[63] FISHERIES OF THE UNITED STATES. 575 



form is entirely different. Its original use was to receive the contents of 

 the trawl instead-of emptying it on deck, as had been done previously., 

 but its advantages were soon found to be so great that it has also been 

 used for washing the contents of the dredge whenever the quantity of 

 mud was considerable. 



" The sieve foundation consists of a large rectangular wooden frame., 

 with wide side-pieces made of inch boards, supported on stout legs, 

 at a convenient height, the legs being made of unequal lengths to 

 correspond with the curvature of the deck. The bottom of the frame 

 consists of stout galvanized iron- wire netting with one-half inch to 

 three-fourths inch meshes. Below this is a funnel-shaped stout canvas 

 bag which terminates in a large canvas tube. This serves to convey 

 the waste water to the scuppers. A light frame of wood is made to 

 fit loosely inside of the main frame, and its under surface is covered 

 with fine wire netting of one-twelfth inch meshes. This constitutes the 

 real bottom of the sieve, the coarse netting below serving only as a 

 support for it. It is fastened to a movable frame so that it can be taken 

 out and its contents emptied upon the assorting table. This also allows 

 the wire netting to be more easily renewed when it becomes worn. The 

 upper or coarse sieve is made with wide, flaring, or hopper-shaped 

 wooden sides, upon which at about the middle there are cleats that rest 

 upon the edges of the main frame. The bottom of the hopper is formed 

 of strong galvanized iron wire netting of three-fourths inch meshes." 



The dimensions of the table sieves used by the Fish Commission are 

 as follows : Main frame — height to upper edge, 30 inches ; length, 66 

 inches; breadth, 38 inches; width of side pieces, 11 inches. Hopper 

 frame — width of side pieces, 13 inches; length at bottom, 56 inches; 

 length at top, 66 inches ; breadth at bottom, 27 inches ; breadth at top ? 

 37 inches. 



The model exhibited is constructed of one-third the full size as to 

 general dimensions and the thickness of the wood, but the wire net- 

 ting is the same as in the large sieves. 



Cradle or Rocker Sieve, for washing the contents of the dredges. 



United States Fish Commission. 



" This sieve was devised, in 1872, by Prof. A. E. Verrill, for the use 

 of the United States Fish Commission. It was so constructed as to 

 afford the means of rapidly washing out the large quantities of mud 

 often brought up by the dredge and rake-dredge, and at the same time 

 to keep the mud and water off the deck as much as possible. It con- 

 sists of two wooden cross-pieces, in shape rather more than half a circle, 

 united by two narrow wooden side pieces set into the end pieces so as 

 to leave a flush surface. The outside covering consists of two thick- 

 nesses of wire netting, the inner one with meshes of one-twelfth inch or 

 less, the outer one of stout galvanized iron wire with one-half inch 

 meshes. The outer netting is only to afford support and protection to 



