exx Proceedings of the Asiatic Society of Bengal. [N.S., XV, 
and annual variations. Automatic fig of the atmospheric conduc- 
tivity and pote: eg koe frecirat have been employed by Kahler at Potsdam 
and Dorno at Davos in order to Miscin the current. A more direct auto- 
= ne - pla 
o 
o the air and kept a © potential was devised by Simpson at 
Simla, but his pee Sai aeler toa ear of only ten phi in the 
month of Novem 
Owing t iflealtive connected with the water-dropper and with the 
insulation of the large plate necessary in this arrangement, the authors 
i by Pp ter 
e 
— one volt by the introduction a —- capaci ty, and is measured 
by itive Dolowslak electrometer, the deflections being + recorded 
photogeaphica lly. The variation of tnt potential gradient, which intro- 
due cting factor, is recorded by a Benndorf nage hale and 
pa roa iaflestor 
The authors give details of the final form of the arrangement, which 
was adopted in August 1918, and i agony the results of a reliable prelimi- 
nary series extending over the wh of the months February to May 1917 
uar ri i i 
' rnoon. e mea 10~'8 amp. ney 
is rather lower than most of the ook G5 whi ch oe been obtained else- 
where, but there are indications that as in the case of the pers the 
eatth-air current at Patna senchae its minimum in the month of April 
A method of measuring 8 parity of gold-leaf electro- 
—— —By A. T. Mux 
The Se te for saa . alti electrometer for accurate 
work, devised by V H. Jackson and the present author (continuation of 
, and shown in 
otential, ne volt. 
As the capacity of the quadrant system can be varied by othe sliding ¢ con- 
denser, the capacity of the electrose can epics easured at different 
voltages. There is a small but definite increase of capacity with voltage. 
The method is compared with those of Lester Cooke (Phil. Mag. Vol. 6, 
1903, page 410) and T. Barratt (Proc. Phys. = peti it dh thus Loft 
pages 162-171). The Secours of a small &@-ray electroscope c 
about 100 volts ~ hip easured by the three ihethade with the ‘Bitiow: 
ing results :—Pre pei ee 0°78 +°01, Lester Cooke’s method, as im- 
proved by the cae: 0. ‘754-01, and Barratt’s method 0°73 + ‘03 E.8.U, 
Some observations of the ionisation of the air in India.— 
By A. SrricuEen 
In the years 1917 and tos I examined th e ionisation of the air in 5 
different places in India. I had a double whpees in view when beginnin 
