xx vi Of the Method of rendering very fenfible 
plate, which is in that cafe actuated by a very (mail degree of in- 
tenfity or endeavour of expanding ; lo that iuppofe, for inffnnee, 
that the piece of metal, or the finger by touching the plate, 
took oil fo much of its electricity as to reduce the intenfity of 
the remainder to the fiftieth part of a degree ; this remain- 
ing electricity would then be almoft nothing ; but when the 
plate, by being feparated from the inferior plane, has its capa- 
city 1 o far dirainifhed as to render the intenfity of its electricity 
iqo times greater, then the intenfity of that remaining electri- 
city would become of two degrees or more, viz. iufficicnt to 
afford a fpark. 
4S. Hitherto we have conlidered in what manner the action 
of electric atmofpheres muff modify the electricity of the me- 
tal plate in its various fituations. We muff now confider the 
effects which take place when the electricity is communicated 
to the metal plate whilff ftanding upon the proper plane. The 
whole bufinefs having been proved in the preceding pages, it 
is caly to deduce the applications from it ; neverthelefs, it will 
be uleful to exemplify it by an experiment. Suppol'e that a 
Leyden phial or a conductor were fo weakly electrified that the 
intenfity of its electricity was only of half a degree or even 
lels : it the metal [ late of our apparatus, when Handing upon 
the proper plane, was to be touched with .that phial or con- 
ductor, it is evident, that either of them would impart to it a 
quantity of its electricity, proportional to the plate’s capacity, 
viz. fo much of it as fllould make the intenfity of the electricity 
of the piate equal to that of the electricity in the conductor 
or phial, luppofe of half a degree ; but the plate’s capacity, 
now that it lies upon the proper plane, is above 100 times 
greater than if it ffood infulated in the air, or, which is the 
lame thing, it requires 100 times more electricity in order to 
lhew the lame intenfity; therefore, in this cafe it muff require 
upwards ot 100 times more electricity from the phial or con- 
ductor. It naturally follows, that when the metal plate is after- 
wards removed from the proper plane, its capacity being leflened 
fo as to remain equal to the 100th part of what it was before, 
the intenfity of its electricity muff become of 50° ; fince, agree- 
3 ably 
