The simplest form of windmill from this source I remember seeing is very easily constructed. It is made from an oblong piece of wood like Fig. 1. Through the center of this bore a hole, a, for the pivot upon which it will finally turn, and mark the two lines at b. Now, commencing at the point b, cut off the corner, b c, and make the surface flat as in Fig. 2; then cut off the opposite side of the other end, indicated in Fig. 1 by the dotted lines d e, in a like manner. Your figure will now resemble Fig. 2, and both ends will form a prism like b c d e f; but b c d e should be a thin flat blade, so the corner or edge, commencing at f, should be cut down in the same manner that e d was treated in Fig. 1. Make the other blade to correspond and chamfer out the middle, or square piece, as seen in Fig. 3. This middle piece is not a square, although I have spoken of it as such, but is oblong, to allow room for another two-bladed piece made precisely like this to interlock with it. When these two pieces are fitted together, fasten them with one or more nails, and then insert the small round stick upon which the windmill is to turn. Fig. 4 shows an arrangement by which two windmills are operated on the same stick. These should turn in opposite directions to make them effective, and this is easily accomplished by simply cutting the vanes of the one so that the wind shall strike it at an angle opposite to that with which it strikes the other. Should you care to decorate them in colors, it had best be done by painting bands or stripes across each vane, all to correspond with each other in width and shade. For instance, take the windmill in Fig. 4; let the outside bands be of chrome yellow and one inch wide; the next red and two inches wide; while the third yellow, and the fourth blue, should each be an inch in width. The axis should have a greater diameter where the larger revolves upon it, but should be cut smaller where it meets the back of the little windmill. Nails in front and back of the larger, and front of the smaller, are necessary to keep them in place.
Perhaps the most satisfactory way of arranging such a windmill is to place it on the end of a weather-vane, as shown in Fig. 5. It is then always presented to the wind. The vane and the windmill may be painted the same color, or the latter may be decorated in stripes, as before described, and the vane given a color which will harmonize with it. Care must be exercised to fasten each part strongly in place, as the strain is very great during a strong wind or in a storm.
THE SCREW-PROPELLER; OR, WEATHER-VANE AND WINDMILL COMBINED.
Take a piece of board, seven-eighths of an inch thick, and large enough to make a vessel of the size you desire. Cut out a hull like that in the illustration. Make a small windmill like that just described, but with rounded ends to the vanes, like that represented in Fig. 2. Pass a strong wire through the hole in the center, and drive it into the stern of Fig. 1; fasten the other end into the rudder, which should be stationary. Be careful when planning your vessel to allow sufficient room for the windmill to revolve below the over hang. Bore a hole at a for the pivot to rest in, upon which the weather-vane is to turn, and insert the two masts in their proper places. Cut a small mizzen-sail from thin board and nail it to the mast.
The flags are of red and blue flannel, the stays of copper or galvanized wire, and the bowsprit a small stick, cut from a tough bit of wood. This propeller may be painted to suit the fancy, but usually is black, with a narrow yellow or white stripe near the top. The lower third is frequently painted green, however, which adds considerably to its nautical appearance. The windmill should be a bright red, and the entire vessel should have plenty of time to dry before being placed in its final position.
THE SIDE-WHEELER.
