a new Electrometer. 387 
■exactly marked and afcertained as by tliefe parts being on 
the inftrument : nor do I mean to confine the number of 
grains or divifions on Gi ; but, I think, my experience feems 
to tell me, that no glais to be charged , as we call it, with elec- 
tricity, will bear a greater charge than that whole repulfive 
force, between two balls of this fize, equals 60 grains weight, 
before it will be perforated or (truck through. Nay, 1 have not 
found many inftances where it would ftand 50 grains; and, T 
think, it is very hazardous to go more than 45 grains. 
Thus, by knowing the quantity of coated furface, and the 
diameter of the balls, as Ii and r, I would fay, lb much or fo 
much coated furface charged to fo many or lb many grains 
repuliion between two balls of fuch or lucli a fize would melt 
a wire of this or that lize, or do fuch a thing, kill fuch an 
animal, &c. ; and if balls, wires, or arms of this lize, are 
found too fmall, larger may be made on the fame plan. 
In refpeCt to the advantages of this electrometer above thofe 
now in ufe , I do not, perhaps, know them all ; and left 
my partiality may prejudice me in behalf of my own con- 
trivance, would rather leave them to the judgement of 
others ; my opinion however is, that all that I have feen 
or heard of are fuch as lpeak no intelligible language, 
and that this fpeaks fo as to be underftood univerlally ; 
for, unlefs the repulfive power of the charge of different 
srlaffes be very different, this electrometer, or anv other elec- 
O - 
trometer, made after this manner, muft, I fhould think, fpeak 
very nearly the fame language, it being known how much coated 
furface there is, and the fize of the balls ; but if the fize of the 
balls be not the lame, the language the inftrument fpeaks will 
be verv different. Although other Electrometers (hewed a 
E e e 2 greater 
