ation: FIG. 79]

[Illustration: FIG. 80]

[Illustration: FIG. 81]

[Illustration: FIG. 82]

A little safety-valve and filler-plug suitable for use on the boiler
are shown clearly in Fig. 78. A piece of sheet tin is cut out to the
size and shape illustrated in Fig. 79 at _A_. The piece is bent up at
the dotted lines and the seams are soldered. Two angle-plates, _B_, are
then cut and fitted and soldered in place. Next a piece of brass tube
with a 1/8-inch bore and 1 inch long is cut and soldered in place for
the bearing of the crankshaft. A lead flywheel 1-1/4 inches in diameter
and 1/2 inch thick is then mounted firmly on a piece of straight steel
wire 1-3/4 inches long, which acts as a shaft.

The shaft is made to run freely in the crankshaft bearing that was
previously soldered in place. The cylinder is shown in section in Fig.
80. If the reader will refer back to the construction of the engine
described in Chapter 4 he will readily understand the operation and
construction of this particular engine.

A little crank must be cut from 1/16-inch brass, and soldered to the
crankshaft after fitting a wire crank-pin to the outer edge. This
crank-pin should be of such a size that the joint on the end of the
piston-rod shown at _A_, Fig. 80, turns on it easily. The throw should
be only half the stroke of the engine, which is 3/8 of an inch.

The boiler is now fixed in place by bending the lugs _B_, Fig. 79, so
that they just support the boiler nicely. They are then soldered in
place. Next fit the short steam-pipe _K_ between the boiler and the
steam block on the cylinder. The builder should take care to keep the
steam-pipe well up to the top of the boiler.

The lamp should be built at this time. The container for the denatured
alcohol is made from a well soldered tin box of suitable size. It can
also be made by cutting a sheet of tin to the size and shape shown in
Fig. 81. The corner joints are soldered and then a tin lid is soldered
in place. The builder should not forget to make the filler-tube _E_ and
air-tube _D_, as shown in Fig. 77, before soldering the top piece in
place. The burners should be made as high as the container, and these
should be made from little pieces of tin bent to shape and soldered on
to a bottom pipe, as shown in Fig. 77. The builder should also remember
to cut the holes through this pipe so that the alcohol can get into the
burner-tubes, and also to solder the open end of the bottom or feed