"Yes, your work," commanded Blake, his face as hard as iron. "We're going to survey Deep Canyon down to the tunnel site. Your work is to carry rod. Do you get that?" "Down the canyon?--deeper!" "We can't get back up here. There's a place down there beyond the tunnel site where perhaps we can make it up the canyon wall." "A place where we--?" shrilled Ashton. "A place--Good God! and you stand here doing nothing!" He whirled to spring out into the swirling water. Blake was still swifter in his movements. He caught the fugitive by the arm and dragged him back. "Wait!" he commanded. "We must first carry the levels down to the tunnel site. You hear that? Stick by me, and I'll pull you through. Try to run, and, by God, I'll shoot you like a dog!" The captive glared into the steel-white eyes of the engineer, anger overcoming his panicky fear. "Let go!" he panted. "Don't worry! I'll do my work--I'll do my work!" "If you don't, you'll never get out of this canyon," grimly rejoined Blake. He released his hold, and started up the slope, with a curt order: "Come along. We can rod down the slope." Ashton followed him, silent and morose. The instrument was screwed to its tripod, and a line of levels from the foot of the last vertical measurement was carried down the slope to the canyon. The last rod reading was on a ledge, three feet above the water, at the corner of the gorge. Blake considered the reading worthy of permanent record. They had measured all the many hundreds of feet down from the top of High Mesa to these profound depths. With his two-pound hammer and one of the few remaining spikes, he chiseled a cross deep in the surface of the black rock. That mark of the engineer-captain, scouting before the van of man's Nature-conquering army, was the sign of the first human beings that had ever descended alive to the bottom of Deep Canyon. When he had cut the cross, Blake took out his Colt's, and, gazing up the heights, began to fire at slow intervals. Confined between the walls of gorge and canyon, each report of the heavy revolver crashed out above the tumult of the river and ran echoing and reechoing up the stupendous precipices. Yet long before they reached the rim of those towering walls they blurred away and merged and were lost in the ceaseless reverberations of the waters. Blake well knew that this would happen. But he also knew that the flash of the shot would be distinctly discernible in the gloom of the abyss. As he fired, he scanned the verge of the uppermost precipices. After the fourth shot he ceased firing and flung up his hand to point at the heights. "Look!" he shouted. "They see! There is the flag!"