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Art. XI. — On the Temperature the different Mines in 
^America'*. By Baron Alexander de Humboldt. 
Mines of New Spain. 
(tuanaxuato is situated in latitude 21° 0' 15", and the height 
of the plain is about 1100 toises above the level of the sea. 
The mean temperature of the air is probably 60°.8 of Fahren- 
heit. The mine of Valenciana is so warm, that in the deep- 
est parts the miners are constantly exposed to a temperature of 
91°.4. 
Temperature. 
In Sejytember the air without the mine was 66°. 7 
Between Despacho del tiro Nuevo and Boveda ) nAo v ci 
de San Pablo, / 
In the Levels ( Planes) of San Bernardo, 92°.8 
Depth in Feet. 
273 546 
1638 
The spring which comes from the same veins at the depth of 
1638 feet, has a temperature of 98°.2, and is 5°.4 warmer than 
the air of the levels (planes ) in which the miners work 
The mine of Rayas, near that of Valenciana, is erroneously 
regarded by the miners as much warmer than the levels of San 
Bernardo. I have found the thermometer, 
Temperature. Depth in Feet. 
Near the Boca de la Mina, - 69 .4 0 
In the levels, - - - 9^®. 7 630 
In the mines of Villalpando, three leagues to the north of 
Guanaxuato, on a plateau of 1330 toises, I have found the 
thermometer. 
Temperature. Depth in Feet. 
In the open air, - - - 72®. 3 0 
In the levels, - - . 84 .9 436 
It was in the mines of Guanaxuato that there was heard, in 
1784, a subterranean noise, unattended with any shock. The 
volcano of Jorullo, which broke out of the earth on the 14th 
• These observations have been just published in the Annales de Chim, 
tom, xiii. p. 207, from the unpublished journals of M. Humboldt. 
•}• In the Nivellement Barometrique des Andes, No. 336, the temperature of 
the spring is said to be 29°.3 Cent., whereas it is 36*^.$ Cent, or 98°.2 of Fahren- 
heit. 
