292 



Irrigation and Drainage 



canals of the Durance, and given an engraving of it in Fig. 48. 

 In further illustration of the methods used in diverting by gravity 

 the water of a stream for purposes of irrigation, Fig. 53 shows 

 diagrammatic ally how the Kern Island canal, in California, is 

 taken from the Kern river, together with the position of the 

 regulator, and of the waste gate by which the unused water finds 



^ 'vu"i7;//U ;c 



Fig. 53. Head of Kern Island canal, California. 

 (Grunsky, U. S. Geol. Survey.) 



its way back into the channel. Figs. 54 and 55 are bird's-eye 

 views of the same thing, showing the regulator and the waste gate. 

 In Fig. 56 is given a nearer view, looking across the canal over 

 the waste gate, the regulator being at the left. 



In aligning these canals, they are led back from the stream 

 as far as the general fall of the valley will permit, and in taking 

 out the laterals and distributaries, these are carried to the highest 

 portions of the fields to be irrigated, and at the same time are 



