THE COLORADO STATUTE INCH AND SOME 
MINER’S INCH MEASURING DEVICES 
By V. M. CONE 
The question iSjOften asked, “What is a Miner’s Inch,” or an “inch 
of water?” 
The “Inch” is a unit of measure of flowing water which has been 
handed down to the irrigators of the West by the early day miners. 
There are several different Miner’s Inches, and they are sometimes called 
“Customary Inches,” which means the “Inch” principally used in any 
certain locality. When the value of the “Inch” or the conditions under 
which the “Inch” shall be measured is fixed by law, it is called a “Statute 
Inch.” 
An “Inch” of water is an indefinite quantity. It is the flow through 
an inch square orifice, but the flow varies with the size of the orifice, the 
distance from the top of the orifice to the surface of the water, and the 
method of placing the orifice. These conditions are not uniform in the 
different localities and it is not uncommon to see different standards on 
a single irrigation ditch. The depth of the orifice varies from 1 to 12 
inches and the water pressure varies from zero to 6 inches above the top 
of the orifice. The orifice may be thin edged or a square cut leaving the 
edge the full thickness of the plank, and the issuing stream of water 
may flow free into the air or it may be partly covered by “back-water” 
on the down-stream side. The orifice may be placed in a large box where 
the water is practically at rest, or it may be placed in a small box whare 
the water approaches the orifice with considerable velocity. Sometimes 
the orifice is the open end of a long box or tube placed in a nearly hori¬ 
zontal position through the ditch bank. Each of these conditions affect 
the quantity of water which will flow through a square inch of the orifice 
and it will therefore be seen that the “Inch” of water may be a variable 
quantity when measured in accordance with the following Colorado law: 
“-; and water sold by the inch by an individual or corporation 
shall be measured as follows, to-wit: Every inch shall be considered as 
equal to an inch square orifice under a five-inch pressure and a five-inch 
pressure shall be from the top of the orifice of the box put into the banks 
of the ditch, to the surface of the water; said boxes, or any slot or 
aperture through which such water may be measured, shall in all cases 
be six inches perpendicular, inside measurement, except boxes delivering 
less than twelve inches, which may be square, with or without slides; 
all slides for the same shall move horizontally and not otherwise; and 
said box put into the banks of the ditch shall have a descending grade 
from the water in ditch of not less than one-eighth of an inch to the 
foot.” (L. ’74, p. 308.) 
