as indicated by the dotted lines. This done, the bottom piece can
be clamped on from behind by means of pieces of lath. These are for the
two end pieces. The other two pieces are made in the same way, except
that they contain holes for the water to pass through, as shown at _B_.
The wood for these frames, or ribs, should be not less than 1/4 inch
thick in order to accommodate the pieces used in the construction of the
remainder of the hull.

When the builder has made the four ribs, he should proceed to construct
the lower deck, which consists of a single piece of wood nicely planed
and finished, measuring 14-1/2 inches long by 8 inches wide and 1/8 inch
thick. This piece must be nailed to the bottom of each of the ribs, one
at each end, and the other two containing the holes at equal distances
apart. Tiny nails, similar to those used on cigar-boxes, will be found
very suitable for this work. Some old cigar-boxes may be broken apart to
obtain the nails for this purpose. Before nailing on the board it should
be marked out to present ordinary deck-boards. The reader is referred
back to Chapter 9 which describes this process, using a straight-edge
and knife.

When this board is nailed in place, the next requirement will be two
pieces for the sides the bottom edges, of which must rest on the top of
the deck-board. These boards are the same length as the deck. They
should reach to the top of the ribs, and be fastened in the same way as
the bottom deck. It is good practice, when doing this, to place a little
white lead on the bottom edge before finally driving the nails in place.
This will tend to produce a water-tight joint. This done, three pieces
of wood 5/8 inch square must be screwed in place, flush with the bottom
ends of the ribs, to form a flat keel. They should be firmly fixed since
a lead keel is afterward screwed on the bottom of the boat. Attention
should now be directed to fitting the two middle decks. These are placed
4 inches from the top and are 4 inches wide. In this space the engine
and pumps are placed. Therefore, the top deck is made in the form of a
lid, and the outside plate made to draw out. In this way the mechanism
below the deck can be made very accessible.

The framework of the dry-dock is now completed, and the builder can
proceed to fix on the side plates. These are made from sheet tin with a
width of 14-1/2 inches. The length must be sufficient to reach from the
top of one side, around the bott