The roof of this inner cavern was hung with undripping solid icicles, and the floor was a conglomerate of ice and frozen earth.

They were assured that the cold is always greatest within when the external air is hottest and driest, and that the ice gradually disappears as winter approaches, and vanishes when the snow comes.

The peasants were unanimous in these statements, and asserted that they could sleep in the cave without sheepskins in the depth of winter.
Sir Roderick Murchison and his friends were at first inclined to explain these phenomena by supposing that the chief fissure communicated with some surface of rock-salt, 'the saliferous vapours of which might be so rapidly evaporated or changed in escaping to an intensely hot and dry atmosphere as to produce ice and snow.' But Sir John Herschel, to whom they applied for assistance, rejected the evaporation theory, and suggested that the external summer wave of heat might possibly only reach the cave at Christmas, being delayed six months in its passage through the rock; the cold of winter, in the same manner, arriving at midsummer.

To this the explorers objected, that the mound contained many caves, but' only in this particular fissure was any ice found.

Dr.
Robinson, astronomer at Armagh, endeavoured to explain the matter by referring to De Saussure's explanation of the phenomena of _cold caves_ in Italy and elsewhere; but this, too, was considered unsatisfactory.