C 47 1 I 
Waters ufed ; warm Water being lighter than cold* 
and Pump-Water generally heavier than River-Water. 
But, taking it for granted, that all Perfons who make 
fuch Experiments ufe common and not Mineral Wa- 
ters, and Waters of the natural Temper, and not 
heated defignedly, I am allured by a Friend, who has 
made many careful Trials for this particular Pur* 
pofe (an Account of which he has promifed 
me fhall be laid before the Royal Society\ that 
the fpecific Gravity of any Body will not differ 
above ~- 0 at the moft, on account of the Qua- 
lity of the Water and Temper taken together ; 
whereas the heavieft of Mr. Boyle’s Diamonds, as in 
his Tables, differs from the lighted of mine by above 
one Thirty-fifth Parr, which is about fix times as 
much as And yet I can think of no other 
Way of accounting for the reft of this Difference j 
unlefs it Ihould arife from the Smallnefs of the Dia- 
monds, or any Defeft in the Inftruments with which 
his Experiments were made. 
The Scales in which thefe Diamonds were weigh'd 
turned veryfenfibly with the two-hundredth Part of 
a Grain; and as one of the Diamonds weighed above 
92 Grains, it was capable of being weighed to lefs than 
the 1 8000th Part : feveral of them were weigh’d twice 
over both in -Water and Air, and the Weights found 
to agree to the greateft Exa&nefs ; and if to this is 
added the very near Agreement of the Weights of 
the feveral Diamonds, tho’ weigh’d at different Times* 
and at a confiderablc Diftance, from each other, I 
think it highly improbable, that there could be any 
considerable Miftake in thefe Trials ; and therefore 
O o o 2 their 
