18 
troducer. The box has been extensively used in the older 
portions of the State, and has fulfilled a useful purpose. It 
has the same fault as the Milanese module, added to the fact 
that much less pains are usually taken in Colorado to look 
after the details, and to secure the best arrangement possible 
to prevent the influence of other causes. 
As the termoncia ” 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 
inches in height, with a pressure of water of 5 inches above 
the opening, and that the number of inches shall be the same 
as the number of square inches in the orifice. But the term 
is not confined to the statute inch. On some ditches water 
is measured with a pressure of only two inches, on others 
without any, but the same term is used in all. 
An inconvenience which was soon discovered in the use 
of the Milanese module was that the discharge was not in 
proportion to the nominal discharge. A person, for instance, 
who drew 100 oncia, receives more than ten times as much as 
one who drew 10 oncia. The difference was so noticeable 
that it was not long before the discharge from anyone orifice 
was restricted to a certain number of oncia, generally six. 
The oncia varies from 34 to 47 litres per second, according as 
the orifice discharges one or six oncia. A similar variation is 
true of the statute inch of this State. The advantage in such 
methods is entirely in favor of those who draw the large 
quantities. The reason for this difference has been shown 
on pages 7 and 8. 
There are other causes of variation, as in the distance 
the opening is above the bottom of the regulating box, in the 
thickness of the sides, in the manner of its discharge; all of 
which render this module, excellent as its service has been in 
the past, inaccurate and unreliable, and is leading to its 
abandonment. 
A module based on an entirely different principle was 
used on the Marseilles canal in France for a time, and was 
described in the earlier editions'of this bulletin. This module 
consisted of a hollow vertical cylinder which was kept at a 
constant distance below the surface of the water by a float. 
The water passed over the edge of the cylinder, and passed 
out through a channel which connected with the interior of 
the cvlinder. The cylinder passed through a water tight 
packing. In the previous editions attention was called to the 
probability that the module would be insensitive. On a per- 
