234 VIEWS, &C. PHYSIOGNOMY OF PLANTS, 



journals.* This Saxifrage, discovered by Boussingault, must 

 therefore be regarded as the highest growing phanerogamic 

 plant in the world. 



The vertical height of Chimborazo is, according to my 

 measurement, 21,422 feet.f This result is a mean between 

 those which have been given by the French and Spanish 

 Academicians. The principal differences do not here 

 depend on different assumptions for the refraction, but on a 

 difference in reducing the measured line to the level of the 

 sea. This reduction can only be made in the Andes by the 

 barometer, and hence every so-called trigonometric measure- 

 ment must also necessarily be a barometric one, whose 

 result will vary according to the different formulae employed. 

 Owing to the enormous mass of the mountain chain, we can 

 only obtain very small angles of altitude, when the greater 

 portion of the whole height has to be measured trigono- 

 metrically, and the observation is made at some low and dis- 

 tant point near the plain or the level of the sea. It is on the 

 other hand extremely difficult to obtain a convenient base 

 line, as the space that is to be determined barometrically 

 increases with every step we advance towards the mountain. 

 These obstacles have to be encountered by every traveller 

 who on the high table-lands, which surround the summit of 

 the Andes, selects a spot for performing a geodetic operation. 

 On the pumice-covered plain of Tapia, to the west of the llio 

 Chambo, at a height of 9477 feet, barometrically deter- 

 mined, I measured the Chimborazo. The Llanos de Luisa, 

 and more especially the plain of Sisgun, whose elevation is 

 12,150 feet, would yield greater angles of altitude. I had on 

 one occasion made every preparation necessary for the 

 measurement of Mount Chimborazo, from the plain of Sisgun, 

 when the summit of the mountain was suddenly shrouded in 

 a dense cloud. 



Some hypothetical suggestions, regarding the probable deri- 

 vation of the name of the far-famed "Chimborazo," may not 

 be wholly unwelcome to etymologists. The district in which 

 the mountain is situated is called Chimbo, a word which La 



* Compare my Asie oentrale, t. iii. p. 262, with Hooker, Journal 

 of Botany, vol. i. 1834, p. 327, and the Edinburgh New Philosophical 

 Journal, vol. xvii. 1834, p. 380. 



f Recueil d'Observ. astron., t. i. Intr. p. Ixxii. 



