VOL. XX.] FHILOSOPHICAL TRANSACTIONS. 333 



always the north pole, I find not always true : for though it hold generally in 

 such small pieces, and always in pieces of any bulk, as large hammers, anvils, an- 

 dirons, bars of windows, &c. yet I found several small pieces of steel, such as 

 the drills are made of, to have fixed poles, one end north, the other south, in 

 whatever positions I held them : some of these very vigorous in the polarity; 

 others showing plainly a tendency to such a pole, rather than the other; yet so 

 faintly, that it applied contrary to their inclination; that is, at the upper end, 

 if it affected to draw the south ; or the lower end, if the north. They caused 

 the needle to stand in aequilibrio east and west ; the particular inclination of 

 either one end seeming in some pieces quite to conquer ; in others, quite to 

 hinder that more general polarity they both acquire, by being either upward or 

 downward. Yet this seems only to be found in small stems of iron ; the being 

 either upward or downward always prevailing in pieces of greater bulk. 



As to the opinion of the magnetic philosophers, that nothing gives or receives 

 a magnetism, but what is in itself truly magnetic, as is only iron ; as to the last 

 part, that is, only iron receiving a magnetism, I have nothing certain to say ; 

 but for giving the same, I suppose it very questionable, whether only iron or 

 loadstone can bestow or impart such virtue, since not only the quenching in 

 water will do it, but the heating also of an iron by violent motion, will do the 

 same; as by quick and hard filing, which is the very same thing as brisk drill- 

 ing in the iron ; and therefore may be said to proceed from the file which is 

 steel or iron. But to show it comes from the mere motion or heat, which is 

 nothing else but the motion continued, this experiment may suffice, if it suc- 

 ceed to others as it seemed to do to me. I took my knife, which had been formerly 

 touched a quarter of a year or more before, and profering it to the needle, it drew 

 the north pole, which happened right for my purpose. I whetted it briskly on a dry 

 dirty threshold, and being thin, it becamevery hot towardsthe point, theedge being 

 whetted away to a wire, as it were, I struck the very top, and back towards tiie top, 

 against the ground, as I had done the sides, to destroy and rub off, if I could, 

 all its former polarity which was southward; then offering it again to the needle, 

 it drew the south end, and was quite changed. To confirm the thing, I touched 

 the same knife again with the north pole of my loadstone, and it drew vigorously 

 the north end of the needle. I whetted it again strongly in the same manner, 

 and it changed again. This I repeated five or six times, and it still changed by 

 whetting, especially on the sides towards the top of the knife, the very top and 

 back, which could not be whetted to so great a heat, retaining still some af- 

 fection for that pole the loadstone had inclined them to. This I tried with a 

 knife of a thicker blade ; but I could not with my hand whet it to that heat as 



