XI 
the iveakejl Natural or Artificial Electricity. 
increafed by this apparatus ; I would anfwer, that it is not eafy 
to be determined, as it depends upon various circumftances ; 
however, cceteris paribus , the augmentation is greater in propor- 
tion as the body which fupplies the metal plate with the elec- 
tricity has a greater capacity, and is larger in proportion as the 
electricity is weaker. Thus we obferved above (§ 2. and fol- 
lowing) that if the atmofpherical conductor has barely power 
enough to attraCt a very fine thread, it is neverthelefs capable 
of infilling fuch a quantity of electricity into the metal plate of 
the electrophorus, as to let it not only actuate an electrometer, 
hut even dart ftrong fparks. But if the electricity of the atmo- 
spherical conductor is fo ftrong as to afford fome fparks, or to 
let the index of the electrometer rife to five or fix degrees, 
then the metal plate of the eleCtrophorus, which receives the 
electricity from this conductor, according to our method, will 
certainly let the index of the eleCtrophorus rife to the higheff 
degree, tlnd will give a ftronger fpark, yet it may be plainly 
perceived, that the condenfation is proportionably lefs in this 
than in the other cafe. The reafon is, becaufe the eieCtricity 
cannot be accumulated beyond the greatelf degree, viz. when 
the eieCtricity is increafed fo much as to be diflipated every 
way. Therefore, according as the eleCtric power, which fup- 
plies the condenfer, is nearelf to the higheff degree, the con- 
denfation is proportionably lefs : but in that cafe there is no 
need of a condenfer, fince its principal ufe is to colleCt and 
render fenlible that fmall quantity of eieCtricity, which would 
otherwife remain imperceptible and unobferved. 
10. Whenever, therefore, the atmofpherical conductor by 
itfelf gives fufficiently ftrong figns of eieCtricity, then there is 
no occalion to ufe our condenfmg apparatus. Belides, when 
the eieCtricity is ftrong, it often happens, that part of the 
eieCtricity of the metal plate is imprefled upon the refin, in 
which cafe the apparatus aCts as an eleCtrophorus, and confe- 
quently is unfit for our purpofe (§ 8 .). 
1 1. In order to avoid fuch an inconvenience, I have thought of 
fubftituting to the relinous plate a plane, which fhould not be a 
perfeCt eleCtric, or quite impervious to eieCtricity, but which 
ihould be an imperfeCt conductor, fuch as might hinder, in a cer- 
Vol. LXXII. C L tain 
