260 PHILOSOi'HICAL TRA.NSACTIONS. [^AlfNO 1705. 



way. But in some wires so twisted, the verticity was wholly destroyed, or 

 rather much confused. For I found by drawing one of the poles of the load- 

 stone along near the sides of the wire, that in some places it would attract, in 

 others repel ; and so attract and repel all along the wire. Nay, I fancied that 

 in some places, one side of the wire would be attracted, the other repelled, by 

 one and the same pole of the loiidstone. These changes sufficiently show that 

 the magnetic virtue is put into great confusion by the violence exerted on the 

 wire by twisting ; which not only separates the fibres of the iron (as may be 

 seen with the eye, but esjiecially when assisted with a microscope) but also 

 changes their situation from lengthwise to screw-wise. 



I next tried what would be the issue of splitting or cleaving touched wires ; 

 particularly, whether they would exert the same effects that magnets are said to 

 do, when sawn in two meridionally ; concerning which. Dr. Ridley, in his 

 Treatise of Magnetical Bodies and Motions, ch. Q, says, " Cut a piece from a 

 magnet-stone meridionally, and that end which was placed south, when it was 

 whole, being severed, will turn north, though naturally at first it was the south 

 point." But Mr. Barlow is of a contrary mind, and says, that the poles of such 

 a piece of magnet, when severed, will repel the same poles, to which it adhered 

 in the whole magnet. But he subjoins, in his Magnet. Advertisements, ch. 2, 

 " But here you must beware of an error, which some have fallen into, who 

 observing the before-mentioned discord, erroneously supposed, that, if both 

 these magnets, the greater and the less, i. e. the piece cut off, were conveniently 

 placed to swim in water, the small one would not with its end point to the 

 south pole of the earth, as it did in the magnet when entire, and when it was a 

 part of the true north-end, but would point contrarily : there is, says he, no 

 such alteration ; but that both the great and small one, and all the like, that 

 are cut meridionally one from another, will absolutely point the very same way, 

 which the entire one did : only, the meridian will be somewhat removed, &c." 



Dr. Gilbert is as express as Mr. Barlow. For, (lib. 2, c. 5) speaking of a 

 magnet divided, and showing how that the parts which in the whole stone 

 coalesced, do by separation repel each other, he says, " That what was the 

 north and south pole before, is such still : for, says he, the verticity is not 

 changed, as B. Porta erroneously asserts ; and though the poles when divided 

 do not incline to each other, yet both are directed towards the same point of 

 the horizon. How the truth lies between Dr. Ridley and the two latter authors, 

 I cannot determine, having never cut a magnet in that manner : but by the 

 magnetic laws, as well as from the authority of Dr. Gilbert and Mr. Barlow, I 

 doubt not but the latter is the truer opinion. 



But in cleft wires the case is very various. Oftentimes the poles are quite 



