CHEMICAL AND PHYSICAL NOTES. 167 
importance of ohn as a climatic factor in Greenland. Where the 
heat disengaged by the contraction of the descending air is sufficient 
to raise its temperature above that of melting ice, its effect is at once 
apparent, and the fact that the West Coast of Greenland is free from 
land-ice at and near the sea-level, is attributed mainly to the heat 
of the Fohn. It is evident that, in the middle of winter with a 
general temperature of —30° C. to — 50°C. #6hn may prevail without 
its being able to raise the temperature of the air to that of melting 
ice. Indeed, it may even raise it above this temperature, but the air 
will not melt any ice in the open until it has raised its temperature 
from —30° or —50° up to 0°C., and this will take some time, 
which may be longer than that during which the ohn prevails. In 
summer in Greenland, the general temperature of the air is above 
that of melting ice, and the effect of /éhn is observed in the increased 
melting of the ice. From the observations of Mr. Bernacchi, there 
seems to be reason to suppose that the surface of the ice which forms 
the great barrier does not usually rise to its melting point even in 
the warmest month, February. Apart from the indications of the 
thermometer, in Greenland the occurrence of Féin was made most 
evident in spring and autumn by its producing melting of the ice, 
which without it did not take place. 
“Later in the year, in the middle of August, I visited the upper 
Engadine, and stayed for some weeks at Pontresina. Here, as else- 
where, the weather was very warm, and I was much struck by 
observing the same blasts of hot air as I had experienced in Scotland. 
The general characteristics of the weather were the same, and the 
temperature of the air in the valley rose nearly as high as it Be 
done at Fort William. 
“On the 18th August I went for an excursion on the Mowaatoh 
glacier with a guide. On my remarking the hot puffs of air, which 
were much more striking on the ice than on the land, he said it was 
the £éhn, of which he considered them a characteristic. The sun 
and the hot wind were causing an enormous amount of surface 
melting of the ice, and having a thermometer with me, I tock the 
temperature of the air by whirling at a height of about 1 m. from 
the ice, and found it 12°-0C.; the wet bulb was 5°°0, so that the 
vapour tension was 2°3 mm., the relative humidity 22, and the dew 
point — 8°-6 C. The great dryness of the air will be remarked. I 
then swung the thermometer in a conical path as close to the ice 
as possible, and the temperature of the air was 10°°0 C. Being 
astonished to find this high temperature close to the ice, | put the 
bulb of ‘the thermometer into a crack in the ice, so’as to be below 
