142 THE SEA. 



when it began to run in obedience to the current 

 alone ; for this latter power was uniform, while the 

 former was regularly retardating. 



Though the depth of the profound sea was thus 

 ascertainable, no tidings as yet had come up from it. 

 The ball and twine were sacrificed, as it was imprac- 

 ticable to weigh the ball with so slight a thread, from 

 so vast a depth. But a beautiful contrivance was 

 now invented by Lieutenant Brooke, U.S.N., by which 

 the long desired object was at length achieved, and 

 specimens were brought up from the very floor of the 

 ocean. It is a most simple affair. The ball (a 641b. 

 shot) is perforated perpendicularly, to admit a rod 

 (which is hollow at the end, and armed with grease) , 

 to slide freely through it. The rod at its upper end 

 bears two arms working on hinges, to which the 

 sounding-line is attached, and which, while the line 

 is strained, are kept projecting obliquely upwards. 

 A tape suspends the ball, fastened by two rings, 

 which are slipped over the ends of the arms. The 

 moment the end of the rod touches the bottom, the 

 line slackens, the arms drop, the rings slip off, and 

 the ball is loose. Then the rod alone is drawn up, 

 with a specimen of the sand or mud, or whatever else 

 may be at the bottom adhering to the " arming," as 

 the grease is called. 



What, then, is the result ? That in- no case in 

 which reliable soundings have been obtained does the 

 depth exceed 25,000 feet, or something less than five 

 miles. This is in the North Atlantic ; but experi- 



