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covered with sand, and, in tho same manner as at the peak, 
iar below the inferior limit of the perpetual snows. 
It was near the Ice-Cavern (Cueva del Hielo), that, in 
the voyage of Lapcrousc, Messrs. Lanianon and Monges 
made their experiments on the temperature of boiling water. 
These naturalists found it SS'7°, the barometer at nineteen 
inches one line. In the kingdom of New Grenada, at the 
chapel of Guadaloupc, near Santa-Fe de Bogota, I have seen 
water boil at S9'9\ under a pressure of 19 inches 1-9 lines. 
At Tambores, in tho province of Popavan, Senor Caldas 
found the heat of boiling water S9'5 0 , the barometer being at 
18 inches 11-6 lines. These results might lead us to suspect, 
that, in the experiment of M. Lamanon, the water had not 
reached the maximum of its temperature. 
Day was beginning to dawn when we left the ice-cavern. 
We observed, during the twilight, a phenomenon which is not 
unusual on high mountains, but which the position of the 
volcano we were scaling rendered very striking. A layer 
ot white and fleecy clouds concealed from us the sight of 
1 he ocean, and the lower region of the island. This layer 
did not appear above 800 toises high ; the clouds were so 
uniformly spread, and kept so perfect a level, that they wore 
the appearance of a vast plain covered with snow. The 
colossal pyramid of the peak, the volcanic summits of Lan- 
cerota, of Forteventura, and tho isle of Palma, were like 
rocks amidst this vast sea of vapours, and their black tints 
were in fine contrast with the whiteness of the clouds. 
While we were climbing over the broken lavas of the 
Malpays, wo perceived a very ciu-ious optical phenomenon, 
which lasted eight minutes. - We thought we saw on the 
east side small rockets thrown into the air. Luminous 
points, about seven or eight degrees above the horizon, 
appeared first to move in a vertical direction ; but their 
motion was gradually changed into a horizontal oscillation. 
Our fellow-travellers, our guides even, were astonished at 
this phenomenon, without our having made any remark on 
it to them. We thought, at iirst sight, that these luminous 
points, which floated in the air, indicated some new erup- 
tion of the great volcano of Laneerota ; for we recollected 
that Bouguer and La Condamine, in scaling the volcano of 
Piehineha. were witnesses of the eruption of’ Cotopaxi. But 
