WATERS IN PERPETUAL MOTION. 33 



shore. Hence the grandeur of the scenery of that 

 bold coast. It is not merely that the waves of the 

 Atlantic breast it in a long, unbroken line, but the 

 deep water comes so close to the rocks, that the ground- 

 swell of that great submerged valley strikes our island 

 with scarcely diminished force. 



The extreme depth of the ocean has yet to be as- 

 certained. Some of the deepest soundings on record 

 were made during the Antarctic voyage, where at one 

 place, in the Atlantic, within the Southern Tropic, 

 4600 fathoms or 27,600 feet of line were run out with- 

 out reaching the bottom. Judging from the elevation 

 of the bordering continents, the mean depth of the 

 Atlantic has been roughly calculated at 50,000 feet, 

 and it is supposed that the deepest hollows do not ex- 

 ceed 80,000 feet, or about 15 miles. But such calcu- 

 lations are scarcely better than mere guesses. The 

 Pacific is much shallower, and is full of shoals and 

 islands that reveal to us the existence of a vast, sub- 

 merged continent, lying dormant, as it were, for a 

 future destiny. 



The waters of the sea, whether under the influence 

 of winds, of currents, or of tides, are in perpetual 

 motion. The effect of winds is felt chiefly at the sur- 

 face, the wildest sea-storm probably not influencing 

 the strata of water a hundred feet below. The lower 

 strata obey the force of currents, which may be com- 

 pared to vast oceanic rivers setting continuously or 

 variably in one direction for hundreds of miles, and 

 causing a circulation between the waters of one por- 

 tion of the ocean and another. But tides alternately 



