72 IRRIGATION FARMING. 



each side of the gates, where there is no rock in place, 

 and these wings should extend in either dire(5lion and 

 especially on the lower side, if the surface of the land 

 be flat for a distance of from fifty to one hundred feet. 



We have often seen headworks left standing alone 

 in the middle of a torrent of water after a heavy storm, 

 and have noted that the damage of the washout might 

 have been averted had wings of piling or masonry been 

 put in. The superstrudlure should be built of heavy 

 timber and provided with a windlass. It is a good 

 plan for large canals to have the gates arranged in 

 stalls, each working independent of the other. A gate 

 of modern construcftion is shown in Fig. 12, the lower 

 end in view with water passing through. It fortu- 

 nately is anchored in rock walls and is not supposed 

 to wash out, nor does it need the protedlion of wing 

 pilings. 



In Scott's Bluff county, Nebraska, the Nine Mile 

 canal has its headgate 900 feet below the intake, which 

 is at a seepage basin formed by damming up a channel 

 in a river at the side of an island. The dam is located 

 above the mouth of the canal, while the channel or 

 basin is left open with the idea that the backwater 

 from the river will flow in at the lower end of the 

 island, and in this way there will be but little sand with 

 which to contend. The plan has many features to 

 recommend it, but it could be adopted only in the 

 situations favorably located as to the island and with a 

 moderate fall of the stream at the desired point. 



The Drop-Head. — The later practice with many 

 of the best engineers in locating the intake of canals 

 is to provide the drop-head instead of the old-fashioned 



