184 



DISCOVERY REPORTS 



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Three phosphor-bronze wire ropes, 3 mm. in diameter, 14 ft. long and having brass 

 eyes let in at each end, support the bucket (described on page 189) 

 and the weight. They are shackled to the eyes on the frame and they 

 have rings to take the closing rope, similar to and seized at a point in 

 line with those on the net ; further, to prevent their twisting round each 

 other, they are seized to a stout brass ring 7 in. in diameter which passes 

 round the net some 6 in. above the bucket; and finally, after passing 

 through and being seized to the eyes on the bucket holder, they meet 

 below the bucket in a shackle which supports an egg-shaped 40-lb. 

 lead. 



The rope for closing the net is 2 in. in circumference and i6| ft. long, 

 with an eye at each end. It passes round the net through the rings on 

 the band D and those on the stay wires ; its two ends are shackled to a 

 link on the closing mechanism, so that when the messenger releases the 

 "bridle" rods, the net falls away and is caught by it in a noose. The 

 closing mechanism is described on page 192. 



As heavy a lead as 40 lb. was used below the net so that it would run 

 out easily under its own weight. To facilitate the handling of the lead 

 when the net comes to the surface a rope is kept attached to it ; this is 

 15 ft. long and has at its upper end a small brass toggle, which can be 

 slipped in and out of a ring on one of the support wires just below the 

 closing band. 



A sketch of the net fully rigged is shown in Fig. 9. 



The arrangement of the bridle rods, support wires, rings, shackles, 

 etc., has been evolved by the gradual modification in practice of less 

 satisfactory designs. The rigging of such a net had seemed at first a 

 simple matter; the practice, however, of carrying out routine hauls down 

 to depths of 1000 m., often from a heavily rolling ship, showed that 

 many and unexpected defects had to be overcome. 



For horizontal use the net is exactly similar except that it has no weight 

 or supporting wires, its bucket is of a simple light pattern (see page 191) 

 and the bridles, instead of being brass rods, are three phosphor-bronze 

 wires, 3 mm. in diameter and 4 ft. in length. 



N 100. Designed for the capture of macroplankton, particularly the 

 Euphausians and Amphipods, this net has been used extensively together 

 with the N 70 for routine horizontal and oblique hauls. Only occasion- 

 ally has it been fished vertically and then its rig was unaltered. 



The ring is made of round-section galvanized iron i in. thick, has an 

 opening of i m. diameter, and has on the outside an eye, of 2 in. diameter 

 opening, as a fair-lead for the closing rope. The three bridles are of ^'ngt J'^ecTfor 

 4 mm. phosphor-bronze wire, each 5 ft. in length. The net which is vertical use. 



