Flow to obtain it. 175 
feet, barriers may be placed, over which the water ripples from 
one section of the bed to another. An excellent material for these 
barriers will be found in ordinary roofing slates. I have used 
them with success for many years, and they are easily stuck into 
the bottom, lowered, or raised, or manipulated in any way that 
may be desired, and a lot of them should always be available 
where fish culture is carried on. They are the cleanest and 
simplest articles to make use of for such purposes that I have ever 
met with. They are cheap, easily cut to any shape, they can be 
laced together if needful by drilling holes through them, and, 
apart from accidents, are almost imperishable. 
The depth of water should be about four inches, and the 
bottom should consist of clean gravel, the grains of which are 
principally about the size of peas. Amongst this gravel the eggs 
are to be sown, and a section ten feet long and one foot wide will 
hold easily about fifteen thousand ova. By making the width 
eighteen inches, the quantity may be increased to twenty thousand 
or more. But with such an exceedingly simple contrivance 
there is no need to crowd the ova, and it is far better to err on 
the side of having too much space than too little. The water, 
after doing duty in the hatching bed, passes on and finally re- 
enters the stream from which it came. Should the width of the 
bed be increased, it should be borne in mind that a greater water 
supply is needful. If two-inch tiles be used for a bed one foot 
wide, then a double set of them will be required for a bed one- 
and-a-half feet to two feet wide; or a single course of three-inch 
tiles will answer the same purpose. 
The ova may be laid on the gravel, or mixed with it. This 
is a question about which there is a difference of opinion. When 
we consider for a few moments the requirements of the ova, and 
examine carefully the state of things in a natural trout bed, we 
shall very soon be in a position to judge which is best. I have 
seen some thousands of trout nests, and I have invariably observed, 
that where the eggs are deposited naturally, water is found welling 
up through the gravel in which they lie buried—and often buried 
deeply. Thus, the necessary conditions for their well-being are 
provided by nature. The same conditions must be found in 
artificial beds. The eggs must have the benefit of the continual 
