178 THE PHYSICAL GEOGRAPHY OF THE SEA. 



487. At the very time that the doctor was gazing with longing 

 eyes upon these strange, green waters, there is known to have been 

 a powerful drift setting out from another part of this Polar sea, and 

 carrying with it from its mooring the English exploring ship Ees- 

 olute, which Captain Kellett had abandoned fast bound in the ice 

 several winters before. This drift carried a field of ice that cov- 

 ered an area not less than 300,000 square miles, through a dis- 

 tance of a thousand miles to the south. The drift of this ship 

 was a repetition of De Haven's celebrated drift (§ 530) ; 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. 



488. This field of ice averaged a thickness of not less than 

 seven feet ; at least that 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 msdiev that is drifted out of the Polar 

 Seas through one opening — 'Davis's 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, ?'. e., the unexplored basin about the North Pole, includes 

 an area of a million and a half square miles ; and as the outflow- 

 ing 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 (§ 484). 



These two currents, therefore, it may be perceived, keep in mo- 

 tion between the temperate and polar regions of the earth a vol- 

 ume of water, in comparison with which the mighty Mississippi, 

 in its greatest floods, sinks down to a mere rill. 



489. On the borders of this ice-bound sea Dr. Kane found sub- 

 sistence for his party — another proof of the high temperature and 

 comparative mildness of its climate. 



