6S2 PHILOSOPHICAL TRANSACTIONS. TaNNO 1706. 



of an apparently clean piece 19,000. A specimen, assayed hereby Mr. Weaver 

 in the moist way, produced from 24 grains, 22-iVr grains of pure gold, and 

 j^i^of silver. Some of the gold is intimately blended with, and adherent to 

 quartz ; some, it is said, was found united to the fine grained iron stone, but 

 the major part was entirely free from the matrix ; every piece more or less 

 rounded on the edges, of various weights, forms, and sizes, from the most mi- 

 nute particle up to 2 oz. 17 dwt. ; only 2 pieces are known to have been found of 

 superior weight, and one of those is 5, and the other 22 ounces. 



Besides these accounts of the gold found in Ireland, the following information 

 has been received on that subject. Wm. Molesworth, Esq. of Dublin, in a letter 

 to Rich. Molesworth, Esq. f. r. s. writes, that lie weighed the largest piece of 

 gold in his balance, both in air and water ; that its weight was 20 oz. 2 dwt. 

 21 gr. and its specific gravity, to that of sterling gold, as 12 to 18. Also that 

 Rich. Kirwan, Esq. f. r. s. found the specific gravity of another specimen to be 

 as 13 to 18. Hence, as the gold was worth ^4 an ounce, Mr. Wm. Moles- 

 worth concludes, that the specimens are full of pores and cavities, which increase 

 their bulk, and that there are some extraneous substances, such as dirt or clay, 

 contained in those cavities. This opinion was discovered to be well founded, by 

 cutting through some of the small lumps. Stanesby Alchorne, Esq. his Ma- 

 jesty's Assay-master at the Tower of London, assayed 2 specimens of this native 

 gold. The first appeared to contain, in 24 carats, 21f of fine gold ; 1^ of fine 

 silver ; a of alloy, which seemed to be copper tinged with a little iron. The 2d 

 specimen differed only in holding 2H instead of 21|- of fine gold. 



V. The Construction and Analysis of Geometrical Propositions, determining the 

 Positions assumed by Homogeneal Bodies which Float Freely, and at Rest, on 

 a Fluid's Surface ; also determining the Stability of Ships, and of other Float- 

 ing Bodies. By George Atwood, Esq. F. R. S. p. 46. 



To investigate the positions assumed by homogeneal bodies which float freely, 

 and at rest, on a fluid's surface, it is necessary, in the first place, to form a just 

 conception of the several principles on which those positions depend. The pro- 

 portion of the immersed part to the whole magnitude of a homogeneal floating 

 body, will always be obtained, from having given the specific gravity of the solid 

 in respect to that of the fluid ; since it is a known law of hydrostatics, that the 

 immersed part of the solid is to the whole magnitude, in the proportion of those 

 specific gravities. But a solid may be immersed in a fluid numberless different 

 ways, so that the part immersed shall be to the whole magnitude in the given 

 proportion of the specific gravities, and yet the solid shall not rest })ermanently 

 in any of these positions. The reasons are obvious. The floating body is im- 

 pelled downward by its weight, acting in the direction of a vertical line, which 



