It is a fearful addition to all these causes of insecurity, that cast iron when it breaks gives not the slightest warning. No external crack, no admonitory sound, gave cause to doubt the soundness of the engine beam which caused the disaster at the Hartley pit; and the large flaw in the casting which was discovered after the fracture was not indicated by the smallest defect on the surface. These objections apply to all cast iron, as such; but the inevitable risks are greatly multiplied if the iron employed is of an inferior quality, or of a character not suited to the purpose. The iron of the Hartley engine beam was neither cheap nor bad, but it was composed of a mixture not well calculated to produce a tough quality of iron.*

In the first instance, cast iron exclusively was applied to the construction of fire-proof buildings. In the year 1801 the first cotton mill of this description was erected, by Messrs. Lee and Phillips, of Manchester, with cast-iron beams and castiron pillars. It was constructed with great skill, and for many years remained the model of all similar works. But since then the subject has been more carefully investigated. The account which Mr. Fairbairn gives of the experiments, chiefly conducted by himself and Mr. Hodgkinson at his works, by which he has established the theory, and improved the practice, of cast-iron architecture, is highly interesting, and very valuable to those who still continue to prefer that material; but he in some degree supersedes his own work by proving (quite, we own, to our conviction), that not only strength, lightness, and roominess, but even economy, will be consulted by substituting wrought for cast iron. The difference in the weight compensates for the difference in the cost. A wrought-iron beam of 18 cwt. Mr. Fairbairn sets down as equivalent to a cast-iron beam of 40 cwt. Moreover in many ways the expenses of construction are diminished by the use of wrought iron, and more especially the supporting columns may be retrenched with not less advantage of convenience than

economy.

Mr. Fairbairn justly remarks that the construction of buildings of this kind must not be attempted without a considerable amount of scientific and practical knowledge. He mentions a

In our opinion the immediate cause of the accident was the contraction of the beam, caused by the cold, while the 'gudgeon' or shaft which passes through its centre was heated by friction, and consequently expanded; thus, in fact, acting as a wedge to split the beam in which it was inserted. A tougher cast iron might have resisted-wrought iron certainly would.

mill at Oldham which fell down in the year 1844, and seems to attribute the disaster to some defect in the construction; but the date leads us to suspect there may also have been some fault in the iron. Long previously to the year 1844 cheap iron was common in the market, and the effect of cheapness upon quality was imperfectly understood by consumers. Would it were duly appreciated even now!

The late destruction of the iron fire-proof warehouses on the Thames has somewhat discredited this application of iron; but we think unreasonably. It is plain that if highly inflammable goods are stored in an absolutely incombustible warehouse, in which there is an unimpeded communication between the parts, and a free circulation of air, they will be much in the condition of fuel arranged for lighting in the grate. Mr. Fairbairn gives many valuable directions for excluding the external air, and dividing the various parts of the building; but sooner or later the skill of the architect is neutralised by the carelessness of the warehouseman. On some unlucky day the requisite combination of untoward incidents takes place, and a conflagration which no exertions can extinguish ensues. In such a case, no doubt, the iron-built warehouse will be destroyed, and as in the great fire at Liverpool, in 1844, the gutters will run molten iron, whereas a series of fire-brick vaults would remain in the state of a kiln when the contents are withdrawn. But the enormous expense of such a construction is hardly repaid by the preservation of the mere shell of the building. The wisest course is to store away all inflammable goods, and especially those which are liable to spontaneous combustion, in separate warehouses, or in vaults which realise Mr. Fairbairn's conditions of safety-exclusion of the external air and non-communication; and here fire-bricks should be the material. But most inflammable substances are far less easily ignited when compressed in bales or stowed away in casks; and they are safe if the building in which they are deposited is secured from the danger of combustion to which buildings of ordinary construction are exposed. Loose paper is highly inflammable, but the closely packed treasures of the British Museum are perfectly safe in the new Library,-the most commodious and the most beautiful of fire-proof magazines.

Iron is quite sufficient to ensure the safety of dwellinghouses; but unfortunately very little advantage of the plentifulness and cheapness of this material has as yet been taken in London, and few of the noble mansions which have been raised in the country within the last forty years are secured, by a fire-proof construction, from the casualties which have reduced so

many of their predecessors within the same time to a heap of ashes. It is strange that in the seat of the iron trade, this most important application of iron should be the one (happily, we believe it is the only one) which is generally neglected. The popular dislike of innovation, and the additional expense of iron, are great obstacles to its introduction; but greater still, we suspect, is the unwillingness of our architects to meddle with a material with which they are not familiar. The objection that by the use of iron an architect is turned into a civil engineer no more appals us than the often-repeated threat that a late dinner may be called a supper. If it means that engineering skill excludes architectural taste, the best answer is supplied by Rennie's Waterloo and London Bridges, which are among the very best specimens of modern architecture. If it means that our architects are often deficient in the constructive skill of the engineer, there is only too much truth in the admission, and the sooner so lamentable a deficiency is supplied the better. We are persuaded that if any able member of the profession would bestow on the construction of private dwellings the study which Mr. Fairbairn has given to that of warehouses, he would discover the means of building houses, on a large or small scale, with fire-proof materials, at very little additional expense, and with as much increase of convenience as of security.

The development of the iron trade was indispensable to the introduction of railways, and, in its turn, was greatly stimulated by it. The quantity of iron which is required for the carriages, the engines, the machinery of all kinds, the cisterns, the roofs and supports of stations and warehouses, can hardly be calculated. There are upwards of 10,000 miles of railway in the kingdom, exclusive of loops and sidings; and merely to re-lay these lines, and keep them in repair, consumes a prodigious amount of metal, probably not less than 500 tons for every working day of the year. Everything connected with these establishments is on a colossal scale. During the present stagnation of the iron trade, a temporary impulse was given to a branch of it by the introduction of the telegraphic wires, and of that crowning marvel of modern invention, the submarine telegraph.

It would be superfluous, even if it were possible, to trace the gradual metamorphosis which is going on around us of familiar objects into iron. We cannot chronicle the first introduction of iron hurdles, iron fencing, iron pumps, iron piping, window frames, spouting, stable fittings, mile and guide-posts, gutter kerbs, and a long list of etcæteras. Portable iron houses, schools, and churches are manufactured, for home consumption

' and for exportation.' But everything sinks into insignificance compared with the great wonder and puzzle of the day — the subject which is in every one's mouth, and which probably was in the reader's mind when he was induced to undertake the perusal of a paper on Iron- the conversion of our hearts of oak into iron plates.

The first attempt to realise the Great Iron Master's' prophecy that we should sail in iron ships was made by himself. He constructed iron boats, to carry goods on the Severn and the canals; but at what time, and how many, is uncertain. Mr. Grantham has found, in a journal of the year 1787, an account of the arrival at Birmingham of a canal-boat, built of British iron' (this point then required special notice), by John 'Wilkinson, Esq., of Bradley Forge;' and the writer then proceeds to describe the construction of this novel monster with as much care as the newspaper correspondents lately bestowed on the Merrimac' and the Monitor.' From this period, similar boats were frequently used in inland navigation; and some of the earliest specimens, Mr. Grantham tells us, are still in existence an incontestable proof of the durability of the materials. The first iron boat that was ever launched in salt-water was a pleasure-boat, built under the direction of Mr. Jevons, of Liverpool, in the year 1815; but it might have been long before iron was adopted as the material for ship-building in good earnest, if, in the meantime, the art of propelling ships by steam had not been brought into practical operation. Without engaging in the attempt to penetrate the obscurity which besets the origin of the steam-boat, like that of most other great discoveries, we may claim for Scotland the merit of having first given a practical solution to the problem which so long engaged the attention of projectors. The first steam vessel applied to practical purposes was the steam tug-boat which was launched on the Clyde and Forth Canal in 1802; and the first steam packet-boat established in Great Britain was the Comet,' which began to ply on the Clyde in January 1812.

The quantity of machinery required by this new application of steam greatly increased the demand for iron, and gradually accustomed the public to include that metal among the principal materials for ship-building.

'A series of experiments instituted by the Forth and Clyde Canal Company in 1829-30, to ascertain the law of traction of light boats at high velocities on canals, led to the application of iron for the construction of vessels; and the lightness of these new vessels, combined with their increased strength, suggested the extended application of the material in the construction of vessels of much

larger dimensions.' (Fairbairn, Lecture on the Properties of Iron, p. 31.)

Iron, it was perceived, was better suited than wood to resist the strain of the engine, and would allow more space for the stowage, which was inconveniently curtailed by the coals and the engine. It was not till long afterwards that the employment of iron in the construction of a sailing vessel was attempted.

The first iron steamboat that ever put to sea, The Aaron 'Manby,' was built by the manufacturer whose name she bore, ' under a patent which was taken out in France for steamboats, in 1820. She was built at the Horsley works at Tipton, in Staffordshire, was sent to London in parts, and was put together ' in dock.' In September 1821, Captain, afterwards Sir Charles Napier, who seems to have been a partner in the speculation, 'took charge of her, and navigated her from London direct to 'Le Havre, and from thence to Paris, without unloading any 'part of her cargo- she being the first and only vessel that for thirty years afterwards sailed direct from London to "Paris.' It is farther worthy of note that 'from 1822 to 1830 'her hull never needed any repairs, though she had been 'repeatedly aground with her cargo on board.' (Grantham, p. 10.)

The iron vessels that were successively built are enumerated by Mr. Grantham in chronological order, and to most of them belongs some circumstance of interest. The Alburkah,' a little vessel, built in 1831, by Mr. M'Gregor Laird for the African expedition, which he conducted himself, drew only 3 feet 6 inches of water, and her success dispelled the prejudice which had previously existed as to the danger of going to sea with so light a draught of water. The Garryowen,' built in 1834, was the first that exhibited a 'regular arrangement of water-tight bulk'heads,' an improvement the adoption of which has since been rendered compulsory by the legislature. The Nemesis' and 'Phlegethon,' built in 1839, whose names seem ominous of their future destiny, were the first iron steamers that were engaged in active warfare, and they took a conspicuous part in the first Chinese expedition. But, in our opinion, the greatest interest which attaches to these and all the other vessels mentioned by Mr. Grantham is, that whereas the average duration of wooden ships is thirteen years, they are all afloat at this day, with the exception of the first, the Aaron Manby,' and she was not broken up till the year 1855.

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Notwithstanding this success, the advocacy of iron steamboats was but uphill work, Mr. Grantham tells us, in the year 1842, when he published his first work on the subject. The judgment