R. W. Fox on Magnetic Attraction and Repulsion, S 



Repelling? 



Distance. 

 1 inch 



* — 



4 — 



■the poles of the lower magnet being reversed: 



— ! ' Weight in Tenths 



Distance. <; faGra j n . 



Vv » nc h - 



Weight in Tenths 



of a Grain. 

 . . 2-5 



. 75 



. 14 5 

 . . 25' 

 ,. 29- 



The arrangement the same as before, but the force of the 



lower magnet diminished 



Attracting. 



Weight in Tenths 

 of a Grain. 



Distance. 



inch . . 2-0 



— .. 8- 



— . . 20-5 



— . . 42 5 



— . . 85- 



— .. 175- 



-r.hr — .. 390- 



t^t — .. SOS- 

 Tissue [japer interposedl 140* 

 1 thin plate of mica . . 2400* 



Repelling, 



T 

 i 



tv . Weight in Tenths 



Distance. ? rf— :u 



ot a (jrram. 



2 thin plates of mica 1320. 



4 Ditto do. 720- 



An exceedingly tiling 



tilm of mica which >9,660* 

 polarised light . . J 



Ditto do. doubled 5,020- 



Surfaces of mag-1 iqqqq. 

 nets in contact J ' 



Edges only in contact 13,60')* 



The above results, which are only a small portion of those 

 I have obtained, may be regarded as tolerably near approxi- 

 mations to the truth under the circumstances of the case, 

 and are, I think, sufficient to show that the laws of magnetic 

 attraction and repulsion alter according to the distance of the 

 magnets from each other, the force at small distances being 

 in the simple inverse ratio of the distance, and when further 

 separated, in the inverse ratio of the square of the distance.. 

 This change of ratio in the case of attraction, gradually took 

 place at the distance of from £th to jth of an inch, and even 

 at -J an inch from each other when I used larger magnets ; and 

 in the case of repulsion, the change in the law occurred at 

 much greater distances, especially when the forces of the re- 

 spective magnets were materially different. 



When soft iron is attracted bv a magnet, the law changes 



B2 



