212 ' TRAVELS AMONGST THE GREAT ANDES, chap. xi. 



lava about one hundred and fifty paces long, mainly firm rock, 

 though strewn with loose, decomposing blocks, amongst which 

 there were a number of lumps of pumice, up to a foot or rather 

 more in diameter.^ Close to the very highest point (15,918 feet),^ 



1 Professor Bonney says : — '' In the rock from the summit of Guagua-Piehincha, 

 the external surfaces have a slightly scoriaceous aspect ; and, where the lichen- 

 growth is chipped away, are of a dull grey to rusty-brown colour. The fractured 

 faces shew the matrix to be of a dull, but not dark colour, in places slightly vesi- 

 cular, the walls of the hollows being coated with a pellicle of iron rust. In the 

 matrix are scattered pretty thickly whitish felspar crystals, not generally exceeding 

 0*2 inch in diameter, and granules of a black mineral, less than 0*125 inch in 

 diameter. . . The rock is a hornblende-andesite." 



The specimen "from the highest point of Rucu-Pichincha " (the peak ascended 

 by Louis Carrel is presumably Rucu) "is a compact grey rock, containing scattered 

 crystals of a glassy felspar up to about 0*2 inch in diameter, and smaller specks 

 of a black pyroxenic mineral. . . Grains of magnetite occur. . . The matrix is 

 often darkened by specks of kaolin and ferrite. . . The rock is a hyperstheni- 

 ferous augite-andesite." — Proc. Royal Soc, Jan. 31, 1884. 



2 At 11.15 a.m., on March 23, the Mercurial Barometer, reduced to 32° Faht., 

 read 16*974 inches, with air temperature 46° Faht. The 11 a.m. reading at 

 Guayaquil (reduced to 32°) was 29*882 inches, air temperature 80° Faht. 



Messrs. Reiss and Stiibel give the height of 15,706 feet (4787 metres) for Guagua- 

 and 15,542 feet (4737 metres) for that of Rucu-Pichincha. These elevations were 

 determined by A, not by barometrical observations on the summit. According to 

 them, Guagua is the western and Rucu is the eastern summit. 



La Condamine, at p. 33 of his Journal du Voyage^ gives 2430 toises as the 

 height of \i\s, '■'■ station on the higliest point of Pichincha {statioii sur le plus haut 

 sommet de Pitchincha) " ; and at p. 56 of his Mesure des trois premiers Degres he gives 

 the same amount (2430 toises) as the height of the eastern summit. As the highest 

 summit of Pichincha is the westeroi one, I feel somewhat perplexed. 



Humboldt makes various references in his works to Pichincha, and in such a 

 way as to lead one to suppose that he had been upon the very highest point of the 

 mountain. I feel unable to say whether he did attain the highest point. At p. 28 

 of the section entitled Nivellement Barometrique in his Recueil d'' Observations Astro- 

 nomiques, he gives 4854 metres as the height of Rucu-Pichincha, "the most eastern 

 of three rocky towers." This is equal to 15,925 English feet, which closely corre- 

 sponds with the height I found for Guagua-Pichincha. He further puzzles me by a 

 footnote, at the beginning of which he states that Pichincha has four principal 

 summits, and speaks of a fifth one at the end ; and he completes my bewilder- 

 ment by saying that M. de la Condamine did not measure Rucu, although that 

 gentleman gives 2430 toises as the height of the eastern summit, which all are 

 agreed is Rucu-Pichincha. 



