36 
one-half the.angle, g the acceleration of gravitation and h the 
depth Giving m the value 0.62, which is about the average 
value for such an orifice, and g its value, the formula becomes 
5 
O —2.6" T/1 2 
where Q represents the discharge in cubic feet per second 
and h is measured in feet. For right angle notches it is then 
5 
Q = 2.65 h 2 . 
EXPLANATION OF TABLES. 
+T _ _ -fstiles I and II in the appendix are for the purpose of correcting to allow for 
lulatio^indfcated ° ltleS * he approachiG S water the troublesome cal 
fw riifS abl + L ] 8 a .n auxiliary table giving the average velocity through the weir 
for different velocities over the weir. It may be used to determine the velocity of 
second 1 table 'todeWm^ under kaown conditions, or with the aid of the 
secona table, to determine the proper conditions of the size of the channel in order 
to bring the errors within assigned limits. The velocity given is the averse 
increaJe a due\VveIomav Pteley formula on page 33, and expresses the 
increase due to velocity over that given m the tables III-VI To use the dm 
charge as given in tables III-VI is determined, and the correction is annl S 
according to the given depth over the weir and the velocity of approach Tt cor 
lection is expressed in per cent. The formula is based on experiments limited to 
titles given a?e?n error. r Sreat61 ' Velocitie9 ’ thorefore ’» Possible that the quan- 
over weir 1 foot deem ^FinTatTo^ttiecoVmn/with^Ioilf^f °i 2 P. e r second, the water passing 
2 feet per second. Follow the line to the ribilnrl nftbo i f i° 0t ’ an< ^/?, t \ eft G (l line with velocity of 
is found which is the nu^berVf^cent bfwhTch l^iSsTha^U^crtS. 1 f °°‘ th '’ nl ™ ber U ' 3 
Tables III and IV are newly computed for this edition and give the die 
charges oyer weirs with the depths measured in inches and f ractions COTrespondii g 
forms 6 teMfrr They are compated f-mTodmed 
tne b rancis formula, the depths being measured in inches. 
8 
Q being in cubic 
. , Table computed from the formula, Q=.006675 LH 2 
feet per second, L and H in inches. 3 ^ 
second^L b L e L V fierH^ d - fr r Q TTf°^ LH ^ where Q is iG cubic feet per 
in 
possessed which are divided intofeet^inche^and 6 fra^ctions ^ 68 WhiCh P6 ° Ple 
the^depths by^ 
Where there °' th ? V en inch and the column“ttMfa?. 
column Thpop n b actl ° us ’ tbe amounts to be subtracted are given in the second 
& i°V f U ^ al ^ haIf inches ’ the quantities there given 
contractions. ° ^ mCh ° f th ° ad j° inin S column, and for two complete 
with two complete SnSaction8 < ? 18Charga ° V6r a Weh ’ 45 inches lon 2 and with a depth of 1114 inches 
Follow this column dmvn^unbHMnt^rs^cts the^l; nf+y. m ^ . !ac ^ at t* ie head of the page, 
for a portion of the weir 1 inch lon°- which 9 “io ° °u-G e G ^ ^he interjection is the discharge, 
long it is 45 times as much or 11 3345 Zi w f S feat per second., Then for a weir 45 incl.es 
’ ° r U ' 5W45 Mcond feet, if without contraction. The second column gives 
