Elmore County Republican. [volume] (Mountain Home, Idaho) 1910-1915, 1912-02-03

ed the expression OF the amount
in cubic feet would involve the
use of such large numbers that
the same would be cumbersome.
In order to simplify these express
ions the term acre-foot' is used,
which represents enough water to
cover an acre one foot in depth or
1850 cubic feet. The use OF
this term has the additional adj
vantage of being easily compared
with the acreage; as for example,
a reservoir containing $4,000 acre
feet of water would furnish
depth of 2 feet for $4,000 acres OF
land. A cubic foot of water per
second flowing continuously for
"a hours furnishes almost exactly
two acre feet of water.
Hydraulic equivalents which
will be found useful to irrigat-
ors -
|. Idaho miners inch-ap-
proximately 1-5O Of a cubic foot
per second, or 9 gallons per min
ute.
2. The flow of a cubic foot
per second-approximately so
miner inches, or $50 gallons per
minute.
3. One cubic foot per second
for "a hours-approximately 2
acre feet.
4. One acre foot-enough wat
er to cover an acre exactly foot
in depth or 1850 cubic feet.
5. One miners inch per acre
for 100 days-3.97 feet deep on
the land.
6. One miners inch per acre
for $50 days-5.95 feept deep ON
the land.
7. Five-eighths miners inch
per acre for 100 days-2.48 feet
deep on the land.
,. One-half miner S inch per
acre for 100 days-1.98 feet deep
on the land.
10. One-half miners inch per
acre for $50 days-2.98 feet deep
ON the land.
Weirs and Weir measurements.
The most accurate, practical
and economical method of water
measurement that has been de-
vised for the measurement of
comparatively small heads of wat
er is the weir measurement. The
weir consists essentially of thin
notch of a specific shape, which
the water is caused to flow over.
The amount of flow depends
upon the depth Of water flowing
over the crest, as the bottom of
the notch is called. The weir has
been used for the measurement
of water for hundreds of years
and the method Of it's installation
and the discharge of water over
it have been worked out SO care
fully that water can be measured
over it with an error of less than
one per cent, if care is used.
There are several forms of
weirs, the name Of each designat-
ing the shae of the notch. Clip
poletti, an Italian engineer, evolv-
ed and perfected the weir which
bears his name many years ago,
this being the weir that is now
most generally used in the west.
Other weirs, namely, the rectan-
gular and the triangular weirs,
are constructed and operated in
much the same way, the same
rules being observed in the meas
urement, practically the only diff
ference existing being, as has
been stated, in the shape of the
notch and the formula used in
the computation of the discharge.
The Cippoletti weir notch is trap
ezoidal in shape, having a straight
bottom or crest with sides that
slope outward from the vertical
at the rate of one horizontal to
four vertical. A one foot Cippo-
letti weir has a straight horizont-
al bottom or crest one foot in
length with a width between the
sides of Is inches at a height of
g inches above the crest. If the
notch is made of wood the sides
and bottom should be beveled off
on the down stream side, leaving
a sharp thin edge on the up
stream side. This is necessary in
order to secure a sharp clear-cut
issuing stream which it is neces-
sary to secure if accurate meas
urement is to be obtained. 1t is
usually the best policy to line or
face the upper side of the wier