§ 483. THE SALTS OF THE SEA. 253 



the iceberg were this day most awfully verified. About three 

 P.M. the iceberg came in contact with our floe, and in less than 

 one minute it broke the ice ; we were frozen in quite close to the 

 shore ; the floe was shivered to pieces for several miles, causing 

 an explosion like an earthquake, or one hundred pieces of heavy 

 ordnance fired at the same moment. The iceberg, with awful but 

 majestic grandeur (in height and dimensions resembling. a vast 

 mountain), came almost up to our stern, and every one expected 



it would have run over the ship The iceberg, as before 



observed, came up very near to the stern of the ship ; the inter- 

 mediate space between the berg and the vessel was filled with 

 heavy masses of ice, which, though they had been previously 

 broken by the immense weight of the berg, were again formed 

 into a compact body by its pressure. The berg was drifting at 

 the rate of about four knots, and by its force on the mass of ice 

 was - pushing the ship before it, as it appeared, to inevitable de- 

 struction. Feb. 24:th. The iceberg still in sight, but drifting away 

 fast to the northeast. Feb. 26th. The iceberg that so lately threat- 

 ened our destruction had driven completely out of sight to the 

 northeast from us." 



483. Kow, then, whence, unless from the difference of specific 

 Temperature of the gravitv duc sca watcr of different degrees of salt- 

 uader current. ^^^^ ^^ji J tcmpcraturc, cau wc dcrlvc a motive pow- 

 er in the depths of the sea, with force sufficient to give such tre- 

 mendous masses of ice such a velocity ? What is the tempera- 

 ture of this under current ? Rodgers's observations (§ 480) would 

 seem to indicate that at the depth of 150 feet it is not below 40°. 

 Assuming the water of the surface current which runs out with 

 the ice to be all at 28°, as De Haven found it (§ 479), we observe 

 that it is not unreasonable to suppose that the water of the under 

 current, inasmuch as it comes from the south, and therefore from 

 warmer latitudes, is not so cold ; and if it be not so cold, its tem- 

 perature, before it comes out again, must be reduced to 28°, or 

 whatever be the average temperature of the outer but surface cur- 

 rent. Dr. Kane found the temperature of the open sea in the Arc- 

 tic Ocean (§ 429) as high as S6°. Can water in the depths below 

 flow from the mild climate of the temperate zones to the severer 

 climates of the frigid zone without falling below 36°? To what, 

 in the depths of the sea, can a warm current of large volume im- 



