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



hemp, 2-J inches in circumference, with a breaking 

 strain of 2£ tons. The 1,000 fathoms next the 

 dredge were ' hawser-laid,' 2 inches in circumference. 

 A Russian hemp rope appears to be the most suit- 

 able. A manilla rope is considerably stronger for 

 a steady pull, but the fibre is more brittle and liable 

 to go at a ' kink.' I have never seen a wire-rope used, 

 but I should think it would be liable to the same 

 objection. The 'Challenger' is to be supplied with 

 ' whale-line ' for her great expedition. The frame of 

 one of the dredges which we used in the Bay of 

 Biscay is represented at Figs. 47 and 48. The length of 



^^ 



^ 



Fig. 47.— The End of the Dredge frame. 



the dredge-frame is 4 ft. G in., and it is 6 inches wide 

 at the throat or narrowest part. The dredge used in 

 the deepest haul was somewhat different. About 

 half of each arm next the eye to which the rope was 

 attached, was of heavy chain. I doubt greatly, how- 

 ever, if this is an advantage. The chain drags along 

 in front of the dredge, and may possibly obstruct 

 the entrance of objects and injure them more than a 

 pair of rigid arms would do. On one side the chain 

 was attached to the arm of the dredge by a stop of 

 five turns of spun-yarn, so that in ease of the dredge 



