56 BULLETIN 462, U. S. DEPARTMENT OF AGRICULTURE. 
allow the installation of a weir for the measurement of water for 
experimental purposes, which is done in Orlando. 
The Palatka plant could have been constructed without the portable 
pipe but at considerably higher cost, as the land is more uneven than 
that in the Orlando grove. This disadvantage might have been over- 
come, however, by the use of additional underground piping. It 
would have been necessary also to have placed a two-opening valve 
at every second tree row, which would have called for an additional 
expenditure. It will be possible to install these improvements at a 
later date if desired. The present system will answer the purpose 
well but requires more labor for its operation. 
The following specifications, prepared by M. B. Williams, irriga- 
tion engineer, should be insisted upon when terra-cotta pipe is 
bought from dealers, as it is of the utmost importance to get the best 
pipe: 
1. All pipe and specials shall be of the best quality standard vitrified salt- 
glazed terra cotta, sound and well burned, impervious to moisture, free from 
cracks, flaws, blisters, or other 'imperfections. All pipe shall be straight in the 
direction of the axis. Variations from a straight line greater than 2 per cent 
of the length of the pipe or from a true circle greater than 4 per cent of the 
diameter of the pipe will not be permitted. 
2. Each pipe shall be of the hub-and-spigot pattern, with deep and wide 
sockets. Each hub shall be of sufficient diameter to receive to its full depth the 
spigot end of the next following pipe or special without any chipping of either 
and leave an annular space of not less than one-half inch all around for a 
mortar joint. Each hub shall have a depth from its face to the shoulder of the 
pipe not less than the following : 6-inch pipe, 21 inches ; 8-inch pipe, 2f inches ; 
10-inch pipe, 2f inches ; 12-inch pipe, 3 inches ; 15-inch pipe, 3 inches. The inside 
of the hub and the outside of the spigot of all sizes shall be grooved. All pipe 
shall be furnished in 3-foot lengths. All specials shall be furnished in 2-foot 
lengths. 
3. On all T-branches the branch shall stand at right angles to the run, and 
have a bell or socket end. 
All pipe and specials shall be delivered f. o. b. cars, and shall be subject to 
inspection there. Pipes or specials having fire cracks of any kind extending 
through the thickness and having a length greater than the depth of the hub or 
socket shall be rejected. Air checks appearing only on the outer surface or in 
the glaze of the pipe will not be objectionable, but the use of a pipe having air 
cracks extending through the shell caused by too rapid cooling, will not be 
accepted. No pipe shall be accepted that has a piece broken from the spigot 
end longer than the hub or socket ; nor which has a piece broken from the bell 
end if the fracture extends into the body of the pipe, or if such fracture can 
not be placed at the top of the pipe. All pipe shall give a clear-sounding ring 
when tested with a light stroke with a hammer. 
The following specifications were prepared for laying the pipe : 
AH terra-cotta pipe should be laid below frost and covered with not less than 
15 inches of earth. Trenches should have the following width of bottom for 
convenient laying and jointing of the pipe: 
Size of pipe inches— 6 8 10 12 15 
Width of ditch do 20 24 28 30 34 
