Irrigation By jMeans ot Unde:rground Porous Pipe 5 
These boxes were constructed of concrete. They were 2 feet 
square at the top and 2^ feet deep. The side walls and bottom were 3 
inches thick. Gates were placed in each box that the water supply in 
all lines leading from the box might be controlled. These gates were 
of ordinary galvanized iron, fitted in slides and placed so as to cover 
the entrance to the pipe line running from the box. 
From Fig. i it will be noted that the subirrigation system was 
laid out in sections. Section No. i is made up of the lines A-B ; B-C ; 
C-D ; D-E; E-F; F-G and G-H, the section ending at point H. Sec¬ 
tion No. 2 tak^s its water from the box K, and is made up of the lines 
K-L ; E-M ; M-N ; N-O ; O-P ; P-R ; R-S : and S-T, the section ending 
at point T. The remaining sections are similar and may be easily fol¬ 
lowed on Fig. I. 
SLOPE OF LINES 
The long lines, such as A-B; C-D; E-F; etc., were carefully laid 
on a grade of i/io of a foot per 100 feet. These lines were so laid 
out on the field that this grade could be obtained and the lines kept 
approximately 2 feet below the surface at all points, except the extreme 
end of each line. The short connecting lines such as B-C ; D-E ; F-G; 
etc., were given the grade of the country at that place. These connect¬ 
ing lines vary from 7 to 30 feet in length and there may be a fall as 
great as i foot in this distance. In other words these short connecting 
lines were laid “on grade'' but the grade varies with each line, the 
idea being simply to get down to the beginning of the next long line 
in order to fill that line with water and keep the same under a pressure 
head of approximately i foot. 
