394 PHILOSOPHICAL TRANSACTIONS. [aNNO 1747. 



the distance of about a quarter of an inch. Then he applied to their ends 2 

 pieces of soft iron. Each piece was laid across from the north end of one bar to 

 the south of the other, in the same manner as the lifter is applied to the feet of 

 an armed loadstone. The intent of this was to draw the magnetic virtue down 

 to the ends of the bars, and to convey it through the pieces of iron from one to 

 the other. In this condition he let them lie for about a month, and then tried 

 if they would lift the same weight as before, which he found they did, and he 

 thought with more vigour. After this he repeated the experiment with other 

 bars of various sizes, and with the same success : he therefore now ventured to 

 fit them up in cases in the manner just descrited. 



The success of this experiment had led him to another improvement : he pro- 

 vided a case of brass that would just contain 2 bars. At one end of the case were 

 fixed 1 feet, of soft iron, like those of an armed loadstone, the upper surface of 

 which was within the case in contact with the ends of the 1 bars : which being 

 parallel to each other, and their poles in an alternate position, the north end of 

 one bar will be in contact with one of the feet, and the south end of the other 

 bar will be in like manner applied to the surface of the other foot. On fitting a 

 lifter to this new kind of annour, he was able to support a weight of about 6 

 pounds : the bars were kept asunder at the distance of about a quarter of an inch, 

 by a slip of wood, which slides in between them. 



An instrument thus constructed, seems capable of answering all the purposes 

 for which load-stones are used ; for when the bars are taken out of the case, they 

 are fit for touching needles, or other magnetical uses, which may require single 

 bars ; when in the case, the whole together becomes an armed magnet, able to 

 lift a considerable weight. And if we want to separate iron filings from those of 

 other metals, the feet, and all the lower part of the case will take them up in 

 great plenty, and by drawing the bars a little way out of the case the filings will 

 fall ofl=: 



• 3. Some further Experiments relating to the General Phenomena of Magnet- 

 ism. Bg the same. p. 665. — The cause of the surprising phenomena of the 

 loadstone has hitherto escaped our knowledge, though diligently inquired after 

 by men of abilities. Such a discovery is not to be made without long experi- 

 ence, and a great variety of facts : and the nature of the subject is such, that 

 the more facts we are acquainted with, the more we find ourselves perplexed. 

 The conclusions drawn from some experiments are seemingly contradicted by 

 others : and yet these seeming contradictions are often very reconcileable on fur- 

 ther experience. If what here follows will in any-wise contribute to remove 

 these difiiculties, it may not be unacceptable, though he should not so properly 

 explain the nature of the cause, as the manner in which it acts. 

 - Prop. 1 . — The magnetic matter of a loadstone moves in a stream from one 



