The hot and salt waters of the tropics are carried north by the Gulf Stream. There are here two counteracting agents at work. Heat inclines the Gulf Stream to rise; saltness inclines it to sink. During the first part of its journey, as we know, its great heat prevails over the other influence, and it flows as a surface-current. But, at a certain point in its northward route, it meets with the cold, brackish, ice-bearing currents that flow out of the arctic basin. Having lost much of its heat (though still possessing a great deal more than the arctic currents), the saltness of the Gulf Stream prevails; it dips below the polar waters, and thenceforth continues its course as an under-current, salt, and comparatively warm.
To state the matter briefly: The hot water, which ought to keep on the surface because of its heat, is sunk by its superabundant salt; and the cold water, which ought to sink because of its cold, is buoyed on the surface because of its want of salt.
Now arises the question—what becomes of the great quantity of salt that is thus being carried perpetually into the polar basin? Manifestly it must be carried out again by the surface-current, otherwise the polar basin would of necessity become a basin of salt. The under-current must, therefore, rise to the surface somewhere near the pole, with its temperature necessarily only a little, if at all, below the freezing-point—which, be it observed, is a warm temperature for such regions. Here, then, where the warm waters from the south rise to the surface, it is supposed this open Arctic Ocean must exist.
So much for theory. Now for facts that have been observed, and that tend, more or less, to corroborate this proposition of an open polar sea. The habits of the whale have gone far to prove it. The log-books of whalers have for many years been carefully examined and compared by scientific men. These investigations have led to the discovery “that the tropical regions of the ocean are to the ‘right’ whale as a sea of fire, through which he cannot pass, and into which he never enters.” It has also been ascertained that the same kind of whale which is found off the shores of Greenland, in Baffin’s Bay, etcetera, is found in the North Pacific, and about Behring’s Straits; and that the ‘right’ whale of the southern hemisphere is a different animal from that of the northern. How, then, came the Greenland whales to pass from the Greenland seas to the Pacific? Not by the Capes Horn or Good Hope; the “sea of fire” precluded that. Clearly there was ground here for concluding that they did so through the (supposed) open sea lying beyond, or rather within, the frozen ocean.
It is true the objection might be made, that the same kind of whale which exists in the North Pacific exists also in the North Atlantic, although they never cross over to see each other. But another discovery has met this objection.
It is the custom among whalers to have their harpoons marked with date and name of ship, and Dr Scoresby, in his work on arctic voyages mentions several instances of whales having been taken near Behring’s Straits, with harpoons in them bearing the stamp of ships that were known to cruise in the Greenland seas; and the dates on the harpoons were so recent as to preclude the supposition that the said whales had, after being struck, made a voyage round the capes above mentioned,—even were such a voyage possible to them. All this does not, indeed, absolutely prove the existence of an open arctic sea, but it does, we think, prove the existence of at least an occasionally open sea there, for it is well known that whales cannot travel such immense distances under ice.
But the most conclusive evidence that we have in regard to this subject is the fact, that one of the members of Dr Kane’s expedition, while in search of Sir John Franklin, did actually, on foot, reach what we have every reason to believe was this open sea; but not being able to get their ship into it, the party had no means of exploring it, or extending their investigations. The account of this discovery is so interesting, and withal so romantic, that we extract a few paragraphs relating to it from Kane’s work.
After spending the dreary winter in the ice-locked and unexplored channels beyond the head of Baffin’s Bay, Kane found his little ship still hopelessly beset in the month of June; he therefore resolved to send out a sledge-party under Morton, one of his best men, to explore the channel to the north of their position. After twelve days’ travelling they came to the base of the “Great Glacier,” where Morton left his party, and, in company with an Esquimaux named Hans, set out with a dog-sledge to prosecute the journey of exploration.
They walked on the sea-ice in a line parallel with the glacier, and proceeded twenty-eight miles that day, although the snow was knee-deep and soft. At the place where they encamped a crack enabled them to measure the ice. It was seven feet five inches thick! And this in June. We may mention here, in passing, that Dr Kane never got his vessel out of that frozen strait, which seems to be bound by perpetual ice. He and his party escaped with their lives; but the vessel that bore them thither is probably still embedded in that ice.
Next day Morton and Hans came to a region of icebergs, which had arrested a previous sledging-party of the same expedition. “These (icebergs) were generally very high, evidently newly separated from the glacier. Their surfaces were fresh and glassy, and not like those generally met with in Baffin’s Bay,—less worn, and bluer, and looking in all respects like the face of the Great Glacier. Many were rectangular, some of them regular squares, a quarter of a mile each way; others more than a mile long.”