A quarter of an hour later from the deck Worsley saw the sun set a second time. This strange phenomenon was due to mirage or refraction. We attributed it to an ice-crack to the westward, where the band of open water had heated a stratum of air.
The drift of the pack was not constant, and during the succeeding days the crevassed berg alternately advanced and receded as the Endurance moved with the floe. On Sunday, April 18, it was only seven miles distant from the ship.
"It is a large berg, about three-quarters of a mile long on the side presented to us and probably well over 200 ft. high. It is heavily crevassed, as though it once formed the serac portion of a glacier. Two specially wide and deep chasms across it from south-east to north-west give it the appearance of having broken its back on the shoal-ground. Huge masses of pressure-ice are piled against its cliffs to a height of about 60 ft., showing the stupendous force that is being brought to bear upon it by the drifting pack. The berg must be very firmly aground. We swing the arrow on the current-meter frequently and watch with keen attention to see where it will come to rest. Will it point straight for the berg, showing that our drift is in that direction? It swings slowly round. It points to the north-east end of the berg, then shifts slowly to the centre and seems to stop; but it moves again and swings 20 degrees clear of our enemy to the south-west.... We notice that two familiar bergs, the Rampart Berg and the Peak Berg, have moved away from the ship. Probably they also have grounded or dragged on the shoal." A strong drift to the westward during the night of the 18th relieved our anxiety by carrying the Endurance to the lee of the crevassed berg, which passed out of our range of vision before the end of the month.
We said good-bye to the sun on May 1 and entered the period of twilight that would be followed by the darkness of midwinter. The sun by the aid of refraction just cleared the horizon at noon and set shortly before 2 p.m. A fine aurora in the evening was dimmed by the full moon, which had risen on April 27 and would not set again until May 6. The disappearance of the sun is apt to be a depressing event in the polar regions, where the long months of darkness involve mental as well as physical strain. But
