Jxxxii NOTES. 



de los Ranches. It still appears to me uncertain which of the two volcanoes, 

 Popocatepetl or the Peak of Orizaba, is the highest. Compare Humboldt, Re- 

 cu'eil d'Observ. astron. .vol. ii. p. 543. 



(s 66 ) p. 248. The Peak of Orizaba, covered with perpetual snow, of which, 

 previously to my journey the geographical position was given extremely erro- 

 neously upon all maps and charts notwithstanding its great nautical importance 

 to vessels coming to Vera Cruz, was first measured trigonometrically, in 1796, 

 by Ferrer from Encero. The result was 17,879 feet. I tried a similar opera- 

 tion in a little plain near Xalapa, and found only 17,374 feet; but the angles of 

 altitude were very small, and the base was difficult to level. Compare Hum- 

 boldt, Essai Politique sur la Nouv. Espagne, 2 e eU t. i. 1825, p. 166; my 

 Atlas du Mexique (carte des fausses positions), PI. X. ; and Kleinere Schriften, 

 Bd. i. S. 468 



f 367 ) p. 248. Humboldt, Essai sur la Ge'ogr. des Plantes, 1807, p. 153. 

 The height is uncertain, perhaps more than ^th too great. 



( 3G8 ) p. 248. I measured, in 1802, the height of the truncated cone of the 

 volcano of Tolima, situated at the northern end of the Paramo de Quindiu, in 

 the Valle del Carvajal, near the little town of Ibague. The mountain is also 

 seen, at a great distance, from the high plain of Bogota. At this distance, 

 Caldas, in 1806, by a somewhat complicated combination, obtained a tolerably 

 approximate result, 18,430 feet; Semanario de la Nueva Granada, nueva edicion, 

 aumentada por J. Acosta, 1849, p. 349. 



C 69 ) p. 248. The absolute height of the volcano of Arequipa has been so 

 variously given, that it is difficult to distinguish between mere estimations and 

 actual measurements. The distinguished botanistof Malaspina's Voyage of Circum- 

 navigation, Dr. Thadclaeus Hanke, of Prague, ascended it in 1796, and found on the 

 summit a cross, which had been ei'ected there twelve years before. By a trigonome- 

 trical operation, Hanke is said to have found, for the height of the volcano above the 

 sea, 20,335 English feet (19,080 Paris feet). This result, for the absolute height, 

 is much too great, and may perhaps have arisen from an erroneous assumption of 

 the absolute height of the town of Arequipa, in the neighbourhood of which the 

 operation was executed. If Hanke had then been provided with a barometer, 

 surely, after having been on the summit, he, as a botanist, unaccustomed to 

 trigonometrical operations, would not have resorted to them. The next person 

 who ascended the volcano, was Samuel Curzon, of the United States. (Boston 

 Philosophical Journal, 1823, Nov. p. 168.) In 1830, Pentland estimated it at 

 18,373 feet, and I have used this number (Annuaire du Bureau des Longitudes 

 pour 1'an 1830, p. 325) for my Carte hypsome'trique de laCordillere des Andes, 

 1831. It agrees pretty well (to almost ^) with the trigonometric measure- 



