Prof. Pictet on the Ice-caves of the Jura arid lUe Alps . 7 
surface of the ice, stood at 34° J during the whole time we re- 
mained there. 
The work-people told us, that if they left two blocks of ice 
close to each other on the bottom of the grotto, they found them 
frozen together next day ; which proves that the process of con- 
gelation goes on continually in the interior of the grotto, even in 
the hot seasons. 
On our return, our guide made us pass by a spring, which 
issues from the middle of an enormous mass of vertical rock. It 
lies a gunshot to the east in descending. The temperature was 
51°. This temperature is nearly that of the mass of rock from 
which it issues, that is, of the soil of the mountain at this 
height. This fact renders the cold which pervades the neigh- 
bouring cavern only the more extraordinary. 
It still remained for me to visit the other two natural ice- 
caves, which I have before mentioned, that of Mont Brezon 
and that of Reposoir , which I accomplished on the 16th and 
17th of July. 
The ascent of Brezon begins at the little village of Thuet, si- 
tuated immediately at the foot of the mountain : almost all its 
inhabitants are afflicted with goitres, more or less projecting. 
We set out at ten o’clock from Bonneville, and at ten minutes 
after eleven, we arrived at the granary called La Croix, a culti- 
vated slope, which is seen from Bonneville. We found by the 
barometer that we had ascended 148.4 toises. A little farther 
on, the path became very picturesque, creeping round the foot 
of enormous masses of calcareous rock, which were on the right, 
and overhanging a torrent, which comes out of the little lake of 
Saxonnet, and rushed through a profound ravine on the left. 
The geologist observes in front, in the twisted strata of the other ’ 
side of the ravine, one of the most striking phenomena to be 
met with. We saw there an enormous vertical mass, surmounted 
by another, horizontal, and nearly of the same extent. The 
first is bent towards the middle of its vertical mass, by a curve, 
which seems to have been the effect of a local pressure, opera- 
ting whilst the whole mass was in a soft state, but which had been 
preserved, notwithstanding its stratification, in parallel beds of 
nearly equal thickness. Soon after, the path is boldly traced in 
the front of two grottoes, the one situated above the other. 
