in Geological Climatology. 257 
Take still another example, that of Greenland. The quantity 
of heat received between latitudes 60° and 80°, which is that 
of Greenland, is, according to Meech, one half that received 
at the equator; and were none cut off, it would be sufficient 
to melt fifty feet of ice. The annual precipitation on Green- 
land in the form of snow and rain, according to Dr. Rink, 
amounts to only twelve inches ; and two inches of this he con- 
siders is never melted, but is carried away in the form of ice- 
bergs. Mr. Hill maintains * that, owing to the great thick- 
ness of the air traversed by the sun's rays, and the loss re- 
sulting from the great obliquity of reflection, the amount of 
heat reaching the ground would be insufficient to melt more 
than sixteen feet of ice. Supposing we admit this estimate 
to be correct, still this is nineteen times more than is actually 
melted. The sun melts only ten inches, notwithstanding the 
fact that it has the power to melt sixteen feet. 
In short, there is not a place on the face of the globe 
where the amount of heat received from the sun is not far 
more than sufficient to melt all the snow which falls upon it. 
If it were true, as the objection assumes, that the amount of 
snow melted is proportional to the amount of heat received 
by the snow, then there could be no such thing as perpetual 
snow. 
The reason why the amount of snow and ice melted is not 
necessarily proportional to the amount of heat received is not 
far to seek. Before snow or ice will melt, its temperature 
must be raised to the melting-point. No amount of heat, 
however great, will induce melting to begin unless the inten- 
sity of the heat be sufficient to raise the temperature to the 
melting-point. Keep the temperature of the snow below 
that point, and, though the sun may shine upon it for count- 
less ages, it will still remain unmelted. It is easy to under- 
stand how the snow on the lofty summits of the Himalayas 
and the Ancles never melts. According to the observations 
made at Mount Whitney, to which reference has already been 
made, the heat of even a vertical sun would not be sufficient 
at these altitudes to raise the temperature of the snow to near 
the melting-point ; and thus melting, under these conditions, 
is impossible. The snow will evaporate, but it cannot melt. 
But, owing to the frozen condition of the snow, even evapo- 
ration will take place with extreme difficulty. If the sun 
could manage to soften the snow-crystals and bring them 
into a semifluid condition, evaporation would, no doubt, go 
on rapidly ; but this the rays of the sun are unable to do ; 
* Geological Magazine, April 1880. 
Phil Mag. S. 5. Vol. 16. No. 100. Oct. 1883. U 
