How to obtain it. 53 



is drawn by means of a sluice from the main stream. They arel 

 on the side of a hill, and the fall from one to the other is thus) 

 excellent. The aqueduct passes through cuttings and along 

 embankments, and where watercourses of a dangerous nature cross 

 its track they are carried over it by means of wooden shoots. The 

 sluice box in this particular instance is two feet by one foot, and 

 under no circumstances can more water be drawn from the stream 

 than can pass through this box. A much smaller one than this, 

 however, or a pipe, may often be used with great success. I have I 

 seen a series of ponds working very well that were supplied through) 

 a three-inch pipe. 



At the lower end of a long open aqueduct it is sometimes 

 desirable to have another sluice and an overflow for waste water, 

 as during heavy rains a good deal of surface water necessarily 

 comes down. And here allow me to give a word of caution, j 

 Avoid lessening the regular supply from the stream at a time like I 

 this, or the water passing into the pond will contain too much of 

 this surface water. Ponds supplied in such a manner, if properly 

 made, are entirely under control and thoroughly workable. Too 

 much water cannot get into them. On the contrary, during flood- 

 time the quantity is found to lessen, as it is desirable to have a 

 leaf screen in front of the sluice, and the flow of water is reduced 

 by the mass of leaves or other floating matter brought down at such 

 a time. I have found this arrangement work most satisfactorily 

 it is in fact the safety valve, and without such an arrangement in 

 some form or other a pond or series of ponds is seldom safe. 



There are several ways of constructing a leaf screen. The 

 simplest of all for the present purpose is to drive suitable wooden 

 stakes into the bottom of the aqueduct, where the soil will allow 

 of it. I make them of larch, and cut them three-sided rather than 

 square, and about one to one and a half inches in diameter. 

 Drive them all carefully so that the apex of the triangle formed by 

 the three sides of each stake is up-stream, and then place a rail 

 across their upper ends behind them, and nail each one to it. 

 Should any of the ends stand higher than the rail, owing to not 

 having been all driven the same distance into the ground, take a 

 saw and cut them off. The rail may be nailed to posts driven 

 into the bank at either end, or otherwise made secure according to 



