542 PHILOSOPHICAL TRANSACTIONS. [aNNO 1732. 



piece of steel, he found It to have a south pole at each end, and a north pole 

 in the middle. 



He put a pretty heavy compass-needle, after having given it its virtue, into 

 the fire, and made it red hot three times, one after another, letting it grow 

 cold every time : it lost some virtue every heat, but at the 3d heat it had a 

 great deal still left; and making it for the 4th time white hot, it lost it all. 



When he covered the anvil with a piece of woollen cloth, and the end of the 

 iron bar with a piece of shamoy leather, it gave no virtue to the steel : then 

 covering only the bar, and leaving the anvil uncovered, it communicated no 

 virtue that way neither : but covering the anvil, and leaving the bar uncovered, 

 it communicated the full virtue. 



He tried whether his vice had any fixed pole by standing long in one position, 

 but he found it had none. 



He tried to do this with an anvil of about 30lb. weight, fixed in wood ; but 

 could not come up to the other proofs. 



He believes if one took an iron bar of 3 inches square, and 10 or more feet 

 long, or several of them on each other, and a suitable piece or bar of iron to 

 rub with, and giving the underpart of the standing bar the figure aforesaid, re- 

 presented by B, fig. 6, it might be brought to a vast strength. N. B. The steel 

 for the needles is always of a spring temper. 



M. Marcel made 1 pieces of iron, at one end :;- of an inch, and so taper 

 to J- of an inch square each, and fixed those 1 pieces of iron to a piece of wood 

 in the shape of an armed loadstone, at about 8 inches one from the other, ap- 

 plying to the under part of these irons, or legs, a piece of iron with a hook 

 to it, as to an armed loadstone: he hung this armed piece of wood with each 

 leg over an iron bar, at a distance that something might hang between them; 

 then he placed the piece of iron with the hook to it to the 1 feet ; and he found 

 it to draw very strongly; but his trial was only with small tools. He supposes 

 if one did this in a large proportion, it would have a considerable effect. 



Having ground some loadstones with emmery, he saved the grindings, and 

 mixing them with water, so that they might easily be moved, he put them into 

 a bottle to sink, placing a loadstone on each side; one with its north, and the 

 other with its south pole towards the bottle ; and he found, after the matter 

 was settled and dried, that it formed itself into a sort of loadstone, which had a 

 moderate strength, and 2 regular poles. 



Fig. 2, pi. 14, represents the end of the iron bar, with which the virtue is 

 rubbed into steel or iron. 



Fig. 3, the needle of a sea-compass. 



