252 IRRIGATION. 



bed and braced or anchored into the bank with timber 

 stays ; and the water surface of the piling should be 

 planked. For small works, piles and wattling of brush 

 may serve a yery good purpose to prevent erosion and 

 undermining. But in whatever way it may be done, 

 some protection against the wearing effect of currents or 

 eddies, or the penetration of water into the work should 

 be provided, wherever the course of the water is changed, 

 and a stream is divided or diverted. 



For smaller ditches or canals, such as those of six feet 

 in width or less, a grade of one foot to the thousand will 

 be found hardly sufficient. Two feet to the thousand 

 would not be an unsafe inclination for such channels, and 

 where the soil is firm or tenacious, an inclination of three 

 feet might be allowed. The narrower the canal the 

 greater ratio of inclination would be needed. 



Caution should be exercised to frequently observe the 

 condition of the banks of secondary canals, when the 

 soil of which they are made is not of a very consistent 

 character, and where the water is confined within em- 

 bankments. The cutting of a bank of earth by a current 

 of water, is a work which grows rapidly from small be- 

 ginnings to great proportions, and a break in a bank may 

 be the work of a very short time, if a little wasting is 

 allowed to pass unchecked. The damage that may easily 

 be done in one short hour, by the escape of the water of 

 a ditch carrying but a square foot and a half, would easily 

 surprise one unused to such effects, and might be irrepar- 

 able for a whole season. While the irrigator is greatly 

 benefited by the water he uses, so long as he can control 

 it in his service, he is always liable to be damaged if he 

 permits his servant to escape control and become his 

 master. This, however, can only happen by inexcusable 

 negligence or mistakes arising from inexperience. 



