HYPSOMETRIC ADDENDA. 209 



are appended three profile delineations of the country; one 

 from Santa Fe to Chihuahua over Passo del Norte ; one from 

 Chihuahua over Parras to Reynosa; and one from Fort Inde- 

 pendence (a little to the east of the confluence of the Missouri 

 and the Kanzas River) to Santa Fe. The calculation is based 

 on daily corresponding observations of the barometer, made 

 by Engelmann at St. Louis, and by Lilly in New Orleans. 

 If we consider that in the north and south direction the dif- 

 ference of latitude between Santa Fe and Mexico is more 

 than 16°, and that, consequently, the distance in a direct 

 meridian direction, independently of curvatures on the road, 

 is more than 960 miles; we are led to ask whether, in the 

 whole world, there exists any similar formation of equal extent 

 and height (between 5000 and 7500 feet above the level of 

 the sea). Four-wheeled waggons can travel from Mexico 

 to Santa Fe. The plateau, whose levelling I have here 

 described, is formed solely by the broad, undulating, flattened 

 crest of the chain of the Mexican Andes ; it is not the 

 swelling of a valley between two mountain-chains, such as the 

 " Great Basin " between the Rocky Mountains and the Sierra 

 Nevada of California, in the Northern Hemisphere, or the 

 elevated plateau of the Lake of Titicaca, between the eastern 

 and western chains of Bolivia, or the plateau of Thibet, 

 between the Himalaya and the Kuenlun, in the Southern 

 Hemisphere. 



