M. Humboldt on the Temperature of Mines in America. 9S1 
September 1759, is fifty leagues distant from the metalliferous 
transition rocks of Guanaxuato. There are warm springs 
around Guanaxuato which issue from a basaltic conglomerate. 
Those of Comangillas which I have examined, have 205®.! of 
temperature. 
The mine of Cabrera, near Moran, (latitude 20® 10' 4") has 
an altitude of 1331 toises, and a mean annual temperature pro- 
' bably of 60®. 4. I found 
Temperature. Depth in Feet. 
The external air, - - - 50° to S3®.2 0 
In the Gallery del Conde de Regia, without -x 
any traces of metal in the transition v 70^.2 164i 
porphyry, ) 
Subterranean water at this place, • - 62^.8 164 
In the village of Tehuilotepec near Tasco, where the latitude 
is 18® 35' 0", its altitude 919 toises, and the mean annual tem- 
perature, probably 68®, I have found the thermometer. 
Temperature. 
Out of the mine in the day-time, - - 80® 
Ditto, during the night, - - - . 61®.7 
In the Gallery of San Ignacio, where there was ) ^ 
no miner, and no current of air, j 
In the water of the mines at the same place, - 68® 
Depth in Feet. 
0 
0 
354 
354 
At Moran, the waters of the mines was 7®. 2 colder, and at 
Tehuilotepec 7®. 7 colder than the air of the mines 
Mines of Peru. 
The only observations made at great depths, but in parts of 
the globe raised more than 1800 toises above the level of the 
sea, are those of Hualgayoc, near Micuipampa, on the back of 
the Andes of Chota, in south latitude 6® 43' 38". The height 
of the plateau is 1816 toises, and the mean annual tempera- 
ture of the air at this height is probably 46°. The metallife- 
rous mountain of Hualgayoc, which is insulated in the plateau, 
appears to be more than 2100 toises above the level of the 
ocean. 1 found the thermometer to stand thus : 
• In the mines of St Ana, in the kingdom of New Granada, I have found 
the air of the interior every where 70®. 5, when the air without was in the day- 
time 72®. 5, and in the night 65®.7, but the depth of the mine was scarcely thirty- 
five toises. It is situated in 5® 10' of north latitude, has 500 toises of height, 
and is in a region whose mean annual temperature is probably from 69®.8 to 71®.6. 
U 2 
