280 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



This form of towing-net is, on account of its lightness and simplicity, 

 convenient for use by hand from all kinds of small sailing craft and 

 open boats. It can be rolled into a small package with all its attach- 

 ments and carried readily in one hand. With a light tow-line passed 

 through a pulley slung from one of the boat davits of the Fish Commis- 

 sion steamer Albatross, it has been hauled in from depths of 20 and 30 

 fathoms by one man with very little exertion, and has not failed to work 

 in a single instance. 



In the summer of 1895 this net, constructed in larger and heavier form, 

 with a net ring 3 feet in diameter, was used successfully on board the 

 Albatross during fishery investigations in Bering Sea, at depths varying 

 from 20 to 200 fathoms. 



Following is a description of a closing-net of medium size constructed 

 for use on the Fish Commission schooner Grampus (pi. 9, figs. 1 and 2): 

 It consists of a tow-net with a folding-ring suspended by rope slings 

 from a tripping-arm attached to the tow-line, and is operated at will by 

 a messenger. The ring to which the net is attached is hinged to fold, 

 for the purpose of closing the net, and is supported by two sets of slings 

 of nearly equal length, one set attached near the hinges, supporting the 

 net in an open position, the other attached at right angles to the hinges, 

 supporting it in a closed position. 



Closing is effected by means of a tripping-arm, from which the slings 

 are suspended, and which, being tripped by a messenger, shifts the 

 weight from the opening to the closing slings with the result of closing 

 the net. The tow-line is attached to the lower end of the tripping-arm, 

 the upper end of which is hooked to a ring on the tow-line. The opening 

 slings are secured near the upper end of the arm, the closing slings 

 to the lower end. A light messenger (pi. 9, fig. 3) sliding down the 

 tow-line detaches the messenger-ring from the upper hook of the 

 tripping-arm, shifting the weight from the opening to the closing 

 slings. A spring catch in the upper hook of the tripping-arm keeps 

 the messenger-ring from slipping out of place until struck by the 

 messenger, while a heavy ring-shaped weight, released by the tripping 

 of the arm, slips from the lower hook of the arm down the closing slings 

 and keeps the jaws from opening after they have been closed by the 

 messenger. The accompanying figures, showing the net in both open 

 and closed positions, illustrate its workings clearly. 



The tripping arm is merely a piece of half-inch brass, ordinarily about 

 2 feet in length and of the shape shown in the cut. The ring is 2 feet 

 in diameter, made of f by J inch brass, and is essentially the same as 

 that employed by Agassiz for use with his modified Chun-Petersen 

 machine. 1 The messenger is a 2-pound bronze casting, in two parts, to 

 lash around the towline. A small lead sinker is lashed to the bottom 

 of the net, of sufficient weight to carry it down clear of the ring, as it 

 is, of course, lowered vertically and the vessel from which it is operated 



Agassiz, Bull. Mus. Coinp. Zool. 1892-93, vol. xxin, p. 45, etc. 



