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Rev. Mr Scoresby on some of the Laws 



But these results, if we consider the nature of the polarities 

 induced in the bar and the suspended substance in their rela- 

 tion to each other, will be seen to be less than what might be 

 obtained by simple induction at the respective distances. For, 

 let the acting end of the magnets be the north pole, then the 

 magnetism induced in the nearest end of the iron bar will be 

 the contrary, or southern polarity ; but the tendency of the 

 magnets on the end of the nail, or other suspended substance^ 

 in contact with the bar, will be to produce also southern pola- 

 rity, — ^because of this end of the nail, under the circumstances, 

 being nearer to the magnets than the lower end ; consequently, 

 the induced magnetisms of the parts of contact of the bar and 

 nail, being, as far as derived from the magnet, of the sam.e kind, 

 must have a tendency to diminish the action of the bar on the 

 nail. 



In order to compensate this defect in the results, another 

 series of experiments was made with the same apparatus, in 

 which the iron bar, whilst kept in the same vertical plane, was 

 raised on each trial so much above the level of the magnets, — 

 namely, one half the length of each ouspended nail, — that the 

 influence of the magnets upon the suspended body might be 

 similar at both its extremities, and consequently neutral. Un- 

 der this arrangement (Plate II. Fig. 2.) the inductive power, 

 as had been anticipated, was much greater, so that the different 

 substances were now suspended according to the distances in 

 the last column of the table. 



