io8 



DISCOVERY REPORTS 



of Stout log-line and later of soft 2 in. circumference tarred hemp known in Admiralty 

 dockyards as "Rumbo", has been replaced by a flat braided sennet, or webbing, of 

 exceptional strength. This material has given every satisfaction, never taking turns in the 

 water and interfering with the efficiency of the net as the " Rumbo" line was inclined 

 to do. 



In the ' Discovery ' experiments the N 450 was towed horizontally,^ at that time the 

 common practice with most if not all types of towed net, particularly those of larger 

 size. Although it had worked well when fished open, yielding substantial catches in 

 first-rate condition, as a closing net the N 450 met with little success. For closing, the 

 familiar Nansen method was used, but even when all difficulties in the actual operation 

 had eventually been overcome the results were never satisfactory : the volume of the 

 catch was in most instances disappointingly small, the material often in poor condition 

 and occasionally damaged so badly as to defy identification. 



Fig. I. Plan of 4I m. net showing principal measurements and main structural features (after Kemp and 

 Hardy). A, cylindrical non-catching part of i| in. mesh netting, 50 ft. in circumference. BCD, conical 

 catching part tapering to a circumference of 3 ft. at e, with meshing as follows: B, | in., C, 7 mm., 

 D, 7 mm., Hned at the cod-end with finer 4 mm. material, e, canvas cylinder to slip over bucket; 

 /, canvas band; g, longitudinal webbing supports; /;, bridles; r, net ring, 450 mm. in diameter, 50 ft. 

 in circumference. 



The curious poverty of material in the closing net gave rise to the somewhat dis- 

 turbing view that a large proportion, perhaps the majority, of the animals captured in 

 a big open net fished horizontally might be taken not from the restricted horizon at 

 which the net was fishing, but during its ascent towards the surface when the speed of 

 towing as a rule is augmented by hauling. In other words it began to be suspected that 

 the N 450, big as it was, was not being towed fast enough to capture the strong and 

 actively-moving species for which it was designed — it seemed exceedingly likely in fact 

 that during the horizontal tow all but the weakest were contriving to make their escape 

 from the net, if they were not indeed eluding it altogether. It was for this reason that 

 in later experiments the old method of slow horizontal fishing was abandoned and the 

 faster method of the oblique tow, which for some time had been employed to advantage 

 with smaller nets, took its place. 



The poor condition of the material is not surprising, for so large an apparatus when 

 closed on the Nansen principle would appear to behave as Kemp has put it " like an ill- 



1 At a speed which is stated to have been about 2 knots. See, however, p. 115. 



