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THE TEMPERATURE OF THE EARTH AS SHOWN BY DEEP MINES.
At a recent meeting of the American Society of Civil Engineers,
observations on the temperature of the earth, as shown by deep mines, were
presented by Messrs. Hamilton Smith, Jr., and Edward B Dorsey. Mr. Smith
said that the temperature of the earth varies very greatly at different
localities and in different geological formations. There are decided
exceptions to the general law that the temperature increased with the
depth. At the New Almaden quicksilver mine, in California, at a depth of
about 600 feet the temperature was very high--some 115 degrees; but in the
deepest part of the same mine, 1,800 feet below the surface and 500 feet
below sea level, the temperature is very pleasant, probably less than 80
degrees. At the Eureka mines, in California, the air 1,200 feet below the
surface appears nearly as cool as 100 feet below the surface. The normal
temperature of the earth at a depth of 50 or 60 feet is probably near the
mean annual temperature of the air at the particular place. At the
Comstock mines, some years since, the miners could remain but a few
moments at a time, on account of the heat. Ice water was given them as an
experiment; it produced no ill effects, but the men worked to much better
advantage; and since that time, ice water is furnished in all these mines,
and drunk with apparently no bad results.
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