




SPRAY IRRIGATION. 13 
mains are also obtainable. These screens can be removed conveniently 
from time to time and cleaned, to prevent undue resistance to the 
water. 
Figure 7 illustrates a screen made for streams or other surface 
supplies. The screen is made on a 6-inch suction pipe for a capacity 
of 450 gallons per minute. Four 2-inch by 38-inch cypress staves 6 
feet long are placed edgewise and equi-spaced against the shell of 
the pipe and allowed to extend 3 feet beyond the open end of the 
pipe. Two pieces of cypress 2 inches thick are used for ends, one 
being made with a hole to slip closely over the pipe and both spiked 
to the ends of the staves. Two half-inch iron rods with nuts on 
ends are run lengthwise through the structure with adequate strap- 
iron ties, so that the frame is clamped together. No. 9 galvanized 
wire 1s wrapped and stapled tightly about the staves, leaving spaces 

Fic. %—Perforated sheet-brass screen to be used in stream. 
of about an inch between ribs. This forms a large wire tube 12 
inches in diameter and 6 feet long, to which perforated sheet brass 
can be soldered and nailed. The sheet brass should have circular 
perforations no larger than the openings in the nozzles used in the 
spray system. The sheets can be purchased from sheet-metal dealers. 
The light portions of the picture show the joints soldered to the 
sheets and solder covering the nail head. The metal should be upset 
and nailed securely to the wooden ends of the screen. 
The screen described above can be used in many cases suspended 
in a stream, where it can be brushed clean occasionally when the pump 
is not running. Care should be taken not to allow the first water 
pumped after cleaning to go into the spray system. In shallow 
streams containing very fine sediment or moss the screen should be 
laid horizontally in a concrete bulkhead or trench made in hardpan 

) Fee See 
en s a 
