138 



SEASON 1874-75. 



so as to slightly turn the water (Fig. 91). A box below the screen 

 collected the water, and a pipe from the box passed through the 



FIG. 91 scale 



bulk-head and conveyed the supply to the short feeder of the dam 

 (Fig. 92). 



. 



FIG. 92 scale 



When the stream was light, the water passed through, and the 

 screen cleaned itself, as in the leaf-screen, the angle of the bulk- 

 head being sufficient to clear the screen ; but when the stream 

 rose in spate, the angle of the revetment, and the narrowed sides 

 of the burn at the head of the new cut (which had been con- 

 structed so as to confine a small spate, and offer little increased 

 resistance to a large one), deepen the water at the bulk-head so as 

 to increase the suction on the screen, and cause it to hold all 

 debris, thus completely stopping the supply to the dam. When 

 the water cleared, the debris gradually washed off, and when the 

 stream fell to its usual size, the screen cleaned itself comfortably. 

 This mode of taking water from a stream is very suitable for 

 obtaining a supply for small water-works where economy is an 

 object, as it not only acts efficiently, but can be erected at a very 

 small cost, requires little or no attention, and thoroughly prevents 

 the entrance of silt into the reservoir below, thus saving the 

 expense and inconvenience of frequent cleanings. The fall required 

 is so slight that it can be used in situations where the ordinary 

 methods would entail considerable works. A plan of the screen, 



