UNDERGROUND GASES AND TEMPERATURE. 
269 
Ophelia tunnel .—The portal of the Ophelia tunnel is located on the east side of 
Cripple Creek, about half a mile south of the town. The elevation is 9,268 feet. 
The tunnel starting in granite soon penetrates the breccia and continues in this rock 
to the end, the breast being somewhat over 7,000 feet distant and almost due east of 
the portal. Considerable difficulty was experienced with the gas when the tunnel 
was driven, especially in the last 700 feet beyond the surface connections through 
the Mary McKinney and Callie workings. At times work had to be suspended and 
frequently, it is said, gas issued from every new bore hole drilled in the breast. In 
March, 1904, work had been stopped for some time owing to other reasons. During 
a visit on March 5, 1904, the temperature at the portal was —3° C. ( + 26° F.) and 
the barometer stood at 20.5 inches. At the World’s Fair drift, 300 feet south of the 
main tunnel, the temperature was +48° F. Near the caved end of the drift on the 
Howard flat vein, 4,605 feet from the portal, the temperature was 50.5° F. At 
6,610 feet from the portal the temperature was 58° F. and candles burned with diffi¬ 
culty, though the percentage of carbon dioxide was only 0.25, and 2 per cent is 
usually considered necessary to extinguish them. This seemed to point clearly to 
the presence of some other gas besides carbon dioxide. At 6,870 feet from the 
portal the temperature was 58° F., the candles were extinguished, and the percentage 
of carbon dioxide in the air was 0.47. At the breast of the tunnel, about 7,000 feet 
from the portal, acetylene lamps barely burned, the temperature was 58° F., and the 
percentage of carbon dioxide was 0.68. 
At a subsequent visit, on March 18, the temperature at the portal was 45° F., 
and the barometer indicated 20.7 inches. The temperature at the breast was 54° F. 
The air was good, and candles burned brightly up to the breast. 
Copper Mountain .—The only record of gas conditions in outlying districts was 
obtained from the Fluorine mine, on Copper Mountain. Tunnels were driven in 
granite extending underneath the workings of the Fluorine mine, and much gas was 
said to have issued from the surrounding rocks in these workings. 
UNDERGROUND TEMPERATURE. 
No accurate measurements have been undertaken to ascertain the exact 
increment of temperature with depth in the Cripple Creek district. A few observa¬ 
tions are, however, available which may serve to.attain at least an approximate 
result. 
Concerning the mean annual temperature at Cripple Creek, which should be 
approximately identical with the rock temperature at the depth of, say, 50 feet, it 
should be stated that the only data available are incomplete records at Cripple 
Creek extending over a period of three years. By estimating temperatures for 
those months which are lacking the figure of +42° F. is obtained for Cripple Creek, 
the probable error being about +2°. The mean annual temperature at Colorado 
Springs is +47° F., while that of the summit of Pikes Peak is 19.4°. The determina¬ 
tion for Colorado Springs is based on the average for twenty-six years and that for 
Pikes Peak on records for fifteen years. 
Cripple Creek has an elevation of about 9,000 feet, while the elevation of Colo¬ 
rado Springs approximates 6,000 and that of Pikes Peak 14,000 feet. At the eleva¬ 
tion of 10,250 feet in the vicinity of Cripple Creek a mean annual temperature of 
+ 41° F. ha,s been assumed. 
13001— No. 54—06-19 
