Chambers's Edinburgh Journal, No. 451. Various

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СКАЧАТЬ p>Chambers's Edinburgh Journal, No. 451 / Volume 18, New Series, August 21, 1852

      WHO SHALL RULE THE WAVES?

      A contest of a very remarkable kind is now going on, one which is pregnant with important results in respect to commerce, to naval architecture, to geographical discovery, to colonisation, to the spread of intelligence, to the improvement of industrial art, and to the balance of political power among nations. The nature of this contest cannot be better made intelligible than by giving the words of a challenge recently put forth: 'The American Navigation Company challenge the ship-builders of Great Britain to a ship-race, with cargo on board, from a port in England to a port in China and back. One ship to be entered by each party, and to be named within a week of the start. The ships to be modelled, commanded, and officered entirely by citizens of the United States and Great Britain respectively; to be entitled to rank "A 1" either at the American offices or at Lloyd's. The stakes to be L.10,000, and satisfactorily secured by both parties; to be paid without regard to accidents, or to any exceptions; the whole amount forfeited by either party not appearing. Judges to be mutually chosen. Reasonable time to be given after notice of acceptance, to build the ships, if required, and also for discharging and loading cargo in China. The challenged party may name the size of the ships—not under 800 nor over 1200 American register tons; the weight and measurement which may be carried each way; and the allowance for short weight or oversize.'

      There is a boldness, a straightforwardness, an honesty in this challenge, which cannot be mistaken. It is difficult to be interpreted in any other sense than that the challengers mean what they say. Brother Jonathan has fairly thrown down the gauntlet to the Britishers, and it behoves the latter to take it up in a becoming spirit. Our ship-builders, especially on the Dee, the Clyde, the Wear, the Mersey, and the Thames, ought to feel that much is now expected from them; for if once the Yankees obtain a reputation—a European reputation it will then be—for outstripping British ships on the broad seas, our ship-owners will assuredly feel the effects in a commercial sense.

      This question of the speed of ships is a very curious one. Empirical rules, rather than scientific principles, have hitherto determined the forms which shall be given to ships. Smith adopts a certain form because Brown's ship sailed well, whereas Jones's differently shaped vessel was a bad sailer; although Smith, Brown, and Jones collectively may be little able to shew why one of the vessels should sail better than the other.

      If opportunity should occur to the reader to visit a large ship-building establishment, such as those on any one of the five rivers named above, he will see something like the following routine of operation going on:—

      There is, first, the 'ship's draughtsman,' whose duties are somewhat analogous to those of the architect of a house, or the engineer of a railway, or the scientific cutter at a fashionable tailor's: he has to shape the materials out of which the structure is to be built up, or at least he has to shew others how it is to be done. When the ship-builder has received an order, we will say, to construct a ship, and has ascertained for what route, and for what purpose, and of what size it is to be, he and his ship's draughtsman 'lay their heads together' to devise such an arrangement of timbers as will meet the requirements of the case. Here it is that a science of ship-building would be valuable; the practical rules followed are deductions not so much from general principles as from accumulated facts which are waiting to be systematised; and until this process has been carried further, ship-building will be an art, but not a science. Well, then; the draughtsman, gathering up all the crumbs of knowledge obtainable from various quarters, puts his wisdom upon paper in the form of drawings and diagrams, to represent not only the dimensions of the vessel, but the sizes and shapes of the principal timbers which are to form it, on the scale, perhaps, of a quarter of an inch to a foot. Then this very responsible personage goes to his 'mould-loft,' on the wide-spreading floor of which he chalks such a labyrinth of lines as bewilder one even to look at. These lines represent the actual sizes and shapes of the different parts of the ship, with curvatures and taperings of singularly varied character. One floor of one room thus contains full-sized contours of all the timbers for the ship.

      So far, then, the draughtsman. Next, under his supervision, thin planks of deal are cut to the contours of all these chalk-lines; and these thin pieces, called moulds, are intended to guide the sawyers in cutting the timbers for the ship. A large East Indiaman requires more than a hundred mould-pieces, chalked and marked in every direction.

      Another skilful personage, called the 'converter,' then makes a tour of the timber-yard, and looks about for all the odd, crooked, crabbed trunks of oak and elm which he can find; well knowing that if the natural curvature of a tree accords somewhat with the required curvature of a ship's timber, the timber will be stronger than if cut from a straight trunk. He has the mould-pieces for a guide, and searches until he has ferreted out all the timbers wanted. Then he sets the sawyers to work, who, with the mould-pieces always at hand, shape the large trunks to the required form. And here it may be noted as a remarkable fact, that although we live in such a steam-engine and machine-working age, very few engines or machines afford aid in sawing ships' timbers. The truth seems to be, that the curvatures are so numerous and varied, that machine-sawing would scarcely be applicable. Yet attempts are from time to time made to construct such machines. Mr Cochran has invented one; and it is said that at the Earl of Rosse's first soirée as president of the Royal Society, a model of this timber-cutting machine was exhibited; that Prince Albert cut a miniature timber with it; and that he thus began an apprenticeship to the national art of ship-building.

      Leaving the supposed visitor to a ship-yard to trace the timbers through all their stages of progress, we will proceed with that which is more directly the object of the present paper—namely, the relation of speed to build. Some sixteen or eighteen years ago, the British Association rightly conceived that its Mechanical Section would be worthily occupied in an inquiry concerning the forms of ships, and the effect of form on the speed and steadiness. The inquiry was intrusted to Mr Scott Russell and Mr (afterwards Sir John) Robison; and admirably has it been carried out. Mr Scott Russell, especially, has sought to establish something like a science of form in ship-building—precisely the thing which would supply a proper basis for the artificers.

      It is interesting to see how, year after year, this committee of two persons narrated the result of their unbought and unpaid labours to the Association. In 1838 and 1839, they shewed how a solid moving in the water produced a particular kind of wave; how, at a certain velocity, the solid might ride on the top of the wave, without sinking into the hollow; how, if the external form of a vessel bore a certain resemblance to a section of this wave, the ship would encounter less resistance in the water than any other form; and thus originated the wave principle—so much talked of in connection with ship-building. A ship built on that principle in that year (1839) was believed to be the fastest ship in Britain. In 1840, the committee stated that they had 'consulted the most eminent ship-builders as to the points upon which they most wanted information, and requested them to point out what were the forms of vessel which they would wish to have tried. More than 100 models of vessels of various sizes, from 30 inches to 25 feet in length, were constructed,' and an immense mass of experiments were made on them. In 1841, they described how they had experimented on vessels of every size, from models of 30 inches in length to vessels of 1300 tons. In the next following year, the committee presented a report of no fewer than 20,000 experiments on models and ships, some of which afforded remarkable confirmation of the efficiency of the wave principle in ship-building. Thus the committee went on, year after year, detailing to the Association the results of their experiments, and pointing out how the ship-builders were by degrees giving practical value to these results.

      Now, a country in which a scientific society will spend a thousand pounds on such an inquiry, and in which scientific men will give up days and weeks of their time to it without fee or reward, ought not to be beaten on the broad seas by any competitor. It affords an instructive confirmation of the results arrived at by the committee, that when some of our swiftest yachts and clippers came to be carefully examined, it was found that the wave principle had been to a great extent adopted in their form, in СКАЧАТЬ