THE AGASSIZ TRAWL 301 



a few feet longer than the spans, and is made fast by 

 one end to the beam, close to the after head, and by 

 the other to the trawl warp just above the shackle. 

 When the spans appear through the fairlead, the 

 beam rope (which is, of course, slack) is taken off, 

 passed through the snatch-block on the port quarter, 

 and led back to the capstan, or to one of the small 

 drums of the winch. One or two turns are taken on 

 the spans, with the result that the weight of the trawl 

 is borne by the fore span and by the beam rope. A 

 rolling hitch is put round both spans ; they are reeled 

 off the drum and the after one unshackled. The trawl 

 is now hauled to the surface by the fore span and beam 

 rope, while the after span is coiled down on deck. 

 When the frame appears at the water's edge, one head 

 after another may be lifted in by the masthead or 

 derrick tackle. The net can then be hauled in over 

 the beam, taking the foot rope first to avoid the loss 

 of any of the contents. 



The Agassiz Trawl.— This is a small trawl useful for 

 work in deep water. When a small trawl of the usual 

 pattern is shot in deep water, it is liable to turn over, 

 so that the beam lies on the ground and the net does 

 not fish. In order to obviate this Professor Agassiz 

 devised a trawl with two ground ropes and an iron 

 frame, so arranged that the net would fish whichever 

 way up the trawl fell on the bottom (Fig. 201). The 

 shape of the frame is shown in the figure. The 

 following dimensions are given by Tanner : 



Beam : 1 1 feet. 



Runners : length, 4 feet ; depth, 3 feet 6 inches ; 



width, 3 inches. 

 Trawl net : length, 17 feet ; mesh, 1 inch to h inch. 



For working in water over 100 fathoms in depth, it 

 has been found advantageous to weight the frame 



