Fig. 162.
Fig. 163.
Fig. 164.
A steamer with screw propeller can be made from a piece of board on edge, shaped as shown in Fig. 162, a small windmill with short and broad fans (Fig. 163), serving for the screw. Before beginning work read carefully Marking, Rule, Square, Saw, Knife, Spokeshave, and look up any other references. This boat must be made of a board so as to give a thin section (Fig. 164), in order that the screw may not be shielded from the wind, for this vessel must always head to windward or the screw will not revolve. To ensure this the fore and aft sail must always be kept set and the sheet close-hauled. This sail answers the purpose of the weather-vanes of the windmills just described. It can be made of tin or any sheet metal, or even of thin wood. The rest of the rigging and the smokestack you can arrange as you wish. The bottom of the rudder can be supported by a little strip extending aft from the keel. For the other details of the work, see the windmills already described.
Water-wheels.—An undershot wheel, turned by the water passing beneath (Fig. 165), can be easily made. It can be of any desired size, and of any wood readily worked.
Before beginning work read carefully Marking, Rule, Square, Saw, and look up any other references.