NOTES. Ixxxi 



and 13,528 according to Homer in Kotzebue's Voyage. The data, on which the 

 last-named result is based, were first published, by Von Buch, in the Descr. 

 phys. des lies Canaries, p. 379. Compare Wilkes, Explor. Exped. vol. iv. 

 p. 111162. The eastern margin of the crater is only 13,428 feet. Mauna- 

 roa being stated to be without snow (lat. 19 28'), the assumption of a greater 

 height would be in opposition to the result found by me in Mexico by many 

 measurements, giving, for the lower limit of perpetual snow, in the same latitude 

 14,470 feet. (Humboldt, Voy. aux Re'g. e'quinox. t. i. p. 97; Asie Centr. t. iii. 

 p. 269 and 359.) 



( 36 ) p. 247. This volcano rises to the west of the village of Cumbal, which 

 is itself 10,563 feet above the sea. (Acosta, p. 76.) 



( 361 ) p. 247. I give the result of Erman's repeated measurements in Sept. 

 1829. The height of the margin crater must be subject to alterations from the 

 effects of the numerous eruptions; for measurements, equally carefully taken in 

 Aug. 1828, had given 16,029 feet. Compare Erman's Physikalische Beobach- 

 tungen auf einer Eeise urn die Erde, Bd. i. S. 400 and 419, with the " Histo- 

 rischen Bericht " of the Travels, Bd. iii. S. 358360. 



( 362 ) p. 247. Bouguer and La Condamine, in the Inscription at Quito, 

 give for Tungurahua before the great eruption of 1772, and before the earth- 

 quake of Riobamba (1797), which caused great mountain-falls, 16,773 feet: I 

 found trigonometrical ly, in 1802, only 16,490 for the summit of the volcano. 



( 363 ) p. 248. The barometric measurement of the highest summit 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 in- 

 dependence and freedom of his native land), is given by Acosta (Viajes cientifi- 

 cos, p. 70) at 17,006 feet. For the little crater (Azufral del Boqueron), from 

 which sulphureous vapours issue with a violent noise, I found 14,414 feet. 

 (Humboldt, Eecueil d'Observ. astron. et d'Ope'rations trigon. vol. i. p. 304.) 



(^^ p. 248. Sangay is exceedingly remarkable for its uninterrupted acti- 

 vity, and for its situation : being somewhat to the east of the eastern Cordillera 

 of Quito, south of the Rio Pastaza, and 104 geographical miles from the nearest 

 part of the coast; therefore (like the volcanoes of the "Celestial Mountains" in 

 Asia) far from lending any support to the theories which say that the eastern 

 Cordilleras of Chili are free from volcanic eruptions by reason of their distance 

 from the sea. Darwin did not fail to remark, in some detail, on the subject of 

 this old and widely diffused coast-theory, in his Geological Observations on South 

 America, 1846, p. 185. 



( 36S ) p. 248. I measured the height of Popocatepetl, also called the Volcan 

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

 VOL. IV. / 



