THE LAW OF MAGNETIC ATTRACTION. 173 



of the heavens." Here the naming of the magnet poles 

 leads to confusion because Peregrinus gives to each magnet 

 pole the same name as that of the quarter toward which 

 the end of the free needle pointed ; an example ever since 

 followed. 



Having thus both located and identified the poles, the 

 next step was to determine their action upon one another ; 

 and then fell all of the old theory which began with the 

 "theamedes," and ended with the supposed power of the 

 magnet to repel as well as to attract iron. Two stones 

 he says, are to be prepared, and the poles determined 

 and marked by cuts. One stone is to be placed in a 

 cup, and floated as before. The other stone is to be held 

 in the hand. Then, "if the north part of the stone, which 

 you hold, be brought to the south part of the stone floating 

 in the vessel, the floating stone will follow the stone you 

 hold, as if wishing to adhere to it;" and, if the south part 

 of the held stone be brought to the north part of the float- 

 ing stone, the same thing will happen. "Know it therefore 

 as a law," he says, "that the north part of one stone attracts 

 the south part of another stone, and the south, the north. ' ' 

 But, if the reverse be done, if the north part of the 

 stone in the hand, be brought to the north part of the 

 floating stone, the latter will flee ; and the same will 

 happen if south be joined to south. Thus was found the 

 fundamental law that unlike magnetic poles mutually 

 attract. 



Peregrinus does not lay down the further law, that like 

 magnetic poles repel ; for, singularly enough, he does not 

 recognize any actual repulsion occurring between these 

 poles of like name, but assumes that the stone merely 

 turns itself around so that the law already stated may 

 come into play that is, so that unlike poles may attract 

 one another. Finally, he attacks the theory that the iron 

 is the natural affinity of the magnet, and that the magnet 

 will attract iron rather than another magnet. Here he 

 finds further support in the doctrine of similitudes, which, 



