CHAPTER II.
THE SLIDE-VALVE ENGINE
The art of soldering plays a very important part in the making of this little cylinder without going into any really difficult methods, a small soldering-copper being all that is required in making the seams and joints. This small engine is intended for a larger class of vessel than the engines of oscillating design described in the preceding chapter. The following proportions are good, and the dimensions are the smallest it is advisable to carry out on this system. The thickness of material used is just right for the size of engine described at present, and it will be wise to construct this engine for the first time according to the following figures. Select a piece of seamless brass tubing, i inch internal diameter, with walls at least 1/8 inch thick, making the tubing 1 1/4 inches external diameter. Polish up the tubing by rubbing with fine emery-cloth, and proceed to mark the tubing off with the dividers, as shown in Fig. 13 (a). This work will be much simplified if a piece of tubing is selected with one end already sawed off square as the tube comes from the tube-works.18
