34 



BULLETIN" 854, IT. S. DEPARTMENT OF AGRICULTURE. 



Table 5. — Elements of experiments for clay tile poorly laid — Continued. 

 12-INCH TILE— Continued. 



2 



Test No. 



884 



,xs:, 

 886 



887 

 sss 

 889 

 890 

 891 

 892 

 893 



2 



3 



1 



5 



6 



7 



s 



9 



10 



Depth 



d 



Area 





Hy- 



Dis- 

 charge. 



Ve- 

 locity. 





Kutter 



of 

 flow. 



D 



of 

 flow. 



A 



rlrauhc 

 radius. 



Slope. 



coeffi- 

 cieno. 



id) 





(<0 





(E) 



(Q) 



(H 



(s) 



(«) 













Cu.ft. 



Feet 







Ncet. 





Sq.ft. 





Feet. 



per sec. 



per see. 







0.756 



0.77 



0. 6280 



0.82 



0. 2987 



1. 8025 



2.870 



0. 0050 



0. 0152 



.636 



.65 



. 5207 



.68 



.2830 



1. 2980 



2.493 



.0050 



.0164 



.519 



.56 



.4368 



.57 



.2630 



-9S20 



2.248 



.0050 



.0170 



.450 



.46 



. 3394 



.45 



.2320 



.5887 



1.735 



. 0050 



.0191 



.356 



.36 



.2485 



.33 



.1955- 



.3231 



1.300 



.0050 





.929 



.94 



.7455 



.98 



.2847 



2. 8640 



3.842 



.0075 



.0137 



.849 



.86 



.6991 



.92 



.2982 



2. 5800 



3.691 



.0075 



.0146 



.709 



.72 



.5877 



.77 



.2941 



2. 1360 



3.635 



.0075 



.0147 



.700 



.71 



.5796 



.76 



.2931 



2. 0380 



3.516 



.0075 



.0150 



.638 



.65 



.5225 



.69 



.2834 



1. 7350 



3. 321 



.0075 



.0154 



.519 



.53 



.4073 



.53 



. 2544 



1. 0260 



2.519 



. 0075 



.0178 



.428 



.43 



.3178 



.42 



.2240 



.6265 



1.972 



.0075 



.0198 



Chezy 

 coeffi- 

 cient. 



(C) 



74.3 

 66.3 

 62.0 

 50.9 

 41.6 



83.1 

 78.0 

 77.4 

 75.0 

 72.0 

 57.7 

 48.1 



Note: Nos. 825 to 832, inclusive, 841 to 848, inclusive,, and 857 to 893, inclusive; grade of flume uniform. 

 Nos. 833 to 840, inclusive, and 849 to 856, inclusive; grade of flume undulating. 



DISCUSSION OF COMPUTATIONS. 



AJ1 of the formulae derived herein are of the exponential type 

 since this seems to be the only form capable of representing the data. 

 It seemed most natural to determine first the relation of velocity to 

 slope, other elements being unchanged. In using for this purpose 

 the same line of tile without disturbing the joints, the most uncertain 

 element in tile observations was removed. The chief remaining diffi- 

 culty lay in the observations of depth of flow, to secure a constant 

 value for comparison at different slopes. When, for a given size of 

 tile and constant depth of flow, slopes are plotted logarithmically as 

 ordinates against their corresponding velocities as abscissa?, the 

 resulting points are approximately on a straight line. The equation 

 of such a line is of the form, 



s = mV z (14) 



which in logarithmic terms may bo written, 



log s = log m +z log V 



(15) 



where m is the intercept on the unity vertical axis, and z is the slope 

 of the line, i. e., the tangent of the angle which it makes with the 

 axis of 1 '. 



For several different sizes of tile of the same material, the values 

 of m follow the ecpuation, 



m = eD x (16) 



