340 Progress of' Foreign Science. 



At the depth of 80 to 90 68.36° F.— 20.2 C. 



90 to 100 69.80 21.0 



100 to 110 68.54 20.3 



110 to 120 69.98 21.1 



120 to 130 69.62 20.9 



130tol40 ...72.14 22.3 



150 to 160 75.02 23.9 



190 to 200 75.92 24.4 



at 230 78.44 25.8 



at 240 82.04 27.8 



In a great number of cases, the thermometer was sunk in the 

 rock to the depth of 6 or 8 inches ; sometimes the temperature 

 of the air or water was merely taken ; generally both methods 

 afforded results slightly differing from each other. The ther- 

 mometer, plunged in the metallic veins, usually indicated a 

 temperature of 1° to 2.8° centigrades (1.8° to 5° F.) higher than 

 that obtained when the thermometer was plunged into the hole 

 of a rock, and particularly in granite. The veins of tin are com- 

 monly a little colder than the veins of copper. In the bottom of 

 the mine of Dolcoath, at 240 fathoms of depth, there issues 

 from the vein a very abundant jet of water, whose constant tem- 

 perature is 27.8° C. (82.04° F.) What more evident proof can 

 be given, says Mr. Fox, of the great heat of the interior strata 

 of the globe ? The draining-pumps of the United Mines were 

 not long ago totally deranged by an accident; two galleries, 

 one at 200, and the other at 190 fathoms in depth, were found 

 eventually filled with water. This state of things lasted two 

 entire days. As soon as the water was 'pumped out, and be- 

 fore the workmen descended to resume their labours, Mr. Fox 

 ascertained the temperature of the two galleries ; that of the 

 first was 31.1° C. (87.98° F.) The thermometer in the second, 

 at a depth of 190 fathoms, continued stationary at 30.8° C. 

 (87.44° F.) It ought to be remarked that, in order to avoid all 

 error in the observation of these temperatures, the thermometer 

 had its bulb plunged several inches under the floor of the gal- 

 leries. Mr. Fox analyzed the waters of Dolcoath, and those 

 of the United Mines, \fho?,Q. temperatures are so high, and he 

 found in the first only a small quantity of muriate of lime, and 

 in the others a proportion equally small of the sulphates of iron 

 and of lime. Mr. Fox adds, that new experiments made in 

 coal-mines confirm p^jrfectly the results obtained in the galle- 

 ries of the mines of copper and tin. Thus in a colliery, 



At 10 fathoms depth, the temperature was 50° F. 10° C. 

 36 . . . 57.92 — 14.4 - 



90 . . . 62.06 — 16.7 — 



