Lincoln County times. (Jerome, Idaho) 1911-1919, 1912-03-14
(Continued from last week ;

T. The issuing stream OF waite
must have full contraction; that IS.
must be sharp and clear cut Thi
is brought about BY making the ~
stream edge Of the weir board q
nearly q knife edge as possible. anl
by keeping the sides and bottom o
the box below the weir a. a good dis
lance from the falling stream so tha'
the air may pass freely clear arouni
and in under the issuing stream. The
water below the weir should never b.
allowed 10 back up 10 the level Of
the crest so as TO exclude the air
from under the issuing stream. else
complete contraction will not be Sc
cured and the discharge will be affect
ed If air can pass freely underneath
the issuing stream the level OF the
water below the weir has no influence
on the discharge. An observance Of
the following rules will usually in
sure complete contraction
a The opening OF the weir or the
weir notch must be made in q plane
surface perpendicular to the direction
Of the flow Of water.
b. The opening itself must have q
sharp edge on the upstream side and
the walls should be beveled away on
the downstream side
C. The distance OF the crest of the
weir from the bottom OF the box or
basin should be at least three times
the depth of the water on the crest.
d. The distance OF the sides Of the
weir notch from the sides OF the box
or channel should be at least twice
as great as the depth OF the water
flowing over the crest.
e. In order that the lateral con-
traction should not be disturbed the
length Of the weir crest should be
approximately three times that of the
depth OF water flowing over it.
5. The depth of water flowing over
the weir should not be less than two
inches nor more than one-third of the
length Of the crest, and it should b
measured where it will not be affect
ed by waves. wind or eddies, and far
enough up stream so that it will not
De Influenced by the curvature in
duced by the falling water. This can
not be done by measuring it exactly
over the crest. The distance above
the crest which is usually found suffi.
elent. is up stream from the crest A 4
distance equal to the length OF the
crest
The most frequent cause of error
iocity OF approach and this must he
guarded against by providing a good
sized pool above the weirs which
must be kept clean and free from |,
sediment.
"Oon'ts" in Regard to Weirs. Il
l. DO not set a weir Immediately
below a curve in the ditch. for the
curve will cause the water to flow 10
he side of the crest. I
2. Do not set it Immediately haIo,, 2
'r 100 close TO head gate where the {
water has high velocity. as by so do :
ne' II VIII cause too high a velocity |
" approach. I
j. Don't allow the water below the
selr to back up even with the crest
s II Will not allow complete contrac- [
ON and will cut down the DISCHARGE q
= DO not set the weir any other
ray than perpendicular and at right v
ngfes to the flow of the stream e
D. DO not attempt to use too small n
weir. Put in larger weir where il
ne water TO be measured exceeds g
epth on the crest of 1-3 the crest o.
myth col il
D. DO not allow the pool above the ei
eir 10 NIL up with sediment. as the ie
decrease in the cross ser. CO
-oach. u ap- Vi
l. The weir box should be set with cl
"ooi even with the bottom Of the a.
Duty of Water. pl
To know the proper amount of ir. -
cation water that should be aDDIied ~,
the Inherent soils and crops in or "
" 10 make the greatest possible nj
eiu, mas Always been a serious prob. n1
III 20 all irrigators. II has ALWAYS AZ
en- known that in order tn secure A.
biggest possible crop it is neceq. ~
~ TO apply different amounts n -
Ierent crops and to different Soils NJ.
IN the same crop, but lust bow no
zen this amount should be has never De De
en- known only in an indefinite Wv oe
me Irrigation Investigations de-. :
rtment, which I represent in tba 49,
tie OF Idaho. has. in co-operation s T'
ID the state engineers office. been - -,
'rylng on a series of experiments ~
me past two years by means NJ ~,
ich 1t is hoped to determine this ~,
y important factor. and we have ~, ~,
ured a vast amount of data con. t ,Lu
ming 1t. These experiments have b a,
been carried out on comparatively an,
&c areas and in a practical way for
does not give any indication of ~
much water is necessary for b b.U
Simum crop production on anv &c nS'
10 merely measure the amount nre
some farmer applies for the rea. rio RI
mat the same or larger crop tnr
piouuoeu Win either yes