290 Mr HARRIS'S Experimental Inquiries concerning 



grains to separate the ring ; when the distance was an inch and a 

 half, between 250 and 280 grains overcame the contact ; on di- 

 minishing the distance to an inch, between 390 and 400 grains 

 were required to separate the ring ; and on again diminishing 

 the distance to half an inch, it sustained a little less than 800 

 grains. The weights and corresponding distances may be there- 

 fore expressed as in the following Table, considering the weights 

 as a fair measure of the attractive force. 



TABLE II. 



The weights, therefore, are in an inverse simple ratio of the dis- 

 tances, or very nearly so *. 



Although this mode of experimenting is not so delicate as the 

 former, it is still sufficient to shew that the force induced in the 

 iron was not, in any inverse ratio, greater than that of the simple 

 distance between the iron and magnet. 



22. A similar result was obtained when, instead of placing the 

 magnet and iron in a vertical position, as in Fig. 5, they were 

 placed horizontally, as in Fig. 9, the suspended cylinder x being 

 immediately over the distant extremity a of the iron a b. In 

 this form of the experiment, we may consider the attractive 

 force as proceeding from that point () of the iron, immediately 



* The weight of the steel ring and brass pan S, with the silk lines, was just 100 

 grains. It was consequently taken into the account at each trial ; and the weights 

 finally added before the contact was broken, did not exceed 10 grains at a time, 

 these being placed carefully in the pan. 



