ANALYSIS OF THE GALVANIC PILE. -££1 



the first case, he gave roe the atmosphere; and with respect 

 to the nature of bodies, he took a Leyden vial discharged 

 without a continued contact, the residuum of which, from 

 its nature, may affect a moderate sized condenser without 

 being much lessened: and to show me the necessity of this 

 condition, he made use of the following analogy. When Explained by 

 a piece of ground, by being swampy, indicates some stag- ° 6y » 

 nant water, if a ivell be dug there, the water will not fill it 

 tip to toe level of the stratum of earth whence it proceeds, 

 unless this stratum be of such an extent, that the quantity 

 of water which gathers in the well has no sensible propor- 

 tion with that contained in the stratum ; so that the sub- 

 traction of this quantity cannot affect the level at which the 

 water stands in the stratum. We have also an example of and by the 



this case in the subject of electricity: when an insulated comrnou e,ec - 



J J . iroscope, 



electrified body is small, we cannot know its real degree of 



electrification by applying a common electroscope; because 

 this, sharing the deviation of the state of the body from the 

 electric standard, lessens it too much for expressing what it 

 was before that application. 



I shall use the former of these examples in explaining Theory ex» 

 my theory concerning the difference of effects of the size p ained » 

 of the plates, and the number of the groups, according to 

 the use of the pile; and this explanation will chiefly con- 

 sist in fixing the points of analogy between the two ob- 

 jects. 



1. I compare the numher of groups in the pile to the 

 elevation of a stratum whence water issues into a weiL 



2. The size of the plates, to the extent of this stratum* 



3. The degree of divergence in the electroscopes at the 

 extremities of the pile to the level which the water can at- 

 tain in the well without overflowing* 



These first analogies are sufficient to explain the case of Last experi. 

 the last experiment. When we attend to what is directly "Ja-Ji^*" 

 expressed by our electroscopes, we certainly do not expect, 

 that this instrument shall indicate the quantity of electric 

 Jiuid possessed by the bodies to which it is applied; for 

 this would require also to measure their surface; we ex- 

 pect only to know the comparative density of the electric fluid 

 Among bodies, or its power to produce certain degrees of 



divergence 



