the Laws of Magnetic Forces. 815 



served to take place. If the distance be increased, the repulsion 

 is evident ; for the strong magnet operating at a greater distance, 

 the inductive effect is diminished (19) ; so that it now proceeds 

 with less energy, and only to a certain extent. If the magnets 

 be supposed equal, then the repulsive effect will be evident at 

 all distances, and the tendency to a new polar arrangement will 

 never pass the limits of equal distribution in each bar, supposing 

 the opposed poles actually in contact. 



The inductive action, therefore, according as it proceeds in 

 the same or in an opposite sense to the polar arrangement al- 

 ready existing in two magnets, will either tend to increase or 

 diminish their force ; an effect so well understood practically, 

 that, to preserve the power of the magnets perfect, they are 

 usually arranged with their dissimilar poles in contact. 



5 1 . Our observations have been hitherto exclusively directed 

 to the action of a magnet on soft iron, or to that of one magnet 

 on another ; but it may not be improper, before concluding 

 them, to consider the law of the magnetic distribution in an ar- 

 tificial magnet of a regular figure ; since, in assimilating these 

 phenomena with terrestrial magnetism, it is of great consequence 

 to determine the law according to which the forces are developed 

 in different points of the longitudinal magnetic axis between 

 the centre and poles, 



For this purpose, two bars were selected, regularly hardened 

 throughout, and magnetized, the poles of each separate bar be- 

 ing equal, and the magnetic centre or point of indifference 

 equally distant from either pole. The centres and poles were 

 carefully ascertained by means of filings of soft iron, which were 

 sifted immediately over them on a sheet of paper strained tight 

 on a hollow frame of wood. The line which divided the mag- 

 netic curves was observed and noted, and equal successive por- 

 tions were marked off on each side of it toward the poles. 



VOL. XI. PART II. R r 



