1856.] Beport on the Magnetic Survey. 15 



Gowhatty, Dec. 1855. Absolute Extremes, 



max. min. 



Surface of the ground, 6 a. m. 20.4 16.2 



10 a. m. 22.0 18.3 



2 p. m. 26.4 23.4 



6 p. m. 22.4 18.5 



At 0.3 meters, (11.9 inches) below the surface, 6 a. m. 23.5 19.2 



10 a.m. 23.4 19.3 



2 p. m. 24.8 20.1 



6 p. m. 24.5 20.4 



At 1 meter, (3 ft. 3 in.) below the surface. 6 a. m. 25.9 23.0 



10 a. M. 25.9 23.0 



2 p. m. 26.5 23.0 



6 p. m. 26.0 23.0 



The temperature of the Brahmaputra near Gowhatty had a daily- 

 variation of 1° 6 between 18.0 and 16.4. 



The height corresponding to a decrease in the temperature of 

 springs of 1° C. is larger, the decrease is less rapid, in comparing 

 Assam with the Khosia hills, than in comparing Sikkini with the 

 plains of Bengal, in the latter case the corresponding height varied 

 between 700 and 760 feet English. 



The snow line could be very well measured and its variation 

 ascertained during our stay on the Singalelah ridge, though we were 

 prevented from proceeding ourselves to the foot of the snow. 



We found a decided difference between its annual variation on the 

 isolated peaks in the spurs of southern direction and on the flanks of 

 the central parts. In the first case, the snow line goes steadily up 

 till the beginning of the rains, and shows the great periodical oscil- 

 lations, its maximum being attained near the middle of July. In 

 the inner parts, much less accessible to the tropical rains, the maxi- 

 mum of snow line coincides with the end of August. In a lateral 

 valley of Phulloot, a snow-bed was found in the beginning of June, 

 but not lasting.* 



* Moisture of the atmosphere — rain, &fc. This snow, first seen by one of my 

 shooters, was reported to me as an immense hailstone, the solid nature of the ice 

 nearly concealing its origin ; many reports of enormous hailstones, so often men- 

 tioned in the lower parts of the Himalayas, might probably be traceable to a simi- 

 lar origin. 



