i;; \\. \ L. E. c; i KI.KY. TKOY. NK\Y YOKK 



USE OF THE CURRENT METER 



The quantity of water flowing in a stream is found by means 

 of a mi-rent meter, by sul>di\ Ming the cross-section of the stream 

 into partial areas or panels and by multiplying each partial area 

 by tin mean velocity of the water that flows past each partial 

 section, then taking the sum of all such products. 



The cross-section of the stream is subdivided by verticals 

 taken sufficiently close together to define the area accurately, 

 a- in cross-sectioning earthwork; that is to say, the lines (Fig. 

 24) on the stream bed between consecutive verticals should be 

 essentially straight. On streams with smooth beds the points of 

 observation will occur at regular intervals, but the method of 

 computing the partial areas is not dependent on the distance 

 apart of the verticals. The length of each vertical in feet is 

 measured by sounding either with a sounding rod, using an 

 engineer's level on the bank if desired, or by a weight and line. 



The mean velocity in each partial area is the average of tin 

 velocities in the verticals that bound the area. Velocities are 

 measured in feet per second; hence, the product of the partial 

 area by the mean velocities will be in cubic feet per second. 

 One cubic foot per second, is the quantity of water that will flow 

 past a section of the stream one foot wide and one foot deep, 

 with a velocity of one foot per second. 



SOUNDINGS 



Rods for sounding should be of a convenient length for 

 handling and may be made either of wood or of metal. Wooden 

 rods should be thin and sharpened on the edges, a section 3 

 inches wide and ^ inch thick being appropriate for a length 

 not exceeding five feet. Longer sounding rods may be made 

 from 2x4 inch lumber, the edges being worked so that the 

 cross section of the rod has the same shape as the hull of a ship. 

 The correct style of metal rod (Fig. 6) is furnished with all 

 Gurley meters. 



Where there is no danger of damaging the meter, the sound- 

 ings are taken with the meter on the rod in all wading measure- 

 ments. It should be noted that the zero of the graduations on 

 the rods is at the center of the cups, so that a distance equal to 

 the distance from the center of the cup, to the bottom of the yoke 



