34 
BULLETIN" 87, U. S. DEPARTMENT OF AGRICULTURE. 
In the preparation of these tables the formula v = c-Jr s was used, 
in which v = ihe 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. 
Inches. 
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 
fumes. 
26-INCH "V" FLUME WITH 1J-INCH BATTENED BOX. 
Kinds of lum- 
ber. 
Lumber required per mile. 
Dimensions. 
Mud sills 
Posts 
Caps 
Braces, sway. . 
Braces, lateral. 
Stringers ^ 
Sills 
Braces 
Arms 
Box boards. . . 
Battens 
4x4 
4x4 
4x4 
1x6 
1 x 6| 
4x6 
2*x 4 
2ix 4 
2lx 4 
Hx54 
1 x 4 
Running boards Ik x 10 
Inches. Ft. in. Ft. in. 
Add for waste. 
Total.... 
3 9 
3 9 
6 4 
4 
6l 3 
32 
6 3 

1 
16 
( 2 ) 
10 
9§ 
Ft. in. 
330 
660 
330 
660 
330 
330 
330 
20 
15 

11,100 
64 

660 
11 
3 
990 


1.980 
10 
10 
1,980 
108 

20 

3.960 
20 

330 
330 
330 
330 
330 
330 
330 
Nails required per mile. 
CD 
Size. 
3.190 10- pennv.. 
6,380 12-penny.. 
1,540 16-pennv.. 
2,970 20-penny.. 
4. 12-5 
330 21,120 One keg of 40-penny 
3. 713 
1,650 
3,575 
35,640 
6,600 
6,600 
97, 103 
2,897 
100.000 
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, on an average, 
will be too close to the ground to require the use of these braces. 
2 Various sizes. 
