12 
MEASUREMENT AND DIVISION OF WATER. 
It follows from this that if such a module is not ad¬ 
justed from time to time it is of no value as a regulator. 
This, however, does not take away from its value if 
properly attended, for it affords a ready means of arrang¬ 
ing that the pressure shall be a certain amount. But it 
should be kept clearly in mind that unless regulated with 
every variation in the level of the supplying canal it does not 
assure a constant flow, which has been its supposed princi¬ 
pal merit. This module consisted essentially of two parts, 
that already described for attempting to maintain a con¬ 
stant pressure, and other apparatus, so that the water 
should reach the outlet without velocity. For this pur¬ 
pose a variety of means has been adopted, mostly by 
varying the chambers in length and breadth, but, accord¬ 
ing to Baird Smith, the object is very imperfectly accom¬ 
plished. 
This method was used in various Italian units, with 
openings of different size and shape under different pres¬ 
sures. The units were called “ Oncia.” No less than ten, 
some of them circular, are given in Carton and Marcc- 
Jongo’s “ Manualedel Ingegnerc Agronomo,” 1888. 
O O O ZD ' 
In this State the same principle has been extensively 
used in the Max Clark box, as it is called, named from its 
introducer. The box has been extensivclv used in 
the older portions of the State, and has fulfilled a 
useful purpose. It has the same faults as the 
Milanese module added to the fact that the shortness 
of the box is such that the movement of the water is im¬ 
perfectly stopped and cannot but have a great influence on 
the discharge. 
As the term oncia was given to the Italian unit, so the 
term inch has been used throughout this western country 
for the corresponding unit. The statutes of Colorado pre¬ 
scribe that water shall be measured through an orifice 6 
