431. Solid matter annually drifted out of the polar basin.—At the very time that the doctor was gazing with longing eyes upon these strange green waters (§ 429), there is known to have been a powerful drift setting out from another part of this Polar Sea, and carrying with it from her moorings the English exploring ship "Resolute," which her officers and men had abandoned fast bound in the ice several winters before. This drift carried a field of ice that covered an area not less than 300,000 square miles, through a distance of a thousand miles to the south. The drift of this ship was a repetition of De Haven's celebrated drift (§ 474); for in each case the ice in which the vessel was fastened floated out and carried the vessel along with it; by which I mean to be understood as wishing to convey the idea that the vessel was not drifted through a line or an opening in the ice, but, remaining fast in the ice, she was carried along with the whole icy field or waste. This at least was the case with De Haven, A field of ice covering to the depth of seven feet an area of 300,000 square miles, would weigh not less than 18,000,000,000 tons. This, then, is the quantity of solid matter that is drifted out of the polar seas through one opening—Davis' Straits—alone, and during a part of the year only. The quantity of water which was required to float and drive this solid matter out was probably many times greater than this. A quantity of water equal in weight to these two masses had to go in. The basin to receive these inflowing waters, i. e., the unexplored basin about the North Pole, includes an area of a million and a half square miles; and as the outflowing ice and water are at the surface, the return current must be submarine. A part of the water that it bears probably flows in beneath Dr. Kane's barrier of ice (§ 429).
432. Volume of water kept in motion by the arctic flow and reflow.—These two currents therefore, it may be perceived, keep in motion between the temperate and polar regions of the earth a volume of water, in comparison with which the mighty Mississippi, in its greatest floods, sinks down to a mere rill. On the borders of this ice-bound sea Dr. Kane found subsistence for his party—another proof of the high temperature and comparative mildness of its climate.
433. The hydrometer at sea.—The Brussels Conference recommended the systematic use of the hydrometer at sea. Captain Pledgers, Lieutenant Porter, and Dr. Ruschenberger, all of the United States Navy, with Dr. Raymond, in the American steamer
