718 



HISTORY OF THE SEA. 



of the United States has contributed fully its share. The 



coast survey has added a great deal to our knowledge of the 

 deep sea, and the ships of the navy took part in the soundings 

 by which the existence of the plateau across the bed of the 

 Worth Atlantic, which has been used for the ocean telegraphic 

 cable, was proved. 



In 1868 the English government provided the vessels and 

 crews for the purpose of conducting deep sea dr edgings, under 

 the direction of Dr. Carpenter and Mr. Wyville Thompson. 

 These expeditions have found that it is quite possible to work 

 with certainty, though not with such ease, at the depth of 600 

 fathoms, as at a depth of 100 ; and in 1869 it carried on deep 

 sea dredging at a depth of 2,435 fathoms, 14,610 feet, or very 

 nearly three miles, with perfect success. Dredging in such 

 deep water is very trying. Each haul occupied seven or eight 

 hours, and during the whole of this time the constant atten- 

 tion of the commander was necessary, who stood with his hand 

 on the regulator of the accumulator, ready at any moment to 

 ease an undue strain, by a turn of the ship's paddles. The 

 men, stimulated and encouraged by the cordial interest taken 

 by the officers in the operations, worked with a willing spirit ; 

 but the labor of taking up three miles of rope, coming up with 

 a heavy strain, was very severe. The rope itself, of the very 

 best Italian hemp, 2 J inches in circumference, with a breaking 

 strain of 2 J tons, looked frayed out and worn, as if it could 

 not have been trusted to stand such an extraordinary ordeal 

 much longer. 



The ordinary deep sea lead used for soundings weighs from 

 30 to 120 pounds. The samples of the bottom which it brings 

 up are marked upon the charts as mud, shells, gravel, ooze or 

 sand, thus 2,000 m. sh. s. means mud, shells and sand at 2,000 

 fathoms; 2,050 oz. st. means ooze and stones at 2,050 fathoms ; 

 2,200 m. s. sh. sc. means mud, sand, shells, and scoriae, at 2,200 

 fathmus, and so on. When no bottom is found with the lead 



