1877.] H. F. Blanford — Movements of Clouds in Upper Assam. 263 



pates ; but not till say half-past 9, does the air below move, so as to be felt 

 as a light breeze, which freshens till say 11 a. m. and remains till 2 p. M. 

 when it dies off slowly, and all is still, till the light evening or night airs 

 again set in from SW. to WSW., the two winds being hardly from 

 opposite points ; they are more like this [sketch showing the directions to 

 be NNE. and WSW.]. I will keep this question of the winds in view 

 as the season goes on, and, ere done with it, may mention, that in arranging 

 houses, such as lines, godowns, &c., we generally place them so as not to be 

 in the NE., SW. direction more than we need or are obliged to." 



On the above passage Mr. Blanfoed remarked " Mr. Peal's observa- 

 tions then, do not confirm the idea of a diurnal interchange of the upper 

 strata of air between the mountains and the valley, but they show a very 

 decided movement towards the sea in the day time, with the reverse at 

 night ; such had been indicated in the case of Calcutta in the discussion of 

 the anemometric records ;* and, as regards the higher cloud-bearing 

 - strata, had been established by frequent observations on the movement of 

 the clouds over the same place. That such a movement takes place, as a 

 general law, had been indicated, on theoretical grounds, in the paper above 

 referred to, and, in a subsequent paper read before the Society at the meet- 

 ing in March last, it had been adduced in explanation of the alternation of 

 land and sea breezes on coast lines. It was nevertheless extremely interest- 

 ing to find that this diurnal oscillation of the winds was so regular and well 

 marked, far up in the interior, viz., in Upper Assam. ' Of course so general 

 a movement must, in a great measure, mask any mere local movement, such 

 as that between valleys and mountains ; (supposing the latter to exist). 

 Within the last few days, another very interesting observation on this out- 

 flow of the atmosphere from the land to the sea, above the diurnal sea- 

 breeze, had been made in a balloon ascent at Bombay, by Mr. Simmons 

 Lynn ; an account of which has appeared in the newspapers. On ascending 

 at Bombay at 4h 40m. in the afternoon the balloon was first carried by the 

 sea-breeze to the S. East, but having attained an elevation of 5000 feet 

 was carried off by the upper current slowly to N. W. This observation is 

 of great interest as assigning a datum for the vertical thickness of the sea- 

 breeze current, t 



* Indian Meteorological Memoirs, Vol. I, p. 12. 



t The foUowing is the account of the aeronaut puhlished in the ' Englishman' of 

 the 30th November, extracted from the ' Times of India.' In two minutes from the 

 time of starting, (at Lai Bagh gardens on the Parell Road, Bombay) I found myself at 

 an altitude of 3000 feet. I proceeded at this elevation in a course S. E. by S. about 6 

 minutes, and determined, if possible, to continue in this direction across to the opposite 

 shore, but I was doomed to disappointment. When I had reached about one-third 

 across the surface of water in the line above given, the gas rapidly expanded and fully 



