246 THE DEPTHS OF THE SEA. [chap. vr. 



men, while a third takes it from the wiuch 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 



