All pursuit of him was out of the question; it was impossible to leap across the fiery torrent, and equally impossible to get round it. Altamont, indeed, was mad enough to make an attempt, and would certainly have lost his life if the others had not held him back by main force. "Hatteras! Hatteras!" shouted the Doctor, but no response was heard save the faint bark of Duk. At intervals, however, a glimpse of him could be caught through the clouds of smoke and showers of ashes. Sometimes his head, sometimes his arm appeared; then he was out of sight again, and a few minutes later was seen higher up clinging to the rocks. His size constantly decreased with the fantastic rapidity of objects rising upwards in the air. In half-an-hour he was only half his size. The air was full of the deep rumbling noise of the volcano, and the mountain shook and trembled. From time to time a loud fail was heard behind, and the travellers would see some enormous rock rebounding from the heights to engulph itself in the polar basin below. [Illustration: Hatteras did not even turn once to look back, but marched straight on, carrying his country's flag attached to his staff.--P.249] Hatteras did not even turn once to look back, but marched straight on, carrying his country's flag attached to his staff. His terrified friends watched every movement, and saw him gradually decrease to microscopic dimensions, while Duk looked no larger than a big rat. Then came a moment of intense anxiety, for the wind beat down on them an immense sheet of flame, and they could see nothing but the red glare. A cry of agony escaped the Doctor; but an instant afterwards Hatteras reappeared, waving his flag. For a whole hour this fearful spectacle went on--an hour of battle with unsteady loose rocks and quagmires of ashes, where the foolhardy climber sank up to his waist. Sometimes they saw him hoist himself up by leaning knees and loins against the rocks in narrow, intricate winding paths, and sometimes he would be hanging on by both hands to some sharp crag, swinging to and fro like a withered tuft. [Illustration: ] At last he reached the summit of the mountain, the mouth of the crater. Here the Doctor hoped the infatuated man would stop, at any rate, and would, perhaps, recover his senses, and expose himself to no more danger than the descent involved. Once more he shouted-- "Hatteras! Hatteras!" There was such a pathos of entreaty in his tone that Altamont felt moved to his inmost soul. "I'll save him yet!" he exclaimed; and before Clawbonny could hinder him, he had cleared with a bound the torrent of fire, and was out of sight among the rocks. Meantime, Hatteras had mounted a rock which overhung the crater, and stood waving his flag amidst showers of stones which rained down on him. Duk was by his side; but the poor beast was growing dizzy in such close proximity to the abyss.