254 THE DEPTHS OF THE SEA. [chap. vi. 



from the dredge, and the dredge itself. The vessel now 

 steams slowly to windward, occupying successively 

 the positions e, r, G, and h. The weight, to which 

 the water oflfers but little resistance, sinks from 

 w to w', and the dredge and bag more 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 im.medi- 

 ately on 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 Hp 

 scraping the bottom in the attitude which it 

 assumes from 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 the vessel, owing to the great 

 weight and spring of the rope the arms would be 

 continually lifted up and the lip of the dredge pre- 

 vented from scraping. In very deep dredging this 

 operation of steaming up to windward until the 

 dredge-rope is nearly perpendicular, after drifting 

 for half an hour or so to leeward, is usually 

 repeated three or four times. 



At 8.50 P.M. we began to haul in, and the ' Aunt 

 Sallies ' to fill again. The donkey-engine delivered 

 the rope at the rate of rather more than a foot per 

 second, without a single check. A few minutes 

 before 1 a.m. the weights appeared, and a little after 

 one in the morning, eight hours after it Avas cast 

 over, the dredge was safely hauled on deck, having 

 in the interval accomplished a journey of upwards 

 of eight statute miles. The dredge contained 1\ cwt. 



