removing the clamps when the outer length holds the inner, until a thickness of about 4 inches has been reached. A little care will prevent any joint being exactly over another, as the more evenly the joints are distributed the firmer will the ring be. Bore a number of holes with a small bit, just large enough to admit long French nails, which should be driven through from the inside and clinched on the outside, especial care being taken to firmly secure the ends of the outer lengths. Countersunk screws may be substituted for the nails. If the ring rests evenly on the brackets its upper and lower surfaces may be roughly planed, and will be ready for the rafters. If the ring has been made on the method first described, before the rafters can be affixed it must be supported on wooden stools or trestles, and great care must be taken that it is perfectly level all round ; but if made on the better plan, the posts and brackets will hold it securely.

Cut out nineteen rafters from 7 feet to 9 feet long, and 2 inches by 1 inch thick, and two more 9 feet by 2 inches by 2 inches on which to hang the shutters. These will all be attached to the ring at equal distances, meeting together at the ridge, and fixed to the two semi-cylindrical blocks and connecting board, called the “ridge piece.” See Figs. 3, 4, 5, and 6.

First set up the ridge piece on a temporary support, one foot out of centre, and to it fix, on one side, the stouter rafters on which the shutters are to be hung, and on the opposite side the rafters corresponding to them. The ends of these having been securely fixed to the ring, the side rafters may next be set up, and joined to the ring and the ridge. The rafters must first be cut to the proper length for their respective positions, and their ends cut to the proper bevels for fixing on to the ring and the ridge. The two stout rafters to carry the shutters will leave an opening—a parallelogram, 3-ft. wide, and about 8-ft. 6-in. long. The shutters, made of the same scantling as the rafters, with tranverse stretchers and diagonal braces, will have three hinges each, and a slip of strong canvas nailed over the joints •„ a light board 4-in. wide, screwed on over the canvas with which they are covered, is to lap over the middle joint. On their upper ends, where they abut against the ridge, they must each have a piece of zinc or galvanized iron, bent like a, b, c, Fig. 5, and nailed over the canvas. The spaces between the rafters should be filled by stretching good sail-cloth upon them, in gore-shaped pieces, and finally strips of wood, i-in. wide, nailed over the tacks, and the lower ends of the canvas brought well down over the outer edge of the ring. A strong bar, turning on an axis fixed to the framework of one shutter, and crossing the other, can be used to keep them securely closed. This bar should have a cord fixed to each end, one cord to pull the bar into a horizontal position against a stop, and the other cord to pull it to a vertical position, and thus allow of the shutters being opened. The only remaining consideration is to make this completed roof revolve.

---

Le texte affiché peut comporter un certain nombre d'erreurs. En effet, le mode texte de ce document a été généré de façon automatique par un programme de reconnaissance optique de caractères (OCR). Le taux de reconnaissance estimé pour cette page est de 99,52 %.

La langue de reconnaissance de l'OCR est l'Anglais.

---