"On bending down the ear to the ice," says this explorer, "we could hear on every side a peculiar subterranean hum, proceeding from rivers flowing within the ice; and occasionally a loud, single report, like that of a cannon, gave notice of the formation of a new glacier-cleft.... In the afternoon we saw at some distance from us a well-defined pillar of mist, which, when we approached it, appeared to rise from a bottomless abyss, into which a mighty glacier-river fell. The vast, roaring water-mass had bored for itself a vertical hole, probably down to the rock, certainly more than two thousand feet beneath, on which the glacier rested."[AJ] [Footnote AJ: Geological Magazine, vol. ix, pp. 393, 399.] At the end of the eighteen days Nordenskiöld found himself about a hundred and fifty miles from his starting-point, and about five thousand feet above the sea. Here the party rested, and sent two Eskimos forward on _skidor_--a kind of long wooden skate, with which they could move rapidly over the ice, notwithstanding the numerous small, circular holes which everywhere pitted the surface. These Eskimos were gone fifty-seven hours, having slept only four hours of the period. It is estimated that they made about a hundred and fifty miles, and attained an altitude of six thousand feet. The ice is reported as rising in distinct terraces, and as seemingly boundless beyond. If this is the case, two hundred miles from Disco Bay, there would seem little hope of finding in Greenland an interior freed from ice. So we may pretty confidently speak of that continental body of land as still enveloped in an ice-sheet. Up to about latitude 75°, however, the continent is fringed by a border of islands, over which there is no continuous covering of ice. In south Greenland the continuous ice-sheet is reached about thirty miles back from the shore. A summary of the results of Greenland exploration was given by Dr. Kink in 1886, from which it appears that since 1876 one thousand miles of the coast-line have been carefully explored by entering every fiord and attempting to reach the inland ice. According to this authority--