264 Rev. Mr Scoresby on some of the Laws 



nets. Still, however, the differences of the tangents in the pre- 

 ceding table afford a ratio not very incongruous with the known 

 law of magnetic influence as to distance. Calling the nearest 

 difference (25780), indicative of the quantity of induced magne- 

 tism 100, then the other differences afford a ratio of 25.2, 11.5, 

 and 7.0, which, expressed fractionally, are very nearly 1, |th, 

 Jth, and i\th, exhibiting the proportion of induced magnetism 

 at the several distances of 1, 2, 3, and 4 lengths. 



Whilst the foregoing experiment affords an indication of the 

 relative force of magnetic induction at different distances, ap- 

 proximating the known law of direct attraction and repulsion, in 

 which the forces are inversely proportional to the squares of the 

 distance ; it likewise shows the facility with which the magnetic 

 energy induced at one end of a bar of soft iron is conveyed to the 

 other. There was nothing in the experiment, however, which 

 could afford any data for ascertaining whether the transmission 

 of the magnetic energy from end to end of the bar was perfect ; 

 or, if not, what proportion of resistance there might be in a bar 

 of soft iron to the free communication of induced magnetism to 

 the remote end of the bar. 



With the view of obtaining information on this point, I pro- 

 ceeded to vary the experiment, by ascertaining the deviations 

 produced by the same end of the iron-bar as that on which the 

 influence of the magnets was immediately acting ; and this was 

 accomplished by the following arrangement. 



With the four magnets placed on a tray, exactly as in the 

 former series of experiments, their inductive influence on the bar 

 of soft iron was now examined, when arranged after the manner 

 represented in Fig. 4. 



The compass, in this case, being betwixt the magnets and the 

 iron, was placed, as in the former experiment, at the distance of 

 Sj inches from the bar ; and the intervals were now measured 

 across the compass, and noted at 1, 2, 3, and 4 feet, as before. 

 Under this arrangement, the south poles of the magnets being 

 presented towards the compass, caused the deviation of its north 

 pole, as before, to be towards the west ; and this deviation, on 

 the application of the iron-bar, was augmented, because the 

 nearer end of the bar becoming a north pole by induction, as- 



