388 PELTIER ON THE CAUSES OF THE 
sinously, they indicate the contrary sign to that of the first ex- 
periment, and where it did not give any indication in the second. — 
The same happens in this case as in the first; the repelling ac- 
tion of the globe increasing faster on the further extremity of — 
the rod which is lowered than on the inferior extremity, this 
force repels a part of the electricity which was accumulated in 
it towards the inferior part, until there be equality of reaction. 
It is this quantity, proportionally more repelled from the su- 
perior part, which makes the leaves diverge resinously. 
25. In order better to understand the preceding demonstra- 
tion, a portion of the atmosphere must be divided into equal 
and superposed strata, having for thickness the length of the — 
stem of the electrometer intended to measure their different 
electric tensions. The action of the electricity, decreasing as ~ 
the square of the distance, reacts more powerfully on the lower 
than on the upper end, and the natural electricity of the stem 
distributes itself equally from one stratum to the other. 
If we cause these different strata to be traversed by this stem, 
kept insulated and free from the approach of any terrestrial 
body, its electricity distributing itself, according to the difference 
of the reactions, upon both extremities, this difference will di- 
minish on receding from the ground. But the law of the 
square of the distance is not applicable to bodies of very dif- 
ferent magnitudes and very near each other; and besides, an 
electroscope is not made of a single insulated stem, it does not 
alone advance in space; on the contrary, the lower extremity 
which supports the gold leaves has before it metallic armatures 
and a copper plate below, which communicates directly with 
the earth. This plate and these armatures touching the ground 
by intermediate conductors, preserve the entire terrestrial reac- 
tion; it is even augmented there, as occurs around the projec- 
tions of electrized bodies. It follows that the lower part of the 
insulated stem is always subjected to the whole terrestrial ten- 
sion, and that it undergoes all its resinous repulsion, whilst the 
upper part is only subjected to it laterally in proportion to its 
distance. The terrestrial repulsion remaining the same for the 
lower part of the stem, and diminishing for the upper part, the 
resinous electricity is accumulated in this latter extremity, and 
is there more abundant to the detriment of the lower part. Com- 
paring these tensions to the point of equilibrium, the upper ex- 
tremity is resinous, the lower vitreous, and the degree of their 
