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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    arise from an independent source of cooling in the coal, such as that just mentioned which would he caused by the escape of gas condensed under great pressure. It is an effect important to notice, inasmuch as not only is the discharge of gas from coal of frequent, and often con- stant occurrence, but also from the circumstance that it affects espe- cially the fresh opened surfaces of coal in which the temperature observations have so commonly been made. The Effects of Irregidarities of the Surface.—Although it was known that the underground isothermals under mountain masses are not prolonged in horizontal planes, but follow in a certain ratio the curves of the ground above, little was known to what extent mines were affected by the smaller irregularities of the surface until Mr. George Elliot, M.P.’s experiments in coal pits in Glamorganshire, showed that there is a sensible increase of heat with an increase in the mass of the superincumbent strata. This important point has been rarely, or never sufficiently, taken into consideration in any of the underground temperature observations. The following observations and sections of Mr. Elliot* laid before the Coal Commission were mostly made in abandoned parts of the pits, so as to avoid as far as possible both the effects of ventilation and of working, and the holes, in which the thermometers were placed, were 4 feet deep. Only the depths and temperature of the coal are given in the original sections. I am responsible for the isothermal lines which I have plotted on these data, for the purpose of showing the more precise manner in which the temperature at depths is influenced by the surface heights. At Upper Duffryn Colliery, in South Wales, the top of the shaft is 400 feet above the sea level, and the shaft 360 feet deep. The seam of coal has been followed southward for a distance of 2327 yards, at Fig. 1.—Section at Upper Duffryn, Aberdare District. which point it is 190 feet lower in respect to the sea level than at the entrance. This difference might account for a lowering of 3° to 4° in the temperature, but not for the difference of l5^which is due to * “ Coal Commission Eeports,” vol. ii, p. 105—111. c 2