560 FISHERIES OF THE UNITED STATES. [48] 



six or seven meshes to the linear inch; it is closed at the lower end, and 

 has a canvas covering like the large dredge. The lower part of the 

 net has a somewhat closer mesh than the sides. 



Blake Dredge, for use on bottoms of soft mud or ooze, in deep water. 



United States Fish Commission. 



The Blake dredge was devised during the winter of 1877-'78 by Com- 

 mander C. D. Sigsbee, United States Navy, and Master H. M. Jacoby, 

 United States Navy, then attached to the United States Coast Survey 

 steamer Blake, for use on the soft bottoms of mud and ooze which 

 characterize the deeper waters off the coast. These officers were led to 

 make this improvement over the old style of dredge, for the purpose 

 stated, from the fact that the latter implement tends to fill and become 

 clogged as soon as it falls upon a bottom of very soft materials, thereby 

 preventing its proper working. The essential features of the Blake 

 dredge are its broad, non-flaring scrapers, and square frame, which 

 cause it to rest flat upon the bottom, and prevent its digging in beyond 

 a suitable depth. It skims over the ground, and, as only a little mud 

 enters at a time, it is being constantly washed from the net, to a greater 

 or less extent, by the great volume of water passing through at the 

 same time, leaving only the coarser portions and the specimens behind. 



This dredge has been in constant use by the Coast Survey since its 

 introduction, and has given entire satisfaction. As used by the Fish 

 Commission it has been altered somewhat in size and proportions, but 

 otherwise retains its original form. The dredge exhibited, which is 

 furnished by the Fish Commission, has the frame 3£ feet long, 4 feet 

 broad, and 8£ inches high, of one-half-inch round iron. The scrapers 

 are 6 inches wide, three fourths of an inch thick, and thin out to a sharp 

 edge in front; they are placed parallel to each other, and at the sides 

 are fastened to the ends of the side pieces of the frame. The handles 

 are 20 inches long and similar in character to those of the common 

 dredge, though differing from them somewhat in shape. The net is 

 constructed of webbing, having a half-inch square mesh, opens at the 

 hinder end, and projects slightly beyond the frame, to which it is tied 

 to prevent reversing while being lowered. The frame is covered on the 

 four sides by heavy canvas to protect the net. On the steamer Blake 

 several weights and hempen tangles were attached to the end of this 

 dredge, but this practice has not been followed by the Fish Commission. 



Chester Rake Dredge, for obtaining marine invertebrates which burrow 

 deeply into the bottom. 



United States Fish Commission. 



The rake dredge was designed for the special purpose of obtaining 

 those species of marine animals which burrow deeply into muddy and 

 sandy bottoms beyond the reach of the ordinary form of dredge. In 

 its present shape, it was first constructed in 1881, by Capt. H. C, Ches- 



