Engineering Wonders of the World
Volume I

354 ENGINEERING WONDERS OF THE WORLD. Fig. 10.—LONGITUDINAL SECTION OF CARGO STEAMER, SHOWING ends unsupported ; and (2) with the hollow of a wave amidships, and each end of the ship resting on a wave, the wave in both cases having a length equal to the ship’s length and a height of one-twentieth of the length. The distribution of longitudinal material will be seen from the comparative sections of i he Lusitania and Great Eastern (page 318), and from Fig. 6, which illustrate . the structural design ot the Design. Atlantic liner Lusitania and a cargo steamer respectively. It will be noticed how the “ topsides ” and deck are thick- Fig. 7.—SECTION OF A DOXFORD “TURRET” FORM STEAMER, WITH LARGE CLEAR HOLD. ened up to form the upper flange of the girder (amounting to no less than 2 to 2£ inches in the case of the Lusitania), while the bottom plating and tank top plating form the lower flange. The framing which supports the outer shell usually consists of transverse girders spaced not more than 2 to 3 feet apart. In passenger vessels, where numerous decks are required for the accommodation, the side frames are comparatively small. In cargo steamers, however, where large clear holds are essential, the intermediate decks or tiers of beams are dispensed with wherever possible, and larger frames, known as “ web ” frames and “ deep ” frames, are fitted. With the same object in view, various patented forms of ship have been designed during late years, of which the most widely adopted— Doxford’s “ turret ” form—is shown in Fig. 7 ; while another type—Harroway and Dixon’s cantilever framed ship—is shown in Fig. 8. Various systems of longitudinal instead of transverse framing have been suggested at different times, a notable example of the application of this principle being, as already mentioned, the Great Eastern. Lately the system of longitudinal framing has been re- vived in the case of several cargo steamers— it is claimed with a considerable reduction