at ja, 8a, qa, 10a, ua, 12a ; from these points draw horizontal projectors across the elevation—in the example, only one-half is shown —also drop projectors from the same points into the plan cutting the line A-B, as shown, in points 7,8, 9,10,11,12 ; this locates the position of the numbered points in the plan, and as the surface of each bay on a line parallel with its curb is straight across from hip to hip, it will be obvious that if the pointsi, 2, etc., are projected to the next hip in planes parallel to the curb they will locate similar points upon that hip. Having done so, reproject them i lto the elevation to meet the corresponding numbered hori zontal projectors, and the intersections will be points in the curve of the hip. Again, we may take the projectors a step farther, to an intermediate, rib, and in like manner obtain its projection ; the method of locating the points will be clear by following the numbers, and the curves can be drawn through the points so obtained. Fig. 3 is an enlarged detail of the joints in the linial; Figs. 4 and 5 a side elevation and plan of the joints at foot of hip and angle of curb.
I.antern Lights.—Lanterns are lights in a roof; they differ from the simpler form of skylight in that they have not only top lights but also side lights more or less vertically arranged. A lantern consists of a rectangular or polygonal frame composed of sills, heads and corner posts, with sometimes intermediate mullions : these openings are fitted with sashes sometimes fixed and sometimes hung, cither by hinges to the top or centre pivots at the sides. The roof is sometimes covered with slates or lead, but is usually glazed also, with either movable or fixed lights, fitting into hip and cross rafters. The lantern itself is usually raised from the roof upon a rough curb or frame of timber, covered with lead outside and having panelled framing inside. There are great varieties of detail, several of which are shown in the author's " Modern Practical Joinery:..! The illustration accompanying this lesson is designed to meet the requirements of the following examination question, and is selected as indicating several difficulties in construction :—
Fig. r. Half Plan of Skylights. Fig. 2. Half Plan of Side Lights. Fig. 3. Half End Elevation. Fig. 4. Half Vertical Section. Fig. 5. Detail at Ridge. Fig. 6. Details of Angle Post. Fig. 7. Detail of Lantern Head. Fig. 8. Key Sketch of Lantern and Roof
" Draw the plan, elevation and section of a lantern light, measuring 6 ft. X 8 ft., to be at the ridge of the roof of a billiard-room. To have upright sides glazed and partly to open, the roof glazed but not to open. The lantern to be ornamental."
It is unusual to have a ridge roof to a billiard-room, these rooms being generally on ground or first floors having flat roofs. Light is required all round, which complicates the treatment.
The sketch diagram, Fig. 8, indicates how the roof is hipped back for the purpose of obtaining sufficient room to open the end lights. lights hung at the top are the best for billiard-rooms, as centre-hung lights may allow rain to be blown in on the table. Fig. i is a half-plan of the skylights, the rigid-hand light being omitted to show the hip rafter, which is similar in detail to the ridge section, Fig. 5, a lamb's-tongue moulding being worked upon its under edge. The bars are checked into the bottom rails, as shown by the dotted lines in Fig. 7. Fig. 2 is a half-horizontal section through the lantern itself, and details of the corner posts anil mullions are given enlarged in Fig. 6. Figs. 3 and 4 are haltend elevation and cross section respectively, the lower part of the former being in section to show the queen post truss necessary to carry the lantern. The interior of the opening in the roof is lined with a i| in. ogee moulded and panelled framing. Above this is a thick moulding, with a gutter formed in its upper side to receive any condensed water or to catch any rain that might drift in ; this escapes through copper pipes at each end of the sills, as shown in Fig. 4. The lights are opened by means of rackwork not shown in the drawing. The oak sills are mitred and bolted together at the corners, and the posts are stub tenoned to them, and secured with coach screws. Sheet lead is dressed up the face of the curb and ail apron piece is turned over and enters a groove in the under side of sill. The curb is dovetailed and spiked at the angles. The roof lights may be fixed with an inserted tongue, as in Fig. 7, or a solid tongue formed on
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