Next take a sheet of copper and cut a piece about 6-1/4 inches long by 6 inches wide and bend it over a wooden roller to the shape shown in Fig. 12, keeping it 1-1/2 inches apart between A and B. Cut also two other pieces of copper to the shape of your bent sheet (Fig. 12), and make it long enough to reach to the dotted line. These form the two ends, and may be placed an eighth of an inch from the edges, as in Fig. 13, and soldered in place, and the projecting rims turned over and sweated with solder from the outside, in the same manner that you did the boiler ends in Fig. 11. Then drill a three-quarter inch hole at B (Fig. 13) for the bottom of the smokestack to go into, and cut a piece of three-quarter inch brass tubing of sufficient length to pass out at top of boiler about half an inch, as shown at A, Fig. 10. You can then hammer out a rim or flange on the bottom end of the smokestack and push it up through the hole in the copper box, soldering it in place from the top as at A, Fig. 14. Then drill two small holes at each end of the box, B C, Fig. 14. These should be a little more than an eighth of an inch in diameter, to allow an eighth of an inch tube to pass through. Now get two 12-inch lengths of hard drawn steam pipe, an eighth of an inch in diameter, and with your screw plate put a thread on each end, about half an inch in length. Then make eight nuts to fit the threads on the piping, filing them up into proper shape. Now take the piping and bend it very gently, to prevent it cracking, around a bar of iron or handle of some tool held in the vise, until it is in the form shown in Fig. 15. Do each one the same, then mix a little turpentine with white lead, and smear each end, where you have formed the screws, taking care not to get any into the tubes, which can be temporarily plugged up. Next put a nut at either end, as far as the thread will take it, then smear a little white lead around the holes drilled in the ends of the box, B C, Fig. 14. Push the tubes in from the inside, and screw up firmly with the remaining nuts, in the position shown at Fig. 16. The inside nuts can then be tightened up with a wrench, and if you do all this carefully, you will never be troubled with any leakage, no matter what pressure you may get in your boiler. These tubes are immensely strong, and owing to their small size, the water in them is raised quickly to a higher temperature than that contained in the rest of the boiler, causing a continual circulation to take place, and a constant supply of steam to be found.