[ 435 ] 
Mr James c Dodfon , in his book called The 
Calculator , printed in 8°. at London in 1747, has 
inferted a ufeful table of Specific Gravities, in which 
he has by the firft initial letter of their names dif- 
A tinguifhed the feveral authors he has quoted : and 
amongft thefe are feveral new experiments marked 
with an L , which I am told were communicated 
from his own trials, by Mr. Charles Labelye, en- 
gineer, and which concern particularly the weights 
of feveral forts of Hone and other materials ufed in 
building. Thefe I have alfo diftinguifhed by an L. 
as they (land in Mr. Dodfons book. 
Mr .Geo. Graham ,F.R.S. made for me, at the requeft 
of a friend, fome accurate trials upon the weight, of 
Gold and Silver, both when reported fine, and when re- 
duced to the Englijh Standard: all which I have inferted 
under his name in the following tables. Wherein I 
have befides reported fome other lingle Experiments 
which I occafionally met with, from Frederick Stare 
M.D .John Keillot Oxford, M.D. Stephen HalesT)XD. 
and Edward Bay ley of Havant in Hampflire, M. D. 
Rich-ard Davies M. D. I have laflly to this 
Colle&ion of Experiments added fome of my own, 
which I endeavoured to make with as much accu- 
racy, as the inftruments I was provided with would 
allow of. My hydroftatical Balance was' one con- 
fir uCted feveral years ftnee by Mr. Francis Hauksbee , 
which I have conftantl-y found to turn fenfibly 
with half a grain : and the bodies upon which I 
made molt of my trials, were taken from a col- 
lection of the Materia Aledica formerly made by 
Signor 
w 
