246 THE DEPTHS OF THE SEA. [cHaP. VI. 
men, while a third takes it from the winch and 
coils it. 
Dredging in deep water—that is, at depths beyond 
200 fathoms—is a matter of some difficulty, and can 
scarcely be compassed with the ordinary machinery 
at the disposal of amateurs. Deep-sea dredging can 
no doubt be carried on from a good-sized steam yacht, 
but the appliances are so numerous and so bulky, 
and the work is so really hard, that it is scarcely 
compatible with pleasure-seeking. 
I do not know that much improvement can be 
made upon the apparatus and method employed in 
the ‘ Porcupine’ in 1869 and 1870. I will therefore 
describe her dredging gear and the dredging opera- 
tion carried on from her at the greatest depths in 
the Bay of Biscay, that which tested our resources 
most fully, somewhat in detail. 
The ‘ Porcupine’ is a_ 382-ton gun-boat, fitted up 
for the surveying service, in which she has been em- 
ployed for some years past among the Hebrides, and 
latterly on the east coast of England. She was 
assigned for our special work in 1869, with all her 
ordinary surveying fittings; and certain very im- 
portant additions were made; among others the 
double-cylinder donkey engine, which worked up 
to about twelve horse-power, with surging drums 
of different sizes, large drums for bringing up light 
weights rapidly, and smaller drums for heavy work. 
This engine was set up amidships, so that lines could 
be led to the drums either from fore or aft. The 
donkey engine proved a most serviceable little 
machine. We almost always used the large drum, 
both in dredging and sounding; and except on one 
