58 HISTORY OF MAGNETISM. 



the single fluid; and in this way removed the 

 necessity under which jEpinus found himself, of 

 supposing all the particles of iron and steel and 

 other magnetic bodies to have a peculiar repulsion 

 for each other, exactly equal to their attraction for 

 the magnetic fluid. But in the case of magnetism, 

 another modification was necessary. It was impos- 

 sible to suppose here, as in the electrical pheno- 

 mena, that one of the fluids was accumulated on 

 one extremity of a body, and the other fluid on the 

 other extremity ; for though this might appear, at 

 first sight, to be the case in a magnetic needle, it 

 was found that when the needle was cut into two 

 halves, the half in which the austral fluid had 

 seemed to predominate, acquired immediately a bo- 

 real pole opposite to its austral pole, and a similar 

 effect followed in the other half. The same is true, 

 into however many parts the magnetic body be cut. 

 The way in which Coulomb modified the theory so 

 as to reconcile it with such facts, is simple and 

 satisfactory. He supposes 6 the magnetic body to be 

 made up of "molecules or integral parts," or, as 

 they were afterwards called by M. Poisson, " mag- 

 netic elements." In each of these elements, (which 

 are extremely minute,) the fluids can be separated, 

 so that each element has an austral and a boreal 

 pole ; but the austral pole of an element which is 

 adjacent to the boreal pole of the next, neutralizes, 

 or nearly neutralizes, its .effect ; so that the sensible 

 6 Mem. A. P. 1789, p. 488. 



