The Sewerage of Sea Coast Towns

onvenient manhole, which will pond up the sewage; and then to ascertain the depth of water passing over the notch by measurements from the

flow, and there will be great probability of incorrect results being obtained by reason of solid sewage matter lodging on the notch. When the depth on a l2 in notch is about 6 in, a variation of only 1-16th inch in the vertical measurement will represent a difference in the rate of the flow of approximately 405 gallons per hour, or about 9,700 gallons per day. When the fl

which will give different results, though comparative accuracy has been claimed for eac

r foot in width o

the weir to the level of the bottom of the notch, the

E No

GULAR

_

oot in width of

-----------

es o

--------+--

in | Feet

---+-----+--

C. ft | Ga

hour. | per min |

---+-----+--

ity. |

5 | 213.6 |

4,296 | 198.6

820 | 200.0 |

0,057 | 214.0

72,949 | 195.0

---+-----+--

he width of the weir, or of the stream above the weir. If a cubic foot is taken as being equal to 6-1/4 gallons instead of 6.235 gallons, then, cubic feet per minute multiplied by 9,000 equals gallons per day. This table can be applied to ascertain

9 \/4^3 = 4.

, but as the weir is only 6 in wide,

c feet, which is the

| +---+ +---+ | | | | | | | | | | | | | |

F DOUBLE RECTANGULAR

\ / | | \ / | | \ / | | \ / | | \ / | | \ / |

OF TRIANGULAR NOT

ECTION, SHOWING WEIR, G

of 20 in, two sets of calculations are required. First 20 in depth on the not

_ _

9/2 \/ 10^3 = 2.3

_ _

x 4.69 \/ 4^3 = 1.

. ft per m

e would be slightly

pproaches the weir with a velocity which varies considerably from time to time. In order to make allowance for this, the head calculated to produce the velocity must be add

____ 195\/(11^

f the usu

_

3, which

e into account. The V represents

approximately the discharge over a notch with any given head varies as the cross-sectional area of the body of water passing over it. The area of the 90° notch is half that of a circumscribing rectangular notch, so that the discharge of a V notch is approximately equal to that of a rectangular notch having a width equal to half the width of the V notch at water level, and as t

ry from that for the rectangular

E No

AR OR V

_

ge = C

es o

ns | C. ft per | per hour | min | per hour. | min -------+-----+------+------+------ Alexander | 59,856 | 160 | 120.0 | 0.321 Cotterill | 57,01

for the discharge in

__

x B \

and can be applied to any proportion of notch. When B = 2H, that i

t is, a notch contai

and the formula

_

\/

ir, as well as the notch, should be fixed level and a peg or stake fixed as far back as possible on the upstream side of the weir, so that the top of the peg is level with the top of the weir, instead of with the notch, as is the case when a rule or gauge-slate is used. The hook-gauge consists of a square rod of, say, lin side, with a metal hook at the bottom, as shown in Fig. 15, and is so proportioned that the distance from the top of the hook to the top of the rod is e