Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

__________________________ ________________________________________________________ 268 Molesworth’s pocket-book Discharge of Water in Open Channels. V = Mean velocity in feet per second. D = Mean hydraulic depth = area -4- wet peri, meter. S = Slope or length of channel to fall of 1. K = Coefficient. (See Table below.) A = Area of channel. Q = Quantity of water delivered per second. V = v^- <^v. Description of Channel. Brickwork________ Earth............ Shingle.. .. ,. . Rough, with boulders Values of K for Velocities Less than 4 feet ! More than 4 feet per second. , per second. 8800 7200 6400 5300 8500 6800 6900 4700 . In very large channels, rivers, &c., the descrip- tion of th© channel aitects the result so slightly that it may be practically neglected, and K as- sumed = from 8500 to 0000. Efflux of Water under Variable Pressure. H = Head of water in feet. V = Effective mean velocity of efflux in cubia feet per second, T = Time of discharge in seconds. A = Horizontal area of vessel in feet. a = Area of discharging orifice in feet. K = Coefficient for orifice. ' ,- m AH V = 4«K VII. T =---------------= • 4«K VH