xxiv Of the Method of rendering very fenfible 
plane. But if in this fituation the inferior plane be touched fo 
as to cut oft the infulation for a moment, then it will imme- 
diately acquire the contrary electricity, and the intenfity in the 
metal plate will be diminifhed. 
44. If the inferior plane, inftead of being infulated, were 
itfelf a non-conduCting fubffcance, then the fame phenomena 
would happen, viz. the intenfity of the electrified metal plate 
laid upon it would not be diminifhed. This, however, is not 
always the cafe ; for if the faid inferior non-conduCting plane 
is very thin, and is laid upon a conductor, then the intenfity 
of the eleCtrified metal plate will be diminifhed, and its capacity 
will be increafed by being laid upon the thin infulating 
ftratum ; becaufe in that cafe the conducting fubftance, which 
hands under the non-conduCting ftratum, acquiring an elec- 
tricity contrary to that of the metal plate, will diminifh its 
intenfity, &c. and then the infulating ftratum will only dimi- 
nifh the mutual aCtion of the two atmofpheres more or lefs, 
according as it keeps them more or lefs afunder. 
45. The intenfity or eleCtric aCtion of the metal plate, which 
diminifhes gradually as it is brought nearer and nearer to a con- 
ducting plane not infulated, becomes almoft nothing when the 
plate is nearly in contaCt with the plane, the compenfation or 
accidental balance being then almoft perfeCt. Hence, if the 
inferior plane only oppofes a imall refiftance to the paflage 
of the eleCtricity (whether fuch refiftance isoccafioned by a thin 
eleCtric ftratum, or by the plane’s imperfeCt conducting nature, 
as is the cafe with dry wood, marble, &c.) : that refiftance joined 
to the interval, however fmall, that is between the two planes, 
cannot be overcome by the weak intenfity of the eleCtricity of 
the metal plate, which on that account will not dart any fpark 
to the inferior plane (except its eleCtricity were very power- 
ful, or its edges not well rounded) and will rather retain 
its eleCtricity ; fo that, being removed from the inferior 
plane, its eleCtrometer will nearly recover its former height. 
Befides, the eleCtrified plate may even come to touch the 
imperfeCtly conducting plane, and may remain in that fitua- 
tion for fome time ; in which cafe the intenfity being reduced 
1 almoft 
