26 V. S. BUREAU OF FISHERIES. 



HATCHEKY EQUIPMENT. 



The hatching trough in use at the Charlevoix (Mich.) station 

 embodies the principles of the Williamson hatching apparatus, 

 with the exception that it has deep pockets and trays (fig. 40). 

 Though simple in construction, this trough possesses more ad- 

 vantages than any other device for the development of large num- 

 bers of eggs within a limited space. It permits of a thorough circu- 

 lation of water; the eggs can be readily handled for picking and 

 cleaning, and the fry may be carried on trays until the yolk sac is 

 absorbed, when they are ready to plant. Only the best l|-inch pine 

 or cypress is used in its construction, all planks containing imper- 

 fections being rejected. The sides and ends are each made of a 

 single piece of lumber, the bottom being made first. All strips of 

 different widths used in the construction are tongued and grooved, 

 and all joints are laid in white lead. 



Referring to Figure 40, it will be noted that the trough is divided 

 by cross partitions into compartments 16^ by 14| inches. The sta- 

 tionary wooden partitions are mortised one-fourth inch in the sides 

 of the trough and are raised three-fourths inch from the trough 

 bottom to allow water to pass under them. They extend to within 

 three-fourths inch of the top. The movable partitions are made of 

 14 or 16 gauge galvanized iron, set 1| inches from the others in one- 

 fourth inch saw cuts in the sides and bottom of the trough and are 

 readily removable. These movable partitions extend from the bot- 

 tom of the trough to the level of the top egg tray. 



In the bottoms of the compartments thus formed strips one-half 

 inch by seven-eighths inch are nailed at the sides, on which the 

 trays rest. Each compartment holds 13 trays, of which 12 are filled 

 with eggs, the top one serving merely as a cover to prevent the 

 eggs on the twelfth tray from being carried off by the current. 

 About three-fourths inch below the top on either side is a three- 

 eighths-inch groove running the full length of the trough. A cross- 

 bar with a five-eighths-inch block is made to fit into these grooves 

 and hold the trays securely in place, preventing them from rising 

 in the water. 



Water enters the head of the trough through a 1-inch pipe, a flow 

 of 5 gallons per minute being the usual volume. By arranging the 

 partition as is indicated in Figure 40, all water must pass from the 

 bottom of the trough upward through each alternate stack of trays 

 containing the eggs or fry, flowing first over an iron partition, under 

 the succeeding wooden one, up through the trays, and so on through- 

 out the length of the trough. 



The troughs are set ujDon iron standards cemented into the floor 

 and are given a pitch of 1 inch to every 8 feet in length. The height 

 from the floor is a matter of convenience to the operator, or it de- 

 pends upon the fall of water available. The trays are wooden 

 frames 14 by 16 inches, made of seven-eighths-inch strips. They are 

 covered with galvanized wire cloth 14 meshes to the inch for eggs, 

 a smaller mesh being substituted for fry, as is described under care 

 of eggs and fry. The trays will conveniently hold 1 quart of eggs 

 (approximately 6,400) or 3,500 fry to the time they are ready to 

 take food. The troughs and trays are given three coats of asphaltum 



