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 3-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 is wrapped and stapled tightly about the staves, leaving spaces 

















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Fig. 7. — 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 haA 7 e 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 



