The thaw was much more pronounced in November, when the ice had nearly disappeared even from the lowest parts of the cave, and they found the air within quite warm.

On Christmas Day they had great difficulty in reaching the glaciere, and narrowly escaped destruction by an avalanche, which for a time deterred them from prosecuting the adventure: they persisted, however, and were rewarded by finding only water where in summer all was ice, and a temperate warmth in the cave.

They observed that the roof had fissures like chimneys.
This account was so circumstantial, that the only thing left was to attempt an explanation of the phenomena reported, and such explanations have not been wanting.

But M.Thury was not quite satisfied, and he determined to visit the cave in the winter of 1860-1.

Accordingly, accompanied by M.Andre Gindroz, who had already joined him in his unsuccessful attempt to reach the Glaciere of the Pre de S.Livres, he left Geneva on the 10th of January, and slept at the Chartreuse in the Valley of Reposoir.