A is the smoke stack and B the steam blast used to increase the intensity of the fire worked by rod C running through the hollow hand-rail D and ending in handle F. G is the steam-dome, which with the safety valve is the same pattern previously used. H is the extra safety valve, worked from the foot-plate. I is the steam whistle, K wind guard, L starting lever, M smoke-box with door, N O spring buffers; P is the line-clearer or wheel guard. Q are the leading wheels, R R the driving wheels, S is one of the cylinders with piston rods and guides bolted to frame and showing double connecting rod at T T. U U are the springs which support the weight of the boiler, etc., on the axle bearings. The spring or rear wheel does not show, being inside the safety guard and hand-rail V. W is the back pressure valve, through which the water is thrown by the force-pump into the boiler, and X is the blow-off tap to clear the engine from all water after having used it. Y shows the side of the ash-pan. HOW TO DO THE WORK ON THE LARGE MODEL LOCOMOTIVE. First of all comes the frame work. It wants to be of eighth inch sheet iron squared up perfectly true and flat and cut as is shown in Fig. 21, beginning 4-1/2 inches from A, and leaving 6 inches at B, and cutting it 6 inches wide there by 8 inches long, and continuing it 4 inches wide for the rest of the distance. Be careful to keep it quite central on the line A B, and leave two connecting strips 1 inch wide as at C C. The side frames come next. These must be much stronger and quite different from those used in the previous model. They may be cut from the same eighth inch iron to the shape shown in Fig. 22. The center of slot B is 17 inches from one end, the center of A 10 inches from B, and the center of C 13 inches from B. In measuring, always start from a given center if you want to be accurate. That is, from B to A and from B to C; not from B to A and from C to B. The slots are each 1-1/4 inches wide by 2 inches deep, leaving 1 inch of iron at the top, as shown. The four large boles shown in Fig. 23 are only ornamental, and can be now cut out. They also serve to lighten the frame. The frames, after being smoothed up can be fastened to the bed plate in the manner described before, by angle-irons, or knees, riveted on.