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a bar of metal suspended immediately above the space 
separating the polar pieces. 
In experimenting with small bars of lead, the length of 
which was three-quarters of an inch, breadth one-tenth, 
and thickness one-twentieth, and suspended above instead 
of between the polar pieces, I found that the like changes 
from the magnetic to the dia-magnetic states, and also the 
like revulsive motions, were exhibited, as when the metals 
were suspended between the polar pieces, due consideration 
being given to the change in the direction of the distribu- 
tion of the magnetic forces, when the polar pieces were 
made to approach very closely to each other. 
Whenever a series of facts are discovered which are 
not readily explicable in accordance with generally received 
theories, we may hope to acquire some useful correction 
of such theories, by either extending their applications to 
the newly discovered facts, or by altogether remodelling 
such parts of the general theory as may be inconsistent 
or inapplicable. In this point of view I conceive that all 
facts relating to dia-magnetism are particularly interesting, 
and may reasonably be expected to lead to an increased 
knowledge of the physical properties of matter. I hope 
this part of the subject will be pursued by those most able 
to do so ; but as I have, in the course of my experiments, 
been unable to explain the phenomena according to the 
theory of Ampere, and have, therefore, attempted to discover 
the laws on which the observed phenomena were dependant, 
I will endeavour to communicate the ideas which then occurred 
to me. I feel, however, the more diffidence on this subject, 
as my opinions are not quite in accordance with those gene- 
rally received in regard to electro-magnetism. 
According to the theory of Ampere, the magnetic condi- 
tion is induced by the action of electric currents, circulating 
around the particles of matter ; and it has been shown 
