"Look," said Hero John with a reassuring smile. "The chin strap buckles so--be sure it fits snug, else it will pound on thy head to the podoko's stride. If thou wouldst turn to the left, pull the rein so, to the right so, and if thou wouldst stop, pull strongly on the nose ring; 'tis not so difficult." He laid a friendly hand on Nelson's flannel clad shoulder. "How wilt thou manage thy curious weapon?" he inquired doubtfully. "Perhaps thou hadst best leave it behind." There was a grim smile on Nelson's weary and wind burned features. "Not on your life, old son! This Winchester and I stick closer together than the Siamese twins." Nelson thrust his foot into a heavy stirrup, eased his weight into the high peaked saddle and gripped the pommel, for though an excellent horseman, he had no clue as to what motion would ensue. It was wise he did so, for the podoko reared suddenly, almost flinging his rider from the saddle. * * * * * Immediately Hero John mounted, raised his right hand and dealt his podoko a stinging slap on the fore-shoulder. The great reptile hissed in protest, but commenced to walk off with an awkward, hopping step. Nelson's mount followed suit. Faster and faster ran the podokos, their long and scale-covered necks stretched far out ahead while their tails lifted correspondingly, much like that of an airplane about to take off. "Whew! He must be doing all of forty-five," gasped Nelson, while the wind whistled about his ears and snapped madly at the yellow crest of his brazen helmet. The ride which ensued remained forever fixed in the aviator's memory. Like so many shots from a gun the three podokos darted off out of the stables, past a gate guarded by a battery of retortii, whose red plumed cannoneers sprang to attention as the three strangely assorted riders sped out into the amber, perpetual light of Atlans. Nelson, on finding his balance, looked about him to receive impressions of immensely tall structures, of pyramids which, like the ziggurats of Sumaria, and Babylon, were surmounted with beautifully proportioned temples. "Must be at least a million people in this burg of Heliopolis," thought Nelson, easing his Winchester. Hour after hour they sped along, frequently overtaking detachments of troops. Twice they halted to change mounts, though the podokos seemed quite tireless. At the end of five hours' furious riding, Nelson beheld a dense white cloud low on the horizon. "What's that?" he demanded. "Fog?" "No," Hero John informed him. "Yonder flows the Apidanus, the boiling river. Not far away to the left lies the frontier fortress of Cierum, where is encamped the Emperor, who will sit in judgment upon thee." Nelson's heart sank. He had been so occupied with his fears for Alden that he had not dwelt upon his own precarious position. * * * * *