and Phenomena of Magnetic Induction. 263 



duced into the end of the bar nearest to the magnets), trans- 

 mitted consequentially to the opposite extremity. For although 

 there is a direct inductive action on the remote extremity, it is 

 the transmitted influence, it is to be observed, which predomi- 

 nates. 



In a similar manner, the relative effects of induction were af- 

 terwards determined, at the several intervals of two, three, and 

 four feet between the magnets and the bar. The results were 

 as follow : — 



Now, since a magnetic force or forces of variable intensity, 

 acting upon a compass needle in a direction at right angles to 

 terrestrial magnetism (as in the foregoing experiment), will pro- 

 duce deviations the tangents of which will be proportional to 

 the actual intensities ; the tangents of the angles of deviation, as 

 above determined, will afford a measure of the relative forces 

 acting upon the needle in the several positions of the magnets 

 and iron-bar ; whilst the differences of the tangents of deviations 

 will indicate the quantity and proportion of magnetism induced 

 and developed in the end nearest the compass, at the several dis- 

 tances of one, two, three, and four feet. Were the magnetism 

 induced upon one end of a soft iron-bar exhibited, as if by a 

 perfect conductor, to the other end, then would these differences 

 exhibit the actual effects of induction ; and the law of induction, 

 as to distance, might be experimentally determined. But this, 

 as will hereafter be shewn, appears not to be the case. There- 

 fore the differences indicative of the actual induction at the re- 

 mote end of the bar are probably not proportional to the rela- 

 tive forces known to be acting upon the end nearest to the mag- 



