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THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



121 



competent for the scientific investigation assigned to it : it is rea- 

 sonable, for instance, to expect much benefit from commissioners 

 selected as those appointed to consider the use of cast-iron girders 

 on railways have been. But on the whole, these eases must be 

 looked upon as exceptions and happy accidents. In naval matters 

 the inefficiency of official philosophy is especially deplorable, be- 

 cause of the enormous expense which it entails upon the nation. 

 After all the visits of the Lords of the Admiralty to Portsmouth 

 — after all the parliamentary returns and parliamentary debates — 

 after all the enormous cost of ships built on new models, to be sub- 

 sequently remodelled and patched as tlie prevailing caprice dic- 

 tated — after all tlie exploits of experimental squadrons— we have 

 come to the very gratifying conclusion that our most weatherly 

 vessels were taken froni the French in the late war. O, for an 

 Ecole Polyteclmique in England ! 



The author of tlie work before us professes no more than " to 

 give some plain directions for actual building," and to put the 

 reader in possession of just so much information as is requisite for 

 carrying him to "larger and more scientific works on the subject." 

 But" the present treatise, though it does not aim at extreme pro- 

 fuiulity, has the greater merit of expressing in simple terms some 

 very important views respecting the application of hydrostatics to 

 tlie theory of sliip building. The stability of a vessel is properly in- 

 sisted upon, as a perfectly indispensable requisite — one without which 

 all other merits are \'alueless. The form of a vessel may enable her 

 to sail fast, but if, at the same time her pitching and rolling 

 motion be excessive, the practical utility of the vessel is proportion- 

 ably lessened, her security endangered, and her durability 

 diminished by the constant strains to which she is subject. Sir 

 A\'illiam Symonds' vessels are, our author remarks, liable to these 

 gra\'e objections. In his vessels, the rake of the stem is some- 

 times so great, that the stem is inclined to the keel at an angle 

 of thirty degrees. By thus cutting away, so to speak, a large por- 

 tion of the fore body, it is clear that when the vessel pitches ahead, 

 there is less immersion or sustaining power to bring lier up again, 

 than there would be if the stem were more upright. He com- 

 mitted a similar error witli respect to tlie lateral rolling. The 

 lateral stability, of course, depends in a great measure on breadth 

 of beam ; but the general form of section amidships must be duly 

 proportioned in reference to it. " Here," says our author, '" we 

 consider, is to be found the great defect in the surveyor's midship 

 section ; it is comparatively straight from the keel to the water- 

 line ; and, as such, is manifestly deficient in bearing, until its ex- 

 treme immersion takes place, which is sudden almost to a jerk ; 

 whereas a rounder line would prevent the great degree of lateral 

 inclination, and what must take place would be much more easy. 

 The advantage of this, in comfort upon the deck, efficiency at the 

 guns, wear and tear of the rigging, and indeed, the safety and com- 

 fort of the whole, must be apparent." 



The conditions of stability, either laterally or longitudinally, are 

 not after all so very difficult to ascertain. The problem is prac- 

 tically a hydrostatical, not a hydro- dynamical one, and therefore 

 much easier than that of determining the forms best adapted for 

 speed. If navy surveyors had only a moderate acquaintance with 

 toe properties of the Metacentre — if their appointments de- 

 pended rather on their knowledge of hydrostatics, than on their 

 government influence, or aristocratical connections, we should 

 have to pay for much fewer of those great wooden coffins which 

 now disgrace our navy. As far as we may judge from Sir \\^illiam 

 Symonds ' actual performances, he either does not know the mean- 

 ing of the word " metacentre," or he cannot have studied its pro- 

 perties. He may possibly have an idea that they ha\e some in- 

 fluence on the stability of a vessel — -but he certainly cannot know 

 that they are, not merely important, but all-important — tliat in the 

 question of stability, the properties of the metacentre constitute 

 the question, the whole question, and nothing but the question. 



Mr. White's practical directions we «ill not venture to criticise 

 at length. The accuracy of his general views, however, and his 

 long experience in his profession, seem just grounds of dependence 

 on liis authority in matters of detail. The folio plates are care- 

 fully drawn and admirably executed : and the descriptions which 

 accompany them are very minute, and appear well suited to the 

 purposes of the ship builder. The work concludes with an ac- 

 count of the methods now in use for measuring tonnage, and with 

 remarks on the complexity and inefficiency of the new method es- 

 tablished by law. W& conclude with the following brief extracts, 

 the first selected for its scientific importance, the second for its 

 curiosity : — 



"The form of body lest adiipted for steam vessels, is a primary consi- 

 ddration. It will be found that most of the principles which constitute a 

 good sailing ship, will also apply to a steamer. We have repealed instances. 



in which first-class steam ships that have afterwards proved of superior cha- 

 racter, have gone as fast, under jury rig, and with not more than half the 

 momentum of canvas allotted to sailing ships of equal tonnage, as they 

 have subsequently gone under the full power of the engines. Many 

 valuable inferences may be drawn from this fact ; and we unhesitatingly 

 bring to our aid, in building steam ships, the whole experience of the pro- 

 fession, to a much greater extent than was at first adopted. Experience 

 shows that the long bow and clean run are indispensable ; for, whatever 

 may be the laws of fluids, the great speed of river boats thus built, the in- 

 crease obtained by lengthening so many of the earlier formation, and the 

 increased acuteness of each succeeding class, amount to a demonstration on 

 this point." 



'* The ark in Scripture was of these proportions, namely, sis times the 

 breadth for the length, and one-tenth the length for the depth. Other pro- 

 portions may in particular circumstances piomote speed ; but for stability 

 and security at sea, the proportions of the aik, destined as she was to en- 

 dure the greatest commotion of waters the world has ever known, are, 

 we fearlessly assert, infallible, since the experience of four thousand years 

 has only confirmed them ; a collateral evidence, at least, of the truth of 

 the Scripture narrative. The ark was twice as long, and twice as wide and 

 deep, as the West-India mail steamers, and consequently would make eight 

 of them, considered as regular figures." 



An Historical, Practical, and Theoretical Account of the Breakwater 

 in Pli/moiith Sound. By Sir John Rennie, F.R.S., F.S.A., F.G.S., 

 President of the Institution of Civil Engineers. London: Bohn 

 and Weale, 1848. 



Sir John Rennie could not have more worthily devoted himself 

 than to the commemoration of the great work of his father, the 

 Plymouth Breakwater, and he could not have erected a monument 

 more munificent than the volume now before us, — one which while 

 it records the merits of his father, and gives proof of his own en- 

 lightened spirit, will be of value to the engineering profession for 

 many generations. AV^ell may we describe it as a monument more 

 lasting than brass, while it bears a more noble inscription than was 

 ever sculptured on marble. Of Sir John Rennie's works we will 

 not speak, for others can put forward a claim to the production of 

 works of equal magnitude and merit, but we cannot refrain from 

 saying that this book is another public service rendered to the 

 engineering profession. As President of the Institution of Civil 

 Engineers, Sir John has upheld the social rank of the profession, 

 and has maintained its public hospitality; by the contribution before 

 us, he has shown his earnestness in the cause of professional litera- 

 ture. These are to our mind merits in addition to the material 

 monuments of his skill, and speak powerfully of his enlarged and 

 liberal mind, and of his public and disinterested spirit. Tliey 

 show that his heart and soul are engaged in the career he pursues, 

 and are a guarantee of his professional independence and integrity. 

 We speak warmly, because it is rarely we have the opportunity 

 of speaking of a book from the hands of one of the higher members 

 of the profession, and therefore it comes more welcome to us. It 

 is true there are excuses for the silence of those members, and Sir 

 John has himself very well explained them, but that does not ex- 

 empt us from our duties towards him, who stands a brilliant exam- 

 ple of successful exertion. Sir John Rennie's words merit atten- 

 tion, for they must be the exculpation of our engineers in the eyes 

 of Europe. He says — 



" Continental engineers have generally more time than English 

 engineers for writing and reflection. The former, confined for the 

 most part to a single work at one time, have leisure to study and 

 reflect upon every operation connected with it, and to deduce 

 general la\« from them which may be applicable in similar circum- 

 stances. Their sphere of action nevertheless is limited, compared 

 1 with that of English engineers, and they have not the same facili- 

 ties of acipiiring that readiness of application, that versatility of 

 inventing remedies to meet every case which occurs in practice, 

 and which alone can be derived from extensive and greatly-varied 

 experience in all kinds of works, such as falls to the lot of English 

 engineers. This defect is necessarily inherent in the continental 

 system, notwithstanding the numerous able engineers we find there. 

 The whole of the works, as well as the engineers, being in the 

 employ and under the control of the government, their energies 

 are impeded, their talents are fettered, and they are deprived of 

 that strongest of all inducements to exertion, viz., competition, 

 which has been productive of so much benefit in this country. 

 Here, as regards engineering, everything has been free and un- 

 trammelled; thus every member of tlie profession has been at liberty 

 to study and follow out that course which appeared to him best 

 calculated to acquire public fa\'Our, and secure his own interest ; 

 and the public, on the otiier hand, has never found any deficiency 

 of talent to carry out any work as often as the emergency required. 



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