APPARATUS EMPLOYED IN DEEP-SEA EXPLORATIONS. 289 
Where the depth was great, however, and especially when the 
surface drift was considerable, special precautions had to be 
observed, the chief of which was to move the vessel by steam 
up to windward, so as to counteract the leeway. An additional 
■device was to attach a weight (1 or 2 cwt.) to the dredge rope 
at some distance from the dredge — usually about one-fourth 
of the known depth. The annexed figure (for which, as for the 
other intercalated cuts, the editor is indebted to the Secretary 
of the Eoyal Society) gives an idea of the relative positions of 
the vessel and the dredge according to this plan of dredging. 
A. 'Wind. 
A represents the position of the vessel when the dredge is let go ; 
a B the line of descent of the dredge. While the dredge is 
going down, the vessel drifts to leeward, say to c, when c w d 
would represent the relative positions of the vessel, the weight, 
and the dredge itself. E, F, a, h, are the positions of the 
vessel in steaming to windward, during which time the dredge 
sinks from d to B, and the weight from w to w 1 . This opera- 
tion is repeated two or three times, and the vessel is then 
VOL. ix. — no. xxxvi. u 
