Depth of water in
terms of radius		κ =.01.05.10.15.20.25.30.35.40.45.50.55.60.65.70.75.80.85.90.951.0
Hydraulic mean depth
in terms of radius		μ =.00668.0321.0523.0963.1278.1574.1852.2142.242.269.293.320.343.365.387.408.429.449.466.484.500
Waterway in terms of
square of radius		ν =.00189.0211.0598.1067.1651.228.294.370.450.532.614.709.795.885.9791.0751.1751.2761.3711.4701.571

Fig. 111.—Scale 20 ft. = 1 in.
Fig. 112.—Scale 80 ft. = 1 in.
Fig. 113.

§ 111. Egg-Shaped Channels or Sewers.—In sewers for discharging storm water and house drainage the volume of flow is extremely variable; and there is a great liability for deposits to be left when the flow is small, which are not removed during the short periods when the flow is large. The sewer in consequence becomes choked. To obtain uniform scouring action, the velocity of flow should be constant or nearly so; a complete uniformity of velocity cannot be obtained with any form of section suitable for sewers, but an approximation to uniform velocity is obtained by making the sewers of oval section. Various forms of oval have been suggested, the simplest being one in which the radius of the crown is double the radius of the invert, and the greatest width is two-thirds the height. The section of such a sewer is shown in fig. 113, the numbers marked on the figure being proportional numbers.

§ 112. Problems on Channels in which the Flow is Steady and at Uniform Velocity.—The general equations given in §§ 96, 98 are

ζ = α(1 + β/m);

(1)

ζv2/2g = mi;