510 Mr HARRIS'S Experimental Inquiries concerning 



fore, supposing them of an opposite kind, tend to neutralize each 

 other's force, and thus extend the limit CD. It is therefore ex- 

 tremely probable, that, in some cases, the opposed polarities N and 

 * may so neutralize each other's action in regard to the other po- 

 larities w, S, that the force may be considered as ultimately reduced 

 to that of two insulated points. A similar result may be supposed 

 to follow, when the polarities are of the same kind ; for although 

 the approximation of similar polarities would seem to reduce the 

 limit CD, yet the inductive influence (43.) tends to reverse the 

 repelling poles ; and thus the forces of the distant polarities be- 

 come also neutralized. The limit CD may be therefore extend- 

 ed in both cases, and in many instances may vanish altogether. 



In the following Table are the results of a series of experi- 

 ments with the attracting and repelling poles. The magnets 

 employed are indicated by the letters a, b y c, d, <?, their dimensions 

 being as follows :. 



, A small cylindrical magnet two inches long, 0.2 of an inch 

 in diameter, and similar in every respect to the sus- 

 pended magnet x. 



b, Four and a half inches long, and four- tenths of an incii 



square. 



c, Seven inches in length, and seven-tenths of an inch dia- 



meter. 



dy Nine inches long, eight-tenths of an inch wide, and three- 

 tenths thick. 



e, Fourteen inches long, one inch wide, and half an inch 

 thick. 



D,. signifies the distance; whilst the letters a,b,c,d,e are 

 placed over the respective forces. 



