(.ANAL CONSTRUCTION. 



51 



ces will permit. The sides and bottom should be regu- 

 lar and smooth, and clear of stones, weeds, etc. The 

 weak spot in every canal is most apt to be found at 

 the curves and angles, and these must be protected. 

 Where, as is the case in some sections, there is plenty 

 of stone, the water line at the curves may be partially 

 protected by riprapping, but this involves a large 

 amount of labor. Where there are no stones other 

 means must be used. Willows are oftentimes planted to 

 give bank protection. Where gravel may be had a shore 



FIG. 10. CANAL ON A HILLSIDE. 



line may be covered with it, thus forming a natural 

 water-break. In some cases it may be best to construct 

 a breakwater of plank sharpened and driven into the 



