10 Aug., 1918.] .Ipp/e Culture in Victoria. 45T 



inetliod to be the more economical. These pipes should be placed in 

 position prior to commencing the building of the embankment. 



The water may be drawn from the dam or reservoir by the siphon 

 principle, but in general practice the pipe method of delivery may be 

 regarded as the more satisfactory. 



A light iron plate placed in the position shown in the illustration 

 receives from the inlet i>ipe connexion the water from the dam and this 

 saves the face of the embankment and crevents its washing in. 



Methods of Applying Water at the Different Degrees of Surface 

 Decline suitable to the Different Classes of Soil. 



Great diversity of physical construction as well as surface decline 

 characterizes the soils of our hilly and rolling lands suitable for dam and 

 reservoir schemes. The soils in these districts range from the stiff 

 retentive order overlying yellow impervious clays to those of the friable 

 loam and loose sandy class with porous sub-soils. Loose soils are more 



WPLAnO// FACE OFBtNIt 



Plate 172a. — Section of reservoir showing formation of embankments, position 

 of inlet pipe connexion with the dam, outlet pipes, &c. 



easily wetted than compact ones, and care should be taken, when treat- 

 ing either class, that the water be systematically applied, in order that 

 all the good results which accrue from scientific irrigation may be 

 attained. 



The drawings in Plate 173, like the others used to illustrate these 

 articles, are original, and they show in longitudinal and cross-sections 

 the methods by which the water may be distributed under the different 

 soil conditions. The furrow method of watering is employed and the 

 long sections represent the furrows in the direction of their length, and 

 running with the slope which is at an angle of 20 degrees from the 

 horizontal. Fig. 1 represents soil suitable for irrigation, friable, yet 

 sufficiently impervious to enable it to carry the water from the delivery 

 pipe along the full length of the furrow in which it may be controlled 

 by means of checks until distributed as required. The arrows from 

 the vertical indicate the downward percolation of the water, and the 

 uppermost row of arrow-heads denotes the line of demarcation between 

 the surface and sub-soils. The lower row of arrow-heads indicates that 

 the water, having percolated through the sub-soil, has reached the 

 stratum below. In this the five arrows running parallel to the surface 

 line depict the free water draining aw^ay. Fig. 2, being a cross- 

 section of Fig. 1, further illustrates that, when the soil is of a character 

 highly amenable to irrigation, the water, as the arrows denote, perco- 

 lates gradually outward and downward from the furrow by almost semi- 

 circular radiant movement Id treating a loose surface with porous sub- 

 soil, however, the furrow is unable to carry the water the necessary 

 distance away from the delivery pipe, because the descent of the water 

 is much more rapid, and gives a considerably less lateral spread. 



