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construction of that marvellous steamer the Great Eastern, he employed a modi- fied system of longitudinal framing which was known as the box unit system, and depended for the continuity of its trans- "TAE. Marine ReEvicys » tance of about 36 ft. in a vessel of, say, 40 ft. beam (which would ofily be a very moderate-sized vessel indeed), he pro- posed to stretch his longitudinals. These were to be bound together by a series of CoG) ~~ lo ofe Oo] L 2. 2h FIG. 1--LENGTH BETWEEN PERPENDICULARS, 340 FT.; BREADTH, EXTREME, 48 FT. 6 IN.; DEPTH, MOLDED, -28 FT. 3 IN. verse strength upon a complete inner skin, which inner skin was continued under- neath the principal deck so as to form a double deck.. There appears to be really little doubt that Scott Russell was greatly influenced in all the details of construc- tion of the Great Eastern by the famous civil engineer, Brunnel, who was in the main responsible for the creation of that leviathan of the deep. In_ practice, Scott Russell almost invariably em- ployed the ordinary transverse _ sys- tem, which there is no doubt he greatly improved by his powerful advocacy of the use of iron for decks. He appears to have thought, with other designers of his day, that the great stumbling block to the adoption of longitudinal framing was a certain lack of skill in the per- sonnel of the ship building yards. This, however, I suggest was not the real cause of his failure to introduce longitudinal framing generally. The underlying error of his attempt was surely contained in this method of endeavoring to secure his _transverse strength. He actually goes out of his way to make it perfectly clear that the shell plating must not be connected with the transverse strength. He an- nounced that the transverse strength was to be secured by means of bulkheads placed at intervals rather less than the length of beam of any ship, but he describes in detail how these bulkheads must not be carried out to the shell and riveted thereto, as the connections of the bulkhead directly to the shell might be expected to cause trouble. From bulk- head to bulkhead, bridging over a dis- iron hoops, fitted in short lengths be- tween the longitudinals. {t is obvious that a vessel built on this system would be of prodigious weight. With very fine model, heavy engines and. boilers, and the enormous quantities of bunkers re- quired' in the time of Scott Russell, it would be a very poor cargo boat indeed. Moreover, Scott Russell's idea of making © the intervals between the bulkheads cor- 25 cal investigation. One experiment only, | Think, was made upon this system, and then it was abandoned, at which one need not be surprised. Notwithstanding the fact that, gener- ally speaking, longitudinal framing dis- appeared from practice for many years, I am sure that every student of naval ar- chitecture will freely admit with me that these two great men--Scott Russell and Brunnel--were a long way in advance of their times in their opinions as to the distribution of materials in iron vessels, and that ship building science, as a whole, owes them a deep debt of gratitude. I need not take up your time in recit- ing how the first generally accepted meth- od of compensating for the lowest deck in vessels of 24 ft. depth was by hold beams and a marginal stringer, which then gave way to web frames connected to strong beams at the next deck above, while to support the intermediate frames, intercostal stringers efficiently attached to the web frames were introduced (see Fig. 1). The intermediate frames fe- mained of the same strength as formerly required if deck and stringer were fitted, and obviously on the removal of this support became, so to speak, weaklings, hence the necessity of supporting them at intervals by intercostal stringers attached to the web frames. I have often won- dered in the drawing officg why the scantlings of these frames were gov- erned by a number obtained by the sum- mation of the measures of the half breadth, half girth, and depth, and had so. little relation to the distance between the intercostal stringers which defined the mr Se. tA Nf \ | | | | | | , 4 ace s u bo | j eer Bio 'gas aes aS ae a - | NI H : | hes | | | | | os Ut east ) Soe LO © 1 Olen ® Co) | | lp I'tc, 2--LENGTH BETWEEN PERPENDICULARS, 330 Fr. 9 IN.; BREADTH, EXTREME, 4/7 FT.; DEPTH, MOLDED, 26 FT. 61%4 IN. responding to about the width of the ship, would rather appear to have been prompted by an instinct for symmetry and not deduced from exact mathemati- points of support of these frames. Web framed ships in their day, however, did good service, and very little fault could be found with them, if we except the