178 How to obtain it. 
over the pipe, which must be fitted into a box. To do this in 
the readiest way, take any old box and cut a round hole in one 
side of it to fit on to the end of the pipe. The opposite side of 
the box should be almost entirely cut away, or it may be knocked 
out altogether and replaced by perforated zinc. Should it be 
found needful a finer screen can be fixed inside the box, which 
itself is to be firmly bedded in the side of the stream from which 
the water is taken. In some cases it may be desirable to put on 
a coarser screen outside, and this is easily done by nailing four 
strips of wood on to the box front, and covering again with 
coarsely perforated zinc. Of course, where a properly constructed 
box is used, grooves can be sawn in the wood and three or four 
screens made to slide into their places, and these can be cleaned 
in a twinkling and put back again when necessary. 
Although, in many places artificial hatching beds may be, 
and are, most successfully worked without filtering the water, yet 
there are many streams which bring down such an amount of 
earthy matter every time there is a spate, that filtration becomes 
absolutely necessary. When such is found to be the case a very 
good plan is to dig out a settling pond, or if necessary two or 
three of them, on the water supply. Do not on any account 
attempt to make one on the stream itself. Draw the water from 
the stream and pass it through a hole sunk in the ground, say 
at least six feet square, and three feet in depth. If twelve 
feet square and four or five feet deep, so much the better. It 
does not matter whether the sides, are rectangular. Let them be 
so if practicable, but should the land not allow of it, it is not 
worth troubling much about. The great thing is to pass the 
water through a large hole or pool, in which it will have a chance 
of being fairly tranquil. The result will be that the bulk of the 
sediment brought: down during a spate, will be left at the bottom 
of this pool, and the water for supplying the hatching bed should 
be drawn off at or just below the surface. If one pool be found 
insufficient, have a couple of them ; they are easily made and at 
a very trifling cost. Where stone is available the sides are better 
built up of loose stonework, as the action of frost is not so much 
felt, as is the case where they are simply dug out and left. 
To make the thing more perfect still, should it be found 
