At a wagon-shop an old wheel can be had for little or nothing, and with a little work it may be converted into the frame of a windmill.
Each spoke is to be cut at an angle on one side so that the blades, when attached to them, will have the necessary pitch to make the wind act on them. This can be seen in Fig. 26, which is an edge view of the wheel showing a top, bottom, and middle blade.
The blades are eighteen inches long, twelve inches wide at the outer end, and six inches in width next the hub. They are three-quarters of an inch thick, and are attached to the spokes with screws. If it is found necessary, a wire can be run from the outer end of each blade to the end of the next spoke, to steady the blades, as shown in the illustration.
The crank and shaft can be arranged as described for the pumping-mill, and a fan-tail to keep the wheel up into the wind is made in proportion to the size of the mill.
All the wood-work should be painted to give it a good appearance. A mill of this size will develop at least quarter of a horse-power in a fifteen-mile breeze.
Chapter V
AËRIAL TOYS
The Elastic Flying-machine
To have a flying-machine is the dream of every boy. To build a large one is exceedingly difficult, but a small one run by a rubber band can be easily constructed. You will not be able to fly up to the roofs of houses and spires of churches, but it will furnish you much amusement, without the danger of a broken neck.
I will tell you exactly how I constructed one of these machines, and then you can make one for yourself. The backbone was a knitting-needle. The wings, or more properly aëroplanes, were light bamboo strips (taken from a Japanese fan) and covered with the Japanese paper which is used for napkins. (Fig. 1.)
Fig. 2 shows the backbone and its parts. Cut from thin brass or copper a piece shaped like No. 1, and bend the top over, as shown at No. 2. Brass suitable for this may be bought at any hardware-store, or an old article made of proper metal may be cut up. The shell of a metallic cartridge is excellent. The brass should be as thin as possible, to be light, and so that it may be cut with an old pair of shears and bent easily. First cut the piece out roughly with the shears, and then trim it into shape with a small file. Scrape that part of the metal bright and clean which will form the inside of the roll, and then bend it around the needle so that it will fit nicely and snugly.