"From the mast-head the mirage is continually giving us false alarms. Everything wears an aspect of unreality. Icebergs hang upside down in the sky; the land appears as layers of silvery or golden cloud. Cloud-banks look like land, icebergs masquerade as islands or nunataks, and the distant barrier to the south is thrown into view, although it really is outside our range of vision. Worst of all is the deceptive appearance of open water, caused by the refraction of distant water, or by the sun shining at an angle on a field of smooth snow or the face of ice-cliffs below the horizon."