3Q0 PHILOSOPHICAL TRANSACTIONS. [aNNO 1747, 



described in this paper, and which is here considerably magnified. — Fig. Q shows 

 another cluster of polypi of the same sort ; the number of the polypi here shown 

 being but small, because the cluster was drawn as it appeared within 2 or 3 days 

 after it had first begun to form itself. One of the branches of this cluster is 

 partly contracted, being in the situation, when a branch after contracting itself, 

 is again expanding to its ordinary state. This cluster is yet considerably more 

 magnified than that exhibited in fig. 8. — ^Fig. 10 represents one branch of a 

 cluster of polypi of the second species described in this paper. On this branch, 

 besides the polypi, which are of a bell-like form, are some of those round bodies 

 from which the clusters of this kind of polypi first spring; and which remarkably 

 distinguish it from many other species. — Fig. 1 1 represents one of these round 

 or globular bodies which, after it has parted from the cluster, has fixed itself to 

 some other body, and after the globule itself and its pedicle have begun to 

 lengthen. It was in this condition June 2 at 5 in the evening. — Fig. 12 exhibits 

 the 2 bodies, formed by the parting of that represented in fig. 1 1 . This parting 

 began at half after 8, and was completed at Q the same evening. — Fig. 1 3 repre- 

 sents the 4 bodies, formed from the 2 represented in fig. 12, and these 4 bodies 

 were also formed before 10 o'clock. 



^ Collection of the Magnetical Experiments communicated to the Royal Society 

 by Gowin Knight, M. B. and F. R. S. in the Years 1746 and J 747. Ap~ 

 pendix to N° 484, p. QsQ. 



I. An Account of some Magnetical Experiments, exhibited before the Royal So- 

 ciety, Feb. 1 9, 1746. Reported by the President, Martin Folhes, Esq. 



Mr. Knight first produced 2 almost equal bars of hardened steel, to which he 

 had communicated a strong magnetic virtue. These bars were nearly square, 

 each being of the length of about l5-i- inches, and of the breadth and thickness 

 of a little more than half an inch ; one of these bars weighed 2 lb. 6 dwt. Troy, 

 the other 4 dwt. less than 2 lb. ; and either of them readily lifted with one of its 

 ends better than 3-^ lb. These bars were then laid down on a table, so as to be 

 nearly in one and the same straight line, the north pole of the one being next to 

 the south pole of the other, and at the distance of about an inch from it; the 

 north poles of both bars thus pointing the same way, but without any regard to 

 the position of the natural meridian, 



Mr. Knight then produced a piece of natural magnet, which was one of the 

 same he had formerly made use of, in some experiments he had before showed 

 to the R. s. This piece was in length an inch and Vtj i" breadth -^, and in 

 thickness about t-V of an inch at a mediom, being considerably thicker at the 

 one end than at the other. This piece of magnet was then applied, so as to lie 



