VOL XXXVI.] PHILOSOPHICAL TRANSACTIONS. 403 



shape, size and specific virtue, and figure of the iron or steel, and their pro- 

 portion of magnitude to each other. And that a small magnet communicates 

 nearly as much virtue as a large one. Some authors write, that the loadstone 

 loses none of its virtue by communicating of it to iron or steel, which Mr. S, 

 doubts the truth of, especially if the stone is small in proportion to the steel, 

 in which case he has known touched steel to lose considerable virtue. 



That steel is not only more receptive, but more retentive of magnetism, than 

 common iron; and iron or steel hammered hard, than the same while soft ; but 

 steel hardened by quenching, than either of them. 



That such iron or steel as has magnetic virtue communicated to it, also com- 

 municates it to other iron or steel after the same manner as a loadstone does. 

 Which virtue, after ever so many communications, is, as to its nature, per- 

 fectly the same with that of the stone itself, having both poles, and will touch 

 other steel, and that a compass, as well as the loadstone itself, and as vigorous, 

 if properly used. 



That every loadstone, within its attractive sphere, has a power to keep one 

 piece of iron suspended to another, especially if that to which it is suspended 

 is the larger, and their ends be bright and clean, where they touch each other; 

 and if the suspended iron is not too heavy, the other will draw it up from 

 either pole of the naked loadstone actually touching it, and will also keep it 

 suspended, till at a considerable distance ; but will not draw it off in such man- 

 ner from the armour of unarmed stone, if the armour and iron are both of 

 them bright and clean at their contact. Hence it must follow. 



That an armed loadstone can lift more with either of its poles, used singly, 

 than the same can lift naked : That not only steel or iron, regularly touched, 

 but also oblong iron void of permanent virtue, will perform all that any load- 

 stone can, though not with the same degree of power : for either of them will 

 attract, keep one piece of iron suspended to another, and communicate some 

 degree of permanent polarity to steel well hardened, as Mr. S. has experienced, 

 and also to an iron wire. 



That, of a soft iron bar void of fixed polarity, as soon as it is in an erect posi- 

 tion, the higher part from the middle upward becomes a north pole in north, 

 or a south pole in south magnetic latitude. And, e contra, the lower part from 

 the middle downward becomes a south pole in north, and a north pole in south 

 latitude : but as soon as the bar is inverted, the polarity is shifted in it, and in 

 north latitude the end newly placed upward becomes the north pole, though it 

 was a south one immediately before, and the other end the south pole, though 

 it was its north one just before. The case is the same, if such a bar is placed 

 horizontally in or near the magnetical meridian ; for the end directed toward 

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