At right angles with this stream, there are twenty-five wooden boxes side by side, about fifty feet in length, placed on a slight decline.

These boxes or troughs, each about two feet wide and one foot deep, are divided into partitions by cross-boards, which do not reach, within a few inches, the top of the siding, so that the water shall make a continuous surface the whole length of the trough.

Each trough is filled with round river stones or pebbles washed clean, on which the spawn is laid.

The water is let out of the mill-race upon these troughs through a wire-cloth filter, covering them about two inches deep above the stones.

At the bottom, a lateral channel or race, running at right angles to the troughs, conducts the waste water in a rapid, bubbling stream down into the feeding-pond, which covers the space of about one-fifth of an acre, close to the river, with which it is connected by a narrow race gated also with a wire-cloth, to prevent the little living mites from being carried off before their time.
This may serve to give the reader some approximate idea of the construction of the fish-fold.