This is a not unusual character of the most beautiful part of the decorations of the more sheltered ice-caves, as for instance the lowest cave in the Upper Glaciere of the Pre de S.Livres; the white appearance is not due to the presence of air, for the ice is transparent and homogeneous, and the naked eye is unable to detect bubbles or internal fissures.
The temperatures at 1.25 P.M.and 2.12 P.M.respectively were as follows:--In the sun, between 3 and 4 feet above the snow, 72 deg..1 and 70 deg..5; in the shade, outside the cave, 36 deg..7 and 35 deg..8; at the Observatory of Geneva, in the shade, 27 deg..3 and 28 deg..2, having risen from 24 deg..5 since noon.

In the cave, 1 foot above the surface of the ice-floor, the thermometer stood at 24 deg..8; and in a hole in the ice, some few inches below the surface, 24 deg..1.

In the large fissure, which has been already mentioned as the source of the summer currents of air, the temperature at various points was from 29 deg..3 to 27 deg..5.

The circumstances of these currents of air were now of course changed.

Instead of a steady current passing from the fissure into the cave, and so out by the main entrance into the open air, strong enough to incline the flame of a candle 45 deg., M.Thury found a gentle current passing from the cave into the fissure, sufficient only to incline the flame 10 deg., and near the entrance 8 deg., while in the entrance itself no current was perceptible at 4 P.M.
M.Thury remarks that less current was to be expected in winter than in summer, because the upper ends of the fissures would be probably choked with snow, and their lower ends with ice.