1214 FISHERIES OF THE UNITED STATES. [60] 



Section of Y-shaped hatching trough — Continued. 



escape pipes, which occur at short intervals. The water enters 

 the apartment between the vertical and sloping sides with the 

 hydrant pressure, and is forced up through the opening and out 

 through the strainer at the top. The eggs, being heavy, tend 

 to sink to the bottom, where they are caught by the current and 

 carried upward and outward toward the sides ; as the current 

 weakens they gradually drop back toward the center, where 

 they are again caught and carried through the same circuit. 

 57,178. Devised by Seymour Bower, Northville, Mich. IT. S. 

 Fish Commission. 



McDonald's Y-shaped hatching-box. 



A wooden box, with glass ends and sloping sides, for eggs. Lengthy 

 12 inches ; width, 24- inches ; depth, 15 inches. Invented by 

 Marshall McDonald, for use in the U. S. Fish Commission work 

 at Gunston,Ya., in April, 1881. U.S. Fish Commission, 57,154. 

 The sides of the box slope toward the bottom center until they 

 come within an inch of each other. Below this opening is a 

 space 3 or 4 inches deep for the introduction of water. This 

 opening is nearly closed by means of an adjustable square 

 wooden bar, one of the angles of which enters the center of the 

 opening, the sides of the bar thus being parallel with those of 

 the box. By this means the current is divided so that the water 

 is deflected along either side of the box toward the surface, car- 

 rying the eggs with it and causing them to pass in toward the 

 center and fall again to the bottom, where they are again caught 

 by the current aud carried through the same circuit. The out- 

 let is protected by a triangular trough running across the top 

 center from side to side. This is placed a little below the top 

 of the box, so that the water shall flow over its side and out 

 through the openings. The current introduced is sufficiently 

 strong to carry away the dead eggs into this trough, thus allow- 

 ing them to escape, but is not strong enough to carry away the 

 good eggs, which, being heavier than the dead ones, drop before 

 reaching the trough. Great care must be taken to see that the 

 flow of water is properly adjusted ; otherwise many of the dead 

 eggs may be retained or the good ones may be lost. 



McDonald's universal hatching-jar. 



A glass jar, with metal cap, containing two circular openings. Through 

 one of these, which is situated in the center, a glass tube for the 

 introduction of water passes to within a short distance of the 

 bottom of the jar. The other, situated near one side, contains 

 a shorter glass tube, which serves as an outflow pipe. Height,, 



