72 PHILOSOPHICAL TRANSACTIONS. [aNNO 1744. 



That a single block of steel of a parallelopiped form, almost 4 inches long, 1-^ 

 inches in height, and VV of an inch in thickness, armed with iron, cramped with 

 brass, suspended by a ring of the same, and weighing all together 14 oz. 1 dwt. 

 lifted by the feet of the armour 14 lb. 2^ oz. Troy weight. 



That a compound artificial magnet was also tried, consisting of 12 bars of steel 

 amned, and that it was found to lift by the feet of the aiTnour as the last, 23 lb. 

 Troy, 24- oz. 



The 1 2 bars, composing this last magnet, were each a little more than 4 inches 

 long, -iV of an inch in breadth, and -^-^ of the same in depth, weighing one with 

 another about 25 dwt. each. They were all placed one on another, so as to make, 

 together one parallelopiped body, of the common length and breadth of the 

 several bars, but of the height of near 2 inches, being the sum of the respective 

 thicknesses of all the bars taken together: and this parallelopiped body, being 

 cramped with brass, and fitted with a handle of the same metal, was armed at the 

 2 ends that were made up of the common extremities of all the bars, with 2 sub- 

 stantial pieces of iron, after the common manner of arming natural loadstones, 

 the whole frame weighing together about 20 Troy ounces. 



Besides these, the president made also the following report of some trials he 

 had seen made at the same time of the effects of an art Mr. Knight is master of, 

 by which he can improve or increase the lifting powers of natural loadstones. 



He carried with him, on Wednesday the 7 th of November, a small armed 

 loadstone belonging to an acquaintance, which weighed, with its armour, 7 dwt. 

 14 gr. ; but which, being reputed but of an ungenerous nature, took up, and with 

 some difficulty, barely 2 ounces. Mr. Knight took it into his study, and return- 

 ing it in about a minute, it then took up more than 4 ounces with ease: but, on 

 his saying it would still gain some more strength, by remaining with him some 

 time, it was left till the 13th, when it took up distinctly, with the same apparatus 

 as before, 6 oz. 18 dwt. 3 gr. ; since which time it has also several times been 

 found to lift nearly the same quantity. 



Mr. Knight further, at the same time, showed the president the following in- 

 stances of his ability to invert or change the direction of the poles in natural 

 loadstones. 



Such a stone belonging to Mr. Francis Hauksbee, weighing about 5 oz, 14 

 dwts. of an irregular cylindrical form, with 2 of the sides somewhat flatted, on 

 which armour had formerly been applied, had the direction of its polarity from 

 one of these flatted sides to the other, notwithstanding the stone had a distinct 

 grain running at right angles to that direction. It was tried, and observed that 

 one of these flatted sides strongly attracted the north end, and repelled the south ; 

 and that the other attracted the south, and repelled the north end of the magnetic 

 needle. The end pf the stone, attracting the south end of the needle, was then 



