Jin all Quantities of Electricity. 1 5 
electrometer, viz. a very light one, that has no great extent of 
metallic or of other conducing fubftance ; becaufe if the 
fmall quantity of eleCtricity that is communicated to it be 
expanded throughout a proportionably great furface, its elafli- 
city, and of courfe its power of feparating the corks of an 
electrometer, will be diminifhed in the fame proportion. 
The other cafe is, when one wants to afcertain the prefence 
of a confiderable quantity of electricity, which is difperfed or 
expanded into a great fpace, and is little condenfed, like the 
conftant eleCtricity of the atmofphere in clear weather, or like 
the eleClricity which remains in a large Leyden phial after the 
flrfl or fecond difcharge. 
To effeCt this, I ufe an apparatus, which in principle is 
nothing more than Mr. Volta’s condenfer; but with certain 
alterations, which render it lefs efficacious than in the origi- 
nal plan, but at the fame time render it much lefs fubjeCt to 
equivocal refults. I place two of the above delcribed tin plates 
upon a table, facing each other, as (hewn in fig. 3 and about 
one-eighth of an inch afunder. One of thofe plates, for in- 
ffance A, is connected with the floor by means of a wire, and 
the other plate B is made to communicate, by any convenient 
means, with the eleCtricity that is required to be collected. In 
this difpofltion the plate B, on account of the proximity of 
the other plate, will imbibe more eleCtricity than it it flood tar 
from it, the plate A in this cafe aCting like the femi-conduding 
plane of M. Volta’s condenfer, though not with quite an 
equal effeCt, becaufe the other plate B does- not touch it ; but 
yet, for the very fame reafon, this method is incomparably 
lefs fubjeCt to any equivocal refult. When the plates have 
remained in the faid fltuation for the time that may be judged 
neceffary, the communication between the plate B, and the 
~ conducting 
