SMALL WATER SUPPLIES. 



kind of float various velocities can be taken, and 

 when the stream is divided into imaginary contours, 

 as shown in the figure, accurate estimates of the 

 flow can be made. For instance, say the velocity at 

 A was 280 ft. per minute while that at B was 270. 



The mean velocity between the two contours will 

 therefore be 270 + 280 -r- 2 = 275 ft, and the quantity 

 flowing in this section will be 275 x 12*41 l = 341275 

 cub. ft. per minute. The mean velocity between 

 B and C is 265 ft., and the corresponding quantity 

 flowing will be 97 5 7 '3 cub. ft. per minute. There- 

 fore the total quantity flowing will be found by 

 calculating the velocity and quantity between each 

 two contours, and adding together the quantities 

 thus found. 



To return however to the question of the gauge. 

 The most accurate results will be gained by the use 

 of this piece of apparatus if properly constructed. 

 It is not an expensive piece of apparatus and can be 

 made and erected by an intelligent carpenter. 



The size of the gauge is determined by the drain- 

 age area. It must pass the greatest floods. That is 

 the reason that most gauges have two or three 



1 12-41 is the area of this particular contour. 



