e hull, which can afterward be painted in.

The engine and boilers must now be constructed and placed on the
dry-dock, so that the water that was permitted to enter may be pumped
out. As a temporary arrangement, a thin rubber tubing is inserted
through a hole in the lower deck and allowed to hang outside the
water-level. The siphon can then be formed by simply drawing the water
up by suction with the lips. A continuous flow will result, emptying the
hull within a short time.

[Illustration: FIG. 123]

Attention is now directed to the construction of the boiler and pumps.
The boiler, which is rectangular in shape, is made of thin sheet copper,
and measures 4 inches long by 3 inches wide by 2 inches deep. A hole is
made in the top, and a brass or copper tube 6 inches long and about 3/4
inch in diameter is soldered in position, as depicted in Fig. 123. This
tube acts as a chimney on the dry-dock, but it is really used for
filling the boiler, and the top is supplied with a tightly fitting
cork.

The ends of the boiler also act as supports, and they are made 4 inches
long. The bottom edge is turned up for about 1/4 inch to enable the
boiler to be screwed firmly to the lower deck. The boiler occupies a
position at one end of the hull, and should fit easily in between decks.
A small spirit-lamp is used to furnish heat, and no description need be
given of this particular part of the equipment. Before the boiler is
firmly fixed in place a small hole should be made near the top at one
end. The feed steam-pipe is inserted in this, and soldered in place.

Two small oscillating cylinders, similar to those made for the engine on
the _Nancy Lee_ (Chapter 6), should be made. They should not be more
than 3/4 inch in length, with a 3/8-inch bore. If the builder has any
old model steam-engines in the shop, he may take the cylinders from them
instead of constructing new ones for the dry-dock.

The engine is set up as shown in Fig. 124. The first job is to make the
frame or standards, and this is in one piece. Two pieces of brass (_A_),
measuring 5-1/2 inches long by 1/2 inch wide and 1/16 inch in thickness,
are cut. Next the builder should mark off 1-1/2 inches from either end,
and carefully bend at right angles, after which holes are drilled to
accommodate the crank-axle _B_. Two holes must also be made for screws
to enable the machine to be screwed to the deck.

[Illustration: FIG. 124]

[Illustration: FIG. 125]

The flywheel