202 DISCOVERY REPORTS 



of the various species. For oblique hauls open N lOO and N 70 were attached to the 

 warp close together and 3 or 4 m. above the lead. With the ship steaming at 2 knots 

 200 m. was paid away, and as soon as this had been done hauling commenced. The rate 

 of hauling was 10 m. per minute; each haul thus took 20 min. and the distance covered 

 was two-thirds of a mile. 



In working Large Horizontal Nets attempts were made to effect some improvement 

 in methods. As a general rule large horizontal nets are fished open and no matter how 

 long they may have been towed at a particular level many organisms must necessarily 

 be caught during the ascent of the net. As a result it is only by a careful comparative 

 study of a large number of hauls that any good estimate can be formed of the horizons 

 at which an abundant species lives, while with scarcer forms the data are nearly always 

 insufficient. If the larger and more active planktonic animals are to be secured, a net 

 of large dimensions is a necessity, and it appeared important to find out some method 

 by which these large nets could be closed. 



Originally it was hoped that it might be possible to send nets down closed, to open 

 them when the full amount of warp had been paid out, and to close them again before 

 hauling. In the arrangement suggested a number of rings were sewn to a canvas band 

 some distance from the mouth and on the inside of the net. A short running line was 

 passed through these rings and the whole fore part of the net drawn through the frame. 

 The fore part thus took the form of a cone inside the bridles, and the running line at 

 the apex of the cone was linked to the primary release of a mechanism attached to the 

 wire rope (a description of this mechanism will be found on p. 194). The after part 

 of the net tailed out in collapsed form from the inner apex of the cone, the bucket itself 

 extending well behind the frame. When, by despatch of the first messenger, the running 

 line was released, the net would be carried by the weight of water through the frame 

 and would take up its normal form. To close the net when the haul was completed the 

 Nansen method was employed. A link carrying the bridles was slipped from the 

 secondary release, and the net was closed and hauled to the surface by a running line 

 passing through another series of rings on the outer side of the canvas band and through 

 a fair-lead on the frame of the net. 



Experiments carried out on these lines resulted, in part at least, in failure. To shoot 

 a large net, closed as described above, proved a matter of very great difficulty, due 

 partly to the inherent inconvenience of the arrangement, and partly to the limited deck 

 space and to the obstruction caused by the mizen rigging. Although on one or two 

 occasions the N 450 has been successfully opened and closed by this method, the 

 operation was far too awkward for routine work and the idea of shooting large nets 

 closed was abandoned. This is perhaps not a matter of vital importance; for if 

 horizontal nets are shot at a fair speed they catch practically nothing during the 

 process, as has been shown by closing them immediately after they have been let 

 out. To close the net before hauling is a much more important consideration: in this 

 manoeuvre greater success was attained, and with experience in manipulation it was 



