To use it you connect the pipe B with a gas bracket by means of a rubber tube, and attach the glass tube D to a pair of bellows by means of another piece of rubber tubing. The bellows should have an air-bag attached. Otherwise you will have a jerky, uncertain flame. When you want to braze any article, bind the parts together with some very fine brass wire and cover with a little powdered borax and water; then lay the article on a piece of charcoal, and if it is necessary to preserve the temper of the steel you are about brazing, cut a potato in half and push each end of the steel rod into the halves, which will keep the temperature from getting too high. Then turn on the gas and start your blow pipe, at the same time working the bellows with your foot, and by either pushing in the glass tube D, or drawing it slightly out, you can regulate the shape of the flame as required. [Illustration: Fig. 2.] [Illustration: Fig. 5.] [Illustration: Fig. 7.] [Illustration: Fig. 8.] [Illustration: Fig. 11.] [Illustration: Fig. 12.] Now bring the flame to bear on the joint you wish to braze, having first supplied plenty of borax. Soon you will find the brass wire melting and running into the joint like water. It must then be neatly filled up and the joint will be scarcely visible. Here are a few tools which will be useful to you in this work. A center punch, or steel spike for mashing metal for drilling, etc., and a small riveting hammer. Three or four files of different degrees of fineness, a screw plate and taps, a small hand-drill with a set of drills to fit and a good firm vise. A lathe is of course desirable. Curves for bending metal you can easily make from pieces of bar-iron, holding them in the vise while working on them. When you have your tools ready get the material for your model. Several sheets of brass and copper, the castings and various sized screws and bolts are what will be required. All being thus prepared the time has arrived to take the FIRST STEP. The first step toward building a model locomotive is to be posted on the action of steam in the cylinder. Go to encyclopedia and read up on that point. If you have no encyclopedia go and look one up in some library. You can't build your engine until you understand this. Next draw an accurate plan of your model. Figure 2 is the idea. It is a side view of our locomotive. Let us describe. A. Boiler. B. Smoke-stack. C. Screwhead, to fill boiler with water. D. Steam chest with safety valve attached on top. E. Whistle. F. Steam tap to start the engine with. H. H. Leading and trailing wheels. I. Driving wheel. K. Cylinders. L. Frame. M. Buffers. N. Set thumbscrew to fasten on the tender. O. The lamp. P. Tap, used to ascertain the quantity of water in the boiler. R. S. Hand rail. To all locomotives there are three principal parts, the frame work, or carriage, the engine, or cylinders, and parts connected with them, and the boiler.