.75 F. The external temperature in the shade was at the
same time 83 deg. F.
A third visit, in January 1835, gave no results; but on January 21,
1838, the Professor succeeded in determining some very remarkable
facts. A depression in the sloping plain is called, _par excellence_,
the ice-hole; and this is surrounded by firs and birches, which grow
within three or four fathoms of the edge of the hole, so that the
rays of the sun do not reach the hole in winter. Fresh snow lay on
these trees; and there was nowhere any sign of melted snow, or of the
formation of icicles. The basaltic _debris_, in which ice had been
found in the summer, covers here a space of 5 fathoms long by 3 or 4
broad, immediately at the foot of a steep basaltic precipice. At
eleven in the morning the temperature was 14 deg. F. in the shade; and
snow lay all round the ice-hole, to a thickness of 1-1/2 or 2 feet.
The snow which covered the _debris_ was pierced by holes, which could
not have been caused by the sun, for its rays did not penetrate the
trees; and, indeed, no sun had been visible for some days.
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