EQUIPMENT. 9 
M. Brooke, then passed midshipman, devised a very ingenious 
apparatus (Fig. 1), so contrived as to disconnect, on touching 
bottom, the heavy sinker — an old cannon-ball 
with a hole bored through it— required for ) 
running out the sounding-line to great depths. P 
This made it possible to use a very heavy sinker 
compared to the size of the line, because the 
latter, being instantly freed from the weight 
on reaching the bottom, need only be strong 
enough to bring back the light iron rod with 
the collecting cup attached to it which passed 
through the sinker. "While going down, the 
cannon-ball was suspended by slings from mov- 
able cranks; on reaching bottom the end of L 
the line became slack, the weight pulled down ne i grt 23 
^ 5 : cher. (Sigsbee.) 
the arms, and the slings slipped off, leaving the 
shot behind, and the line free to bring back the small sample 
of the bottom attached to the armature of the rod. This arma- 
ture has since been greatly modified and the rod changed to 
a cylinder by Commander Belknap, so that in the deep-sea 
sounding-machine as used on the “Blake” quite a large sam- 
ple of the bottom can now be brought up. The apparatus 
used by Brooke for detaching has also been greatly improved 
by Lieutenant-Commander Sigsbee ; his detacher is now at- 
tached to the Belknap cylinder when deep soundings are made. 
The principle upon which it works is that of a bell-crank 
suspended excentrieally; so long as the weight of the shot 
is suspended from the crank, it cannot be detached, but the 
moment the extremity of the sounding-cylinder touches bottom, 
the pressure is relieved and the bell-crank is tripped, the shot 
slips off, and the sounding-cylinder and detacher alone, weigh- 
ing together about fourteen pounds, are drawn up to the sur- 
face, with a small quantity of the bottom which has forced its 
way into the collecting cylinder. 
The examination of the specimens of the bottom collected by 
the United States Coast Survey was intrusted at first to Pro- 
fessor: Bailey, and in later years to Mr. Pourtalés. The results 
showed at once how large a part in the economy of the life of 
