THE SPECIFIC GRATITT OF THE SEA, ETC. 215 



431. Solid matter annually drifted out of the polar hasin. — 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 "Eesolute," which her ofticers 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 tJirough 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 hept in motion hy 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 

 Mi.ssissippi, 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. Tlie hydrometer at sea. — The P>russels Conference recom- 

 mended the systematic use of the hydrometer at sea. Captain 

 Pledgers, Lieutenant Porter, and Dr. Euschenberger, all of the 

 United States Navy, with Dr. Eaymond, in the American steamer 



