Taking the average depth of the ocean at two miles, and its average saltness at 3½ per cent, it appears that there is salt enough in the sea to cover to the thickness of one mile an area of 7,000,000 of square miles. Admit a transfer of such a quantity of matter from an average of half a mile above to one mile below the sea-level, and astronomers will show by calculation that it would alter the length of the day.
These 7,000,000 of cubic miles of crystal salt have not made the sea any fuller.
PROPERTIES OF SEA-WATER.
The solid constituents of sea-water amount to about 3½ per cent of its weight, or nearly half an ounce to the pound. Its saltness is caused as follows: Rivers which are constantly flowing into the ocean contain salts varying from 10 to 50, and even 100, grains per gallon. They are chiefly common salt, sulphate and carbonate of lime, magnesia,[41] soda, potash, and iron; and these are found to constitute the distinguishing characteristics of sea-water. The water which evaporates from the sea is nearly pure, containing but very minute traces of salts. Falling as rain upon the land, it washes the soil, percolates through the rocky layers, and becomes charged with saline substances, which are borne seaward by the returning currents. The ocean, therefore, is the great depository of every thing that water can dissolve and carry down from the surface of the continents; and as there is no channel for their escape, they consequently accumulate (Youmans’ Chemistry). They would constantly accumulate, as this very shrewd author remarks, were it not for the shells and insects of the sea and other agents.
SCENERY AND LIFE OF THE ARCTIC REGIONS.
The late Dr. Scoresby, from personal observations made in the course of twenty-one voyages to the Arctic Regions, thus describes these striking characteristics:
The coast scenes of Greenland are generally of an abrupt character, the mountains frequently rising in triangular profile; so much so, that it is sometimes not possible to effect their ascent. One of the most notable characteristics of the Arctic lands is the deception to which travellers are liable in regard to distances. The occasion of this is the quantity of light reflected from the snow, contrasted with the dark colour of the rocks. Several persons of considerable experience have been deceived in this way, imagining, for example, that they were close to the shore when in fact they were more than twenty miles off. The trees of these lands are not more than three inches above ground.
Many of the icebergs are five miles in extent, and some are to be seen running along the shore measuring as much as thirteen miles. Dr. Scoresby has seen a cliff of ice supported on those floating masses 402 feet in height. There is no place in the world where animal life is to be found in greater profusion than in Greenland, Spitzbergen, Baffin’s Bay, and other portions of the Arctic regions. This is to be accounted for by the abundance and richness of the food supplied by the sea. The number of birds is especially remarkable. On one occasion, no less than a million of little hawks came in sight of Dr. Scoresby’s ship within a single hour.
The various phenomena of the Greenland sea are very interesting. The different colours of the sea-water—olive or bottle-green, reddish-brown, and mustard—have, by the aid of the microscope, been found to be owing to animalculæ of these various colours: in a single drop of mustard-coloured water have been counted 26,450 animals. Another remarkable characteristic of the Greenland sea-water is its warm temperature—one, two, and three degrees above the freezing-point even in the cold season. This Dr. Scoresby accounts for by supposing the flow in that direction of warm currents from the south. The polar fields of ice are to be found from eight or nine to thirty or forty feet in thickness. By fastening a hook twelve or twenty inches in these masses of ice, a ship could ride out in safety the heaviest gales.
ICEBERG OF THE POLAR SEAS.
The ice of this berg, although opaque and vascular, is true glacier ice, having the fracture, lustre, and other external characters of a nearly homogeneous growth. The iceberg is true ice, and is always dreaded by ships. Indeed, though modified by climate, and especially by the alternation of day and night, the polar glacier must be regarded as strictly atmospheric in its increments, and not essentially differing from the glacier of the Alps. The general appearance of a berg may be compared to frosted silver; but when its fractures are very extensive, the exposed faces have a very brilliant lustre. Nothing can be more exquisite than a fresh, cleanly fractured berg surface: it reminds one of the recent cleavage of sulphate of strontian—a resemblance more striking from the slightly lazulitic tinge of each.—U. S. Grinnel Expedition in Search of Sir J. Franklin.