TH|] DEPTHS OF THE OCEAN. 
205 
a test which requked 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 was small, and stood the test required, 
a pound of it measuring about six hundred feet in length. 
431. 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. 
432. 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 counter 
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 currents, 
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 when- 
ever the reel was stopped and the line held fast in the boat. 
433. 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 293) in their mute way tell us of. : 
This systern of circulation commenced on the third day of cre- 
ation, 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. 
434. 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 
of the same shape and weight, we at last established the law of 
descent. Thus the mean of our experiments gave us, for the sink- 
er and twine used, 
