TRUE VOLCANOES. 409 



Lagos (lat. 21 20'), 6376 feet, Bt. 



Villa de Leon (lat. 21 C 7'), 6134 feet, Bfc. 



Silao, 5911 feet, Bt. 



Guanaxuato (lat. 21 0' 15"), 6836 feet, Ht. 



Salamanca (lat. 20 40). 5762 feet, Ht. . 



Celaya (lat. 20 38'), 6017 feet, Ht. 



Queretaro (lat. 20 36' 39"), 6363 feet, Ht. 



San Juan del Rio, in the State of Queretaro (lat. 20 SO'). 

 6490 feet, Ht. 



Tula (lat. 19 57'), 6733 feet, Ht. 



Pachuca, 8140 feet, lit. 



Moran, near Real del Monte, 8511 feet, Ht. 



Huehuetoca, at the northern extremity of the great plain 

 of Mexico (lat. 19 48'), 7533 feet, Ht. 



Mexico (lat. 19 25' 45"), 7469 feet, Ht. 



Toluca (lat. 19 16'), 8825 feet, Ht. 



Venta de Chalco, at the south-eastern extremity of the 

 great plain of Puebla, 7712 feet, Ht. 



San Francisco Ocotlan, at the western extremity of the 

 great plain of Puebla, 7680 feet, Ht. 



Cholula, at the foot of the ancient graduated Pyramid 

 (lat. 19 C 2'), 6906 feet, Ht. 



La Puebla de los Angeles (lat. 19 0' 15"), 7201 feet, Ht. 



(The village of las Vigas marks the eastern extremity of 

 the elevated plain of Anahuac, lat. 19 37' ; the height of 

 the village is 7814 feet, Ht). 



Thus, though previous to the commencement of the 19th 

 century not a single altitude had been barometrically taken 

 in the whole of JS"evv Spain, the hypsometrical and in most 

 cases also astronomical observations for thirty-two places in 

 the direction from north to south, in a zone of nearly 16^ 

 of latitude, between the town of Santa Fe and the capital 

 of Mexico, have been accomplished. We thus see that the 

 surface of the wide elevated plain of Mexico assumes an 

 undulating form varying in the centre from 5850 to 7500 

 feet in height. The lowest portion of the road from Parras 

 to Albuquerque is even 1066 feet higher than the highest 

 point of Vesuvius. 



The great, though gentle, 15 swelling of the soil, whose 



15 Compare Fremont, Report of the Exploring Exped. in 1842, p. 60; 

 Dana, Geology of the United States Expl. Exped. pp. 611 t>13; aud fof 



