would result from the 
actual substance of a diamagnetic solid receiving by induction a 
@ perpetual motion, such 
to as opposed to the theory of the polarity of bismuth. 
Prof. 1omson_ Sp tacned that those views led to the conclu- 
ton, not that ismt th experienced no magnetic polarity, but that 
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