I835.J Ascent of Chimhorazo. 257 



for the summit was crowned by a glacier. I may remark, 

 that, during the time I was ascending, and until I attained 

 the snow limit, this blue tint seemed much less deep. 



On Antisana, before reaching the snow, the sky possessed 

 its usual colour, but whenever we reached the great mass 

 of ice, it appeared to have assumed an inky blackness. This 

 phenomenon struck the negro who carried my barometer 

 with consternation. In the evening we were seized with 

 inflammation of the eyes, which rendered us blind for some 

 days. 



Lastly, when I ascended Cotopaxi, I, as well as my com- 

 panion, wore coloured spectacles. When we had walked 

 for five hours, over the snow, we halted at 5,719 metres 

 (18,758 feet.) 



The sky then appeared, to the naked eye, not to possess a 

 deeper colour than that of the plain ; just as upon Chimhorazo 

 we recognized the sky of Rio Bambo and Quito. I do not 

 mean to deny that the colour of the sky is not really more 

 intense on high mountains than at the level of the sea, as 

 I had no cyanometer. I am rather disposed to admit the 

 general results obtained by Saussure by means of this instru- 

 ment. All that I wish to establish is, that this difference 

 of tints is only perceptible by comparison, and that the 

 black colour of the heavens, as seen upon the glaciers, is 

 occasioned by the weakness of the organs of vision ; per- 

 haps, also by an effect of contrast easily conceived. 



The mountaineers who accompanied Saussure on his 

 memorable ascent of Mount Blanc, afiirm that they saw the 

 stars by day light. Saussure, himself, was not a witness of 

 the phenomenon, his attention was directed to other objects ; 

 but he has not expressed any doubts with regard to the 

 assertion of his guides. 



On Chimhorazo, I may add, on none of the mountains of 

 the Andes, upon which I attained. a greater elevation than 

 ever Saussure did upon the Alps, I could never perceive the 

 stars in the day-time. Several times, and especially at the 

 station of Pena Colorada, I was situated most favourably 

 for observing this phenomenon ; as I was placed in the 

 shade, and at the bottom of a very high wall of trachyte. 



During the time that we were occupied in making our 

 observations on Chimhorazo, the weather was extremely 



VOL. II. s 



