132 'rhirli/si.rUi Aiiiuinl Mrrliny 



ground eluuivd for the eiiibankiiicnl slKnild liavo a dit'h o.\- 

 tending its full length into whidi ilie new earth will settle, thus 

 increasing- the stal)ility of the dam. 



'I'he emlianknient of the dam if ii is to be six feet hiuh 

 should be ten or twelve feet wide at the base and four feet broad 

 on top. The earth used in its construction will naturally b ■ 

 derived from the bottom of the ])]-oposed pond, which will, of 

 course, serve to increase its de])th. The overflow should be large 

 enough to carry off the surplus, when the water is high, without 

 danger to the dam and the outlets in general should be screened 

 with wire netting to prevent the escape of fishes. The drain 

 for drawing off the water should, of course, be put in place be for,- 

 the dam is thrown up. Earthen drain-pipes are risky, as no 

 matter how closely the joints may be set and cemented, plant 

 roots will eventually find their way inside and clog them u]). 

 Iron pipe of not less than four inches diameter-, with the joints 

 well soldered, is more reliable. A hollow log will serve the pur- 

 pose of a drain-pi]3e, and wear well. If the drain, or bottom 

 outlet, is built of concrete and large enough to be conveniently 

 cleared, it would be more effective in lowering a large area of 

 water. The upper end of the drain should fit tightly into th ■ 

 foot of the upright penstock in the ])ond. The penstock itself 

 is merely an upright drain or sluice of planks or concrete, having 

 about the same capacity as the drain])ipe itself. It is fitted on 

 one side with short "water boards'' sliding in grooves which can 

 be removed one after another, to permit the escape of the water. 

 A heavy plank should connect the head of the jienstock with the 

 top of the dam. 



Before the new pond is filled, all roots, stumps, rocks and 

 everything else that would prevent the free sweep of a net along 

 the bottom should be removed. All ponds, whether natural or 

 artificial, accumulate debris of which they can not be cleared, 

 e.\|)ect when empty. A muddy ])ond will give tlu' lish a muddv 

 flavor. When a pond is being cleaned, it is necessary to remove 

 the fishes from the deep hole or kettle. Any attempt to remove 

 decayed matter and sediment, while fishes still occupy the deeper 

 portions of a pond, may be fatal to them, as dangerous gases are 

 then liberated among the crowded fishes. If the pond is very 

 foul, it should be only partially lowered at first and the fishes re- 



