cli Proceedings of the Asiatic Society of Bengal. [N.S., XVII. 
important bearings on weather: to do this at as many places as 
our financial resources wiil allow ; and to use the results for formu- 
lating the normal state of the atmosphere. With normal infor- 
mation once gathered, we should be ina position to make an 
attempt at a physical interpretation of abnormal features subse- 
quently observed, and with sufficient insight in the interpre- 
tation to increase the correctness of forecasts and extend their 
range. 
22. For several years we have been measuring in India 
the strengths and directions of winds daily at a number of 
stations in plains and hills, mostly in the north, the range of 
measurement embracing all levels from the ground upwards to 
some 10 or 12 km.; and in addition we have measured, as far 
as our powers have gone, the temperature and humidity up to 
10 or 15 km. at Jhang in the Punjab, and Agra in the U.P. 
You may be interested in having some details of the way 
these measurements have been carried out. 
€ may consider first the measurement of air move- 
ment. For this we have without expense the evidence of 
means, h means are at hand in the form of free-flying 
balloons filled with hydrogen and watched, either by two theodo- 
lites placed at the ends of a base-line of known length, and 
recording on a time-scale the altitude and azimuth observed, or 
by a single theodolite with an independent determination of 
the height of the balloon. 
In E gl 
theodolite, to assume for the balloon’s vertical velocity the 
India we have applied this method in an improved form by 
iserting in the eyepiece a ruled micrometer scale, and reading 
upon it the angular measure of a tail, 100 metres long, hanging 
from the balloon. 
“4. The method of two theodolites is obviously capabl 
of great accuracy; and, regarding that as a standard, we hay 
taken many comparative observations of the alternative meth- 
ods by using them simultaneously on a given balloon. As 
a result, the limits of accuracy of the single theodolite method 
are known to suit our present purposes with balloons, and as 
