1C)6 PHILOSOPHICAL TRANSACTIONS. [aNNO 1725. 



balance, and put a scale to one arm, and a thread several feet in length to the 

 Other: to the lower end of the thread he tied an unarmed magnet; he made 

 the thread very long, that the experiment might not be disturbed by any action 

 of the magnet on the iron balance; and he likewise pitched on a place in the 

 house, where there was as little iron as possible. He took two very good 

 magnets, perfectly spherical, which Mr. Gilbert calls terreliae, whose poles 

 were exactly in each extremity of the axis of the sphere; and consequently he 

 could very accurately measure the distances of both poles; he first counter- 

 poised the magnet, by means of a weight in the scale, and afterwards he put 

 the magnets under each other: and as the balance was moveable, by means of 

 a cord over a pulley, he let it down to different distances at pleasure; and when 

 the upper magnet was attracted downwards by the force of the lower, he always 

 laid so much weight in the scale, till the force of the magnet and the weight 

 were in equilibrio. The following table contains the experiments made at the 

 different distances of inches and lines; and corresponding to them are columns, 

 with the number of grains which counterpoise the attractions at these distances. 

 Distance. Grains of 



inches, lines. attraction. 



13 6 o 



1-2 O OV-y 



11 O Oi 



10 O 0^ 



9 o Oi 



7 6 li. 



7 o 2i 



12 70i 



Ji 7H 



10 87 In the very point of contact or 



9 9'J 



M. Muschenbroek made use of Rhinland inches, and the grains were apo- 

 thecary's weight, very accurately adjusted, in order to have them true, and of 

 equal weight. 



After having proceeded so far, he suspected whether the suspended magnet 

 were not in some measure heterogeneous, and whether another, substituted in 

 its stead, might not render the event more successful, and from which he might 

 at least receive more light ; lor, these experiments were too tedious, to have 

 reaped so little advantage from them. The following table exhibits the obser- 

 vations he made with another very good small magnet, while the lower terrella 

 was the same as before, and firmly fixed on a table; these experiments were 

 made in the same manner as the former. 



