CHAP. VI.] DEEP-SEA DREDOING. 245 



cates rougMy whether the dredge is going down 

 properly. When it reaches the ground and begins 

 to scrape, an experienced hand upon the rope can 

 usually at once detect a tremor given to the dredge 

 by the scraper passing over the irregularities of the 

 bottom. The due amount of rope is then paid out, 

 and the rope hitched to a bench or roUock-pin. 



When there is anything of a current, from what- 

 ever cause, it is usually convenient to attach a weight 

 varying from fourteen pounds to half a hundred- 

 weight, to the rope three or four fathoms in front of 

 the dredge. This prevents in some degree the lift- 

 ing of the mouth of the dredge. If the weight be 

 attached nearer the dredge, it is apt to injure delicate 

 objects passing in. 



The boat should move very slowlyj probably not 

 faster than a mile an houi\ In still water, or with 

 a very slight current, the dredge of course anchors 

 the boat, and oars or sails are necessary ; but if 

 the boat be moving at all it is all that is required. 

 I like best to dredge with a close-reefed sail before a 

 light wind, with weights, against a very slight tide 

 or current ; but these are conditions which cannot 

 always be commanded. The dredge may remain 

 down from a quarter of an hour to twenty minutes, 

 by which time, if things go well, it ought to be 

 fairly filled. 



In dredging from a small boat the simplest plan is 

 for two or three men to haul in hand over hand and 

 coil in the bottom of the boat. Eor a large yawl 

 or yacht, and for depths beyond fifty fathoms, a 

 winch is a great assistance. The rope takes a couple 

 of turns round the winch, which is worked by two 



