[51] FISHERIES OF THE' UNITED STATES. 563 



attached. The net has two different sizes of mesh, each making up one- 

 half of the net in length. In the front half the meshes are 1 inch square 

 and in the lower half one-half inch square. 



Larger trawls of the same construction as the above, with the beam 

 from 11 to 17 feet long and the net from 20 to 40 feet long, are most 

 commonly employed by the United States Fish Commission, even in 

 considerable depths of water. The otter trawl has also been frequently 

 tried with good success in shallow water. Wherever the common beam 

 trawl can be used advantageously, it is much preferred to the double 

 trawl next described. No difficulty has ever been experienced in lower- 

 ing it right side up to depths of 600 and 700 fathoms, and when used on 

 the same spot in connection with the double trawl has always yielded 

 the better results. On very soft bottoms it tends to sink too deeply into 

 the ground, and for this a remedy has been suggested, namely, to fasten 

 broad and thin wooden shoes to the bottoms of the runners, but this 

 feature has not yet been put to trial. The towing-net attachments to 

 this trawl are described elsewhere. 



Blake Trawl, or Double Beam Trawl, for use in deep water. 



United States Fish Commission. 



The difficulty of landing the ordinary beam trawl right side up on the 

 bottom in considerable depths of water resulted, during the first dredg- 

 ing cruise of the steamer Blake, in the winter of 1877-'78, in the con- 

 struction of a new form of trawl, which, like the dredge, can work equally 

 well either side down. For this new and valuable invention we are in- 

 debted to Prof. Alexander Agassiz, Lieutenant-Commander Sigsbee, 

 United States Navy, and Lieutenant Ackley, United States Navy. The 

 construction and appearance of this trawl, in its original shape, are 

 illustrated in the Sigsbee series of plates. Although the United States 

 Fish Commission has hitherto confined its explorations mostly to mod- 

 erate depths of water, where the ordinary beam trawl answers every 

 purpose, it has frequently experimented with the double trawl, and has 

 introduced slight modifications, mainly as regards the height of the run- 

 ners, which has been increased, in order to afford a larger opening for 

 the capture of fish. The trawl exhibited is an exact copy of the pattern 

 recently adopted for the use of the steamer Albatross. 



The runner frames form a very broad D-shaped figure, being equally 

 curved above and below in front, and extending thence straight back 

 to the upright hinder end, which they meet at right angles, and beyond 

 which they project a short distance, being perforated for the attach- 

 ment of the net. These frames are 4 feet long and 3£ feet high, and 

 are made of half-inch iron, 3 inches broad. The beams are two in 

 number, and consist of pieces of gas-pipe, 10f feet long and 2^ inches 

 in diameter outside. * They screw into brass collars at the middle of the 

 runners, one on the inner side in front, one on the inner side at the back. 

 The bridle, constructed of 3f-inch rope, is attached to two screw eyes, 



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