122 FISH CULTUEE 



Clark hatching box: "A tank 15 feet long with 

 a partition running its entire length and so placed 

 that its lower end rests upon the upper end of a 

 similar one 13 feet long, which differs from the upper 

 one only in that it contains two boxes less. Nine par- 

 titions placed crosswise of the tank form, with the 

 lengthwise partitions, a double row of compartments, 

 each of which is 19 inches long, and 15J inches wide, 

 and is provided with a waste-water channel or sluice- 

 way leading into the next compartment. In these 

 compartments are placed the hatching boxes." 



The Clark box is 18 inches long, 14 inches wide, 

 and 9J inches deep, and is made from three-quarter- 

 inch dressed white-pine lumber. On its under side 

 the box is provided with short feet to allow a free 

 circulation of water under it and to prevent it from 

 resting on any sediment or refuse that may be de- 

 posited on the bottom of the tank; and on the inside 

 of each bottom corner is fastened a thin block to sup- 

 port the trays. Five small auger-holes permit the 

 escape of water from the box. A slot is cut in one 

 end of the box, so that the water from the compart- 

 ment above cannot flow into the one below without 

 falling into and passing through this box. Upon the 

 feet or risers inside the box rest nine trays, made of 

 perforated zinc, or fine wire netting, tacked upon a 

 pine frame 16 inches long, and 12 inches wide. The 

 trays are placed one upon the other, in the box, the 



