1869.] on the Scientific Exploration of the Deep Sea. 427 



A represents the position of the vessel when the dredge is let go, and 

 the dotted line A B the line of descent of the dredge, rendered oblique 

 by the tension of the rope. While the dredge is going down, the vessel 

 drifts gradually to leeward ; and when the whole (say) 3000 fathoms of rope 

 are out, C, W, and D might represent the relative positions of the vessel, 

 the weight attached 500 fathoms from the dredge, and the dredge itself. 



Fig. 4. 



The vessel now steams slowly to windward, occupying successively the po- 

 sitions E, F, G, and H. The weight, to which the water offers but little 

 resistance, sinks from W to W, and the dredge and bag move slowly from 

 D to B. The vessel is now allowed to drift back before the wind from 

 H towards C. The tension of the motion of the vessel, instead of acting 

 immediately upon the dredge, now drags forward the weight W, so that 

 the dredging is carried on from the weight, and not directly from the 

 vessel. The dredge is thus quietly pulled along, with its lip scraping the 

 bottom in the attitude which it assumes from the position of the centre of 

 weight of its iron frame and arms. If, on the other hand, the weights 

 were hung close to the dredge, and the dredge were dragged directly from 



