This method is the very worst possible. What is wanted is a constant moderate supply of water, keeping the pressure as nearly even as possible. Nothing can beat this. When injectors are used one of them should be screwed down so that it will act moderately like a pump. This will save the water which is usually lost in turning injector on and off. ON THE FOOT-PLATE. When the train is under full headway the engineer should stand in his proper place on the foot-plate so as to be able to command the regulator and reversing valve at an instant's notice. Especially is this necessary at night, when the engineer's attention should always be on his engine, listening constantly to its beats to detect any irregularity which may arise from some defect in the machinery, frequently casting his eyes on the pressure gauge, and on the level of the water in the gauge glass. When the fireman puts on coal, the engineer should look round occasionally, to be sure that he is doing it right, placing the coal next to the walls of the fire-box, and not piling them in a heap in the middle. When the rails are slippery, great care is required to prevent the engine from slipping, by closing the regulator in time. When about to enter a tunnel, the sand valves should be opened, and the sand allowed to flow freely until the train emerges from the tunnel--sand is cheaper than steam. Never forget that lives and property depend upon the faithful performance of your work. CHAPTER VI. HOW TO BUILD A MODEL LOCOMOTIVE. As a preparatory step toward becoming an engineer, it is highly desirable for the boy who looks forward to that honorable calling to familiarize himself with the different parts of the locomotive engine. This we have stated before. There is no better way to accomplish it than to build a model locomotive. At first glance this may seem to be among the things impossible, but it is not so, providing the boy has a mechanical turn, and any boy who has not better not think of becoming an engineer. We now propose to give simple and accurate directions for building a model locomotive, accompanying the same with a series of illustrations, which we trust will be sufficient for the purpose intended. Before beginning we have one word of caution to offer. Don't do your work in a hurry. Don't calculate on the length of time it is going to take you to do it. Make up your mind to understand each detail before you begin, and to work slowly and carefully. If you remember this you will probably be able to build your locomotive. If you forget it you certainly will fail. HOW TO BEGIN.