the Laws of Magnetic Forces, 



305 



of the res ult. The same law may be likewise made evident, in 

 substituting for the suspended iron oc a small magnet, and approxi- 

 mating toward it a mass of soft iron, as in the following Table, 

 which are the actual results obtained from an experiment so ar- 

 ranged. 



TABLE XI. 



Sfwwlng the Attractive Force, by opposing 

 a Mass of Iron to a Magnet. 



41. It has been observed (24) that the ratio of the inductive 

 effect of a magnet on a mass of iron begins to vary when the iron 

 and magnet are very nearly approximated. The precise point 

 depending on the magnetic intensity ; we may therefore suppose 

 that a small mass of iron opposed to the pole of a very powerful 

 magnet, would become magnetised, nearly to saturation, even be- 

 fore the magnet and iron were brought into contact, so that, for 

 a short distance, the increments of the force induced in the iron 

 would be so very small, that, in such case, it might be considered 

 as constant ; and hence the reciprocal attractive force would, for 

 near approximations, no longer vary in the duplicate inverse ra- 

 tio of the distances, but in an inverse ratio very near that of the 

 distance only, the induced force in the iron being considered 

 constant (38) ; and such is found to be the case, as will be fur- 

 ther shown (47.). 



42. We have more immediately considered, in the preceding 

 inquiries, the attractive force exerted between a magnet and a 

 mass of magnetized iron, in which case a permanent magnetic de- 



