88 
THE VOYAGE OF II.M.S. CHALLENGER. 
Brooke's Sound 
mo Apparatus. 
i achinu the bottom. Lieutenant Parker, U.S.N., of the sloop “Congress,” ran out 
50,000 feet of line without touching the bottom. 
Walsh’s experiments on board the “Janey” convinced Maury that wire was less 
suitable than cord. He then had lecourse to a line with a 32-lb. bullet attached, 
which was allowed to descend, and when it touched bottom the twine was cut near 
the surface, the depth being calculated by measuring what was left of the twine on 
board. The experiments of Lieutenant Rogers Taylor on board the “Albany” showed 
that it was necessary to use something stronger than twine. Maury demonstrated 
;he influence of submarine currents by sounding on the same spot with one and with 
two 32-lb bullets, for he found invariably that the depth indicated was less when the 
two bullets were used ; the double weight descends, faster, and is therefore not so long 
exposed to the action of the currents. From this it was considered advisable to use 
stronger lines, reckoning the time each 100 fathoms took to run out, but still the 
moment of touching bottom, if bottom were reached, remained doubtful. Lieutenant S. 
P. Lee of the “ Dolphin ” obtained, however, some good results, and afterwards every 
American ship, the officers cf which would undertake deep soundings, was supplied with 
: sufficient quantity of prepared line and 32-lb. bullets. Every opportunity of sounding 
in deep water was to be taken advantage of, still one important particular was wanting, 
— there was no positive proof that Lee and his predecessors had touched bottom, and 
up till that time it had been deemed impossible to bring up samples of the deposit. 
It was then that Midshipman J. W. Brooke, a young and distinguished officer 
attached to the Observatory, proposed to Maury that the well-known apparatus, which 
now bears Brooke’s name, should be adopted. This consisted of a detaching apparatus 
.ffixed to the lead of the sounding line, on a principle similar to that employed by 
Cusanus, Puehler, and Alberti without a line. 1 With this apparatus Brooke collected in the 
Pacific -umples from depths down to 3500 fathoms; Midshipman J. G. Mitchell of the 
“ Dolphin ” and his men acquired such dexterity in the use of the apparatus that they 
seldom failed to bring up a sample of the bottom. The samples thus obtained were 
carefully labelled and sent to the head of the Hydrographic Office. Brooke made use 
" f hi- apparatus on board the “Vincennes” in the North Pacific, 2 but he confesses that 
the motion of the boat interfered with the precision of the observations. After several 
trials in the Indian Ocean and Coral Sea, however, he came to the conclusion that it was 
f •--il.; to take soundings down to any depth. He mentions a sounding taken in the 
Indian Ocean at a depth of 7040 fathoms, but the line broke; this failure he attributed 
to the currents. In the Coral Sea some excellent results were obtained ; from a depth 
of 2150 fathoms, in lat. 13° S., long. 162° E., the tube came up full of clayey cal- 
■ areou- matter so compact that it retained the marks made by the bullet in slipping 
along the tube. 
* 8«c anU, pp. 66 and 57. 
* Maury, op. cit., vol. i. p. 169. 
