79 



2nd. The distributing lines which conduct the water from the main 

 pipe line, and which are connected to the distributing stands. 



3rd. The distributing stands or basins by means of which the water is 

 brought to the surface and distributed into the furrows through small 

 galvanized iron spouts inserted in the sides of the basin. 



4th. Regulating boxes and accessories. 



A typical system is shown in the accompanying sketch (Fig. 67). The 

 pipe lines are made of hand tamped pipe placed in trenches of such depth 

 that there is at least one foot of earth covering. The method of making 

 the pipe sections and joining them, as well as the properties of the pipe 

 and the cost of making and laying have been fully described (pages 

 47 to 57.) The main pipe line or feed line is not necessary where only 

 one line of stands is necessary, such as where the orchard is small and 

 can be irrigated with one set of furrows 330 or 660 feet long. But for 

 larger orchards it is desirable that the orchard be supplied by two or more 

 head ditches or distributing pipe lines in order to limit the length of the 

 furrows to not over 660 feet and preferably 330 feet for sandy soil. The 

 main supply pipe feeds the distributing lines and conducts the water from 

 the measuring box or point of delivery to the head of the line of stands. 

 At the junction of the line of stands with the main pipe, turnout boxes with 

 suitable gates are necessary to control the flow into each line. The lines 

 of distributing stands extend across the direction of the furrows. At the 

 head of each tree row and in line with the trees a stand is connected to the 

 distributing line. 



There are various ways of making the stands and of regulating the 

 flow. They vary only in details and can be classified into two distinct sys- 

 tems, one known as the overflow system, and the other, the pressure system. 



The overflow system is best adapted where the line of stands is placed 

 on a flat uniform grade. The pressure system is best where the slope of 

 the ground is steep and not uniform. These two systems are illustrated in 

 the accompanying diagram (Fig. 68). With the overflow system the lines 

 of stands must usually be divided by means of overflow boxes or pressure 

 regulating boxes into a number of sections depending on the grade, and 

 each section includes a number of distributing stands, the tops of which 

 are placed at the same level. The overflow box acts as a check in a head 

 ditch and by closing or regulating the gate of the overflow it causes the 

 water to rise in the distributing stand and maintains the water surface 

 in the stands at about a uniform level. If the gate of the overflow box is 

 closed the water which is not distributed through the stands above it, 

 passes over the overflow to supply the stands below; this makes the system 

 practically automatic. The distributing stands are seldom made higher 

 than 16 inches above the ground; when it exceeds this a new section or 

 group of stands is made by inserting another overflow box. On steep grade 

 the cost is much increased because of the great number of overflows. 



The pressure system, or valve system, is so called because the dis- 

 tributing line is divided into a number of sections, depending on the grade, 

 so that each section is under a water pressure which the pipe will safely 

 stand. Because of the pressure it is necessary to regulate the flow into 

 each basin by means of a valve. Usually the sections should not be longer 

 than 600 feet and the pressure head should not exceed 15 feet. The boxes 

 which divide the line in sections control the pressure by means of a gate. 



