The new North-west. [volume] (Deer Lodge, Mont.) 1869-1897, 1883-03-09
OVER FOUR THOUSAND FATHoMs.
The Deepest Soundings Ever Made in the
Atlantic Ocean.
". Y. Herald.

". Y. Herald.
The Coast and Geodetic Survey steamer
Blake swung alongside the long dock at the
Brooklyn Navy Yard yesterday morning af-
ter an absence of sixty-seven days. The
Blake left early in December, and since then
has been engaged in running line of deep
sea soundings and serial temperatures from
Bermuda to the Bahamas, and q number Of
lines normal to the latter islands. She comes
back with the distinction of having made the
deepest soundings ever made in the ATTAIN
tic ocean. On the 10th of January, In lati-
tude 10 degs. Al minis. north, longitude 90
degs. 81 min. west, about los miles north
west from St. Thomas, the lead did not touch
bottom until 1851 fathoms of line had been
paid out. The greatest depth heretofore
found in the Atlantic has been Z, ,S62 fathoms.
The location of this sounding was close to
that of the present one, and was made by the
Challenger, which, sent out by the Royal
Society Of England, made soundings in the
Atlantic between the years 1872 and 1876.
All the way along the coast to the north
east of the Bahamas the soundings in
crease very abruptly and very rapidly.
There is no gradual deepening, as In other
places. Starting at ten fathoms, for instance,
the next sounding made near by might be
100, then 200, 500, and perhaps 1000 next,
up to 1890 or $500. Between the southern
end of Great Abaco Island and Cape Samana,
at the northwestern point of st. Domingo
Island, we ran seven lines of soundings.
"The deepest sounding made during the
trip-and the deepest ever made In the At
lantic ocean-was seventy five miles north of
San Juan, Porto Rico. 1t was about
eighty miles southwest of the place where
the Challenger made her deepest sounding.
1t was inside basin--that Is, many hundred
fathoms down 1t was enclosed by ridge.
The temperature Of the water at this great
depth was thlrty-six degrees. II Is curl
GUS fact in connection with such basins rs
this that the water of the bottom Of them Is
of exactly the same temperature IS that
which runs over the top of the ridge several
hundred fathoms above. The specimen of
the bottom which we secured at this sound
ing showed . soft, brown ooze, with evidence
of fauna"
The apparatus by which in deep ssa-sound-
ing the temperature of the water at the bot
tom and at varying depths Is learned Is msst
ingenious and complete. The chief reliance
l.. ha
Thermometer. The glass tube which con-
tains the mercury is U-shapsd, the curve be-
ing at the bottom and the tube running up
on either side. At the top of one of its ex-
tremities is glass bulb containing prepa-
ration of creosote and alcohol. This bulb Is
enclosed in an outer one of very thick glass.
The tube itself Is also of very great thickness,
this being rendered necessary on account Of
the tremendous pressure of water which 1t Is
compelled to withstand. At the depth of q
thousand fathoms the pressure Of the water
is one ton per square inch. At the top of the
other extremity of the tube is another bulb
enclosed in wood. This contains alcohol
and compressed air. One side of the tube
registers degrees of heat, the other degrees Of
cold.
Inside each section Of the tube, above the
continuous column Of mercury, Is 9 steel In
dex, which is adjusted to Its position by
means of a magnet held outside. As the
thermometer is lowered into the water and
reaches lower temperature the mercury as
cends the left hand side tube, lifting with 1t
the steel index. After 1t reaches the bottom
the thermometer Is permitted to remain for
some minutes, that the correct temperature
may be registered. During its return in its
passage through the water Of higher tenn
perature the incorrect registering Of the mer.
curry is guarded against by the steel index,
for, though the mercury may drop, the steel
index remains at the point to which 1t has
been raised. To make assurance doubly
sure two "checks" are brought into play
One is mercurialIthe Negretti-Zambra), the
other (Siemens' apparatus) being electrical.