The cross sticks, thirty inches long, are cut and lapped at the middle and attached to the edge of each hoop with screws or nails. The wire hoops are twenty-two inches in diameter, and are fastened to the cross sticks with staples. The plan of one hoople and the cross sticks, the wire hoop and the location of the blades, is shown in Fig. 15.
The outer corners of each blade are tacked fast to both the upper and lower hoople, while the inner corners are wired fast to the stout wire hoop. The blades are made from tin or sheet iron twelve inches long and six inches wide, and, when bent in the shape of a V, the width across the open end should be four inches.
The blades are depended upon to hold the upper and lower frames in place, and when the turbine is on the top of a post with a rod running through the middle of the cross sticks, around which it revolves, the wind will keep it spinning at a high speed.
Power can be developed with this turbine, but only a very small percentage as compared with a windmill the entire surface of which is continually exposed to the breeze. In the turbine only two or three of the blades are effective at any one time.
A Barrel-hoop Pinion-wheel
From a flat hoop, a few pieces of tin or sheet iron, and some thin wood, a barrel-hoop pinion-wheel may be made similar to the one shown in Fig. 16.
The barrel-hoop will measure about twenty-one inches in diameter, and the hub should be made five inches in diameter, two inches thick, and cut in, as shown in Fig. 17 A, with nine places to receive the small ends of the metal blades. The hub revolves on a pin which is driven into a block of wood three inches square, as shown at Fig. 17 B. A hole is made in the block from top to bottom, through which a half-inch rod will pass. The rails that support the tail are let into each side of the block and are securely fastened with screws, as shown also at Fig. 17 B.
The fan-tails are twenty-four inches long, one inch and a half wide, and half an inch thick, made of ash or hickory that will bend easily, so as to be drawn in against the blades forming the tail.
The tin blades are cut five inches wide at one end and one inch and a half at the other, and fastened to both the hoop and hub with tacks, as shown in the illustration.