204 REPORT OP COMMISSIONER OF FISH AND FISHERIES. 



enters tlie main compartment from below, coming up through the scrim 

 covered bottom into the movable box. 



The partition forming the ])ocket at the lower or front end of the box 

 only extends to within 1^ inches of the bottom, leaving a space 

 through which the water runs from the compartment. In the bottom 

 of the pocket there is an opening in which the vertical waste-pipe fits. 

 This pipe is brass, ^ inch in diameter and 10 or 11 inches long; the top 

 of the pipe is 7 inches above the bottom of the table. The waste-pii)es 

 from the different boxes discharge into a trough which carries the water 

 from the building. 



A particularly important part, and the one which gives the name 

 "tidal box" to the apparatus, is used in conjunction with the waste- 

 pipe. This is a brass siphon-cap, which fits over the upper end of the 

 waste pipe. Tlie cap is a tube, closed at the top, 9 inches long and 1 J 

 inches in diameter. It is kept at any desired height on the waste-pipe 

 by wire springs in the cap or by other means. 



By virtue of the siphon attachment the water in each box rises to 

 the height of the top of the waste-pipe and begins to run over. This 

 partly exliausts the air in the cap, more water rushes in, and the pipe 

 becomes filled with water; then the siphon begins to act and takes off 

 the water to a level of the bottom of the siphon-cap. Usually the cap 

 is pushed about half down the waste-tube, although the h<ight of the 

 water in the box after the discharge ot the siphon is regulated by the 

 manner in which the eggs are working. About 7 minutes are required 

 for the water to be drawn down and the box to again fill, and approxi- 

 ma'tcly two-fifths of the water is taken off at each discharge. By this 

 arrangemeiht the water in the boxes is constantly rising and falling 

 automatically; the movements of the waves are thus simulated, the 

 eggs are kept iu constant circulation, and fresh water is continually 

 entering the boxes. 



The Chester box was generally used in cod-culture up to a com- 

 paratively recent date, and is still occasionally employed in marine 

 fish cultural operations. The general object of its construction is the 

 production of an automatic rise and fall of water, as in the McDonald 

 box, although it differs from the latter in some essential particulars. 

 It consists of a box of variable dimensions in which jars are placed for 

 the reception of the eggs. A convenient size of box is 7J feet long, 2 

 feet wide, and 2^ feet deep. From 4 to 8 large glass jars are arranged 

 on wooden supports 7 or 8 inches above the bottom of the trougli. 

 Smaller boxes, to accommodate only 2 or 4 jars, are also used. The jars 

 are about 9 inches in diameter and are of two heights — 9 inches and 17 

 or 18 inches; they have straight sides and a flat bottom with a central 

 half inch hole. 



The jar is placed in the box in an inverted jmsition, with its bottom 

 above the level of the top of the trough. The sea water supplying the 

 trough enters the compartment at one end of the trough and escapes 



