is 
MEASUREMENT AND DIVISION OF WATER. 
being greater as the discharge is greater would again be 
to the advantage of the large consumer. On a delivery 
of 100 inches the effect of this velocity would he to in¬ 
crease the amount by some 5 per cent, over that due to 
the head proper. This could be lessened by proportioning 
the size of the box to the amount it is expected to dis¬ 
charge. 
Fig. 5. -the spill-box. 
(As usually placed, in pairs.) 
The weir is placed across the ditch, making the ditch lower below than above, 
giving opportunity for the water to spill back into the ditch. G is a movable gate 
to regulate the amount of water admitted at different stages of water in the canal. 
Though used on these canals to measure in statute 
inches, there is no reason why the device should not be used 
with the weir system, especially of the Yilloresi form, shown 
in fig. 7, and have the superior advantages of the weir. 
THE WEIR MODULES. 
The form of module which best satisfies the condi¬ 
tions of accuracy is that of the overfall or sharp-crested 
