The impulse which these branches of naval science have lately received, is well exemplified in the above periodical work. This work is worthy of particular notice at the present eventful period of the arts. Not only do the national prosperity and honour depend on our naval ascendancy, but even our safety and existence as a nation would be endangered by signal defeats at sea. It may be asserted, without fear of contradiction, that the whole range of nautical economy never demanded more serious and ardent attention from our government than at the present time. A vigorous branch of the British stock now actually rivals us in commerce, and has shown the native prowess of its descent by deeds in war, worthy of the original and experienced parent. The junction of France and Spain, uniting a long and contiguous coast of ports to this country, and the internal aspect of affairs in Britain, enforce on us the watchfulness of serious concern, if they do not sound the tocsin of enthusiastic exertion. So much is the present compound existence of the British nation engrafted on her command of the seas, that a single defeat, or a suspension for a short time of her domination, would be a most convulsive crisis, fraught with ruin and inexpressible distress.
The progress of events and new discoveries render alterations expedient; and it is only by constant examination of these circumstances, and by fostering a knowledge of the principles on which they depend, that we can determine on the line of conduct to be adopted. Repeated epochs have shown us, that the forms of our ships have frequently become antiquated and unfit for further use. Such were the lofty, broad, high-sterned vessels of the seventeenth century. Subsequently, the forty-four gun ships, on two decks, came into disuse. Then followed the sixty-fours; and the seventy-fours are fast going out of vogue. The same might be said of other descriptions of vessels, which there is no occasion to particularise. It is worthy of remark, that they were all rendered useless by the superiority, in sailing qualities, of the vessels of our antagonists, who adopted other descriptions of ships, which we were soon obliged to imitate.
As all those manœuvres which are performed in military struggles by the marching of troops, are effected in naval encounters by the sailing and the evolutions of ships, it is evident that victory may greatly depend on the qualities and characters of our floating batteries. On land it is not to be expected that any advantage can be calculated on from inherent superior celerity of movement, as the agents in each case must be supposed to be possessed of the same physical powers; in such case, it must be skill and valour alone that can give the ascendant: but, at sea, not only is ability advantageous, but increased facility of execution may be possessed by the superior architecture and equipment of vessels. In the instance of preponderating force being possessed by the enemy, celerity of motion in the retreat becomes of augmented benefit; as it is also, when, from the inferiority of the enemy, pursuit must be resorted to.
A large ship of superior velocity has the power of making every ship of inferior force its easy prey. The same may be said of fast-sailing fleets, which ought always to have the ships composing them of equal powers of sailing; as the velocity of the whole must be regulated by that of the slowest, in order to insure her protection.
Our enlightened naval historian, Captain Brenton, vol. i. p. 40, of his work, says "Whoever reads with attention the history of our naval actions in the East or West Indies, America, or the North Sea, will readily attribute the failures of Hughes, Rodney. Graves, Byron, and Parker, to the miserable state of our shipping." And further on, he observes "The Dutch, Spanish, and Russian armaments of 1787, 1790, 1791, called forth men who applied themselves with much assiduity to the improvement of the marine; the suggestions of officers of experience were attended to; the best and most approved models were selected and built after; and the Courageux, of seventy-four guns, taken from the French as far back as 1761, was the favourite of the service: the Leviathan was as near a resemblance to her as the builder of Chatham dock-yard could produce; and in the actions of 28th and 29th of May, and 1st of June, 1794, under the command of that high-spirited nobleman, the late Lord Hugh Seymour, this ship was one of the earliest in action."
Captain Brenton attributes the glorious victory under Lord Howe, in a principal degree, to the fast sailing of the Queen Charlotte and Royal George, ships of enlarged dimensions, which brought the enemy to action, by cutting the line at the desired time before the others.
From the same work we extract the following remarks, as further proof of the lamentable comparative state of our shipping, and our deficiency of knowledge in the principles of the art. "The Victory is one of the most perfect vessels, of her size, we ever had; but we have unfortunately failed in our attempts to produce one exactly similar to her. The Boyne was so intended, but, on being launched, was discovered to be two feet narrower on the quarter-deck, and found to sail wretchedly."
It is unnecessary further to point out our degrading inferiority. The cause of this is plain; the nautical arts and sciences have been less cultivated in this country than in any maritime nation in the world. By the wise encouragement of talent, foreign nations have produced men learned in the art, and distinguished by their scientific acquirements[20] *. It is not, therefore, matter of surprise, that the nation at large, and the navy in particular, have been loud in their complaints on the subject. The evil was in consequence remedied in part, by following the foreign nations closely in their models, for which we have been indebted to the unrivalled intrepidity of our sailors, who have captured their vessels; but this uncertain expedient has necessarily been accompanied with detracting attendants: our enemies have in the mean time improved on their models; and thus, with all the expense of dispensing with badly-constructed vessels, we have constantly been inferior to foreigners in the qualities of our warlike navy.
This exasperating deficiency, which has been so often reiterated throughout the nation, excited the ardent attention of many public-spirited noblemen, who proposed the formation of a "Society for the Improvement of Naval Architecture;" accordingly, a public meeting was convened at the Crown and Anchor Tavern, on the 14th of April, 1791, at which the late Marquis of Hastings presided. The institution was unanimously established and supported by numerous noblemen and gentlemen; among whom were, His Royal Highness the Duke of Clarence, Earl Stanhope, Lord Mulgrave, Sir Joseph Banks, Sir Charles Middleton, and Dr. Hutton. They all agreed to a resolution "That the theory and art of ship-building being objects of the first magnitude and importance to these kingdoms, and not so well understood in this country as matters of so much consequence deserve, a remedy for this radical deficiency merited the attention of every well-wisher to the true interests of Great Britain." It is with regret it must be remarked, that the society totally failed in their object, by wasting all their energies and funds, in attempting to investigate the laws of resistance. In taking this step, they injured considerably the interests of naval science in this country, as will be presently noticed.
The murmurs and complaints, which we thus see reverberating through the nation, at length were made the subject of parliamentary interference. From the legislative authorities it echoed to the throne; and finally, by order of council, the proper remedy was proposed, and carried into effect, of expressly devoting young men of distinguished talent to the professional art of ship-building. The country at large, by public advertisement, detailing the most flattering prospect, and encouraging treatment, was invited to send its youth of education and ability to an open competition, in which the successful candidates were to be elected, and further promoted, solely from their merit. This important measure, which had long been pointed out to us for imitation, by the French and Spanish governments, with whom it had been so successful, was definitively regulated by the Board of Naval Revision in 1808. A school of naval architecture was therefore attached to the Naval College, Portsmouth; in which the students, chosen as above mentioned, are initiated in the elements and practice of their profession. As their attainments are carried to a wide extent in the mathematics, their capabilities are enlarged to a full and competent examination of their professional duties.
The work under consideration is the production of a few of these gentlemen. Its object, as expressed in its introductory pages, is "utility." It not only comprises original matter, but invites communications from all conversant with naval matters; and it leaves its pages open for the reception and collection of the vast quantity of valuable information published in foreign works. Thus, while it diffuses the principles of the art, it excites a spirit of inquiry. It was thought preferable to publish its matter in small and frequent portions, rather than in large numbers, for the purpose of admitting more extensive circulation, and communicating earlier intelligence of passing occurrences in the art. We are sorry to observe that there is now a suspension of these interesting labours.
Another periodical work was commenced on the same day, January 1, 1826, entitled, Papers on Naval Architecture. It appeared, however, that it was conducted on exclusive principles, several papers having been refused insertion in it, though coming from persons of undisputed attainments in the art; it was, therefore, judged expedient and conducive to the best interests of the science, to continue the Essays and Gleanings, as it was founded on a liberal and fair basis. Accordingly, the Essays and Gleanings made its appearance every subsequent fortnight, offering to its contributors a more convenient and beneficial opportunity of adding information to the general stock. We are happy to be able to say, that much good has been done by both publications; and, while we see emulation thus produced, we cannot but think it highly beneficial.
One peculiar advantage of tho Essays and Gleanings over the Papers on Naval Architecture, consists, in the former taking a wider scope, in the admission of practical, as well as theoretical knowledge the actual construction of the machine, as well as the design of it. By this means, able practitioners have contributed their valuable observations in the art; among which may be particularly mentioned several interesting communications from Messrs. Harking and Blake, who are superior officers in His Majesty's dockyards.
The Papers on Naval Architecture are almost wholly confined to the enunciation of the theorems that have been taught at the School of Naval Architecture, from the works of Atwood and Chapman. It must be confessed, however, that while all the problems so taught are proper to be known, they form but a feeble instrument in guiding the designer of ships. His information must proceed from an enlarged view of ships used for war on the ocean; he must be acquainted with the mutual relations of the different parts of a ship, and the relative proportions of the various classes, in order to systematise his ideas, and form a true theory from practice for, in this case, theory must be practice reduced to system. It is on this account, that while we are glad to see Dr. Inman's translation of Chapman, with some valuable notes and new theorems, we regret that the materials to guide the constructor of our floating batteries, which may be found in that work, are of so scanty a nature.
We conceive that the theory of projectiles, as applicable to gunnery, previous to the experiments of Robins, was in a similar state to that of naval architecture at present, in relation to its practical use. In fact, the deficiency of data to teach the science must be admitted in both cases. A theory must be formed from facts. First, the facts must be collected, with all their connexions; they must then be analysed and compared; and, by a clear, penetrating, and capacious mind, inferences must be drawn of general and correct application, or the nearest approximations sought to such general deductions.
By the talents of Robins, the intricacies of the resistance which the air opposes to cannon-balls were elucidated; and it is to similar deductions that we are to look for a penetration through the obscurities which darken the theory of naval architecture. When we turn to Dr. Inman's work, with every respect for the learned gentleman, which was published after he had been Professor to this National Institution only ten years, we look in vain for principles of this kind. From the example of construction given by Dr. Inman, we apprehend, however, that the calculations for ships, formed under his eye, have been nice to a degree, in some immaterial points, while the more weighty elements have been overlooked. Nothing is more necessary in the construction of ships, as in all other things, than duly to appreciate the importance of its different component parts and uses, according to the amount of their effect on the whole: to refine on minutiæ, while the elements of great consequence are neglected, is a mode perfectly erroneous; they may follow after, but ought not to go before. In order to determine these things, we must say that our theories of hydrodynamics and pneumatics are insufficient for the purpose. To the analysis and comparison of ships, as proposed by Mr. Major[23] *, and approved by the Navy Board, we turn with great expectations: some deductions, with respect to increasing the dimensions of ships, have already been made and acted on, from that mode of pursuing the subject, which tend greatly to improve our navy; and by pursuing the subject in that way, we may hope to be placed at that pre-eminence in the art which our nation's wants require, and render so highly desirable. When the plan was first proposed (five years ago), visionary and merely speculative notions were attributed to it: the examination of ships has since been found to be the true source of improvement; and while we see alterations made, we cannot but regret that they are made from partial views of the subject, and in many cases from incomplete and incorrect data. If the theory of Naval Architecture had been cultivated in England as in other countries, a Digest of the Navy would not have been so requisite, as calculations to a considerable extent are made in foreign maritime nations; but, in this country, we are very hazardous in our procedures without it. "Experience is a dear school," and it is the object of wise men to foresee its dictates, and profit in the future from the experience of the past, before they feel its severe lessons, which often come too late for their beneficial operations.
Whilst, however, we are speaking of experience, we must distinguish between experience in ship-carpentry and experience in the proper formation of ships for their destined purposes. In barbarous countries, fastening pieces of wood together for the mere purpose of forming floating bodies, or the imitation of other ships, with a crude idea of their fitness for sailing purposes, forms the whole of ship-building; but in civilised countries, where large ships of war are built at a vast expense, the deduction of principles, and the application of the exact sciences to the art, becomes an object of the very first importance. It is, therefore, with much satisfaction we look to the institution before spoken of the School of Naval Architecture.
The superintendence of the practical carpentry of our floating citadels, together with that of their stores, &c., was inevitably attended with great expenses, especially in time of war; but it is to be lamented that, until the year 1808, none was avowedly bestowed for the purpose of insuring the excellence of the sailing qualities of such costly fabrics. On the contrary, every thing seems to have been left to chance; and, with regard to any foreknowledge of their properties, we were left to float in the immense regions of uncertainty: they were therefore as likely to turn out bad as good, excepting when we submitted to the humiliating necessity of making servile copies of foreign ships, which were so dearly earned by the gallantry and skill of our seamen: thus copying those models which they had abandoned for improved designs.
We observe that the conductors of the "Papers on Naval Architecture" still cling to obsolete theories of resistance, and recommend pursuing the mode of conduct of the "Society for the Improvement of Naval Architecture;" which, as we have before noticed, only produced disappointment, though carried into effect with accumulated talent. For our own parts, without waiting to show the extreme improbability of success by this means, we give our decided preference, in the present state of the science, to devoting our energies to the application of the inductive philosophy to ships, in which the whole of the causes and effects are embodied. While on the subject, we cannot but remark the want of judgment shown by these gentlemen in underrating the truly valuable experiments of Romme[25] *, experiments which were made on a large scale, were repeated, and received the approbation of the Royal Academy of Sciences of Paris.
We perceive that the conductors of the "Essays and Gleanings on Naval Architecture" have avoided pretending to develope the intricate laws of the resistance of fluids; and for this we commend them. We are naturally led here to say a few words on this subject, which must be very limited. Newton was decidedly the best acquainted with this subject, as has been clearly shown by our eminent English authors, Dr. Young and Professor Robison, and admitted by the great foreign mathematicians. By experiment, and the application of mechanical laws, he investigated the subject to a very great extent. He proves, and pronounces positively, that depth from the surface has no additional effect in producing resistance in water. Now, we cannot but express our surprise that, after his clear experiments, an attempt should be made to introduce the contrary notion of Don Juan. It must be remarked, that Don Juan does not himself apply his own theory to ships, nor show its correspondence with experiments that are subsequently detailed in his book and yet the student of naval architecture is to be perplexed with all the undigested opinions of a verbose and confused writer, who has not discovered one new problem, but has put forward and supported numerous errors. Without wasting time on this subject, we remark, that there is a great difference between a mathematician writing on resistance, and a naval architect; the one, if he displays additional powers of mathematical analysis, advances abstract knowledge; the other, unless he succeeds in making the practical application to ships, totally fails.
The "Essays and Gleanings" was designed, by a familiar and interesting mode of treating its subjects, to obtain a general circulation in all the various ship-building yards of country. It is not commonly known that, even to the present period, the English ship-builders are not even furnished with proper rules for the mensuration of the bottoms of ships. Their practice, when they wish to measure the solid contents of the submerged part of a ship, is to divide the bottom, by model or draught, into sections of a foot apart; they then divide these sections into square feet, by ruling lines at a foot apart, and count the number of square feet, adding something for the gore pieces, or angular parts at the edge of the sections; afterwards, they add all the square feet together, and allow a little more for the corner pieces, for the whole number of cubic feet in the bottom!!! We need not say, that the mathematician is in possession of short and correct rules, as a substitute for this inaccurate, although monstrously laborious method: these rules, by means of this publication, have been made available to all concerned in such computations.
The first number contains introductory remarks, diagrams and explanations of Captain Philips's capstan, in which the principle of the contrivance, understood by few, is lucidly shown; a theoretical view of the influence of length on a ship, being an analysis of Du Hamel's remarks on the subject; the values of ships of all rates, as estimated by the French, in the "Archives Navales;" account of the durability of French ships, from the same work; notice of the performance of the Enterprise, steam-vessel, in her voyage to the East Indies; and finally, a very luminous historical view of the origin, rise, and progress of steam-navigation. The variety of subjects thus embraced, it is evident must give a peculiar interest to the publication. In the same manner the contents of the other numbers might be separately cited, of which there are fifteen, to show that the work offers attractions not exclusively to the theorist, nor to the ship-builder, but to all concerned in the naval arts. We especially notice Rotch's lever-fid, Sir Robert Seppings's diagonal system of ship-building, and other late introductions, given, as projected by the inventors, with further explanations.
There is also a peculiar benefit attached to the plan of this work, which is, that scarce documents, naval tracts out of print, are reproduced at a cheap rate. Of these, are to be found the Outlines of Naval Philosophy of Sir William Petty, with an interesting account of his lite; and Sir Walter Raleigh's valuable notes on the British navy, &c. Amongst the original articles, is a good account of the origin and advancement of naval ordnance, and new and concise demonstrations of the various problems of the stability of floating bodies, with their practical applications to ships. The tract on the stability opens with an interesting historical account of this branch of hydrodynamics, from Archimedes to the present day. For our parts, we are always advocates for this manner of engaging the attention of the reader in the cause of science, which renders even the most abstruse subjects, in some degree, familiar with every body. We thus enlist in its service the prime mover of human intellect curiosity; and having once done that, investigation closely follows. We see this method now employed in almost every scientific treatise; and much of the wonderful increase of knowledge of these periods must be ascribed to it. The subject of the disquisition under consideration is divided into four sections; the first section consists in the enunciation of definitions and elementary truths; the second section contains a very clear, and in some degree original, method of investigating the laws of the equilibrium of floating bodies generally, when deflected from their quiescent positions; the equilibriums of stability, instability, and of insensibility, are clearly defined, and made comprehensible to moderate capacities. The opening of this section strikes us as being of general importance.
"In preparing a draught for a ship, it becomes an object of primary importance to ascertain and regulate, as we proceed in its construction, the properties which it would give to the vessel, and especially whether she would be sufficiently able to restore herself to the upright position, after having been deflected from it by the usual causes. If a draught be not constructed with due attention to this point, a ship may be built which will prove inefficient in boisterous weather, and endanger her own safety, and the lives of those on board. An accurate knowledge of the laws by which the equilibrium of floating bodies is governed, is therefore highly necessary to the constructor; and, indeed, every person intrusted with the command of a ship ought to be acquainted with, at least, the general principles by which the stowage, especially of merchant-ships, should be governed. If we suppose, for instance, that a ship is sailing with the wind abeam, or in other words, propelled by a side wind, the motive power not only gives the vessel head-way, but also inclines her from the upright; if, therefore, this last mentioned effect be not sufficiently resisted, she will be in clanger of upsetting in sudden and violent squalls; and when under a press of sail, will always heel so much, that the wind will lose a considerable portion of its impelling power, from the obliquity with which it must strike the sails; hence, cæteris paribus, the velocity of the vessel must also be diminished. Thus, whether safety or good sailing be regarded, we see how important it is to insure a counteraction to the inclining power of the wind."
The third section comprises all the useful problems in Atwood's paper on the subject, printed in the "Philosophical Transactions of the Royal Society;" for 1798; but a more general and elegant analysis has been used, by means of which the greater part of Atwood's Paper has been compressed into a few octavo pages. It also gives two concise rules for the mensuration of all irregular bodies. These rules are deduced, not from the method of differences, as is usually done, but by a simple algebraical process, which can only be appreciated by those who are conversant with the higher branches of this science.
The author of this tract then proceeds to give the method of determining the displacement, &c., of a ship from its design, which is effected in a manner intelligible to any person acquainted with arithmetical operations; and there can no longer, in our opinion, be any excuse, even for the most ignorant shipbuilder, for neglecting the determination, at any rate, of that important element of a ship the displacement.
The fourth and concluding section, professing to treat on the metacentre and metacentric curve, is not yet published, but we hope soon to see it. It is now well known, that Atwood, in controverting the propositions of Bouguer, has printed glaring errors[28] * in the "Philosophical Transactions," while he has properly investigated the stabilities of the isosceles wedge, in its upright and inverted states, which Clairbois has erroneously discussed.
The enterprising, learned, and remarkably acute philospher, M.C. Dupin[28] † (since created peer of France) has not escaped particular notice in the "Essays and Gleanings." His account of the "Progress of the French Marine, since the Peace," which was read in March, 1820, before the Royal Academy of Sciences, forms the subject of an article, which deserves considerable attention. On the instruction of the French artisans, we extract the following: "The system of mutual instruction among the working classes prospers in the bosoms of our ports, and schools are founded for the particular instruction of the sons of the inferior officers of the arsenals, in the elements of calculation, of geometry, and of design, as far as necessary for the plans of ships; also the principles of statics, so as to enable them to judge of the action and effect of machinery. Prizes of gold medals and special promotions are to be the rewards of the most deserving students.
"The plan of these schools, which may be cited as models, is due to M. Tupinier, subdirector of the ports and arsenals of France.
"With regard to the creation of establishments of general utility to the progress of the marine, Brest was formerly the only port properly furnished with them. Since the peace, however, libraries are forming in each of the others; and, in almost all, cabinets of natural history and botanical gardens are enriched at every voyage undertaken by our ships, either to foreign coasts, or to those of our colonies." "An observatory has been given to Toulon; and Rochfort is to be similarly enriched. In both these ports naval museums are formed, in order to preserve types of the most eminent vessels, whose originals either are, or soon will be, destroyed by time. Models of ingenious machines, representations of interesting manœuvres, a methodical collection of raw materials, of tools, and of the product of all the arts exercised in a dock-yard, such are the riches collected in these interesting repositories."
We are of opinion, that the establishment of institutions of learning, similar to those of France, at each of our three great naval arsenals, Portsmouth, Plymouth, and Chatham, would be highly beneficial to the country. Advocates of a fallacious economy would deplore the expense of such national undertakings; and the malignant opposers of advancement in knowledge would also object to it; but it may be asserted, that past experience, and a present view of naval affairs, loudly call on the country for some struggles for our attainment of superiority in naval science. Who could remark a young naval power, like America, possessing superior vessels to our own, in the last war, without perceiving the necessity of this step? it reverberated through the houses of parliament, with just complaint.
At the present time it is well known that ships of the United States possess a far superior character to our own. How many expensive alterations have been rendered expedient in our ships, that a precedency in the theory of naval architecture would have rendered unnecessary! Of what purpose is it to copy models in the present day, which were taken from foreign nations thirty years ago, and are of a still earlier date in point of design? It is thus that we have been always a step behind them: improved models, we know, replace, in the French navy, those of ancient construction.
It is true that we have some names among us that are cited as those of good ship-builders; but it must be observed, that as tapers shine in the dark, which are dimmed by the approach of day, so it is impossible to determine the relative merits of our naval artists till open competition shall duly distinguish them. That time is now approaching: nay, from the enlightened and judicious measures of our naval administration, is now ushered in. Our public experimental squadrons, in which direct contrast and impartial trial alone decide on merit, are as fair and beneficial modes of advancing our attainments in the arts as probably could have been devised. Again, we have a corps of naval engineers, who are admitted into the service, solely on their general capacities and mathematical abilities. At the School of Naval Architecture they pass public examinations every year, the accounts of which are communicated to the Lords Commissioners of the Admiralty; and it is in the order in which they stand at their final examination, under the Professor, that they have hitherto been promoted. Although nothing can be conceived more impartial than this plan at the present period, yet it must be allowed that it does not give the desired excitement to perseverance in science, subsequent to their departure from the institution; and we have no doubt, for this reason, that some distinction will be made for remedying this deficiency: already the theorems and principles for ship-building have been explored to an extent far surpassing what was known seven years since at the School of Naval Architecture.
It must be remarked that superior genius, where it does not meet with protection and reward, is always productive of much real injury to the possessor: as an instance of this, we cite the contempt and obscurity in which Mungo Murray, our only native writer on the theory of ship-building, lived and died, which is related by Mr. J. Knowles, the present Secretary to the Committee of Surveyors of the Navy, in the preface of his work on the "Preservation of the Navy." "While the Dutch possessed and encouraged Witsen, the French, Bouguer, Du Hamel, Clairbois, Borda, and Romme, the Spaniards, Juan, the Germans, Euler, and the Swedes, the celebrated Chapman; the English neglected the only work which they possess on this subject, that can lay any claim to science[31] *, and suffered its author, whom tradition represents to have been a man of the most amiable manners and correct conduct, to live and die a working shipwright in Deptford Yard." In the following page, in adverting to the students of the School of Naval Architecture, he says, "it is to be hoped that their ardour may not be damped, but that the encouragement will be extended to them which has hitherto, in this country, been withheld from those who have endeavoured to promote the difficult but useful science of constructing ships."
On the paper inserted by Sir Robert Seppings, in the Phil. Trans. for 1814, on his diagonal system of ship-building, which is here reprinted for convenient circulation, it behoves us to make a few remarks. The adoption of this plan is a great triumph over inveterate prejudices, and we are inclined to bestow praise on the introduction of this new mode of carpentry; but we do not conceive we should abandon investigation respecting it. The late writers on it, in addition to Sir Robert, are Baron Dupin, Dr. Young, and Mr. Knowles. Of these Dupin, being a naval architect, has by far surpassed the others in its discussion. Dr. Young's more limited acquaintance with ships has necessarily confined his illustrations, though his elegant analysis has much enriched the subject. Mr. Knowles's descriptive view is unassisted by mathematical investigation.
Dupin remarks, in his paper, in the Phil. Trans. of 1816, that the principle has often been recommended in theory, but found deficient in practice. He says, introducing the subject, "The old French builders saw so distinctly the truth of the principle now produced by Mr. Seppings, that they even put it in practice for the same purpose to strengthen their ships, and to prevent arching." Again, "Chaucτt, a French ship-builder, obtained the prize, in 1755 (of the Royal Academy), and in a Treatise very little known, reproduced the idea (of Bouguer and Du Hamel) on this point." In subsequent remarks he observes, that Groignard, in 1759, proposed, and that Clairon des Lauriers put in practice, in 1772, similar principles. The celebrated Chapman also applied it.
We conceive that the subject cannot be decided ΰ priori; but must be referred to general principles in ships. Hence, Dupin remarks, its superiority must be determined by showing that the efficient ship of war, on Sir Robert's adaptation of this principle, is constructed with less timber and. fastening than on the old plan; that it has the weight placed lower; that it is of less expense, or has improved qualities. Now, we cannot avoid remarking, that this has never been shown, but only asserted; and that there is a great deficiency of calculated data on these points. Dupin himself only hazards an opinion on the subject; but, as a mathematician, he ought not to have been satisfied with anything less than an accurate statement. He passes over the new plan of attaching the beams to the side, as of little consequence, without showing it to be attended with less weight than the old methods; whereas they must be estimated in the comparative weights of the ships. It is evident, from mere inspection, that the new mode is the heaviest, and that it contributes, in too material a degree, to raise the centre of gravity of the ship, and diminish its stability. To determine the efficacy of the diagonal riders to prevent arching, Dupin ought to have shown that they are equal, for this purpose, to the internal coat of planking, so boldly dispensed with by Sir Robert, independent of the massy interior ranges of timber, between which the beam-ends are confined; for it is evident, that these strong longitudinal binders would of themselves effect the same object in a very material degree. The shelf-pieces, which were used by former English surveyors, are not of English introduction, nor of French solely; as, by reference to ships constructed in the Archipelago and the Levant, they will be found to have been used for ages.
We think it but justice to observe, that when some new mode of fastening the beam-ends was required from the scarcity of warden-knees, that Mr. Roberts proposed a plan which was found to succeed so well as to obtain for him a parliamentary grant of 800 ℓ. Whether Mr. Roberts derived it from Du Hamel we are unable to decide there is a similarity in the plans; but the objection urged against the plan by Mr. Knowles, of the beams of free growth being split by the bolts in the beam-arm, is certainly futile; as it was easily remedied by placing them out of the same line of fibre.
A great deal of irrelevant demonstration has been injuriously applied to prove the excellency of the diagonal riders. There are no sources of error and confusion so prolific as inappropriate analogies. To liken thirty bending riders, in the curved bottom of a ship, to the straight crossbar of a common field-gate, is an assimilation so unapparent, that we are surprised how it could ever be adduced[33] *. If the side of a ship were perpendicular, and one cross-timber reached from the hold in midships to the extremity forward, and another aft, the comparison would be more admissible. But, in that case, there would still be great dissimilarities: the side of a ship is planked from the top to the bottom, and this coating is so close, as to prevent the admission of water; while the bars of a gate are only intended to prevent cattle getting through. A ship is six or seven times in length of hold what it is in depth; whereas a gate is only about twice the length of its height. In the case of a ship dropping at its extremities, the upper-works must lengthen; whereas, in a gate, this deformation takes place by a revolution on the fastenings, by which the bars approach each other, and which the planks of a ship are prevented from doing by their immediate contiguity. If this train of reasoning can be allowed, it will only apply to the mode of placing the diagonal riders, adopted by surveyors, previously to Sir Robert, as exemplified in the top-sides of the Caledonia, a ship which has received an universally good character. But the question can only be determined, as we have observed, by general results.
Some persons have supposed, that, in the diagonal system, the strains are transmitted endwise on the fibres, in which direction wood is the strongest; but it is evident, that if the enormous angular momentum, producing the working of a ship, depended for resistance on the bolts of a few cross-riders, the strain would not be so well supported as by the multiplicity of bolts in the thick stuff and ceiling covering the concavity of the hold; for this reason, we find Dupin, in preference, recommending interior diagonal planking between wind and water.
The resistance to arching must depend on the distance at which the opposing force is applied from the neutral axis. Thus, the upper planks afford more strength than those at the water's edge, which cannot come into action till those above or below are considerably stretched or compressed. For this reason Dr. Young observes "The least obvious advantage attributable to the obliquity introduced by Mr. Seppings, appears to be in his mode of laying the planks of the decks; parts which seem to be principally required to co-operate with the sides of the ship as ties in a longitudinal direction."
The fillings between the timbers certainly cannot afford any strength to the ship; their resistance to compression is not equal to that of a coat of planking, which acts in the direction of its fibres, with numerous fastenings, both to prevent compression and extension the latter of which the fillings can have no sort of pretension to. As the ship is not filled up to the floatation, water is not excluded by them in all cases from entering the ship. Their introduction only became necessary when the ceiling was dispensed with; and thus forming a part of the new system, they must stand or fall with it. It has been adduced in favour of filling in a ship, that the weight being below the centre of gravity, it must act as ballast: to this fallacious recommendation it need only be observed, that one ton of ballast, placed at the bottom of the hold, would have the effect of two or three tons placed in the situation of the fillings.
It must also be recollected, that an objection has arisen to the interior planking on account of its weight, while the same has not been alleged of the fillings; but Dupin, who notices this, sometimes writes with mere political views, without a scrupulous regard to correctness; for the truth of which assertion we need only adduce his account of the British treatment of French prisoners, and his omission of taking the weight of the new fastenings of the beams into consideration, so properly descanted on by Dr. Young, which was mentioned before.
We cannot conceive with what propriety, persons can say that a coat of planking contributes little to the strength of a ship, when it is merely the four-inch planks of the bottom of a ship that bind together and protect three or four thousand tons of heterogeneous matter from all the ravages of the winds and waves. Perhaps, there is no parallel to this prodigious combination of strength, with dis-proportionably small substances, in the whole range of the arts: the arch and the hoop, where the separating forces are equally distributed and counteracted by the continuity of strength, appear to present some comparative idea of the accumulation of its strength; but it is in the construction of the egg, in which the wisdom of the Divine Author is exhibited, that we must probably look for the nearest resemblance to it. The decks of a ship contribute above water, in the straight part of the planking, to maintain the form, but its sole security under the water depends on that peculiar species of support mentioned above.
It is proper to advert to one circumstance, hitherto not noticed, in the discussion of this important subject, and which appears to destroy the whole chain of reasoning adduced for showing the strength of the diagonal system: we allude to the shrinking of the principal riders, against which the secondary or truss timbers abut. This necessarily leaves a vacancy at the extremities of the trusses, so that they are totally ineffectual for their designed purposes, till plates of iron, or other hard substances, are forced into these interstices a very common, we are told, and inconvenient practice. Abutments in ship-building are a very bad species of support, as they receive the shocks to which a ship is liable too suddenly; but the diagonal system appears to be destitute even of the abutment, by the shrinking of the principals.
Whether the expense of constructing the navy on this new system is greater or less than on that of the old, we are unable to determine. We are glad to see a mixture of the diagonal riders and the ceiling now adopted in frigates, instead of all wooden riders.
As a convincing proof of the excellency of the diagonal mode of placing part of the timbers of a ship, it has been adduced that the French have again adopted it for trial, in a few instances; but here it must be remarked, that with them time has not elapsed for the demonstration of its value; nor have wars, and other circumstances, occurred, to decide the question. Our English merchant ship-builders, in several cases of its adoption, have proved its inefficiency: the steam-vessels, now built with it, sag, or drop down in the middle, from six to twelve inches; and we fear, on a full view of the subject, its boasted advantages to our navy, must fall to the ground.
A more complete examination of the cross-carpentry of Sir Robert Seppings, than the sketches hitherto before the nation, is much required; and as it involves the construction of an immense navy, which costs twenty millions sterling to replace, we hope it will soon appear.
It is not so much in a longitudinal direction as in athwartship one, that ships are weak. It would appear that this was felt to be the case by Sir Robert Dudley, at the latter end of the sixteenth century, when he proposed his construction of ships from the galleon downwards, and endeavoured to remedy the evil by struts, extending from the keelson to the quarters of the beams of the different decks. Mr. Snodgrass also, as shown in Steel's large work, brought forward almost a similar plan, with this difference, that the upper ends of the struts were fastened to the side of the ship instead of the quarters of the beams. The latter method failed when put in practice, which, we may infer from Charnock, was not the case in Sir Robert Dudley's mode. Vide vol. ii. p. 177, of his History of Marine Architecture.
If, however, we do not give our entire assent to all that has been advanced respecting the diagonal system of Sir Robert, we must still yield him the praise due to perseverance in what he believes to be the true principles of construction, and more particularly in that exerted in the behalf of the round sterns of his introduction. We feel persuaded that, whatever modifications it may be found hereafter necessary to make in them, the curvilinear shape will never be abandoned. We should prefer to see them, however, as the French have adopted it, without any external projection, to load and hamper the ship abaft.
It is to be regretted that the accommodations of the officers should be infringed on; but surely, in a ship of war, every thing is of minor importance to her efficiency as such. No doubt, deeply-rooted prejudice in favour of old customs renders it obnoxious to many; and when once that is overcome, opinion will be as violently in favour of the round stern, as it was previously inimical to it.
The remarks on dry rot seem to be written in true philosophical spirit, a determination to investigate the subject with strict impartiality. We perfectly agree with the opinion of the Noble Lord at the head of the Admiralty, expressed in Parliament "that all nostrums are ineffectual towards the preservation of timber; and that the durability of it depends on its quality, and on its being well seasoned." For this reason we agree to what experience has taught all ages respecting the time of felling oak-timber; namely, that period when the vegetating juices, after spring and summer, are converted into ligneous fibre, and not when they are in a state of action ascending the capillary tubes. The high price of oak-bark alone operated against this dictate of experience in the time of James II.; and subsequently has brought into use, even in the Royal Navy, timber felled in the spring. All authors, except Mr. Knowles, agree to this. The reader will find ample satisfaction in the perusal of this article.
We cannot afford space for the mention of other papers, on Steam Navigation, the Centre of Gravity, Blake's Midship Section for Fir Ships, and several practical improvements.
We think His Majesty's navy may derive the greatest advantages from scientific discussion; and whether ignorance, envy, or prejudice, actuate the opposers of it, we assert that they are no true friends to their country. Every empirical introduction, without it, may pass for the extension of science and discovery. But we have too much confidence in our enlightened naval administration, to fear that the admirable beginning that has been made in fostering the true principles of naval architecture will ever be discontinued; but, on the contrary, we believe this country that of Newton and Locke, is now destined to surpass every other, as much in the theory of the art, as in the solid construction of her navy.
[20] * When a bridge, or other national edifice, is contemplated, many hundred pounds are given for plan and estimates; but how contrary is the practice in ship-building!
[23] * For a more particular account of this plan, see Annals of Philosophy for November 1825, January 1826, and June 1826.
[25] * The "Papers" in the 3rd Number retract this error.
[28] * In the observations on Atwood's Paper in the "Papers on Naval Architecture," these errors are not admitted, but their justification is attempted by the conductors.
[31] * A Treatise on Ship-building and Navigation, by Mungo Murray, 1754.
[33] * A ship has been likened in this discussion to various other articles; even Indian rubber has been brought forward as an analogy, the application of which we do not exactly perceive. By comparing it with the moon, or any thing else, we may obtain any imaginable results we may desire.
The Quarterly Journal of Science, Literature and Art. January to June, 1827.
London, Henry Colburn, 1827. pp 18-37.
Transcribed by Lars Bruzelius.
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