686 Memoirs of the Indian Museum. [Vol. V, 



seen to be normally taking place at the 10 foot level, brought about in order to com- 

 pensate for the increased outflowing surface-current caused by the wind, since there 

 seemed to be no appreciable fall in the surface level of the water of the bay ; but I 

 am inclined to think that we have here an additional inflow from a source not indi- 

 cated in my previous observations, namely from the extensive and somewhat enclosed 

 area lying between the mainland and Cherriakuda, Barkuda, and Samal Islands. 

 The surface current due to the wind must have blown a quantity of water into this 

 area through the passages between the mainland and Cherriakuda Island and between 

 this latter and Barkuda Island, and this must produce a corresponding outflow. 1 



A study of the temperatures and salinities found at stations 2 and 3 in section 2, 

 August, 1919, and again at station 23, section 3, August 1919, further seems to indi- 

 cate that we have present in the lake at this season of the year a condition of affairs 

 that is very similar to that which is known to exist in the Oyster f Polls ' in Norway. 

 The depth of the water in the lake is considerably less than that present in a typical 

 'Poll', such as the Kverne-Poll, but a comparison of the vertical distribution of 

 temperature and salinity at the above stations in the Chilka Lake with the distri- 

 bution present in the Kverne-Poll in June as given by Murray and Hjort (1912, p. 226)* 

 reveals many features in common : and this is particularly well shown in the chart of 

 station 23 which I give above. In both cases the water on the surface is of appreci- 

 ably higher temperature and slightly higher salinity than that present at a depth of 

 about 4-5 feet and below this level both temperature and salinity steadily increase. 

 The differences present in the Chilka Lake are not so marked as those in the Kverne- 

 Poll but the conditions present are essentially similar. 



2. Observations in April, 1920. 



My second visit to the Chilka Lake was from the 27th-29th April, 1920. 

 Throughout this period the weather was fine. Each morning there was little or no 

 wind, but, as the day wore on, light airs sprang up from the S.S.W. and by midday 

 a strong breeze was blowing from this direction. As the weather conditions on all 

 three days were exactly similar, the results obtained are all comparable with each 

 other, 



A very considerable change had occurred in the level of the lake since my visit 

 in August, 1919, and the depth of water in the bay instead of being about 11 feet 

 was now only 5 feet— that is to say was 3 feet lower than the maximum depth given by 

 Annandale and Kemp for the dry season {vide loc. cit., p. 5). In consequence it was 



1 From observations made in August, September, October, and December 1919, and in April 

 June and July, 1920, Dr. Annandale tells me that he is convinced that the normal direction of the wind 

 at Barkuda island is approximately S.W. throughout the year. This wind blows the water of the bay 

 past the island during the day so that the water-level of the lake sinks appreciably. The breeze 

 tends to fall in the evening, however, and is usually less strong at night. The water then returns to 

 the bay, with the result that the level is usually higher in the morning than it is in the evening. 



1 Murray and Hjort, " The Depths of the Ocean " (London, 1912). 



