2 08 THE IRR1 GA TION A GE. 



Use the triangle and run a level line each way from this point to the 

 side of the field. Then return to the supply point and proceed, as de- 

 scribed previously, to find a point at, say, one foot lower elevation. 

 When that is done work both ways from the starting point until that 

 line is carried to the sides of the field. If stakes rising about 18 

 inches from the surface have been used to mark the line, these will 

 show the top of the levee to be constructed. When the whole field has 

 been marked in this way, loose dirt is gathered up with team and scra- 

 per and placed along the levee lines. But only a slight skimming is 

 taken, that the surface may be kept free from depressions. If there are 

 knolls and hummocks, they are scraped off and put into the levees and 

 more plowing done here and there as needed. On the sides of the field 

 a continuous levee is made to hold the water where wanted. If the 

 levees are very far apart and the checks, therefore, too large for the 

 stream of water in use, they are reduced in size by running cross 

 levees. After the scraper work is done the levee is shaped into a low, 

 rounded form with hand tools, if the job is a small one, and then the 

 whole field is harrowed lightly so as to even the slopes without drag- 

 ging down the levees too much. If the dirt has been dumped to the 

 top of 18-inch stakes, the harrowing and subsequent settling will re- 

 duce it quite as much as is admissible and still have it set water back 

 to the upper levee a foot higher. On small work much less than a 

 foot difference in elevation is often used and the levees are propor- 

 tionally lower. 



If the checks are to be filled from each other (Fig. 13), simple 

 water gates are placed in the levees at such places and distances as 

 one can best judge will facilitate the distribution of tHe water. These 

 gates are simply boxes, each having a bottom and two sides, with 

 slats across the top to hold the sides in place. About the middle and 

 on the inside of eaeh side two cleats are nailed just the right distance 

 apart to admit the sliding board or gate to pass up and down between 

 them. These gates are about a foot high and wide in small work, and 

 larger if a large stream of water is available. Where cross levees are 

 used to make smaller checks, more gates are placed in the highest 

 levee, so as to allow the water to flow down in one direction and then 

 in another until all the series have been filled. 



Sometimes the contour-check system is used without gates by 

 simply allowing the water to fill the higher checks and then flow over 

 the levee into the next, and so on. In this case the levees are quite 

 low and the checks are small. 



As a rule the size of the check should depend upon the head or 

 stream of water to be used, and all the appurtenances should be in 

 proportion. The check should be of such size as to be quickly filled, 

 else the lower side will be saturated and the upper side merely moist- 



