CHAP. V. |] DEEP-SEA SOUNDING. 291 
_ 
every occasion, even at the greatest depths, he felt 
distinctly the shock of the arrest of the weight upon 
the bottom communicated to his hand. A careful 
sounding was always taken immediately before letting 
go the dredge. I will take as an example the sound- 
ing which determined the depth of the deepest haul 
of the dredge yet made, in 2,435 fathoms in the Bay 
of Biscay on the 22nd of July, 1869, and describe 
the modus operandi. 
The ‘ Porcupine’ was provided at Woolwich with 
an admirable double cylinder donkey-engine of 12- 
horse power (nominal), placed on the deck amidships, 
with a couple of surging drums. This little engine 
was the comfort of our lives; nothing could exceed 
the steadiness of its working and the ease with which 
its speed could be regulated. During the whole ex- 
pedition it brought in with the ordinary drum, the 
line, whether sounding-line or dredge-rope, with 
almost any weight, at a uniform rate of a foot per 
second. Once or twice it was over-strained, and then 
we pitied the willing little thing panting like an over- 
taxed horse ; and sometimes we put on a small drum 
for very hard work, gaining thereby additional power 
at some expense of speed. 
Two powerful derricks were rigged for sounding 
and dredging operations, one over the stern and one 
over the port bow. The bow derrick was the stronger, 
and we usually found it the more convenient to 
dredge from. Sounding was most frequently carried 
on from the stern. Both derricks were provided with 
accumulators, accessory pieces of apparatus which 
we found of great value. The block through which 
the sounding-line or dredging rope passed was not 
