52 H. Goldmark— Atmospheric Electricity. 
Art. VI.—The effect of Temperature upon Atmospheric Electricity ; 
by Henry GoLDMARK. (Contributions from the Physical 
Laboratory of Harvard College. No. 24.) 
Str Wiii1Am THomson, by means of the different forms of 
electrometers, devised by himself, has investigated the electric 
potential of the atmosphere under varying conditions and in 
different localities. The effect of an increase of temperature 
upon the potential of the air he does not appear to have ascer- 
tained, and the following experiments were undertaken with a 
view of arriving at some conclusion upon this subject. From 
the nature of the case the measurements made were approxi- 
It consists merely of a can of water A, insulated by standing 
upon a glass support, and discharging by the small pipe p 
through a fine nozzle. The insulation is made more perfect by 
drying the atmosphere around the insulating stem by means of 
small pieces of pumice stone, moistened with sulphuric acid 
and placed around its base. 
The water breaking into drops from the nozzle assumes the 
potential of the air at the point and communicates it to the cop- 
per plate C, from which the insulated wire B leads to the elec- 
trometer. In order to investigate the effect of different tem- 
peratures upon the potential, it was n to have a lim- 
ited volume of air upon which to experiment. To do thisI _ 
enclosed the nozzle of the water-dropping tube and the copper 
plate in the interior of the cylindric: mD. This drum was 
made of several layers of sheet iron, so arranged that the air, 
after being heated oy three Bunsen burners below, would pass 
several times around the cylinder and so raise the temperature 
of the enclosed air, without otherwise affecting it. The water 
which dropped from the plate collected in the glass dish below 
from which it was deaiaod out by a syphon, as fast as it fell. 
