How to obtain it. 109 
getting up into the ponds. Keep the bottom of each pond 
nearly level for two-thirds of the length, and let the tail end slope 
upwards to the level of the raceway (one foot deep). This slope 
may be covered with gravel. About the centre of each pond 
place a four-inch pipe or tile lengthways on the bottom. I use 
four-inch sanitary pipes. If these be selected, place the pipe with 
the flange up-stream, and over it build an enbankment of sods up 
le 
Fig. 3. 
to the water level, leaving a gap in the middle. Take care to 
make it tight, so that the water can only pass it by flowing either 
through the pipe or over the gap in the sod bank. The sides of 
the ponds may be perpendicular, or bevelled, as may be most 
convenient. Where the nature of the soil will admit of it, make 
them nearly perpendicular ; should it be necessary to build them, 
do it to a large extent at least with sods. 
