THE SALTS OF THE SEA. 163 



'^ February 23d. Latitude 68° 37^ north, longitude about 63^ 

 west. 



" The dreadful apprehensions that assailed us yesterday, by 

 the near approach of the iceberg, were this day most awfully ver- 

 ified. 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 di- 

 mensions 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 our ship ; the intermediate 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 w^as 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 ap- 

 peared, to inevitable destruction." 



" Feb. 24:th. The iceberg still in sight, but driving away fast to 

 the northeast." 



" Feb. 25th. The iceberg that so lately threatened our destruc- 

 tion had driven completely out of sight to the northeast from us." 



324. Now, then, whence, unless from the diff'erence of specific 

 gravity due sea water of different degrees of saltness, can we de- 

 rive a motive power with force sufficient to give such tremendous 

 masses of ice such a velocity ? 



325. What is the temperature of this under current ? Be that 

 what it may, it is probably above the freezing point of sea water. 

 Suppose it to be at 32°. (Break through the ice in the northern 

 seas, and the temperature of the surface water is always 28^. At 

 least Lieutenant De Haven so found it in his long imprisonment, 

 and it may be supposed that, as it was with him, so it generally 

 is.) Assuming, then, the water of the surface current which runs 

 out with the ice to be all at 28°, we observe that it is not unreas- 

 onable to suppose that the water of the under current, inasmuch 

 us it comes from the south, and therefore from warmer latitudes. 



