248 THE PHYSICAL GEOGRAPHY OF THE SEA. 



really subjected to quite a heavy strain, and that, consequently, 

 the t'-.vine to be used must be strong ; it was therefore subjected 

 to a test which required it to bear a weight of at least sixty pounds 

 freely suspended in the air. So we had to go to work anew, and 

 make several hundred thousand fathoms of sounding-twine espe- 

 cially for the purpose. It w^as small, and stood the test required, 

 a pound of it measuring about six hundred feet in length. 



693. The officers intrusted with the duty soon found that the 

 soundings could not be made from the vessel with any certainty 

 as to the depth. It was necessary that a boat should be lowered, 

 and the trial be made from it ; the men with their oars keeping 

 the boat from drifting, and maintaining it in such a position that 

 the line should be "up and down" the while. 



694. That the line would continue to run out after the cannon 

 ball had reached bottom, was explained by the conjecture that 

 there is in the ocean, as in the air, a system of currents and coun- 

 ter currents one above the other, and that it was one or more of 

 these submarine currents, operating upon the bight of the line, 

 which caused it to continue to run out after the shot had reached 

 the bottom. In corroboration of this conjecture, it was urged, 

 with a truth-like force of argument, that it was these under cur- 

 rents, operating with a swigging force upon the bights of the line — 

 for there might be several currents running in different directions, 

 and operating upon it at the same time — which caused it to part 

 whenever the reel was stopped and the line held fast in the boat. 



695. A powerful train of circumstantial evidence was this (and 

 it was derived from a source wholly unexpected), going to prove 

 the existence of that system of oceanic circulation which the cli- 

 mates, and the offices, and the adaptations of the sea require, and 

 which its inhabitants (§ 498) in their mute way tell us of. 



696. This system of circulation commenced on the third day of 

 creation, with the ''gathering together of the waters," which were 

 "called seas," and doubtless will continue as long as sea water 

 shall possess the properties of saltness and fluidity. 



697. In making these deep-sea soundings, the practice is to 

 time the hundred fathom marks as they successively go out ; and 

 by always using a line of the same size and " make," and a sinker 



