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line, so that towards the end of a 1,200 or 1,300 fathoms’ sound- 
ing between two and three minutes were required for 100 
fathoms to run out. Capt. Calver took each sounding with his 
own hands, and was able to tell with great certainty the precise 
moment when the weight struck the ground. In the fine 
weather with which we were usually favoured, the sounding- 
line even at these great depths hung quite vertically over the 
stern of the vessel, and the bottom could be felt at the end of 
it, by slightly raising and lowering the line by hand. Five 
minutes were then allowed for the thermometers to take up the 
temperature of the surrounding water, after which the line was 
hove-in by the donkey-engine, and when the instruments arrived 
at the surface the indices of the thermometers were read and 
the results recorded. Soundings were taken in this manner at 
ninety different stations, and when it was desired to take the 
temperature of the sea, and samples of water at various 
vertical depths (short of the bottom) over the same spot, the 
operation was repeated with the cup-lead, letting it down, e.g., 
to 1,250, 1,000, 750, 500, and 250 fathoms, and drawing it up 
again after each operation. In this way the serial temperature 
soundings were obtained. 
The contents of the water-bottle were immediately examined 
for their specific gravity by delicate glass hydrometers reading 
to four decimal places ; for the organic matter contained in 
them by the chameleon (permanganate of potash) test ; and 
for the quantity and relative proportions of gases dissolved in 
it. This last point was determined by Dr. W. A. Miller’s 
apparatus, which was first adapted to the necessities of ship- 
board by the writer. The gases were expelled from the water 
by boiling it in such a way that no air had access to it, and 
were collected over mercury and measured. The carbonic acid 
was then absorbed by potash, and the oxygen by pyrogallic 
acid ; the remainder being taken as nitrogen. In addition to 
being thus tested, some of the contents of the water-bottle 
were preserved for further analysis on shore. 
It now remains to describe the process of deep-sea dredging 
proper. In water less than 500 fathoms’ depth, two dredges 
were frequently employed, one from the bow, another from the 
stem ; but at greater depths only one dredge was used. The 
object to be attained was to get the dredge to fall vertically 
through the water to its right position on the bottom, over 
which it was to be dragged by the motion of the vessel at the 
surface. In small depths this was a matter of little difficulty, 
as the time occupied by the dredge in falling to the bottom 
was so short that the vessel did not drift much from one spot, 
and then, if the drift of the vessel was not enough, recourse 
was had to the paddles to move the dredge over the ground. 
