This page has been validated.
CHAP. IX.
MODERN EFFECTS OF HEAT.
275
| Littry. | ||||||
| Surface temperature | 0 | mètres | 11.00° | cent. | ||
| Rock at the bottom of St. Charles mine | 99 | 16.18 | ||||
| Decise. | ||||||
| Water of the well | Pelisson | at | 8.8 | mètres | 11.40° | |
| Puits des Pavilions | 16.9 | 11.67 | ||||
| Rock in the Jacobe mine | 107.0 | 17.78 | ||||
| Ditto | 171.0 | 22.10 | ||||
The general result of a complete discussion of these observations on subterranean temperature made in mines and collieries, appears, to give a ratio of 1° cent, for about 25 metres, or 1° Fahr. for 45 feet English.
Mr. Kenwood's observations on subterranean temperatures in the rocks, made on the waters issuing from them, extend to no less than 95 in slate, and 39 in granite, and from the surface to SOO fathoms and upwards. The following is a summary.
| Slate. | Granite. | ||||
| Average Depth. (ft.) | No. of Observa- tions. |
Temperature. | Average Depth. (ft.) | No. of Obser- vations. |
Temperature. |
| 35 | 21 | 57.0° | 31 | 7 | 51.6° |
| 73 | 19 | 61.3 | 79 | 17 | 55.8 |
| 127 | 29 | 68.0 | 133 | 12 | 65.5 |
| 170 | 21 | 78.0 | |||
| 221 | 5 | 85.6 | 237 | 3 | 81.3 |
Thus at all depths the slate appears to be about 3.9° warmer than the granite at the same level.
The progressive increase of temperature in descending is in a mean of
| 95 | observations on slate | 1° | for 6.5 | fathoms | (39 feet). |
| 39 | granite | 1 | 6.9 | (41.4). | |
| (Reports of British Association for 1837.) | |||||
