34 



BULLETIN 87, U. S. DEPARTMENT OF AGRICULTURE. 



In the preparation of these tables the formula v = c-yjr s was used, 

 in which v = the velocity of the water in feet per second, c = a con- 

 stant, r = the hydraulic radius in feet, and s = the slope. Each step 

 was carried out to three significant figures. The following values for 

 c and r were used : 



Slant depth. 



c 



r 



Slant depth. 



c 



r 



Slant depth. 



c 



r 



Inches. 







Inches. 







Incites. 







20 



108 



0.417 



34 



121 



0.708 



48 



128 



1.00 



22 



111 



.458 



36 



122 



.750 



50 



129 



1.04 



24 



113 



.500 



38 



123 



.792 



52 



130 



1.08 



26 



115 



.542 



40 



124 



.833 



54 



131 



1.12 



28 



116 



.583 



42 



125 



.875 



56 



132 



1.17 



30 



118 



.625 



44 



126 



. .917 



58 



132 



1.21 



32 



119 



.667 



46 



127 



.958 



60 



133 



1.25 



This formula is based upon experiments with slopes of less than 

 10 per cent, and while its application to steeper grades has not been 

 thoroughly checked by actual determinations of velocity, the results 

 are considered sufficiently accurate for use in the design of timber 

 flumes. 



Table 4. — Estimate of approximate amount of material required for construction of 



flumes. 



26-INCH "V" FLUME WITH lJ-FNCH BATTENED BOX. 



Kinds of lum- 

 ber. 



Mud sills 



Posts 



Caps 



Braces, sway... 

 Braces, lateral.. 



Stringers 



Sills 



Braces 



Arms 



Box boards. . .. 



Battens 



Running boards 



Add for waste. 

 Total.... 



Lumber required per mile. 



Dimensions. 



Inches. 

 4 x 

 4 x 

 4 x 

 1 x 

 1 x 

 4 x 

 2£x 

 2£x 

 2Jx 

 l|x54 

 1 x 4 

 HxlO 



Ft. in. 

 7 3 



7 



3 



9 



7 

 16 



4 



11 



2 2 

 16 



5 

 16 



Ft. in. 



( 2 ) 



Ft. in. 

 9 I 

 19 '. 

 4 ? 



10 10 



108 



20 



20 



330 



660 



330 



660 



i 1,100 



660 



990 



1,980 



1,980 



3,960 

 330 



330 

 330 

 330 

 330 

 1275 

 330 

 330 

 330 

 330 

 330 

 330 

 330 



*' a 



Nails required per mile. 



97, 103 



2,897 



100, 000 



Size. 



T3 





s 





O 





Ph 



10-penny.. 



763 



12-penny. . 



682 



16-penny. . 



113 



20-penny. . 



425 



One keg of 40-penny 

 nails and 1 keg of 

 60-penny nails should 

 usually be allowed for 

 such preliminary work 

 as bridging, etc. 



Total....! 1,983 19] 



1 Lateral braces are only figured for five-sixths of a mile, as at least one-sixth of each mile, onanaverage, 

 will be too close to the ground to require the use of these braces. 

 - Various sizes. 



