VOL. LXXVII.] PHILOSOPHICAL TBANSACTIONS. ^ lj^3 



tionable method is the following : first, if the floating body be in motion let it 

 stop, then hold a strong artificial magnet nearly in a perpendicular direction, and 

 with one pole just over one side of the floating body, or rather so that the per- 

 pendicular let fall from the pole of the magnet to the surface of the quicksilver, 

 may be about y^ of an inch distant from the body to be tried. The height of 

 the magnet above the quicksilver should be just sufficient to let the floating 

 body pass under it without touching. In this situation the magnet must be held 

 steady ; and if the floating body has any magnetism, it will be soon drawn 

 directly under the magnet. 



In these experiments it will be generally found, that one part of the floating 

 body is more magnetic than the rest, which appears from that particlar part 

 being constantly drawn directly under the pole of the magnet ; whereas, when 

 the magnetism is diflfused equably, the centre of gravity of the body, provided 

 its shape be not very irregular, becomes stationary just under the pole of the 

 magnet. It is not every magnet that will discover the very weak magne- 

 tism of certain substances ; for sometimes a powerful magnet will evidently 

 attract what a weaker one will not move in the least. I shall lastly ob- 

 serve, with respect to the experiments of last year's lecture, that though then 

 I thought to have fused and incorporated together brass and iron, yet some sub- 

 sequent trials gave reason to believe, that the iron is concealed in some part or 

 other of the melted brass, rather than equably diffused through the substance of 

 the latter ; and the principal reason for this suspicion is, that when those pieces 

 of mixed metal are tried on the quicksilver, some points in their surfaces are 

 generally attracted by the magnet in preference to others. 



The remainder of this paper may be consulted in the author's Treatise on 

 Magnetism^ in 8vo. p. 283, &c. published in 1787. 



//^ Description of a New Electrometer. By the Rev. Abraham Bennet, M. A. 

 Dated Wirksworth, Sept. 14, 1786. p. 26. 

 This electrometer consists of two slips of leaf gold, suspended in a glass. The 

 foot may be made of wood or metal ; the cap of metal. The cap is made flat on the 

 top, that plates, books, evaporating water, or other things to be electrified, may 

 be conveniently placed on it. The cap is about an inch wider in diameter than 

 the glass, and its rim about ^ of an inch broad, which hangs parallel to the 

 glass, to turn off the rain and keep it sufficiently insulated. Within this is an- 

 other circular rim, about half as broad as the other, which is lined with silk or 

 velvet, and fits close on the outside of the glass ; thus the cap fits well, and may 

 be easily taken off to repair any accident happening to the leaf gold. Within 

 this rim is a tin tube, hanging from the centre of the cap, somewhat longer 

 than the depth of the inner rim. In the tube a small peg is placed, and may be 

 occasionally taken out. To the peg, which is made round at one end and flat at the 



