THE PAN-AMERICAN EXPOSITION. silky) 
eggs. The water supply is obtained from Rock Creek and springs on the reserva- 
tion. The temperature of the water throughout the year varies from 37° to 46°, 
the mean being 43°. 
Model of hatching barge: 
The barges were generally equipped with hatching cones and Ferguson plunging 
buckets, and were extensively used by the U. 8. Fish Commission for many years 
in the waters of North Carolina, Virginia, and Maryland in hatching the eggs of the 
shad. After the establishment of permanent shore stations the use of the barges 
was abandoned. : 
Hatrcuinc APPARATUS. 
Cod box: 
This apparatus consists of a series of double rectangular wooden boxes, usually 
arranged in nests of 8 or 9. The eggs are placed in the inner box, the bottom of 
which is slightly oval instead of flat, and is covered with scrim cloth. The water is 
introduced from the water chamber through the bottom and through a hole several 
inches above the bottom, which gives the eggs a slightly rotary motion; it escapes 
through an intermittent siphon, which produces the tidal motion essential in hatching 
floating eggs. 
Originally designed by Marshall McDonald in 1880 and perfected in 1888. 
Model of plunging buckets: 
This model illustrates the methods employed in hatching shad during the early 
days of the Commission. It was invented by Maj. T. B. Ferguson in 1880 and was 
used in the Chesapeake Bay and on the Albemarle Sound. The plunging buckets 
were on the outside of a barge which was fitted up with the machinery necessary 
for operating the same. It has also been used with slight success in the hatching of 
floating eggs. 
McDonald’ s Y-shaped hatching box: 
A wooden box, with glass ends and sloping sides, for eggs. Length, 12 inches; 
width, 24 inches; depth, 15 inches. 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 cen- 
ter 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, carrying 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 and carried through the same circuit. The outlet is protected by a triangu- 
lar 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 dead eggs into 
this trough, thus allowing them to escape, but 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. 
Invented by Marshall McDonald in 1881. 
Williamson hatching trough with Stone salmon basket: 
A section of the hatching trough, showing three compartments complete, with 
three tiers of wire trays in each. In the trough a double partition separates each 
compartment, the first extending from the bottom of trough to within an inch of 
the top, while the second extends from the top to within an inch of the bottom, the 
two sections of the partitioning being 1 inch apart. The water passing over the first 
partition and under the second, into the compartment, forces its way up through the 
eggs on the baskets and over and under the next partitions. 
Trout trough with wire trays: 
_ This is an ordinary trout trough, 8 feet long, 12} inches wide in the clear, and 6 
inches deep, fitted with ordinary galvanized-iron wire trays, 7 meshes to the inch. 
Used at most of the hatcheries in the Commission for hatching brook, rainbow, 
and black-spotted trout eggs. The troughs in the hatcheries vary in length from 
12 to 16 feet. Both the trays and troughs are painted with asphaltum varnish. Wire 
trays for the hatching of trout eggs were first used in 1867 by Mr, E. A. Brackett, of 
Winchester, Mass. 
Ferguson hatching-jar: 
A cylindrical jar of glass, with a contraction near the base, which serves as a 
support to the 7 wire-cloth egg-trays which it contains, It has two circular open- 
