How to obtain it. 55 
diverted into the channel DD. The water flows from the direction 
shewn by the arrow at F, and what is not required for the pond 
passes off by the channel DD, which rejoins the stream below the 
dam. At the point d a horizontal leaf screen may be placed in 
the stream, which passes over it, and the amount of water required 
for the pond KK is drawn off from the box underneath this 
screen. Should a perpendicular leaf screen only be used, then let 
it be placed across the stream at the point C. A sluice may be 
fixed just below it for greater safety, but my experience of the 
working of these screens is that no sluice is as a rule required, as 
the surplus amount of water gets away by the channel DD, and 
SG 
K Fig. 1. 
> 
the screen at C becomes partially stopped by floating matter and 
prevents any excess of water entering the pond. One great 
advantage of the horizontal screen is that no fish can escape from 
the pond in that direction. Where a perpendicular screen only 
is made use of, it is needful to have another screen below it to 
keep in the fish. 
It is not at all necessary that the leaf screen be close to the 
dam. It may be some distance from it, so as to allow the fish 
access to some spawning ground, and this spawning ground may 
often be largely increased by making a serpentine spawning race. 
This, in a great many places which I have examined, the ground 
will admit of. 
