260 Mr. Cavallo’s Defcription , See, 
It Teems, therefore, to be clearly (hewn by thefe experi- 
ments, that the tin plate of this inftrument can collet and re- 
tain a vaft quantity of eleCtricity, when the conducing furfaces 
of the lateral frames are contiguous to it, in comparifon to that 
quantity which it can either collect or retain when thofe fur- 
faces are removed from its vicinity. 
The quantity of eleCtricity, which the tin plate ABCD is 
capable of collecting, principally depends on three circum- 
ftances, viz. ift, on the diftance between the tin plate and the 
conducting lateral furfaces; the fmaller that diftance is, the 
greater being the collecting power ; 2dly, on the (ize of the 
inftrument; and, 3dly, on the quantity of eleCtricity pof- 
fefled by the body from which it muft be collected or taken 
away. 
1 need not expatiate on the principle upon which the aCtion 
of this inftrument depends; this being the fame as that of the 
eleCtrophorus, of M. Volta’s condenfer, and of many other 
eleCtrical experiments ; namely, that a body has a much greater 
capacity for holding eleCtricity when its furface is contiguous 
to a conductor which can eafily acquire the contrary eleCtricity, 
than when it ftands not in that htuation. 
I (hall laftly add, that having actually ufed this new inftru- 
ment in feveral experiments, I have found it to anfwer perfectly 
well ; one of its principal recommendations being the cer- 
tainty of its operation. 
