CHEMICAL AND PHYSICAL NOTES. 173 
return of the breeze the wet bulb went back to 3°-0. The Féhn 
puffs were now very troublesome. At 2.52 p.m. the wet bulb at 
1 m. was 7°°0; the dry bulb showed—at 2.54 pm. 11°-0; at 
2°55 p.m., 13°°5; and at 2.57 p.m. 14°-5. In one puff the ther- 
mometer was observed to rise one degree in eight seconds, which 
would make the true temperature of the air at the moment about 
6°:0 higher, or 19°-5, 
“ At 3.30 p.m. I returned to the land stations, and again found the 
same variable temperatures. Between 3.35 and 3.45 p.m. the tem- 
perature varied between 16°:0 and 13°:5. The following averages 
were taken : 
3.45 p.m., dry, 14°°3; wet, 8°°0; relative humidity, 35. 
4.0 ,, » 14°90; ,, 8°°5; ” i 42°5, 
“Taking the first of these and the observations at 1 o’clock, we 
have for the mean temperature of the air 14°-15, and the wet bulb 
7°°75. On the ice we have— 
At 1 metre, dry bulb, 9°°85; wet, 5°°6, and 
At2 centimetres ,, T3345 42°60. 
“The difference in the temperature of the air at 1 m. is only 4°-3, 
and that between 1 centimetre and 2 metres above the ice is only 
2°°55, while the air at 2 centimetres is 7°:3 warmer than the ice. 
“On the 22nd August the observations on the ice were re- 
peated, with very much the same results. The temperature of the 
air ranged from 9°°0 to 9°°5 at 1 metre, and was 5°°5 at 1 centi- 
metre from the ice. 
“The result of the few observations here quoted is to show that the 
air, which over land has a temperature of 15° to 20°, or higher, in 
passing over a glacier is cooled to a comparatively slight degree. 
Although the air appears to be thoroughly mixed by its own motion, 
very sharp gradients of temperature are produced and maintained. 
The great and abnormal temperature of the air of the valley is kept 
up by the heat liberated by the compression accompanying the descent 
of local streams or strie of air from high levels. These keep up an 
extra supply of heat over and above what is supplied by the direct 
radiation of the sun. The result is that the melting of the glacier in 
Féhn weather greatly exceeds that of even the hottest day of ordinary 
weather. 
“Tn order to convey a general idea of the climate in the neighbour- 
hood during the period when my observations were made, I subjoin a 
table of the air temperatures observed at the Pfarrhaus in Pontresina 
