AUSTRIAN ARCTIC VOYAGES.
INTRODUCTION.
CHAPTER I.
THE FROZEN OCEAN.
1. The ice-sheet spread over the Arctic region is the effect and sign of the low temperature which prevails within it. During nine or ten months of the year this congealing force continues to act, and if the frozen mass were not broken up by the effects of sun and wind, of rain, waves, and currents, and by the rents produced in it from the sudden increase of cold, the result would necessarily be an absolutely impenetrable covering of ice. The parts of this enormous envelope of ice sundered by these various causes now become capable of movement, and are widely dispersed in the form of ice-fields and floes.
2. The water-ways which separate these parts are called “leads,” or, when their extent is considerable, “ice-holes.” The meshes of this vast net, which is constantly in motion, open and close under the action of winds and currents in summer; and it is only in its southern parts that the action of waves, rain, and thaw produces any considerable detachments. Towards the end of autumn, the ice, forming anew, consolidates the interior portions, while its outer edge pushes forward, like the end of a glacier, into lower regions, until about the end of February the culminating point of congelation is attained. Motionless adhesion of the fields, which naturally reach their greatest size in winter, does not, however, exist even then; for during this period they are incessantly exposed to displacement and pressure from the currents of the sea and the air.
3. When the ice is more or less closed, so as to render navigation impossible, it is called “pack-ice,” and “drift-ice” when it appears in detached pieces amid predominating water. Since there are forces operating which promote the loosening process at its outer edge, and its consolidation within, it is self-evident, that the interior portions tend to the character of “pack-ice,” and its outer margin to that of “drift-ice.” This general rule, however, is so modified in many places, by local causes, currents, and winds, that we find not unfrequently at the outer margin of the ice thick barriers of pack-ice, and in the inner ice, ice-holes (polynia[1]) and drift-ice.
4. Ice navigation, during its course of three hundred years, has created a number of terms to designate the external forms of ice, the meaning of which must be clearly defined. Ice formed from salt-water is called “field-ice;” that from the waters of rivers and lakes “sweet-water ice.” The latter is as hard as iron, and so transparent that it is scarcely to be distinguished from water. Icebergs are masses detached from glaciers. The words “patch,” “floe,” “field,” express relative magnitude, descriptive of the smallest ice-table up to the ice-field of many miles in diameter. The term “floe,” however, is generally applied to every kind of field-ice, without reference to its size. The ice which lies along coasts, or which adheres to a group of islands within a sound, is called “land-ice.” Sledge expeditions depend on its existence and character. Along the coast-edge land-ice is broken by the waves and tide, and the forms of its upheaval and deposition on the shore constitute the so-called “ice-foot.” Broken ice, or “brash,” is an accumulation of the smaller fragments of ice which are found only on the extreme edge of the ice-belt. “Bay-ice” is ice of recent formation, and its vertical depth is inconsiderable.
5. Land-ice is less exposed to powerful disturbances, and its surface, therefore, is comparatively level, and is only here and there traversed by small hillocks called “hummocks” or “torrosy.” These are the results of former pressures, and they are gradually reduced to the common level by evaporation, by thawing, and by the snow drifting over them.
6. But ice-floes exposed to constant motion from winds and currents, and to reciprocal pressure, have a more or less undulating character. On these are found piles of ice heaped one upon another, rising to a height of twenty or even fifty feet, alternating with depressions, which collect the thawed water in clear ice-lakes during the few weeks of summer in which the temperature rises above the freezing point. The specific gravity of this water, where it does not communicate with the sea by cracks, is in all cases the same with the specific gravity of pure sweet water; and as the salt is gradually eliminated from the ice, the water produced is perfectly drinkable. In the East Greenland Sea ice-floes frequently measure more than twelve nautical miles across—these are ice-fields properly so called.[2] In the Spitzbergen and Novaya Zemlya Seas, they are much smaller, as Parry also found.
7. The thickness which ice acquires in the course of a winter, when its formation is not disturbed, is about eight feet. In the Gulf of Boothia, Sir John Ross found the greatest thickness about the end of May; it was then ten feet on the sea and eleven feet on the lakes. In his winter harbour in Melville Island, Parry met with ice seven or seven-and-a-half feet thick; and Wrangel gives the thickness of a floe on the Siberian coast, which had been formed in the course of a winter, at nine-and-a-half feet. According to the observations of Hayes the ice measured nine feet two inches in thickness in Port Foulke. He estimates it, however, by implication, far higher in Smith’s Sound: “I have never seen,” he says, “an ice-table formed by direct freezing which exceeded the depth of eighteen feet.”