VOL. XLIT.] PHILOSOPHICAL TRANSACTIONS. SQS 



way, on the armed poles of this artificial magnet ; after which it discovered a 

 strong verticity, and was able to lift at one of its ends, the heavier of the a 

 above-mentioned weights, viz. somewhat more than 3 quarters of an oz. 



The hard needle, which still retained a considerable part of the virtue it had 

 acquired by the touch of the large steel bars, was lastly touched also in a con- 

 trary sense, on the armed poles of this artificial magnet ; by which it not only 

 lost the polarity yet remaining, but acquired a new one the other way ; it would 

 not however after this last touch lift more than Q dwt. 



After reading this report, Mr. Knight produced before the Society the two 

 large bars and all the other particulars above mentioned, with which he publicly 

 repeated all the same experiments ; which notwithstanding the disadvantageous 

 circumstances of the place, succeeded perfectly in every particular, and to the 

 entire satisfaction of all the company. 



It was then further proposed, that the tempered needle, having its virtue again 

 destroyed, should be touched on the fine armed terella belonging to the Society, 

 which was the noble present of their late worthy member James earl of Abercorn, 

 which is esteemed one of the best in England, and is said to have lifted in his 

 lordship's hands upwards of 40 pounds : the same was immediately brought, and 

 the needle, being touched with it, was found to have acquired a strong polarity, 

 and to lift about the same weight, as when it was before touched on Mr. Knight's 

 large armed artificial magnet ; viz. about 1 3 dwt. 



2. Some New Experiments lately made with Artificial Magnets. By the same. 

 June A, 1747. p. 662. — The apparatus for touching needles, sometime before 

 shown before the r. s., was as perfect as he could have wished, as far as relates 

 to the intended use of it : but the manner in which the two bars were disposed in 

 their cases made their length rather incommodious, especially in those of the 

 largest size. This made him desirous of trying if some method could not be 

 found out of placing the bars parallel to each other without danger of weakening 

 their force, by which means the cases would be reduced to half their length. 

 He remembered that some years ago, before he had tried some experiments to 

 this purpose, by placing some bars parallel and in contact, but so that their poles 

 were turned difl^erent ways : in which position he found the virtue of some of 

 them remained pretty entire, but that others were weakened by it. He ima- 

 gined the reason of their losing their force was this ; that the magnetic virtue 

 was by degrees habituated to pass out of the side of one bar into that of the 

 other in contact with it, and thus was hindered from arriving at the ends in its 

 full vigour. The reason why some suffered more than others, was doubtless to 

 be ascribed to their difference in temper. He repeated the experiment about 2 

 months before, with a little alteration. He placed the bars parallel with their 

 poles in an alternate position, as before, but not in contact, having kept them at 



VOL. IX. 3 E 



