At odd times, night times perhaps, the boy will ride in engine cabs and gradually acquire a knowledge of one of these great machines such as no text-book would ever give him. Then comes his first big opportunity. There is a vacancy among the engine crews; the road foreman of engines gives him a good report, and he begins to have dealing with the train-master. He is made a fireman, and he travels the division end to end, day in and day out. Now he knows why the railroad requires physical tests as well as tests of eyesight and of hearing. Even after he has taken another step in advance and been promoted to the passenger service (we will assume that ours is a bright, ambitious boy), he will only find that his labors in the engine-cab have been increased. It is no slight task, firing a heavy locomotive over 100 or more miles of grade-climbing, curve-rounding railroad. It is a task that fairly calls for human arms of steel; for some firemen handle some 17 tons of coal in a single run. The appetite of that firebox is seemingly insatiable. There is hardly a moment during the run that it is not clamoring to be fed, and that the fireman is not hard at it there on the rocking floor of the swaying tender, reaching from tender coal to firebox door. But the day does come, if he sticks hard at it, when he becomes an engineer. He has learned the line well, during his countless trips over it as fireman. He has come to know every signal, every bridge, every station, every curve, every grade, every place for slow, careful running, every place for speeding, as thoroughly as ever river pilot learned his course. There have been many times when he has had to assume temporary charge of the engine. He is a qualified man at least to sit in the right hand of the cab, to have command over reverse lever and over throttle. His work is of a different sort already. The hard physical labor is a thing of the past, most of the time he sits at his work. But responsibility replaces physical stress, and the farmer boy now realizes which of the two is more wearing. Upon his judgment--instant judgment time and time and time again--the fate of that heavy train depends. After he has been promoted from freight engineer to passenger engineer he has a train filled with humanity, and he knows the difference. By day the inclination of a single blade, by night the friendly welcome or the harsh command of changeable lights must never escape him. One slip, and after that--