392 REACTION OP THE INTERIOR OF THE EARTH 



four-wheeled carriages, without artificial roads. The 

 possibility of such communication was already known 

 to the Spaniards at the end of the sixteenth century, 

 when the viceroy, the Conde de Monterey ( 535 ), planned 

 the first settlement of Zacatecas. 



In confirmation of what has been said above in gene- 

 ral of the relations of altitude between the city of 

 Mexico and the town of Santa Fe del Nuevo Mexico, I 

 subjoin the principal elements of the barometric level- 

 lings taken from 1803 to 1847. I have given the 

 places in the order from north to south, so that the 

 more northerly being highest in the page may corre- 

 spond most conveniently to the arrangement in ordinary 

 maps. ( 53S ) (The initials indicate the observer, W. signi- 

 fies Wislizenus ; B., Burkart ; H., Humboldt.) 



Santa Fe del Nuevo Mexico (lat. 35 41' N.). Eleva- 

 tion 7046 feet, W. 



Albuquerque ( 537 ) (35 08' N.). Elevation 4849 

 feet, W. 



Paso del Norte( 538 ) on the Eio Grande del Norte 

 (29 48' K). Elevation 3791 feet, W. 



Chihuahua (28 32' N.), 4638 feet, W. 



Cosiquiriachi 6273, feet, W. 



Mapimi in the Bolson de Mapimi (25 54' K), 4782 

 feet, W. 



Parras (25 32' N.), 4985 feet, W. 



Saltillo (25 IV N.), 5240 feet, W. 



Durango (24 25 ' N.), 6848 feet, Oteiza. 



Fresnillo (23 10' N.), 7244 feet, B. 



Zacatecas (22 50' K), 9012 feet, B. 



San Luis Potosi (22 08' N.), 6090 feet, B. 



