Measurement and Division oe Water. 17 
is to be divided so that a certain number of hilas, according to the 
result of the sale, may enter the channel. No account is taken of 
the difference introduced by contraction. The discharge is assumed 
to be proportional to the size of the opening. The same principle 
is used occasionally in Colorado. One divisor near Greeley divides 
into four channels. It is not so good as the old Spanish ones 
because of neglect to look after details. The value of the water 
now justifies a considerable expense in a permanent divisor. 
Time Method of Division .—On small ditches or laterals where 
the amount of water is not too great for one user to manage, and 
especially where the flow is uniform or nearly so, a time method 
of division may be used to advantage, and gives a more equitable 
division than boxes of the types described. Besides it allows the 
use of water in large enough quantities to make the use much 
more economical. For when a stream is divided it often happens 
that the parts are. too small to accomplish much. It thus becomes 
desirable in almost all localities in times of low water to arrange 
so that one will combine the streams of several for the time during 
which he is irrigating. There is then some prospect of doing some 
good. The time method of division is especially applicable to small 
ditches where the amount of water is small. In such case the ex¬ 
change is systematized. Each one takes the whole stream of water 
for a time proportional to his share in the ditch. The period is 
usually so arranged that the rotation will be completed in some 
definite time, as a week or two weeks, or such other time 
as the experience of the locality has shown to be desirable for 
an irrigation to be repeated. The water will then be given out 
at night or day according to schedule, and in order that the 
inconveniences may be fairly distributed, the period of rotation 
may be made to include a fractional day, so that those whose 
turn comes in the night during one rotation come in the day 
during the second, and vice versa. Thus, suppose the period of 
rotation be taken as one week, or for reasons above given, 7 1/2 
days, and the number of shares be fifteen, of which some own 
one, others two and some three shares. In this case each share 
would give its owner the right to use the water for one-half 
day, or twelve hours; the owner of two shares would be entitled 
to its use for twenty-four hours, and the owner of three shares 
to thirty-six hours. Where there are a large number of rights or 
of users the same period would be carried out, but to a greater 
extent. As carried out in the countries where it is applied, the 
division is sometimes carried out to minutes. 'A time table is 
prepared at the beginning of the season, and each is furnished with 
a copy of it. The water is shut off or turned on the different 
gates according to schedule. The user must be ready to take 
