Researches in the Theory and Calculus of Operations. 295 



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and as the spiral direction of the current from a" is dextror- 

 sal, the moving forces take hold of the resting force of the 

 wire of the outer cylinder, as though these forces were the 

 interlacing cogs of two wheels : consequently the spiral path 

 is determined dextrorsal from the extremity 6'", making 

 the reverse current as before (Delabjve). 



29. A magnet (fig. 37) presents the following peculiari- 

 ties : 1° There is spherical emanation from the centre O, 

 the extension of which increases with the length of the 

 radius ; 2° cylindrical emanation from the axis AA', uni- 

 form in all its length ; 3° transmission of rotative force in 

 dextral direction' from A, uniform throughout the surface 

 and body of the cylinder (or parallelopipe). These compo- 

 nent forces form two opposite resultant forces in i and f, 

 the positive and negative poles of the magnet. The mag- 

 netic action is greatest at a and a', and decreases to the 

 value zero at c the central circle of the cylinder. The plane 

 of this central circle is therefore a position totally exempt 

 from the action of the poles, which, however, extends all 

 the way to that centre as its limit; but in the solid magnet, 

 the atomic forces at this limit (which limit only exists in 

 virtue of the action of the poles, and changes place with 

 their change of distance) resist separation like those of any 

 other solid. 



For this solid magnet, substitute one of a semifluid con- 

 sistence, immersed in a fluid of lesser density, as water. 

 All may be conceived to pass with the atomic forces as be- 

 fore, differing only by the difference in density. This dif- 

 ference of density will more particularly affect the central 

 plane of atoms at c; for the magnetic centres land i' have 

 no action on that plane, but do affect all on each side within 

 that limit. As fluid and even semifluid atoms are easily 

 separated, it fairly follows that in this central plane, their 

 weakest position in the premises, they will yield in parti- 

 tion to the effect of any external force which may interfere 



