472 Irrigation and Drainage 



1-2 will have an elevation of 10.2 feet, as stated in 

 the table. 



Table giving data obtained in leveling field, Fig. 156 



Station Back-sight Fore-sight Difference Elevation 



1-1 4 10 



1-2 4.2 3.8 .2 10.2 



1-3 3.8 4 .2 10.4 



1-4 4 * 3.6 .2 10.6 



1-5 3.9 3.8 .2 10.8 



1-6 4 3.7 .2 11 



II-6 3.8 3.98 .02 11.02 



II-5 3.9 3.995 .195 10.825 



II-4 4 4.095 .195 10.63 



II-3 4.1 4.19 .19 10.44 



II-2 3.9 4.26 .16 10.28 



II-l 3.8 3.98 .08 10.2 



III-l 4 3.6 .2 10.4 



III-2 3.9 3.96 .04 10.44 



111-3 4.2 3.775 .125 10.565 



III-4 4.1 4.045 .155 10.72 



III-5 3.8 3.93 .17 10.89 



III-6 4.1 3.625 .185 11.075 



iV-6 4 4.185 .085 11.16 



1V-5 3.84 .16 11 



The level is now moved to & and the distance of 

 [-2 below it again measured and found to be 4.2 feet, 

 which is entered in the notebook under " back-sight," 

 and the instrument turned upon 1-3, where the read- 

 ing is found to be 4 feet, and entered in the table. 

 The difference between the fore- and back-sights, 

 placed in the column headed " Difference," shows how 

 much higher one station is than another, and when 

 the first is added to the elevation above datum, 10 



