288 Mr HARRIS'S Experimental Inquiries concerning 



19. The experiment being, therefore, arranged, as before ex- 

 plained (15), it was observable, that, when the magnet m and 

 iron be were an inch apart, and the distance ab adjusted to two- 

 tenths of an inch, the index moved forward to 3 ; on diminish- 

 ing the distance cd between the iron and magnet to half an inch, 

 and again adjusting the distance a b to two-tenths, the index 

 pointed to 6 ; on removing the intermediate iron, the index re- 

 turned to zero, thereby shewing that it was not acted on except 

 by the magnetic development induced in the iron be*. 



In the following Table is given the results of this experiment 

 in relation to other decrements of the distance between the 

 iron and magnet, in which D signifies the distance cd between 

 the iron and magnet, and F the corresponding force induced in 

 the iron be, the distance ab being always adjusted to two-tenths 

 of an inch. 



TABLE I. 



It may be perceived by reference to the above Table, that the 

 magnetic development induced in the iron, increased in an in- 

 verse simple ratio of its distance from the magnet. 



* The distance cd between the iron and magnet is readily varied, either by ele- 

 vating the magnet m, or depressing the iron be, the brass bands allowing them to 

 slide beneath with sufficient ease, but yet, at the same time, exerting a sufficient de- 

 gree of pressure to retain the iron and magnet in the required position. 



