ART. III.-1. A Comprehensive History of the Iron Trade. By Harry Scrivenor. London, 1841.

2. The Theory, Practice, and Architecture of Bridges of Stone, Iron, Timber, and Wire; with Examples on the Principle of Suspension. London, 1843-1853.

3. Iron Bridges. (Article in the Encyclopædia Britannica.') Edinburgh, 1857.

4. Traité Théorétique et Pratique de la Construction des Ponts Métalliques. Par MM. L. Molinos et C. Pronnier, Ingénieurs Civils. Paris, 1857.

5. A Practical Treatise on Cast and Wrought Iron Bridges and Girders. By W. Humber, C.E. London, 1857.

6. Grand Trunk Railway of Canada-Correspondence and Reports on the Victoria Bridge. 1855-6.

7. Boyd's Marine Viaduct, or Continental Railway Bridge between England and France. 1858.

6

RANCIS HORNER once observed, after inspecting a steel manufactory, that 'Iron is. not only the soul of every other manufacture, but the mainspring perhaps of civilized society.' John Locke even went so far as to aver that notwithstanding man's extraordinary advancement in knowledge, we should in a few ages, were the use of iron lost among us, be unavoidably reduced to the wants and ignorance of the ancient savage Americans: so that he who first made known the use of that contemptible mineral, may be truly styled the father of arts and author of plenty.' Nor will this view be deemed extravagant, if we reflect that but for iron man would be virtually without tools, since it is almost the only metal capable of taking a sharp edge and keeping it. Of the various definitions of man by philosophers, not the least forcible is that of tool-making animal, for with tools he tills the ground, builds dwellings, makes clothes, prints books, constructs roads, manufactures steam-engines, and carries on the whole material business of civilization, on which its very highest developments in a great measure depend.

Perhaps the most curious and interesting museum of antiquities ever collected is that formed by M. Worsaae at Copenhagen, in which the remarkable parallelism in the advances made in civilization and in working in metals, has been illustrated by articles gathered from ancient burying-places. From these remains it appears that, in the first instance, the only tools of man were sharpened stones, such as are still found in use amongst savage tribes, and which are insufficient to enable him to till the ground, or build, or carve. If he felled a tree, and hollowed out

a canoe

a canoe from its trunk, he had to summon fire to his aid. He could only gather a precarious subsistence by hunting or fishing, using a flint head for his arrows and crooked bones for fish-hooks. The skins with which he covered himself were joined together by thongs or skewers; and anything like domestic comfort could not exist, for the construction of a dwelling was as yet impracticable. This first stage of man's primeval history M. Worsaae designates The Stone Period.' Copper, which is found in such a state of comparative purity as to require very little smelting to fit it for use, preceded the discovery of iron, which in its native state looks more like a stone than a metal. The progress of man was now more decided, especially after the art of hardening the copper by admixture with tin had been acquired, when various tools and weapons of bronze were fabricated. Tillage could now be practised, trees could be cut down, and houses and boats built. M. Worsaae designates this 'The Bronze Period.' During the same epoch, as is curiously illustrated by the Copenhagen collection, gold was well known and highly prized for its beauty. But the utility of gold to man was always very small compared with that of iron, which was the metal next discovered. There was not an art but felt the impulse given to it by the improvement of tools which was immediately effected. The first to profit was the art of war, bows and arrows being shortly supplanted by muskets and cannon. But the beneficent uses of this metal were more extensively experienced in the various branches of peaceful industry-in agriculture, in architecture, in shipbuilding, and in manufactures of all kinds.

The superiority of this metal over all others consists in the vast number of purposes to which it can be advantageously applied, and the various modifications of which it is susceptible in the process of manufacture. There is no other metal which could be so worked up as to serve equally well for a needle and as shot for a ninety-eight-pounder gun; as a surgeon's lancet and a five-ton Nasmyth tilt hammer; as the spring of a watch the size of a shilling, and the hull of a Leviathan steamship; and which is alike indispensable in the construction of a pair of scissors and an electric telegraph, a steel pen and a railroad, a mariner's compass and a tubular bridge. The iron machines of our manufacturers are driven by the iron steamengines of Watt, and their products are distributed over iron railroads by the iron locomotives of Stephenson. Intelligence is telegraphed to and from the ends of the earth by means of the iron wire. Our Crystal Palaces are built of glass framed in iron. We have iron roofs, iron houses, iron churches, iron bedsteads,

iron lighthouses, iron ships, iron palaces, and iron bridges. In short, we now seem to be in the very midst of M. Worsaae's 'Iron Age.'

Although the iron industry of Great Britain may be pronounced indigenous, by reason of the juxtaposition of coal, ironstone, lime, strong men, and cheap transit-a combination not yet known to exist in the same perfection in any other country in the world-it is only of comparatively late years that the manufacture has assumed its present gigantic magnitude. So long as the ore was smelted by means of charcoal made from wood, the produce of the metal was very limited, and its price excessive. The manufacture was for some time partially prohibited in England, the consumption of wood charcoal in the process of smelting being so great as to create apprehensions that if care were not taken of the remaining forests, enough timber would not be left to supply the wants of the royal and mercantile navy. Hence acts were passed in the reigns of Elizabeth and James, forbidding the felling of timber for the smelting of iron, except in certain districts of Kent, Sussex, and Surrey, then the principal seats of the manufacture, and even there the erection of new works was expressly forbidden. These enactments had the effect of greatly checking the manufacture, which shortly ceased in the southern counties, the last iron forged in Kent having been the rails round St. Paul's Cathedral, which were cast at Lamberhurst, about the beginning of last century.

Attention was then directed to the smelting of ironstone by means of pit coal. Large stores of both these minerals existed side by side in the midland counties. Amongst others Lord Dudley gallantly struggled to establish a manufactory in the neighbourhood of Stourbridge, and partially succeeded; but what with riots among the iron workers, who broke into and destroyed his works, and the wars of the Great Rebellion, which ruined his fortunes, the noble lord reaped no advantage from his enterprise. Nothing contributed to arrest the decline in this branch of trade, and towards the middle of last century the number of furnaces, which in James I.'s reign had amounted to 300, fell off to 59, the principal part of the iron consumed in England being imported from foreign countries. The partial use of pit-coal in the process of smelting was revived at Coalbrookdale, in Shropshire, about 1713. The chief difficulty was to keep the coal in a state of combustion sufficiently intense for the purpose of smelting the ore; the hand-worked bellows, or the more powerful water-movement, which produced blast enough for charcoal, having comparatively little effect upon coal. This obstacle was finally overcome through the perse

verance

verance and enterprise of Dr. John Roebuck (grandfather of the present member for Sheffield), who may be said to have originated the modern iron manufacture of Britain, though his merits as a great public benefactor have as yet received but slight recognition. Being a good practical chemist, his inquiries led him, when residing at Birmingham, where he practised as a physician, to seek for more economical methods of smelting iron ore than those then in use. Several gentlemen having joined him in his enterprise he selected a site on the banks of the River Carron, in Stirlingshire, in the neighbourhood of which both coal and iron abounded; and there he planted the germ of the now celebrated Carron Works. With the assistance of Mr. Smeaton, the engineer, he erected powerful blowing cylinders, worked by water, and supplied by means of an atmospheric engine. The original works were completed in 1759, and before long the Carron castings acquired an extensive celebrity. But, besides being the first to manufacture cast-iron by means of pit-coal on a large scale, Dr. Roebuck was the inventor in 1762 of the process for converting the produce into malleable iron, a discovery usually attributed to Henry Cort, whose patent was taken out twenty years later. Dr. Roebuck's specifications leave no room for doubt: the cast-iron was melted on a hearth with a blast, and then worked until reduced to nature;' in that state it was exposed to the action of a hollow pit-coal fire, heated by the blast of the bellows until reduced to a loop,' which was then 'drawn out under a forge hammer into bar-iron.' Successive improvements were made by other inventors,-by the Carneges, in 1766, who invented the reverberating, or air furnace; by Onions, in 1783, who patented the puddling process; and finally by Cort, in 1783-4, who, besides embodying these processes in his patent, introduced the use of grooved rollers, an addition of great importance. But all these appliances would have proved of comparatively small value without the aid of the steam-engine, which was about the same time taken in hand by James Watt. Dr. Roebuck had early discovered the value of Watt's improvements, encouraged him in their prosecution, and eventually became a partner in the patent. But having taken a lease of the Duke of Hamilton's coal near Boroughstoness, with the object of securing an abundant supply of coal for his ironworks, the difficulties encountered in the mining proved so great, that the Doctor was involved in serious embarrassment, and made over his share in Watt's invention, by this time perfected, to Mr. Boulton of Soho, to whom it proved a source of vast wealth.

From the period of the introduction of Boulton and Watt's engines,

engines, and their employment in blowing the iron furnaces, the progress has been truly astonishing. The total quantity previously manufactured in Great Britain did not amount to more than twenty thousand tons annually: but by the end of the century the production had increased ten times. The introduction of the hot blast by Mr. Neilson of Glasgow in 1828, and the discovery by Mr. Mushet of the Black Band ironstone, gave a further impulse, especially in Scotland,-a country in which the metal was formerly so scarce that in the times of the Edwards, the Scotch were accustomed to make predatory incursions into England for the sake of the iron they could carry off, but in the course of last year they not only manufactured sufficient for their own use, but exported 500,000 tons. In England the pig iron produced during the past year reached the astounding quantity of 3,636,377 tons; which, at an average price of 47. a ton, represents a total annual value of fourteen millions and a half sterling. Nor does there seem to be any limit to the supply, for almost boundless stores of the mineral have recently been discovered in Yorkshire, Northamptonshire, and other counties. It is this extraordinary abundance and comparative cheapness of manufactured iron in England which has enabled it to be applied to purposes which formerly were never dreamt of. It promises before long to supersede timber in ships' hulls of large burden. Indeed, a timber ship of even half the tonnage of the Leviathan would be an impossibility. The modern structures in this metal bid fair to equal in grandeur the monuments which have been the admiration of ages; and amongst these triumphs of engineering in our day, iron bridges and viaducts undoubtedly occupy the first rank.

The progress of bridge building has at all times kept pace with that of road making. The best ferries are insufficient to connect the opposite banks of a river, across which there is any considerable amount of traffic. Like everything else, bridges had very humble beginnings. As the prototype of the man-of-war was a canoe hollowed out of the trunk of a tree, so the magnificent bridge of modern times began with a log thrown across a stream: A number of these laid together and planked would form a track sufficient for foot-passengers and pack-horses. But as vehicles came into use, something better was required, and then the bridge of timber or stone was devised. Public benefactors in past times were accustomed to leave money* for

* One of the first stone bridges in England was erected and endowed by Queen Matilda, who on one occasion narrowly escaped drowning when crossing the river Lea, at Stratford, in Essex. The place was hence afterwards called De Arcubus, or Le Bow.

structures