Chamberss Edinburgh Journal, No. 451 | Page 2

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 soir��e 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