14 BULLETIN 77, U. S. DEPARTMENT OF AGRICULTURE. 
Table 7. — Amounts by species of round mine timbers produced in Colorado in 1911. 
Species. 
Lodgepole pine 
Engelmann spruce. . . 
Douglas fir 
Western yellow pine. 
Limber pine 
Bristle-cone pine 
Aspen 
Alpine fir 
Blue spruce 
White fir 
Oak 
Amount. 
Percent- 
age of 
total. 
Boardfeet. 
23,421,000 
8, 242, 000 
2, 244, 000 
1,354,000 
431,000 
183,000 
149,000 
109,000 
75.000 
65,000 
1.000 
Total. 
36,274,000 
100 
Table 8. — Unit costs for various diameters. 
Diame- 
ter. 
Cost per piece 16 
feet long. 
Cost per linear foot. 
Cost per inch of 
diameter 16 feet 
long. 
Inches. 
3 
4 
6 
8 
10 
12 
14 
16 
SO. 35 
. 40 to SO. 50 
. 45 to . 65 
.60 to 1.25 
1.15 to 1.60 
1.50 to 2.15 
2. 00 to 2.25 
2.50 
SO. 022 
.025 to SO. 031 
.028 to .041 
. 038 to . 078 
. 072 to . 100 
. 094 to . 135 
.125 to .141 
.156 
SO. 117 
. 100 to SO. 125 
. 075 to . 108 
. 075 to . 156 
.115 to .160 
. 125 to . 180 
. 143 to . 161 
.156 
Table 7 shows that lodgepole pine is the main source of supply for 
round mine timbers, and, together with Engelmann spruce, makes up 
88 per cent of all the props cut. Douglas fir, although a very desir- 
able wood, formed only 6 per cent of the total. 
COSTS FOR DIFFERENT SIZES. 
Table 8, giving costs for props of various diameters, was compiled 
from such data submitted by the operators as were definite in regard 
to the size of the material. Several methods of purchasing round 
material were reported — cost per piece for a given length and diam- 
eter, cost per linear foot for a given diameter, and cost per inch of 
diameter at the small end for a given length. A large majority 
reported the cost per linear foot. 
LIFE OF TIMBERS. 
There was a large variation in the reported life of timbers in the 
different mines, especially in the metal mines. The timbers in the 
coal mines had an average life of only about one-half that found in 
the metal mines, but their size was also only about one-half as great. 
Tables 9 and 10 give the average values obtained from statements of 
the operators. 
