56 BULLETIN 115, U. S. DEPARTMENT OF AGRICULTURE. 
stalls between them guide the sand around into a direction at right 
angles to the flow in the canal and discharge it out through the waste 
gate forming an L with the check gate. One of these gates is included 
in the joint head works spoken of on page 14. 
SAND GATE, MAXWELL LAND & IRRIGATION CO., MAXWELL, N. MEX. 
After trying out a wooden structure, the Maxwell Land & Irriga- 
tion Co. has designed a concrete gate to eliminate the sand and coal 
dirt from its water, 700 feet below the river headgate. At this point 
an arroyo leads back into the river. 
The canal,, which is 32 feet wide on the bottom, carrying water 
7 feet deep, with the top of the levees 3 feet above high-water mark, 
is lined with 6 inches of concrete for a distance of 400 feet above the 
gates. This lining (fig. 17) commences at the normal grade of the 
canal and slopes on a grade of 1 foot per 100 feet on the side next 
to the river and 3 inches per 100 feet on the other. This slope forms 
a long pit having a maximum depth of 4 feet directly in front of 
the gates, and it is expected that even a small head of water in the 
canal will effectually sluice out all silt deposited on the concrete 
lining. The end of the pit terminates in a vertical wall, crested with 
a rectangular weir, which serves the double purpose of deepening 
the pit by the height of the weir and giving an approximate measure- 
ment of the water in the canal, after the proper bottom-contraction 
conditions are effected by sluicing out the deposit above the weir. 
The shutters are simple wooden slides with double stems separated 
by iron bolts and spreaders, on the principle of the one on Plate I, /. 
An iron-mounted lever 12 feet long gives a fast and effective lift 
when inserted under the bolts. The silt above such gates causes 
them to stick, and some lift is necessary which will jerk the gate, 
rather than to exert a steady pull. For this reason the lever is better 
than a screw lift. 
Bids for the concrete construction varied from $3 to $3.60 per 
cubic yard, the company to furnish the material at the site. Bids 
on the excavation for the structure were 14 and 18 cents per yard. 
This will make the total cost of the concrete in place $10.50 to $11.25 
per yard. 
SAND AND WASTE GATE, AMITY CANAL, COLORADO. 
One of the best examples of the modern construction and use of 
the " Land " sand gate is the concrete sand and waste gate installed 
on the Amity Canal by the Arkansas Valley Sugar-Beet & Irrigated 
Land Co. This structure (as shown on Plate XI, fig. 1) forms an 
L, one leg of which extends across the canal and acts as a check 
gate, while the other leg contains the openings of the sand ducts at 
