APPLICATION OF THE PRELIMINARY RESULTS 

 TO THE THEORY OF MAGNETISM. 



(14.) The electric fluid appears to pass freely from one part 

 of a continuous conductor to another, but this is by no means the 

 case with the magnetic fluid, even with respect to those bodies 

 which, from their instantly returning to a natural state the 

 moment the forces inducing a magnetic one are removed, must 

 be considered, in a certain sense, as perfect conductors of mag- 

 netism. Coulomb, I believe, was the first who proposed to con- 

 sider these as formed of an infinite number of particles, each of 

 which conducts the magnetic fluid in its interior with perfect 

 freedom, but which are so constituted that it is impossible there 

 shall be any communication of it from one particle to the next. 

 This hypothesis is now generally adopted by philosophers, and 

 its consequences, as far as they have hitherto been developed, 

 are found to agree with observation ; we will therefore admit it 

 in what follows, and endeavour thence to deduce, mathema- 

 tically, the laws of the distribution of magnetism in bodies of 

 any shape whatever. 



Firstly, let us endeavour to determine the value of the po- 

 tential function, arising from the magnetic state induced in a 

 very small body A, by the action of constant forces directed 

 parallel to a given right line ; the body being composed of an ' 

 infinite number of particles, all perfect conductors of magnetism 

 and originally in a natural state. In order to deduce this more 

 immediately from Art. 6, we will conceive these forces to arise 



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