306 PHILOSOPHICAL TRANSACTIONS. [aNNO 1747. 



Exper. 5. — If the north or south poles of two magnets be opposed to each 

 other, the filings will exhibit the appearance of two streams meeting ; and the 

 curves of each will all be turned towards the opposite pole of the same magnet. 

 The appearance is altogether the same, whether the two north or two south 

 poles be opposed to each other. So that it is not to be determined, from any of 

 these experiments, at which of the poles the magnetic stream enters. As we 

 have some reason to think it enters at the north pole, we may suppose that to 

 be the case, without danger of error ; provided we build nothing on the suppo- 

 sition, but what would hold good, mutatis mutandis, if the contrary should be 

 true. This being supposed, when the south poles are opposite, the two streams 

 coming out at them are directly contrary, by which the magnetic matter is ac- 

 cumulated, and therefore diverges so much the faster to return back, to the north 

 poles. When the north poles are opposed to each other, the streams of mag- 

 netic matter returning from the south poles are directly contrary; and, by crowd- 

 ing at once towards each polar surface, are accumulated between them, and 

 converge towards them so much the faster. 



These 5 experiments seem sufficient to establish the truth of the proposition ; 

 and many more might be produced to the same purpose. 



Prop. 1. — ^The immediate cause why two or more magnetical bodies attract 

 each other, is the flux of one and the same stream of magnetical matter through 

 them. 



Exper. 6. — It appeared in the 3d experiment, that when the south pole of 

 one magnet was opposed to the north of another, a stream of magnetic matter 

 was carried from one to the other, and did not return back to the pole where it 

 first entered, till after having passed through both bars : and it is needless to 

 observe that two bars in this position are in a state of attraction. The 5 th ex- 

 periment showed, that when the two south or north poles were opposed, there 

 was no stream common to both. Now it is well known, that magnetical bodies 

 in this situation are so far from attracting, that they strongly repel each other. 

 If the 3d experiment be repeated, with the magnets placed at different distances 

 from each other, we shall find that more of the magnetical matter will pass from 

 one polar surface to the other, in proportion as the distance between is less. 

 The attraction is therefore greater as the distances diminish. And at distances 

 where none of the magnetic stream passes from one magnet to the other, there 

 Is no sign of attraction. So that this cause is not only co-existent with the ef- 

 fect, but also proportionable to it. 



Exper. 7. — If a piece of soft iron, which has no fixed magnetism, be any 

 where placed in the magnetical stream, it will be in a state of attraction while it 

 remains in that stream, and no longer. 



Exper. 8. — A ball of soft iron, in contact with the pole of a magnet, will at 



