EARTHQUAKES AND VOLCANOES. 



Guanaxnato is the capital town of the mining district of that 

 name, situate in the Sierra de Santa Rosa, at 160 miles north- 

 west of Mexico, and at an elevation of 6000 feet above the level of 

 the sea. It is irregularly built on mountain declivities, and is 

 surrounded by deep shafts, through which the produce of the rich 

 gold and silver mines is brought to the surface. More than an 

 hundred of these shafts are sunk within a radius of fifteen miles 

 round the town. There is no active volcano in the neighbour- 

 hood. 



The subterranean sounds were first heard at midnight on the 

 9th January, 1784, and they continued without intermission 

 for more than a month. A circumstantial description of the 

 progress of the phenomenon was obtained by Humboldt on the spot, 

 from the reports of numerous witnesses, and from the documents 

 of the municipality, which he was allowed to copy. 



From the 13th to the 16th it seemed as if a rolling thunder 

 alternately with loud and sharp thunder-claps issued from storm 

 olouds beneath the foundation of the town. These sounds, which 

 increased from the beginning by slow degrees, until they attained 

 their greatest loudness and violence, ceased by the same slow 

 degrees. It was remarked, however, that the range of the phe- 

 nomena was not considerable, the sounds being heard only in the 

 mountainous part of the Sierra, from the Cuesta de los Aquilares 

 to the north of Santa Rosa. No sounds were heard in a basaltic 

 district at a few miles distance, nor in the detached portions of 

 the Sierra, twenty-four to twenty-eight miles north-west of 

 Guanaxuato. Not only was the surface of the ground free from 

 the least trembling or other movement, but none was felt in the 

 workings of the mines, which passed in all directions at great 

 depths below the surface. 



30. When this extraordinary phenomenon commenced, the 

 inhabitants of the place were seized with uncontrollable terror, and 

 with a spontaneous movement began to take flight. This was at 

 first resisted by measures of extraordinary severity on the part of 

 the authorities. Flight from the city was punished with a fine 

 of 1000 piastres, or two months imprisonment, and the militia 

 were ordered to arrest and bring back the fugitives. One of the 

 most curious circumstances attending the commencement of the 

 disturbance was a proclamation issued by the magistracy, declar- 

 ing "that in their wisdom they would be well aware of the 

 approach of real danger, and that whenever it might arise they 

 would give notice to the inhabitants to fly, but that as yet it 

 would be sufficient to continue the processions," meaning no doubt 

 some religious ceremonies. 



The inhabitants of the surrounding table lands being prevented 

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