378 IRRIGATION PRACTICE 



cheapest and most satisfactory where the materials are 

 near at hand, but the effects are never permanent as 

 with masonry or concrete linings. Finally, silting a canal 

 is often recommended. Clay or clayey materials, thrown 

 into the water at various places, settle wherever the grade 



FIG. 108. Wooden stave pipe carrying irrigation water. 



is not too steep. Afterwards, the silt deposits are puddled 

 by the chain puddler. This is a very cheap and often an 

 effective method of preventing seepage. (Figs. 106, 107.) 

 In California, whole canals have been lined with cement 

 concrete, and the definite attempt to reduce seepage by 

 first-class canal linings has become established. In other 

 states, also, large canals are rapidly being lined. One of 



