386 - BULLETIN 495, U. S. DEPARTMENT OF AGRICULTURE. 
installed as the first part of the construction so that the posts for the 
nozzle lines can be set to correspond with the risers from the main. 
Excavating for the main can be facilitated by plowing and throw- 
ing the loose materials out by hand. The second and following plow- 
ings should be done with a narrow plow hitched to a steady horse. 
The main pipe should be put together while lying on timbers across 
the trench, so that each joint can be fitted easily and tightened. 
Usually a section of 200 feet or more can be put together and then 
allowed to sag gradually into the trench as the length increases. 
There are two points where installation of a main feed pipe may 
begin. If the pumping plant has been installed and careful measure- 
ment has been made to the first lateral, the main can begin at the 
pump. If there is an important branching of mains, then the start- 
ing point-can be at the branch or the first definitely located nozzle 
line nearest the pump and the pipe then laid in two directions toward 
the pump and through the field. The main pipe then can be cut to 
fit to the pump or the pump set to fit the main with the aid of the 
expansion joint and flange couplings. | 
INSTALLING NOZZLE LINES. 
The first parts of the field system to be installed are the posts. 
These should be located carefully to line up in every direction, so 
far as possible, like trees in an orchard. The risers from the main 
feed pipe should form the first post to each line and form a starting 
point for measuring. It usually is advisable to locate the posts on 
the two outside lines of the field and then one center line in which the 
posts will line up with the outside ones. It is an easy matter then to 
locate the remainder of the posts by intersection sighting. In the 
ease of wooden posts, the tops should be cut to uniform heights. 
Posts made from pipe can be driven a short distance into the earth 
in the bottom of a post-auger hole, and after they are lined up and 
adjusted to a uniform height the auger hole about the pipe can be 
filled with concrete. 
After the posts have been set in the field the bearings are fastened 
to them and the sections of pipe placed on the ground along the side 
of each line. Each nozzle line is then screwed together tightly, great 
care being taken to remove all dirt and filings from each section. 
Paint or lead should not be used on the inside of the joints, as such ra 
material on the inside would cause clogging of the nozzles. It is 
better to apply heavy graphite grease after the thread has been 
started. When wooden posts are used, the pipe line is laid upon 3 | 
60 to 90-penny spikes, one of which is driven firmly into the side of ~ 
each post. The spikes should be placed about 33 feet to + feet above ~ 
the ground, depending upon the height of the man who will do the ~ 

