tube. Before the wicks are put into the lamps, the container should be
tested by filling it with alcohol to see that it is perfectly tight at
all joints. If it is not the container should be gone over again with
solder to assure its being leak-proof.

Before operating the engine with steam, it can be tested with a small
bicycle pump through the opening for the safety-valve. The engine should
turn over briskly at every stroke of the pump, providing it does not
come to rest at "dead center." If it does come to rest at "dead center,"
where no air can enter the piston, the crankshaft should be given a
little twist and the engine will then start. Before steam is applied it
will be well to experiment until the engine runs with the air-pump.

Having made the engine run smoothly with air, steam can be generated in
the boiler. The wicks should not be placed too tightly in the burners.
After they are in place the container may be filled with denatured
alcohol, and the burners lighted and placed under the boiler. In a very
few minutes steam will be up. At the first indication of pressure in the
boiler the engine should be given a twist with the fingers until it
starts and goes of its own accord. The constructor should remember to
keep his engine well lubricated.

The propeller-shaft is merely a piece of steel wire, perfectly straight
and fitted with a crank _A_, Fig. 82. This crank is similar to the one
fitted to the engine, but with a small slot cut out for the crank-pin to
fit into. This is done so that, as the crank-pin on the engine turns
around, it also turns a slotted crank on the propeller-shaft.

A short piece of tube, _C_, is now fitted to a flat brass plate, _D_.
The plate is mounted at an angle to the tube, so that when it is in
place on the stern of the boat the propeller-shaft will be in line with
the crankshaft of the engine.

A clearance hole is now drilled through the hull, so that the
propeller-shaft can be put in place. Solder the tube to the plate, and
punch four small holes in the plate, so that it can be screwed firmly
to the hull. Solder a short piece of tube, as shown at _B_, Fig. 82, to
keep the propeller-shaft in position.

The propeller must now be made. This is easily done by cutting out a
disk of brass 1-1/2 inches in diameter, as shown in Fig. 83. The shaded
portions of the brass disk are cut away. The blades are bent to shape,
care being taken to see that they are all alike. This done, the
pro