It is remarkable however, that although experience seems to have taught mankind, that certain general relations in the formation of ships, are necessary to be observed, in order to insure success in their con struction; yet within the limits which this experience has revealed, so many varieties of form have been produced, as to create in the qualities of the vessels constructed the greatest diversity. Some ships, when constructed with only a tolerable approximation to wards the limits which experience seems to have ap proved, appear to possess every good property we can desire; whereas others, framed apparently with equal care, and with no visible deviation from the limits before observed, will nevertheless, from differences in the mode of stowage, and from different Methods of management when at sea, display qualities alto gether at variance with the former. It often happens also, that constructers, in order to avoid one defect, create another, and sometimes, too, when endeavour ing to get rid of a bad quality, the evils arising from it are augmented; and so intricate are the conditions connected with any theoretical investigation of the cause, that any attempt to account for it in such a way, has but slender chances of success. The great object indeed in the construction of a vessel, is to se cure to it as many good qualities as possible; that if it be necessary in one case to sacrifice any portion of an acknowledged good property, in order to secure a more advantageous application or extension of ano ther, care must be taken, that no greater proportion of the first should be abandoned, than the actual ne cessities of the second require; in other words, that the aggregate of both should approximate as nearly to a maximum as possible.
We have seen, however, that experience has taught us certain principles in shipbuilding, which may be safely adopted as data, on which to ground systems of reasoning connected with the properties to which those principles refer: and is it not therefore possi ble, by careful attention, to discover other properties, at present classed with the accidents and chances at tendant on fortunate constructions; but which would, nevertheless, in the hands of one competent to the un dertaking, be found to possess some definite relations to other general laws? All ships, it has been before remarked, have their centres of gravity a little before the middle of their lengths. This is known in a ge neral way; but the precise quantity of the deviation of this very important point, from the centre of the length. cannot, in the present imperfect state of our knowledge, be made known. Would no useful results therefore flow from an experimental inquiry into the exact position of this centre? Or rather, might we not say, would not many conclusions of the first im portance to naval architecture, be obtained front a di gest of the properties of a few of the best ships of each class of the British navy? Mr. Major, at pre sent foreman of Chatham dockyard, and formerly of the school of naval architecture, published, in the An nals of Philosophy for November 1824, a paper on this very important subject; setting forth the advan tages that would accrue to shipbuilding, by obtaining, experimentally, many of its leading elements, such as the foreign and light displacements of our ships of war; their principal dimensions, such as the greater axis of the load water plane, the breadth and draught of water; the forms and areas of the load water, and midship sections; the place of the centre of gravity of the entire from hypothesis, but experiment; the position of the centre of gravity of the displace ment; the elevation of the metacentre, at the mean height of the ports out of the water; the dimensions of the masts and sails, with the position of the centre of effort of each sail, the force of stability at some determined angle, &c. &c. These elements, it must be admitted, are of the highest importance to naval architecture; and from their correct and accurate de termination, would result much useful knowledge. Mr. Harvey, in the number of the same Journal, for January 1826, has a paper on the same subject, and in which he particularly insists on the advantages likely to result from a practical exemplification of Mr. .Major's plan. Mr. Harvey proposes to have all the elements that may be deemed necessary to be determined as well as the essential steps on which they depend, me thodically arranged in tables, according to the rela tion which the different forms bear to each other. "I know of nothing," observes Mr. Harvey, "that at the present moment would so much tend to increase our stock of information on shipbuilding as Me. Ma
jor's proposal; since it would be carrying at once into the very heart of shipbuilding, that spirit of genuine induction, which in so many other branches of know ledge, has produced such mighty consequences." " Let us inquire," says Mr H., •‘ how we obtain in formation in other cases; how the philosopher works in his difficult investigations, and what are the instru ments and methods employed by him when tracing the hidden mysteries of nature? Are they not Expe careful watching after re semblances and relations of every kind? Does he not analyze every principle, separate every part, and in the end collect into general and connected laws, the individual results which his sagacity has discover ed:" "Just so," continues Mr. 11., "ought it to be in the pursuit of naval architecture; for there are about that subject, elements of a very peculiar kind, whose individual properties and collective laws, it is of the highest importance to determine. Much may indeed be said about theory; but pure theory has yet done little for shipbuilding; what we want is a theory founded on the basis of experiment and observation. The first mathematicianin Europe may speculate for ever on the forms of floating bodies; he may dazzle his imagination with his ideal creations; he may multiply his analytical combinations, and pile his highest orders of integrals on each other; and yet, when called upon to make his practical applications, his formula al most lose their identity, and all his golden specula tions vanish. But place in the hands of such a man a well-digested body of experimental results; show hint how, in numerous instances, one property of a vessel has been invariably found connected with another; give to him those constants which are to link together the disjointed elements of liks problem; fur nish him with experimental data on which he can de pend, and from which he can with confidence draw such results as his growing investigations require; and we shall lind in the end a striking contrast to his former results. The data supplied to him will have dis closed relations never before anticipated, and conclu sions never before imagined. Naval architecture would thus be in a high degree benefited; and an art which, it is not too much to say, is of the very first importance for the British nation to cultivate and en courage, would be freed from the trammels of uncer tain and antiquated rules, and placed on a basis better suited to its dignity and value." But, it may be asked, to what causes are we to at tribute so singular a neglect or an art, so essential to the welfare of Great Britain, as the art of shipbuild ing confessedly is; and how is it that states, confess edly our inferiors in maritime importance and strength, should excel us in the construction of their ships? To this it may be replied, that our triumphant supe riority on the ocean affords a ready solution. Our su periority has induced neglect, while other nations, jealous of our nautical power, have strained every nerve to rival and surpass us, and have endeavoured to make up the want of numbers by superior constructions. The French, for example, have endeavoured, and in many cases have succeeded, in producing better sailers; and the Americans, by enlarging the scale of their different ships of war, are endeavouring to turn the balance against us. France, to obtain all superiority, wisely enlisted on her side the genius and science of her geometers. By prizes, by public rewards, by honourable distinctions, by every thing that could ex cite emulation and scientific enterprise, she invited her geometricians to consider all the great problems connected with shipbuilding; and to transfuse into the practical operations of her clock-yards, all that the most enlightened theories could teach. Some advan tage surely must result to an art to which such a mind as D'Alembert's could direct its attention. It is im possible for a mind, accustomed to the higher orders of human thought, to descend to the lower walks of human contemplation, without the latter being in some degree improved. A mere theorist, applying his speculations to the practical details of an art, can do nothing; but a man, whose habits and modes of thought are built upon the genuine principles of in ductive science,—who looks at shipbuilding, for ex ample, neither with the eye of a merely speculative curiosity, nor with the blank intelligence that too often unfortunately characterises the daily operators in the mechanical arts, can scarcely direct his atten tion to any one of its departments, without in some degree imparting to it a benefit.