Measurement and Division ob Water. 23 
and upon the certainty that it was placed under the same conditions. 
There are, nevertheless, several different types of weir, any 
one of which may be used satisfactorily. The important condition 
is that it should be placed under conditions duplicating those of 
the original tests. It is simple, does not easily get out of repair, 
and can be easily tested. It is, therefore, making its way steadily 
as the most satisfactory form of measurement. In Colorado, in 
A Double Spill Box—On a Lateral of the Monte Vista Canal Where It 
Crosses the Rock Creek Ditch. 
This shows the spilling of the excess water, when more than the required 
depth. 
the West in general, in Australia, India, Italy, Alberta and British 
Columbia, it is the measurement most generally used. The Cip- 
poletti or trapezoidal weir is a special form of weir proposed in 
order to avoid one of the difficulties found in the introduction of 
the rectangular weir. 
Practically all forms of weirs are based upon the experiments 
of J. B. Francis at Lowell in 1858.* His experiments are an 
instance of the value of careful work for though there are many 
attempts to develop other formula, all such formula are based upon 
his experimental results. His experiments were made to determine a 
better measurement of water suitable to the needs of the manu¬ 
facturing enterprises at Lowell with capital of millions of dollars. 
The stream was divided among these large users. This justified 
the expense needed to perform the experiments with care and 
with such attention to minute sources of error that they were above 
criticism. The same conditions have continued since the time of 
*Lowell Hydraulic Experiments 
