Measurement and Division oe Water. 9 
2. The ordinary stockholders, each entitled to a proportionate part 
of the water remaining after the first class has been supplied. Some¬ 
times the amount of water is limited to a prescribed amount. In this 
case, serving as an illustration 4 shares is limited to 1.4 4 second feet, 
intended for 80 acres of land. 
3. A class of residuary rights—persons who are not entitled to 
any water until classes 1 and 2 have received their amount; they are 
entitled to whatever is in excess. These are surplus rights without vote 
in the management. 
4. Persons using the canal as a common carrier. A case arises, 
for example where the water of a reservoir is run through the canal to 
its stockholders, who may or may not be stockholders in the canal. 
There may be several different and independent sources of water each 
requiring independent treatment. The charge for carriage may be for 
money or for a fraction of the water carried. 
The classes of the first three kinds have been common in Ital¬ 
ian practice for generations. Some of these privileges existed in 
the time of the Caesars and are mentioned in Frontinus account 
of that period. They have developed with us and will in any irri¬ 
gated country, because the situation naturally gives rise to the con¬ 
ditions calling for them. 
Hence it may be realized that the problem of distribution, 
which is necessarily a difficult one, becomes additionally compli¬ 
cated. It may be realized that the solution is not exact, especially 
as additional complications are introduced from the ever-varying 
losses from evaporation and from seepage; from the fluctuating 
needs of different users, which vary from hour to hour; from the 
fluctuating supply entering the canal, due to the effect of the vary¬ 
ing draft of other ditches and from the diurnal fluctuation in the 
river itself; and to the complicating effect of the time which is 
required for water to pass down the canal, which in some of the 
larger ones may be several days. 
In the measurement of water from ditches there are two 
distinct classes of measuring boxes—one is the dividing box and 
the other the measuring box or module. The object of the former 
is to furnish a definite portion of the water flowing in a ditch. 
The need of this form of box is more common in small ditches 
owned by two or three neighbors, or in minor ditches with a lim¬ 
ited number of stockholders. The intention is to give one person, 
for example, one-fourth, or some other fraction, of all the water 
that enters the ditch, this fraction being in proportion to his inter¬ 
est. It is thus best adapted to short ditches or cases where the 
number of people are few and where the expense of a ditch rider or 
patrolman is to be avoided. 
The other class of box is the measuring box, whose object, 
in general, is to give a certain definite quantity of water, as one 
cubic foot per second. Sometimes the attempt is to deliver a 
constant quantity of water. This purpose, however, is not usually 
necessary or desirable. Under conditions in the western part of 
