TRUE VOLCANOES. 251 



The volcano TunguraJiua : 16,494 feet, according to a trgonometrical 

 measurement 33 by Kumboldt. 



The volcano of Purace, 39 near Popayan: 17,010 feet, according to 

 Jos Caldaa. 



Fifth group, from 16,000 to more than 20,000 Paris or from 

 17,056 to 21,320 English feet in height. 



The volcano Sangay, to the south-west of Quito: 17,128 feet, ac- 

 cording to Bouguer and La Condamine. 40 



The volcano Popocatepetl: 41 17,729 feet, according to a trigonometri- 

 cal measurement by Humboldt. 



The volcano of Orizaba: 4 ' 2 17,783 feet, according to Ferrer. 



38 Bouguer and La Condamine, in the inscription at Quito, give 

 16,777 feet for Tungurahua before the great eruption of 1772, and the 

 earthquake of Riobamba (1797), which gave rise to great depressions of 

 mountains. In the year 1802 I found the summit of the volcano trigo- 

 nometrically to be ouiy 16,494 feet. 



39 The barometrical measurement of the highest peak of the Volcan 

 de Purace" by Francisco Jose Caldas, who, like my dear friend and 

 travelling companion, Carlos Montufar, fell a sacrifice to his love for 

 the independence and freedom of his country, is given by Acosta 

 (Viajes Cientifaos, p. 70) at 5184 metres (17,010 feet). I found the 

 height of the small crater, which emits sulphureous vapours with a 

 violent noise (Aznfral del Boqueron) to be 14,427 feet; Humboldt, 

 Recueil d'Observ. Astronomiques et d' Operations Trigonometriques, vol. i, 

 p. 304. 



40 The Sangay is extremely remarkable from its uninterrupted activity 

 and its position, being removed somewhat to the eastward from the 

 eastern Cordillera of Quito, to the south of the Rio Pastaza, and at a 

 distance of 120 miles from the nearest coast of the Pacific, a position 

 which (like that of the volcanoes of the Celestial mountains in Asia) 

 by no means supports the theory according to which the eastern Cor- 

 dilleras of Chili are free from volcanic eruptions on account of their 

 distance from the sea. The talented Darwin has not omitted referring 

 in detail to this old and widely diffused volcanic littoral theory in the 

 Geological Observations on South America, 1846, p. 185. 



41 I measured Popocatepetl, which is also called the Volcan 

 Grande de Mexico, in the plain of Tetimba, near the Indian village San 

 Nicolas de los Ranchos. It seems to me to be still uncertain which of 

 the two volcanoes, Popocatepetl or the pe;ik of Orizaba, is the highest 

 (see Humboldt, Receuil d'Observ. Astron., vol. ii, p. 543). 



42 The peak of Orizaba, clothed with perpetual snow, the geogra- 

 phical position of which was quite erroneously indicated on all maps 

 before my journey, notwithstanding the importance of this point for 



