xciv Proceedings of the Asiatic Society of Bengal. [N.S., XV IT, 
to day. It has come to be recognised, therefore, that an 
essential requirement in Jong-range gunnery is a know edge 
of the winds and of air temperature, up to heights of at least 
iles. 
rance ; while in France aeroplanes were set apart for the sole 
purpose of measuring continualty the temperatures and pres- 
sures in the upper air. 
- The system of observation was served by coded wire- 
less telegraphy, and as practically all information from the 
West, whence European weather largely comes, was necessarily 
hidden from the Germans, the enemy experienced a great handi- 
cap in many matters affecting warfare. 
5. ith the close of the war, public interest in these 
things has largely withdrawn itself, but the expert in gunnery 
and flying must always hereafter retain his sense of their im- 
portance; and I have recently had to pay attention to the 
tainly benefit from an extensive system of air-current observ- 
ing stations spread over the countries to be traversed. 
_ 6. The problems of to-day vary with the country present- 
ing them. In Europe the Indian anxiety for rain does not 
exist, nor in India the anxiety regarding frost which in a single 
night can, in the West, ruin a season’s crop of fruit. But what- 
ever the problem, the conditions which will solve it. are largely 
- At the surface of the earth the old-time meteorologist 
could measure his temperature and pressure, his wind and hu- 
midity ; but apart from the indications of cloud he had nothing 
to guide him in judging of the conditions prevailing in the 
% : 
country during the hot weather the enervating heat of a layer 
of air which has altered its characters at a height of half a 
