GENERAL INTRODUCTION TO THE ZOOLOGICAL REPORTS. 11 



of the deck engines on the starboard side corresponding in diameter to the drum used 

 on the port side, and from this it was finally taken and coiled. The strain was of course 

 greatest at the yard-arm and the first leading-block, and by this arrangement it gradually 

 diminished as the line passed round the series. 



The Dredge-Rope. — For dredging and trawling we were supplied with rope of three 

 difi'erent sizes — 2 inches, 2^ inches, and 3 inches in circumference respectively. This 

 cordage was made of the best Italian hemp, tarred, well hackled and rubbed down, and 

 laid up softly. The 2-inch rope weighed 95 lbs. per 100 fathoms, and its breaking strain 

 was 1 ton 12 cwts. ; the 2^ weighed 158 lbs., with a breaking strain of 2 tons 6 cwts. ; 

 and the 3-inch, 220 lbs. per 100 fathoms, with a breaking strain of 2 tons 11 cwts. In 

 proportion to its weight, therefore, the 2-inch was the strongest rope, and this or the 

 2^-inch was used for deep trawling or dredgings, the 3-inch rope being reserved for 

 comparatively shallow water. The dredge-rope was "marked red" at every 100 

 fathoms. 



When we left England we had 10,000 fathoms of 3-inch rope on board, 4200 fathoms 

 of which were expended. Of 2^-inch rope we had 10,000 fathoms; we got out 21,000 

 fathoms during the voyage, and expended a total of 27,100 fathoms. Of 2-inch rope we 

 started with 5000 fathoms, got 10,000 fathoms additional, and expended 10,860 fathoms. 



The rope was spliced together so as to form an uninterrupted length of 4000 fathoms, 

 and it was kept coiled away in racks on the forecastle, each size by itself. When we 

 first used rope in such great lengths we spliced swivels in at each 500 fathoms to take 

 the turns out ; but if care be taken in splicing that all the lengths of rope are twisted in 

 the same direction, this precaution is unnecessary, and as the swivels sometimes got 

 jammed in the blocks they were shortly discarded. 



The Deep-Sea Dredge. — The dredge in ordinary use in the Challenger is repre- 

 sented in fig. 8. The dredge-frame, of hammered iron, is 4 feet 6 inches long, and 1 foot 

 3 inches broad. The scrapers are 3 inches wide, and are connected at the ends by bars 

 of 1^-inch round-iron. The arms are of inch round-iron and slightly curved ; they are 

 bolted together to a short iron tongue which ends above in a swivel and ring. Two bars 

 of square iron of some strength are attached by eyes to the round cross-bars at the ends 

 of the dredge-frame, and have the other ends lashed to an iron bar which bears the 

 hempen tangles. These rods keep the dredge-bag at fuU length and prevent it or the 

 tangles from folding over the mouth of the dredge. 



The dredge-bag is 4 feet 6 inches in length ; it is made of netting of soft hue (something 

 like marhne), the meshes an inch to the side, and the lower third is Lined with bread-bag 

 stufi" to prevent even the smallest animals washing out whilst the dredge is being hove in. 

 The bag is guarded by three loops of bolt-rope attached to the frame of the dredge, to 

 the bottom of the bag, and finally to the tangle bar. The canvas pads represented in 



d 



