Arizona republican., 1906-10-31
MEASURING WATER.
Some Facts Every Farmer in an Irri-
cation Country Should Know.

Requests have been received from a
number of readers of the Times who
are users of water for irrigation, for
information that will enable them to
ascertain accurately the quantity of
water, measured in miners inches,
delivered to them in their bitches. The
miners inch is the common unit Of
measurement in California 1t is the
quantity of water that passes through.
an opening one inch square under "a
head of four inches The United
States reclamation service treats one
cubic foot of water per second as the
equivalent of fifty miners inches.
If an irrigator has means of ascer-
tanning accurately the volume of water
in cubic feet delivered to his ditch in a
given time, it is easy to reduce that to
miners inches, but in general prac-
tice it is not feasible to measure the
volume without going into complicated
calculations and taking into account
many modifying conditions.
Having some skill in mathematics
and means of measuring accurately
the head" OF water, one may ascer-
tain the flow through a weir by this
formula: Multiply the width of the
product by the square root of the cube
the discharge in cubic feet per sec
ond, and that multiplied by 80 viii
give the miners inches.
But the farmer usually is unable to
avail himself of that method. and
desires to know a simple means of as
certainiug quickly whether or not he
is receiving approximately the guam
tity of water to which he is entitled.
There is no rule of thumb" by which
the flow OF water can be measured at
glance, but with the aid of certain
tables and an accurately constructed
Weir the process may be simplided
The first thin necessary is a proper
weir, which may be readily constructed
in the box to which water is usually
delivered at the head of a farmers
ditch. The box should be large enough
to rsceive the inflow and allow the wa
ter 10 become stiH before passing
through the weir. For convenience Of
calculation, ct the width of the weir
be twenty-four inches; the height
may be anything sufficient TO take
care of the flow.
The edges of the weir opening
should be of thin metal plates of
which may be fastened on the inside of
the box to form the crest and vertical
sides of the weir. The length must be
accurate, and the sides must be truly
vertical. Graduations in hundredths
of a foot are to be marked with pre-
cision on the side or on a scale rod
inside the box. The purpose of the
graduations is 10 show the head or
heighth of water above the crest of the ,
Weir. and that must be taken at the
top of-the curve of water flowing over
the crest which viii be inside the box +
Having this device. il is easy to APP
ply a weir table, which may be OBJ
from almost any pump manu-
or large dealer in well mach 4
inery. Some concerns print such tab .
les in their catalogues for the con-
venience of customers. ANY standard
work on hydraulics contains weir tab +
les.
The following table adapted 10
twenty-four inch Weir and showing
flow In cubic second feet and in min .
er's inches. will be sufficient for ord
nary use. but il would be wei for the
iIrigator to employ an engineer to
mark the graduations on his weirs
The engineer could readily make the
graduations show directly the flow i'm
miners inches.
WEIR TABLE FOR RANCHERS
Head of water above crest of weir