1823.] On the Temperature of Mines. 443 



II. The table which accompanies Mr. Fox's second paper 

 (Trans. GSC. ii. 19 — 28), contains a general view of the heat 

 observed in, or near, the metallic veins, in different mines. 



I had made a second table, he remarks, containing the results of 

 several experiments on the temperature of cross levels, and shafts, 

 in some of the same mines, at a distance from anjr metallic veins ; ^ 

 but as its contents are too various, and extensive, to be com- 

 prised in a printed sheet, I will merely mention a few of the 

 particulars. 



In Dolcoath, at the depth of 130 fathoms, where the temper- 

 ature of the earth in the vein was 63° ; its temperature in a cross 

 level, at the distance of 60 fathoms from the vein, was 62°. 



In the United Mines, at the depth of 160 fathoms, the temper- 

 ature of the earth in the vein, was 75°; but in a cross level, 

 south of the vein, only 69°. 



In the same mines, the temperature of the water in the vein at 

 140 fathoms deep, was 67° ; and that of the earth, 9 fathoms 

 north of the vein, was exactly the same. 



In Ting-tang, at 80 fathoms deep, the temperature of the 

 earth in the vein was 64® ; and at the depth of 110 fathoms, it 

 was 68°; whilst in a cross level, 90 fathoms deep, and 30 fathoms 

 distant from the vein, it was 64°. 



In Huel Squire, at the depth of 1 10 fathoms, the temperature 

 of the air near the vein was 72° ; but in a cross level, at some 

 distance, it was 69°. 



In Treskerby, at 120 fathoms deep, the temperature of the air 

 near the vein was 72° ; but at some distance, in a cross level, 

 66°, 



In Chacewater, the temperature of the earth in the vein at 100 

 fathoms deep was 82° ; and that of the air at some distance 

 north of it, 79°. 



These instances, which are selected from a great number, the 

 result of which is very similar, will suffice to show, that the tem- 

 perature, at a distance from the metallic veins, and at the same 

 depths, is, on an average, nearly three degrees below that of the 

 veins, as given in the printed table. 



In many of the observations referred to in the tables, the bulb 

 of the thermometer was buried in the veins, or rock, to the depth 

 of at least six or eight inches, and was filled round with earth, 

 8cc. so as to prevent the free admission of air. 



If we take the mean temperature of the surface of the earth in 

 this latitude at 53°, as given in Prof. Mayer's Tables ; the mean 

 of the accompanying table shows an increase of a little more than 

 6° of Fahr. for every 50 fathoms, or 300 feet in depth. As ray 

 second table gave a less ratio, perhaps we shall not much err, if 

 we suppose an augmentation of one degree of heat for every 10 

 or 12 fathoms in depth, at least in this part of our island. It is 

 however difficult to determine satisfactorily the true ratio of the 

 increase of temperature, as it is evident that there exist many 



