C 245 ] 
bably have been caufed by the Glafies which covered 
the Inftruments made ufe of: And, fecondly, That 
the flat Pieces of Glafs, often placed under the Scales 
of an Efiay-Balance, are likewife very capable of at- 
tracting, and making even the lighter Scale prepon- 
derate, where the whole Matter weighed is fo very 
fmall. I have not tried this laft, but do remember, 
that Mr. Ellicot, a Member of your Society , did fome 
Years ago fufpect, if not find it certain, that fuch 
Pieces of Glafs did diflurb his Balance, and had given 
him a vaft deal of Trouble, upon a Suppofition, that 
the Beam itfelf was defective. 
Tour maft humble Servant , 
June 19. the Society adjourned to Obi- 23. 174^ 
Printed for C. Davis, over-againfl: Gra/s-Inn Gate 
in Holbourn, Printer to the Royal Society, 
M.dcc.xlvii, 
