ensed with.

[Illustration: FIG. 133]

The boiler of a flash steam plant is extremely simple. Such a boiler is
shown in Fig. 133. It consists merely of a coil of copper or Shelby
steel tubing with an internal diameter of 1/4 inch. The boiler coils
should be wound around a circular form of wood about 2-3/4 inches in
diameter. In the case of copper it will not be found very difficult to
do this, providing the copper is heated before being wound on the wooden
form. If the copper is heated it is advisable to wind the wood with a
layer of sheet asbestos before the copper tube is wound on. It is almost
necessary to do this winding with a lathe, but if the mechanic does not
have access to such a tool he may have to find other means of doing it,
or possibly he can take it to a local machine shop and have the work
done for a few cents. The boiler coil should be wound about 9 inches
long.

A casing of Russian sheet iron is made to slip over the boiler, leaving
sufficient space between. Ventilating holes or slots are cut in the
cover to permit of a free circulation of air. The boiler covering is
also provided with a funnel through which the exhaust gases from the
blow-lamp pass.

[Illustration: FIG. 134]

[Illustration: FIG. 135]

The blow-lamp used operates on the same principle as the ordinary
blow-torch. The details of such a lamp are given in Fig. 134, and a
finished torch is shown in Fig. 135. Instead of making the valves
necessary for the blow-torch, it is advisable to purchase them, for they
are very difficult to make accurately. The valve at the back of the
torch regulates the gasolene supply that passes through the nipple. The
hole in the nipple should be about twenty thousandths of an inch. Owing
to the fact that the copper coil wound about the burner is short, the
tube can be filled with molten resin before it is bent. In this way the
tube will not kink or lose its shape while being wound. After it is
wound it is placed in the fire and the molten resin forced out with a
bicycle-pump. Such a blow-torch produces a tremendous heat and throws a
hot flame far up into the boiler coils.

CHAPTER XIII

SAILING YACHTS

BEFORE attempting to construct model sailing yachts the young worker
should become thoroughly conversant with the different types of yachts
and their fittings. In the following pages the author briefly outlines
the general science of yacht-making and sailing.

Sailing yachts are made in four