POLAR CURRENTS
Bearing these facts in mind, the reader will perceive
that it is the surface-water only which ever
reaches so low a temperature that it is changed to
ice; and he will also perceive that when the wind
moves the surface-water, the particles which have become
chilled by contact with the air mingle in the
rolling waves with the warm waters beneath, and
hence that ice can only form in sheltered places or
where the water of some bay is so shoal and the current
so slack that it becomes chilled to the very bottom,
or where the air over the sea is uniformly calm.
He will remember, however, that the winds blow as
fiercely over the Polar Sea as in any other quarter of
the world; and he will, therefore, have no difficulty
in comprehending that the Polar ice covers but a
small part of the Polar water; and that it exists only
where it is nursed and protected by the land. It
clings to the coasts of Siberia, and springing thence
across Behring Strait to America, it hugs the American
shore, fills the narrow channels which drain the
- [Footnote: April 10th, 1865, by W. E. Hickson, Esq., from which I extract the following:—
"It had always been supposed that the immediate areas of the Poles must be the coldest regions of the globe, because the farthest points from the equator. Hence the argument that the higher the latitude the greater must be the difficulties and dangers of navigation. Quite an opposite opinion, however, had begun to prevail among meteorologists on the publication, in 1817, of the Isothermal system of Alexander Von Humboldt, which showed that distance from the equator is no rule for cold, as the equator is not a parallel of maximum heat. The line of maximum heat crosses the Greenwich meridian, in Africa, fifteen degrees north of the equator, and rises, to the eastward, five degrees higher, running along the southern edge of the Desert of Sahara. In 1821, Sir David Brewster pointed out, in a paper on the mean temperature of the globe, the probability of the thermometer being found to range ten degrees higher at the Pole than in some other parts of the Arctic Circle. No new facts have since been discovered to invalidate this conclusion—many, on the contrary, have come to light tending to confirm it."]
