HIGH LAND AND GREAT MOISTURE. 
83 
marked —6° F. as tlie lowest winter temperature, while in many parts 
of Siberia mercury freezes for several weeks in winter, showing a tem¬ 
perature below — 40° F. ; yet here the summers are hot, all the snow 
disappears, and there is a luxuriant vegetation. Even in the very 
highest latitudes reached by our last Arctic Expedition there is very 
little perpetual snow or ice, for Captain Nares tells us that north of 
Hayes’ Sound, in lat. 79° N., the mountains were remarkably free from 
ice-cap, wdiile extensive tracts of land were free from snow during 
summer, and covered with a rich vegetation with abundance of bright 
flowers. The reason of this is evidently the scanty snowfall, which 
rendered it sometimes difficult to obtain enough to form shelter-banks 
around the ships, and this was north of 80 Q N. lat., where the sun was 
absent for 142 days. 
It is a very remarkable and most suggestive fact that nowhere in 
the world at the present time are there any extensive lowlands covered 
with perpetual snow. The Tundras of Siberia and the barren grounds 
of North America are all clothed with some kind of summer vegetation; 
and it is only where there are lofty mountains or plateaus—as in 
Greenland, Spitzbergen, and Grinnell’s Land—that glaciers, accom¬ 
panied by perpetual snow, cover the country, and descend in places to 
the level of the sea. 
The reason why no accumulation of snow or ice ever takes place on 
Arctic lowlands is explained by the observations of Lieutenant Payer, 
of the Austrian Polar Expedition, who found that during the short 
Arctic summer of the highest latitudes, the icefields diminished four 
feet in thickness under the influence of the sun and wind. To replace 
this would require a precipitation of snow equivalent to about forty-five 
inches of rain, an amount which rarely occurs in lowlands out of the 
Tropics. In Siberia, within and near the Arctic circle, about six feet 
of snow covers the country all the winter and spring, and is not sen¬ 
sibly diminished by the powerful sun so long as northerly winds keep 
the air below the freezing-point and occasional snow-storms occur. 
But early in June the wind usually changes to southerly, probably the 
south-western anti-trades overcoming the northern inflow ; and under 
its influence the snow all disappears in a few days and the vegetable 
kingdom bursts into full luxuriance. This is very important as showing 
the impotence of mere sun-lieat to get rid of a thick mass of snow so 
long as the air remains cold, while currents of warm air are in the 
highest degree effective. If, however, they are not of sufficiently high 
temperature, or do not last long enough to melt the snow, they are 
likely to increase it from the quantity of moisture they bring with 
them, which will be condensed into snow by coming into contact with 
the frozen surface. We may therefore expect the transition from 
perpetual snow to a luxuriant Arctic vegetation to be very abrupt, 
depending as it must on a few degrees more or less in the summer 
temperature of the air, and this is quite in accordance with the fact 
of corn ripening by the sides of Alpine glaciers.— A. R. Wallace , from 
“ Island Life.” 
