J wall Quantities of Electricity. - 
being difturbed by the wind ; for it frequently happened, that 
neither the exigence, nor the quality, of the electricity could 
be afcertained on account of the wind agitating the in ft rumen t, 
and becaufe the eleCtricity being in fmall quantity would not 
remain on the electrometer a time lufficient to bring the initru- 
ment within doors, where it might be examined without any- 
obftruCtion. In order to remove this imperfection, I inclofed 
the electrometer in a bottle, as it is deferibed in the Philo- 
fophical TranfaCtions, Vol. LXX. which conftru&ion has been 
found to anfwer remarkably well. 
This bottle electrometer has been fince altered by various 
perfons ; though, in my opinion, thofe alterations do not tend to- 
improve it altogether. M. de Saussure, by altering the fhape of 
the bottle, and depriving it of a neck, has rendered it capable of 
retaining, the communicated electricity only for a very (hort 
time * ; whereas, fome of thofe electrometers, conftruCted on 
my original plan, have retained the communicated eleCtricity 
for more than four hours. 
* 
Betides this, M. de Saussure, as well as fome who make 
thefe electrometers for fale, have fubitituted pith balls, in dead 
of the conical corks of the original plan, the latter of which, 
are preferable for two reafons ; viz. firft, becaufe the balls of 
pith are apt to adhere to each other, fo that on communicating 
the eleCtricity they often do not Ihew any repullion at all; or 
if the communicated eleCtricity be confiderably great, the pith, 
balls, after adhering to each other for fome time, are at laft fepa- 
rated with violence, fo as to fly to the tides of the bottle, which, 
fruftrates the experiment ; whereas the corks are not near fo 
fubjeCh to this inconvenience ; and, fecondly, becaufe the coni- 
cal lhape renders thofe corks capable of prefenting a much 
* Saussure’s Voyage dans les- Alpes, Tom. II. 
greater 
