Appe7idix, 1 6 1 



= opening of a bridge or sluice with square piers, or 



where the doors are so hung as to cause eddies . . ^Z(> 



= small openings of sluices, as in a lock, whether sub- 

 merged or not, or sluices with tankard-lid doors 

 causing resistance on all four sides * 64 



These constants have been selected as appearing to give the most 

 correct result. 



TABLE IV. 

 To find the velocity of water in open channels. 



V = ( VR X F 2 ) C. 



V = velocity in feet per second, 



R := hydraulic mean depth, or area of water divided by the length 

 of the sides and bottom of the channel in direct contact 

 with the water. 

 F = fall in feet per mile. 

 C = constant for friction, &c. 



= large streams , '90 



= large drains in good order 'So 



= secondary drains *10 



= small drains . . . . * 60 



The mean velocity of a stream is equal to the surface velocity in 

 the centre multiplied by o • 83. 



Example, — The mean velocity of a large drain having 10' -6" 

 tiOttom, 7' '6" depth, slopes 2 to i, and inclination 2 inches per 

 mile : — 



Area = 191*25 feet, contour 44* 16 feet. 



IQI*2c; 



44* 10 



V = (V4'33 X '16 X 2>-8o 



V = 0*9432 feet per second. 



M 



