From the tier of the upmost holes came at length the terrific burst of the heavy mines. The travail of an awful instant followed, the face of the spur parted from its side, toppled an instant in the confusion of its rending and with an appalling crash fell upon the river below. With the fragments still tumbling, the nearest men started with a cheer from their concealment. Smoke rolling white and sullen upward obscured the moon, and the canyon air, salt and sick with gases, poured over the high point on which the Pittsburgers stood. Below, torches were shooting like fireflies out of the rock. From every vantage point headlights flashed one after another unhooded on the scene, and the song of the river mingled again with the calling of the foremen. "That ends the fireworks," remarked Bucks to those about him. "Let us watch a moment for Mr. Glover's signal to me. As soon as he inspects he is to show signals on the Cat's Paw, and if it is a success we will return at once to Sleepy Cat." "And by the way, Mr. Bucks, I shall expect you and Mr. Glover up to the car for my game supper. Have you arranged for him to come?" "I have, Mrs. Whitney, thank you." "Oh, see those pretty red lights over there now. What are they?" asked Louise, who stood with Allen Harrison. "The signals," exclaimed Bucks. "Three fusees. Good for Glover; that means success. Shall we go?" When the sightseers made their way out of the canyon material trains working from both ends of the break were shoving their loaded flats noisily up to the ballasting crews and the water was echoing the clang of the spike mauls, the thud of tamping-irons, the clash of picks, the splash of tumbling stone, and the ceaseless roll of shovels. Foot by foot, length by length, the gap was shortened. Bribed by extra pay, driven by the bosses, and stimulated by the emergency, the work of the graders became an effort close to fury. Watches were already consulted and wagers were being laid between rival foremen on the moment a train should pass the point. Above the peaks the stars glittered, and high in the sky the moon shot a path of clear light down the river itself. The camp kettles steamed constantly, and coffee strong enough to ballast eggs and primed with unusual cordials was passed every hour among the hundreds along the track. In the lower yard at Sleepy Cat the pilot train was being made ready and the clatter of switching came into the canyon. From still further came the barking exhaust of the first-train engine waiting for orders for the canyon run.