Fig. 310
Fig. 311
Fig. 312
Join the several points to each other and to O. With radius about 3 inches make arc C D. Join points where C D cuts radii, by dotted lines. Draw the flanges; make half cuts along the dotted lines, cut out along the dark lines, and fold into shape. Fasten together with seccotine; turn in the flanges at the bottom, and fasten them to the platform.
The Top of the Windmill can be cut from one piece of cardboard. Draw square, A B C D (Fig. 312), large enough to project beyond top of hexagonal pyramid (side of square should be about 3 inches). On the middle of D C draw M K = 4 inches, and draw a similar line on A B. Join A J, J B, K D and K C, by curved lines. Produce A B and D C both ways. Make B F, C E, D H, A G, equal in length to arc B J. Draw the flange E F P O. Make holes in the middle of A J B and D K C through which the knitting-needle (on which the sail is fastened) may pass. Draw flanges on B J, J A, etc. Make half cuts along the dotted lines, and cut along the dark lines.
Before fastening the top together, put a very small paper-clip through the middle of square, A B C D, and fasten it to a square of cardboard of the same size, so that it turns freely on it. This second square will be gummed to the top of the hexagonal pyramid, so that the top of the windmill may be turned in any direction. Bend up A J B and D K C at right angles to square, A B C D. Bend up B C E F and A D H G and gum them to the flanges of A J B and D K C; gum flange F O to A D H G. The sails are made as already described.
A Water-wheel (Plate XII). The Wheel. Cut two discs of cardboard, 4 inches in diameter. Make holes in the centre, glue them to a small reel (about an inch high), and pass a round rod through for an axle. This wheel is an overshot water-wheel—that is, one that receives the water shot over the top, and must be fitted with 'buckets.' These receive the water at the top of the wheel and retain it until they reach the lowest point (see Fig. 313).
The 'buckets' may be made of stiff paper or thin cardboard. Cut pieces 1 inch in width, and in length the distance of the two wheels apart plus ½ an inch. Mark these out as in Fig. 314, where a b is the distance between the wheels, and c, d, e, f are flanges for fastening the bucket to the wheels. Fold as in Fig. 315. Make at least twelve of these buckets; divide the wheel into twelve parts, and fasten the buckets between the wheels.