On underground temperatures : with observations on the conductivity of rocks, on the thermal effects of saturation and imbibition, and on a special source of heat in mountain ranges / by Joseph Prestwich.

  • Prestwich, Joseph, 1812-1896.
Date:
1886
Catalogue details

Licence: Public Domain Mark

Credit: On underground temperatures : with observations on the conductivity of rocks, on the thermal effects of saturation and imbibition, and on a special source of heat in mountain ranges / by Joseph Prestwich. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    and cross-veins—“of which the effects may either bo to raise the tem- perature of the underground springs when chemical decomposition is going on in the upper part of the lode, or to lower the temperature when the surface-watej’s are abundant and infiltrate rapidly. The following observations made in the rock appear to be amongst the most reliable of the results obtained, the temperature having been taken in holes 2 to 3 feet deep, and the stations having been selected at places where no working had recently been going on, and as distant as possible from the shaft: — No. in Table I. Name of mine. Eock. Depth. Temp, of rock. Eate of increase for 1° F. Observer. feet. feet. 19 Dolcoath Grranite .... 1350 78° 48 Fox. 9 li a,—^ ^ TjRva.nf, (rra.Tiitp n.nrl 1530 87 1 slate n 85 ^ 43-7 n 92 Botallock Granite and 1128 79 40 >> greenstone 80 Bowey Consoli- dated Slate 1728 93 41 91 Par Consols. .. jy 1248 84 38 40 Consolidated.. Slate 1740 85-3 49 Henwood. 122a Tresavean .... Granite .... 2130 99 43-5 Hunt. 98 Tresavean .... n 1572 82-5 48-5 Fox. Mean.. 44 feet This gives a mean thermometric gradient of just 44 feet per 1° F., or combining the results obtained by observations in springs with those in rocks, we get an average gradient of 43’2 feet per degree. Mean of observations in springs 42*4 feet „ „ rock 44 0 „ Mean.. 43 2 „ Foreign Mines.—We know too little of all the conditions which obtain in foreign mines to draw any definite conclusion as to the rate of increase of temperature. Possibly the observations may prove available when we have more certain information respecting the mean annual temperature at each place, the height of the mine above the sea, and the position, especially in mountainous districts, of each station with reference to its depth beneath the surface. This latter element is one, which the coal-mines observations pre- viously given, clearly show should be taken into account. In Cornwall it is not of much importance, as the elevations are small, and the