Then they went on to the end of the cross-cut, and, turning at a sharp angle, they came into the drift, the long gallery running through the vein. For some distance, the drift, like the cross-cut, was lined with timbers, then the lining ceased, as they neared the end of the drift, where the miners were hard at work, drilling for fresh blasts, or tearing out the ore loosened by the last explosion, and loading it into the little car which stood ready to be run down the track to the station. Seven feet above, so that the roof of the lower level formed the flooring of the next, was another short gallery, where the men were busy stoping, digging out the ore from the upper tier. Dingy and grimy as they were, it was fascinating to watch them, burrowing, like so many moles, in the depths of the earth. The visitors lingered to look at them until they were frightened away by the preparations for a blast; then they slowly made their way back to the station, pausing a moment to watch a loaded car, as it rolled from the rails to the polished steel flooring, and swung around the corner into position, to wait for the cage. Mr. Everett looked at his watch. "I'm sorry to hurry you," he said; "but I think we ought to be going; don't you, Somers? It's change day; and at three the cages will be full." "Change day!" remarked Charlie to his cousin, in an undertone; "what's that?" "Hush!" she whispered. "Don't show Dr. Hornblower how little you know. Remember that you're from the East, too." But Dr. Brownlee was animated by no such motives of prudence, and quietly asked for an explanation of the term. "We have two sets of men," Mr. Everett answered. "The day shift goes on at seven, and works till half past five; and the night one comes on at seven in the evening, and stays till half past five in the morning. Of course that's harder on one set of men than the other, so, once in two weeks, we have what we call change day. The day shift goes on at seven, and works till three; then the night fellows come right on and stay till eleven; and the old day shift comes back at eleven. By the next morning, you see, their places are just changed, and the night men are working in the daytime. Now," he added, as he stepped to the shaft, to ring his own private signal; "we'll go up and take a look through the smelter before--Why, where are Mrs. Pennypoker and Dr. Hornblower?"