the Lines of Magnetic Force. 419 



lines of force end on (3226.), such a needle, when surrounded by 

 a bad magnetic conductor, determines on to itself 'many of the 

 lmes which would otherwise pass elsewhere, has a high magnetic 

 polarity, and is affected in proportion; every experiment, as far 

 as I can perceive, tending to show that the attractions and repul- 

 sions are merely consequences of the tendency which the lines 

 of physical magnetic force have to shorten themselves (3266.). 

 So when the magnetic needle is surrounded by a medium gra- 

 dually increasing in conducting power, it seems to show less 

 and less force in its locality, though in reality the force is 

 increasing there more and more. We can easily conceive a 

 veiy hard and feebly charged magnetic needle surrounded by 

 a medium, as soft iron, better than itself in conducting power, 

 i. e. carrying on by conduction more lines of force than the 

 needle could determine or carry on by its state of charge (3298.). 

 In that case I conceive it would, if free to move, point feebly in 

 the iron, because of the coalescence of the lines of force, but 

 would be repelled bodily from the chief magnet, in analogy with 

 the action on a diamagnetic body. As I have before stated, the 

 principle of the moving wire can be applied successfully in those 

 cases where that of the magnetic needle fads (3155.). 



3281. If other paramagnetic bodies than iron be considered 

 in their relation to the surrounding space, then their effects may 

 be assumed as proportionate to the conducting power. If the 

 surrounding medium were hard steel, the contraction of the 

 sphondyloid of power would be much less than with iron; and 

 the effects, in respect of the magnetic needle, would occur in a 

 limited degree. If a solution of protosulphate of iron were used, 

 the effect would occur in a very much less degree. If a solution 

 were prepared and adjusted so as to have no paramagnetic or 

 diamagnetic relation (2422.), it would be the same to the hues 

 of force as free space. If a diamagnetic body were employed, as 

 water, glass, bismuth or phosphorus, the extent of action of the 

 sphondyloids would expand (3279.) ; and a magnetic needle 

 would appear to increase in intensity of action, though placed 

 in a region having a smaller amount of magnetic force passing 

 across it than before (3155.). Whether in any of these cases, 

 even in that of iron, the body acting as a conductor has a state 

 induced upon its particles for the time like that of a magnet iu 

 the corresponding state, is a question which I put upon a former 

 occasion (2833.) ; but I leave its full investigation and decision 

 for a future time. 



3282. The circumstances dependent upon the shape and size 

 of magnets appear to accord singularly well with the view I am 

 putting forth of the action of the surrounding medium. If there 



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