This, when reduced and combined with the mean of the aneroid levels, made the height of the old crater rim, just above the camp, 11,400 ft. At 6 A.M. the party left the camp, and, hastening to reach the summit of the present crater, were soon ascending rather steep slopes, formed of alternating beds of hard snow and vast quantities of large and perfect felspar crystals, mixed with pumice. And a little farther on they reached the base of the volcano's active cone. Progress now became painfully slow, as the height and cold combined to make it difficult to breathe. The cone of Erebus is built chiefly of blocks of pumice, from a few inches to a few feet in diameter. Externally these were grey, or often yellow, owing to incrustations of sulphur, but when broken they were of a resinous, brown colour. At last, just after 10 A.M. on March 10, the edge of the active crater was reached, and the little party stood on the summit of Erebus, the first men to conquer perhaps the most remarkable summit in the world. From measurements made while at the crater's edge, Erebus may be calculated to rise to a height of 13,370 ft. above sea-level. The report most vividly describes the magnificent and awe-inspiring scene before the eyes of the travellers. [Illustration: The "Lion" of Erebus. (_See page 86_)] "We stood on the verge of a vast abyss, and at first could see neither to the bottom nor across it on account of the huge mass of steam filling the crater and soaring aloft in a column 500 to 1000 ft. high. After a continuous hissing sound, lasting for some minutes, there would come from below a big, dull boom, and immediately great globular masses of steam would rush upwards to swell the volume of the snow-white cloud which ever sways over the crater. This phenomenon recurred at intervals during the whole of our stay at the crater. Meanwhile the air around us was extremely redolent of burning sulphur. Presently a pleasant northerly breeze fanned away the steam cloud, and at once the whole crater stood revealed to us in all its vast extent and depth. Mawson's angular measurement made the depth 900 ft., and the greatest width about half a mile. There were at least three well-defined openings at the bottom of the cauldron, and it was from these that the steam explosions proceeded." As soon as the measurements had been made and Mawson had taken some photographs, the party returned to camp, because it had been decided to start the descent during the same afternoon. Numerous specimens of the unique felspar crystals and of the pumice and sulphur were collected on the way back to camp, and, having arrived there, the travellers made a hasty meal, packed up, and started down the steep mountain slope, Brocklehurst insisting on bearing his own heavy load in spite of his frost-bitten feet.