IRON-MAKING

THE first knowledge of Iron, it is not improbable, was derived from the discovery of a meteoric mass of this metal. Such mass, existing in a state of considerable purity, and capable of being hammered into form, may have exposed the first rudiments of those valuable properties which have been applied with so much ingenuity and labour to the advancement of human affairs. Tradition says that the discovery of iron took place in Greece, in consequence of the accidental burning of a wood. This is certainly a possible case, where there might happen to exist on the surface masses of iron ore, a circumstance not very uncommon. Perhaps it is a more probable conjecture to suppose that the discovery may have taken place, and been brought to a comparative state of perfection, in the process of converting wood into charcoal for domestic purposes. If the sylvan carboniser happened to pursue his art in a forest, occupying the surface of the mountain lime, abounding with ores of iron common to that formation, the casual introduction of masses of the ore in mixture with the covering matter of the fire would be unavoidable. In a fortunate moment, and under a happy conjuncture of circumstances, a lump might penetrate the ignited fuel,—a strong current of air might have arisen while the woodman slept,—an unusual temperature might thus have been excited,—and (though injurious to the result of his labours) iron might in this way have obtained its first artificial existence. Supposing a partial knowledge of its properties to have been derived from the meteoric mass, this would lead to its immediate application to similar purposes. The success of the experiment would, of course, depend upon the quality of the product,—similarity of surface or polish, would, for a long time, most likely be the only properties in common to both,—uniform malleability, and extension under the hammer, could only result from a regularly constructed furnace, governed by long experience, and certain established rules of process.

Until the invention and use of bellows, the Air-bloomery seems the only mode by which iron could have been obtained. To say what was the first form or shape of this furnace is impossible. Such furnaces have long since ceased to exist in this country, and it is only by the remains of scoria, in elevated situations, that their former existence may be inferred. Park represents the air-bloomery of the Africans as a low conical structure, containing, within very narrow limits, the aperture for admitting the air, and passing off the ignited gas. Air-bloomeries are still in use in Spain, and on the shores of the Mediterranean, where the ores of Elba are worked to considerable extent.

The rationale of this process is the deoxidation of the ore, by means of the contact of heated charcoal.

To produce a beneficial result, it is necessary to use ores rich in iron, and united with as small a dose of oxygen as possible. The ores are stratified, and covered with charcoal, which is from time to time replaced as it becomes wasted by the progress of combustion. The ores during the lower degrees of heat, and period of deoxidation, are sheltered as much as possible from contact with the air. When the metallic particles are developed, an increased temperature is then necessary to unite the masses, and then exposure to air facilitates the process of welding. Lumps of the coalesced ore, impregnated with its earthy parts, and a portion of the iron in the state of scoria, are then taken from the furnace, and hammered into a rough bar called a bloom. This is subsequently reheated and drawn into ploughshares, or other implements which may be wanted.

As the facility of the air-bloomery would depend in a great measure upon a steady and uniform current of air, seasons would occur, and even insulated periods of the same operation, wherein the process would either not proceed at all, or with languor. When the high temperature was necessary to complete, by a union of masses, the result of the previous deoxidation, a falling off in the current of air would not only retard but destroy the economy of the process. Under such circumstances, during summer, or in hot climates, the invention of bellows would be hailed as a powerful auxiliary to the air-bloomery. Their application, at first, would most probably be confined to that part of the operation necessary to produce the welding temperature, but experience and observation would soon lead to higher and more important advantages, which, in the end, though they must have been the result of infinite labour and perseverance, amply compensated for the additional expence of a bellows blower.

The era of the Blast-bloomery must indeed have been the commencement of an important revolution in the art of iron-making. This will be better understood by contrasting the principles in the two operations respectively. In the Air-bloomery, the ore was, by means of the charcoal in contact deprived of its oxygen, and, as an inevitable consequence, aided by the increased temperature, passed into the state of soft or ductile iron. In the Blast-bloomery, not only was the ore deprived of its oxygen, but, by the higher and more uniform temperature occasioned by the use of bellows, a union took place between the iron of the ore and the charcoal of the fuel. This combination would immediately produce fusibility; and crude, or cast-iron, or an imperfect steel, would first make its appearance in the early stages of the blast-bloomery. The soft and ductile preparation of iron, which resulted from the air-bloomery, would no longer appear, but become

mixed with a new and crude species of the metal, incapable of being hammered, and communicating to the more perfect product a deleterious quality,—the bellows would, in many instances, be laid aside, and their usefulness in the process denied, or at least doubted. Chance would discover to some smith, more intelligent than others, that, by frequent attempts in forging, the new metal was improved; he would soon observe, or discover, that this additional process might be considerably abridged, by directing the nose of the bellows upon the metallic regulus, before it was, in the first instance, removed from the furnace. Thus a new form of furnace would be suggested, having for its object the complete fusion of the ores, and the separation of the iron from them in a fluid state. Hence eventually resulted the blast-bloomery, in its most perfect and expeditious form, making in one day as much iron as an air-bloomery could in a week, and in a manner more economical, whether the measured result in metal from the ores or the abridgment of labour are considered.

The blast-bloomery of this country is still recollected by some very old men. Its form was either circular or square, its height from three to four feet. Previous to blowing, it was nearly filled with charcoal, then a charge of ore, over which was thrown a larger charge of charcoal. The blast was urged by means of bellows variously constructed. The ores were thus rapidly heated, and deoxygenated in the upper part of the furnace. As the ore descended and approached the blast, a portion of the fuel, by the increased temperature, united with the ore,—fusion ensued, and nearly the whole metallic contents were precipitated on the bottom of the furnace. The nose of the bellows was then inclined, and directed upon the surface of the molten mass,—combustion and a copious scorification ensued, which was removed from the furnace by repeated tapping. This operation was continued, and hastened by frequent stirring, till the remaining iron had, by an effectual decarbonization, passed into the state of soft or malleable iron. It was then broken into convenient masses, carried to the hammer, and formed, as in the bloomery, into blooms. In a more advanced and enlightened period the defects of the air-bloomery are many and striking. The cementation necessary to deoxygenate the ore, previous to fusion, must have been, from the smallness of the furnace, partial and imperfect, and acquired at an immense sacrifice of fuel. The process was not, as in the modern blast-furnace, continuous; each charge, composed of a certain measure of charcoal and ore, was smelted, separated, and worked, before the furnace was filled for a renewed operation. When the charge of fuel happened to be in excess, which would sometimes be the case, the iron would imbibe an extra quantity of carbon, and be proportionally fusible; this would demand a prolonged action of the blast on the surface of the iron, and thus consume time in an unprofitable waste of the metal. The imperfection of the process may be pretty correctly estimated from the variety of slags, and the quantity of iron they contain. The Roman and Danes' cinders now found, and which were the current production

of the blast-bloomery in remote ages, contain from 25 to 55 per cent. of iron, and have, in the last three hundred years, been extensively in use as ores, for the production of iron, in the blast-furnace.

To the blast-bloomery, in the art of iron-making, succeeded a larger furnace, which is now known by the name of the Blast-furnace, and from the discovery of which, the Foundery and Forge, including the Finery, must have resulted. The vast advantages of this furnace arise from the continued action of reduction, a complete separation and recovery of all, or nearly all, the iron originally in the ore,—a greatly increased quantity in a given time,—and a lessened consumption of fuel in the manufacture. Unlike the imperfect reguli of the bloomery, the metal of the new furnace was fluid, could be collected and remain so for many hours in the bottom of the furnace, and then be run into channels formed in sand,—but in this state, from the extra dose of carbon, it did not possess any property fitting it for the hammer, or for rendering it capable of being formed into a bloom, without subsequent operation. The effect produced in the blast-bloomery, by directing the bellows upon the surface of the separated iron, most likely suggested the idea of a separate furnace, in which a similar operation might be performed, without any connection with the previous smelting. The latent but unerring operations of chemical causes, accidentally associated with a larger furnace, and the favourable proportions of ore to fuel, would produce a fluid metal, which, along with the scoria flowing unexpectedly from the furnace, might thus first exhibit iron under a new form of existence. This would directly lead to experiments in the bloomery, with a view to obtain uniform and regular results. In time it would be found out, that adding to the height and capacity of the furnace increased the fusibility of the iron, and produced it of sufficient fluidity to run from the furnace. This fact once ascertained, would open a new field of observation and experiment, and the dimensions of the furnace would only be limited by the sparing quantity of air, or blast, afforded by the imperfect bellows of the day. For a time this would be partially remedied by the use of a suspending medium in the furnace, since called boshes, but, in the end, the advantages of the large furnace would lead to an improved construction of bellows. The foot and hand blast bellows would give way to others moved by greater animal power, and these in their turn yield to larger bellows moved by the water-wheel. The power of a dozen bloomeries would be now concentrated in the new furnace,—convenience and locality to ore and fuel would be sacrificed to moving power, only to be obtained by the concurrence of water and fall.

In tracing the art through the lapse of ages (during which no memorial of facts has been preserved relative to the progress of iron-making), it seems evident, that its first general establishment, under the system of bloomeries, must have been on elevated situations, for the purpose of obtaining a powerful current of air. After the invention of bellows and the blast-bloomery, the art must have been carried into the plain,—every village and township where ore and

wood abounded would have its furnaces and smiths. The completion of the blast-furnace would once more remove the site of the manufacture, and the powerful blast of the new bellows, and the sturdy blows of the forge hammer, would, in the valley, supersede the more languid operations on the plain.

It is difficult to ascertain the period of the introduction of the blast-furnace into this country. Even in Dean Forest, the most ancient iron-making district, there exist no facts to show when it was there introduced, nor does tradition in any way assist us in the difficulty. In a publication of Dudley's in the reign of James I., the blast-furnace and other improved branches of the iron trade are there spoken of as having been extensive, "but now falling into decay, owing to the scarcity of wood." The art of the founder seems, too, at this period, to have been extensively practised, and judging from specimens still in preservation, considerable taste and skill in carving and relief must have been practised by the model makers of that period; and we know the fact of England's exporting, in the early part of Elizabeth's reign, a considerable quantity of such heavy ordnance as was then in demand. The civil commotions, excited by the long and disastrous contentions of the houses of York and Lancaster, were most unfavourable to the introduction or improvement of the arts or manufactures. It is more than probable, the use of the blast-furnace was first known in the time of Henry VII. Whether it was a native or an imported discovery does not now appear. On examination, the sites of the first class of blast-furnaces are found to have been placed on small streams near their source. The supply of water for moving the bellows was, of course, confined to the winter months, and, according to the copiousness or permanency of the stream, the furnace would be kept blowing four, six, or eight months. In an age when the division of labour was little understood and less practised, the disadvantages of this partial supply was not so great as they at first sight appear. The summer months were employed in procuring a supply of charcoal and ore for the winter consumption, and the same class of labourers passed from the furnace to the mines, or to the woods, and practised with equal facility their various callings.

From the period above alluded to, up to the present time, the only improvement to be traced in the charcoal blast-furnace is the increased size, and corresponding increased power of the blowing-machine. By the removal of the establishment from a solitary stream to a greater depth in the valley, where a larger portion of the drainage of the district had united, giving greater power and permanency of supply to the water-wheel, the weekly produce in iron has been increased from 10 to 25 and 30 tons; and a furnace, under the improved system, has been kept in blast for three years together. In the plates which accompany this article will be found drawings of furnaces used in the time of James and Charles I., and in our own time. The former are proportioned from the hearth of one of the King's furnaces, lately discovered in Dean Forest, and which

furnace has not been at work since the commencement of the Civil Wars.

Although in tracing the progress of iron-making from the bloomery to the blast-furnace, it is seen, that, in all cases, the great object to be obtained was soft or malleable iron, yet we see the career of improvement, as if resting in the completion of a furnace, for the purpose of making an entirely new species of iron, possessing (except in weight) no properties in common with the tough iron of the bloomeries. But in this, as in every department of manufactures and the arts, the division of labour and of process have proved the true road to excellence. The division of iron-making, by whomsoever invented, into two distinct processes, must, at the time, have been marked by great and permanent effects. The manufacture of crude iron in the blast-furnace, and its subsequent malleabilization in the refinery, being operations not at all connected with each other, could be let alone, or carried forward, as best suited the views of the iron-maker. One man might smelt, and another purchase his iron and refine it. In place of obtaining from the bloomery one-fourth and one-third of malleable iron from the ore, the blast-furnace revived and returned, in a manner strikingly perfect, the whole iron of the ore, though in a state of crudeness or brittleness: though this was afterwards subjected to a loss of 25 per cent. in passing through the refinery, still, on the whole, it may be properly estimated, that, by the invention of the blast-furnace and the refinery, nearly double the quantity of iron, from the same weight of ores, was brought to market. The difference between the scoria of the bloomery and the blast-furnace would be so striking and manifest, that comparison would be succeeded by experiment. When the former were found to yield an abundant supply of iron by being smelted in the blast-furnace, a new species of property was created in the country. The spoil of the iron manufactures, from the time of the Romans downward, became at once, and for centuries, mines for the principal supply of the blast-furnace. Extensive proprietorships of Roman cinders (as they were called) were formed. Forests, covered with decayed oaks, were uprooted, and plains that had slept for ages under a great depth of soil, were unbarred to pour forth their newly created treasures. In Dean Forest, it is computed, that nearly twenty furnaces, for a period of upwards of 300 years, were supplied chiefly with the bloomery cinders as a substitute for iron ore. These were used in the proportion of five-eighths of the whole charge, the remainder being made up of the calcareous ores from the mines of the mountain lime, and a portion of lean argillaceous and siliceous iron-stones, accompanying the coal measures.

Dudley says, that in his time there were in England 300 furnaces for the manufacture of pig-iron; that each had forty weeks supply of fuel, and made, while at work, fifteen tons weekly, making in all the incredible total of 180,000 tons annually; and this, too, at a time when he represents the trade as in a decaying state, from the failure of the supply of wood. Either his statement must have been un-

Iron-Making. thinkingly exaggerated, or a great falling off in the manufacture must have taken place in the next hundred years; for we have it on good authority, that some time before pit-coal became the fuel of the blast-furnace, about the year 1740, the following quantities were respectively made in the English and Welsh iron-making counties:

Hitherto we have only spoken of the manufacture of iron in this country, as connected with the charcoal of wood as the basis of its operations. The gradually increasing population of the country had converted to other purposes a great portion of these woodlands that had formerly supplied fuel for the furnaces, and a period had arrived, when either a substitute must be found, or the manufacture of iron cease to be one of the staples of the kingdom. From Dudley, we learn, that James I. had granted many patents in divers parts of the kingdom for the manufacture of iron with pit-coal; that the attempts had uniformly failed, except in his own case, in 1619, when he succeeded to the extent of three tons weekly. The same gentleman, applying in 1663 to Charles II. for another patent for the same object, states, that he had succeeded at one time in making to the extent of seven tons of coke pig-iron weekly. But it was not till about the year 1750 that pit-coal became a general and profitable substitute for charcoal of wood in the blast-furnace. Subsequent experience shows the cause of this tardy advancement to have arisen from the want of a sufficiently powerful blowing apparatus. The introduction of the steam-engine, and the consequent increase of iron now made, soon pointed out the deficiency under which all former experiments had been made with pit-coal. The incombustibility of coke, compared with charcoal, requires a more copious and powerful discharge

of air, in order that it may perform profitably the functions of smelting and carbonating the metal. As soon as this was made evident, it not only stimulated the manufacturer to erect appropriate blowing apparatus for his coke pig furnace, but it led to an immediate improvement in the blowing machinery of the charcoal furnaces, still supplied with wood, so that, in 1788, about forty years after the collation of the foregoing table, we find the state of the charcoal pig-iron manufacture to be as follows:

But, during the same period, it is evident, that an annual diminution of the manufacture of charcoal pig-iron was experienced to the extent of 4250 tons, attributable to the decrease of wood, and consequently the use of coke pig-iron as a substitute. This deficiency was, however, amply compensated by the rapid increase of the manufacture of coke pig, as proved by the following statements:

Coke Pig Furnaces in England and Wales, in 1788.

About the year 1796, Mr Pitt had it in contemplation to add to the revenue, by a tax upon coal at the pit. This, of course, led to a powerful opposition on the part of the manufacturing consumers, particularly in the iron trade. A committee was appointed, witnesses examined, facts collected, and the measure abandoned, as being unwise and impracticable. The following table, while it exhibits an abstract of the facts collected, shows the rapid progress of the iron trade in the course of the eight previous years:

The return from Scotland exhibited a list of 17 furnaces, and an exact return of pig-iron manufactured, - 16,086 tons. Making a whole annual quantity of 124,879

Annual average produce from each furnace, which also includes the charcoal furnaces, 1032
Annual average of 1788, including the charcoal furnaces, - 800
Increase tons, - 232

In the six following years, there were built and

building in England and Wales 40 additional furnaces, and in Scotland 7, the collective manufacture of which was computed at upwards of 170,000 tons annually. Nor did the trade, at this period, become stationary. Its unexampled increase and prosperity attracted the cupidity of the minister of the day; and it was reserved for a popular administration to fail in a financial speculation, which, if carried, was to cripple one of the main-springs of national prosperity. In 1806, a bill was brought into Parliament, having for its object a tax of L. 2 a ton on all pig-iron made, and of placing the manufacture itself under the supervision of the excise. The bill itself was an anomaly in legislation, and, though armed with powers and clauses in abundance, could not possibly have been acted upon. It was framed in utter ignorance of the nature or details of the manufacture, and contributed much by its absurdity to the failure of the cause it was intended to support. The union necessary to oppose the bill with effect produced a new series of facts, regarding the extent and progress of the iron trade in the kingdom, showing at that time its annual amount of product to be at least 250,000 tons. Since that period, the manufacture has gone on increasing; and, though subject to great depression in 1815 and 1816, has, during the last three years, resumed its former activity. The manufacture of pig-iron, in Wales only, may be computed at, tons per annum, 150,000
Shropshire and Staffordshire, - 180,000
Yorkshire and Derbyshire, - 50,000
Scotland and other places, - 20,000

Tons, 400,000

Having thus narrated the progress and increase of the manufacture of pig-iron, we shall next describe, as concisely as possible, the economy and order of the process itself, both in the charcoal and coke blast-furnace, as at this time practised. Plate LXXXIX. fig. 1. represents a charcoal-furnace of the largest dimensions, blown by three iron cylinders, moved by a water wheel, and so constructed as to be blown at either side, or at the back through openings called twyers. The furnace is filled with charcoal, which is gradually ignited to the top, when a charge of ore is put in, with a proportion of flux, along with a certain number of baskets of charcoal. The furnace is from time to time opened below, and large bars of iron are introduced to serve as a temporary grate, through which the air may pass to the whole body of materials in the furnace. By the time the ore reaches the bottom, a considerable temperature has been excited, indicated by occasional fusions and scintillations. These are the general signals for introducing the blast. The furnace is shut up in front by means of a stone called the dam-stone, and space is left between this and the front-stone or tympan, which is filled with sand. The twyer is then opened and the blast introduced. Entire fusion commences. In a few hours the earthy matter of the ores accumulate in the state of glass, and are allowed to flow out at the opening in front, between the dam and tympan-stone. In the mean time the iron, by its superior weight, falls to the bottom,

where it is allowed to collect for twelve or eighteen hours. The furnace is then tapped in an opening left on one side of the dam-stone, and the metal flows along a channel made in sand, called the sow, into the moulds prepared for it in the pig-bed. The charge introduced from time to time as the smelting and reduction take place, is called the burden, and this burden varies considerably, and at different works materially, owing to the quality and richness of the ore. For many years past charcoal iron has been made chiefly with the red hematitic ore of Lancashire, the uniform quality and richness of this "mine" rendering the operation of smelting a matter of greater certainty. Four large baskets, containing about ten bushels of charcoal, will smelt and carbonate the iron contained in four hundred weight of ore. With the necessary proportion of an argillaceous ironstone flux, this quantity will yield 2½ hundred weight of iron. In the neighbourhood of Dean Forest, the calcareous ores of that district have been superseded by the use of Lancashire ore, except as a flux, for which purpose a lean carbonate of iron, much mixed with a sparry carbonate of lime, containing about 20 per cent. of iron, is used in the proportion of one-sixth to one-eighth of the ore. A charcoal furnace will consume from twenty-five to thirty thousand sacks in a year, each containing eleven to twelve bushels charcoal, the produce of at least one hundred and twenty acres of woodland. If the wood replaces itself fully in twenty years, then twenty-four hundred acres of land would be necessary to keep such a furnace at work.—Coke to manufacture the same quantity of iron is obtained from less than half an acre of the Staffordshire main coal.

The preparation of the coke blast-furnace is similar to that practised with the charcoal blast-furnace, but its workings and burdens are infinitely more varied and complex than that of the latter, which, from the uniform quality of wood charcoal and Lancashire ore, experience has reduced to a certainty in every possible change and proportion arising from burden. In the coke furnace the case is widely different;—every new situation has, in the nature of the coal, and the quality of the ore, something novel and characteristic. The argillaceous ironstones generally used, are not very various in point of richness; few when roasted are under 35 per cent., and equally few exceed 45 per cent., and their composition generally unite silex, lime, and clay. As it is the convenient practice at most works to mix lean and rich ores together, so as to reach a common standard of 40 per cent., there can be no material difference occasioned by the quantity of the iron used in the ore, the average produce of which may be correctly taken all over the kingdom at 37½ per cent. It was long considered a fair burden if the coke carried, that is to say, smelted and carbonated the iron contained in an equal weight of the ore.—This is now materially exceeded in Wales and in Staffordshire. At Blanavon, in the former, the coke smelts double its weight of ores, and in that principality generally, it smelts 50 per cent. more ore than its own weight. The same thing takes place in Staffordshire and in Shropshire; but at some furnaces

in Derbyshire and in Yorkshire, the coke does not smelt above two-thirds its weight of ore. Again, some coals in coking yield 65 to 70 per cent., while others yield not more than 35. Hence a ton of iron is made at some furnaces under three tons of coal, and at others eight or nine tons are required for the same purpose. This great variety in the fuel renders general rules of little or no avail; a few simple principles, however, arising out of observation and experience, are understood and practised at all iron works.

The ironstones of this country, were they fused under the most favourable circumstances as to coke and blast, would not, without a mixture of lime or limestone, afford a perfect result,—the glass or scoria, from the excess of silex, would be languid and tough, the iron would separate imperfectly, and its quality be injured by combination with silicium, in the absence of lime. The latter having a greater affinity for silex than for iron, readily unites with the former, and leaves the iron to the full action of the carbon, and, like all mixtures, forms a more fusible compound than either separately. This mixture of the earthy matter of the ores is called cinder, scoria, or slag. In flowing it indicates, by its degree of heat, colour, and fluidity, with the most accurate precision, the quality of the iron accumulating in the furnace. Lime, however essential to a proper flow of cinder from the furnace, is not primarily the cause of change in the quality of the iron,—coke is the powerful vital agent,—on its properly apportioned quantity and its quality the whole result depends. In vain will it be to harmonise in quality and proportion the other materials, if the proper quantity of cokes be not present to reduce the charge into a proper state of division, and to carbonate the iron to such an extent as to pass the blast without oxydation. When the due proportion of lime and coke are present in the charge, the cinder flows from the furnace, sometimes transparent, opaque, white, glassy, variously mixed with fine tints of blue, and nearly free from oxyde of iron. The metal accompanying such a cinder is what is called carbonated, or grey pig-iron. If a portion of the coke is withdrawn from the charge which gave out such results, the cinder instantly changes to a brownish black, or entirely black colour,—the iron parts with its carbon, becomes white in the fracture, deteriorated in the quality, and the whole operations of the furnace become disordered.

Having thus traced the general progress of the iron trade in Britain, commencing in a period of conjecture, and from beginnings the most limited and rude, to a state of most unexampled prosperity and national grandeur, during which the object of the iron-maker had changed from the production of malleable iron, in the first process, to that of crude iron, it is now necessary to retrace our steps, and pursue the subject as connected with the manufacture of malleable iron, or, as it is now called, bar iron. The advantages produced by the inflection of the bellows pipe in the blast-bloomery, as has already been noticed, most likely furnished the first idea of the refinery furnace, or the discovery might have been purely

accidental. A piece of cast iron, by some unforeseen, but possible circumstance, formed in and tapped from the bloomery, would, by its novelty, arouse curiosity and conjecture; and although, by simple heating, it would not yield to the impression of the hammer, yet, by a second fusion in a common smithy fire, new properties would be developed, and in the end, ductile iron would be obtained. It is likely that, for a long time, these occasional runnings from the bloomery would be considered as a species of waste, and from time to time worked up by the common smith, while the bloomery performed its more extensive functions. As the smith became more perfect in his art and manipulations, iron produced in this way would be possessed of superior strength and ductility, and would eventually obtain a preference in price and demand in the market. Thus a powerful inducement would be held out to the Bloomery proprietor, to increase, by direct experiment, the quantity of cast iron, and to devise a method by which it could be regularly made; nor would the manufacturer stop short till a furnace was constructed, continuous in its operations, and regular in its results, as to the production of cast or pig-iron. From that moment the refinery became a furnace of the utmost importance to the iron trade. The process here performed was bold and philosophical—nothing short of subjecting the most refractory of all metals to a violent combustion could free it from an admixture which, but for this, must have remained a perpetual bar to its ductility. The open cavity of the furnace being filled with charcoal, a fire, by means of the bellows pipe, more or less inclined, was soon created; the cast iron of the furnace was placed upon the burning fuel; in time it melted, and, dropping in detail, passed before the current of air issuing from the bellows, and, deprived of its carbon, sunk under the level of the nose-pipe, having lost its fluidity, and become sufficiently coalesced. Iron bars were then introduced; the clotted iron, broken into pieces, and brought a second or a third time up above the level of the blast, till a sufficient refinement had taken place to enable it to stand the blows of the forge hammer. In this operation of refinement, or burning out the carbon, the iron entered into a complete state of combustion, and a considerable portion of it was converted into scoria. The creation, management, and quantity of this scoria were matters essential to be understood, and properly practised, both as to the quality of the iron and the economy of the process.

The quantity of iron wasted in this operation depended upon the quality of the cast iron made use of. If the iron was highly carbonated, an extra tendency to fusibility existed; and a greater duration of exposure to the blast was necessary, to render the iron tough and ductile. From 25 to 35 per cent. of the whole iron introduced was, by this process, converted into a glass of iron, containing from 45 to 50 per cent. The operation in itself, compared with after events, was simple and expeditious, and the quality of the iron good. It is by a similar process that the superior qualities of iron brought from Russia and Sweden are at this day manufactured; and the same mode is in general practice all over

the Continent of Europe. In this country, the use of the finery continued as the only means by which iron could be profitably rendered malleable, until some time after the introduction of pit coal in its manufacture. When coke was first made use of in the blast-furnace, charcoal was still used in the common refinery, for the decarbonization of the iron to be made into bar iron; but it was found necessary to add another process to overcome the deterioration in the quality of the coke pig-iron. The lumps formed in the refinery were afterwards heated, and drawn out into blooms, and these again into bars, according to the quality of the iron wanted. As charcoal became scarce, the manufacturer ventured to add, in the refinery, a small portion of coke along with the charcoal, endeavouring, in the after part of the manipulations, to overcome the consequent deterioration of quality; but, as charcoal was at last entirely abandoned, and coke exclusively used, a considerable variation took place in the process. In place of forming the product of the refinery into lumps, which exposed very little surface when afterwards re-heated, the masses from the refinery were carried and put under a heavy hammer, of four or five tons weight, and beat out into a ragged sort of plate, called stamp iron; these were again broke, by mechanical force, into small pieces, and their qualities examined. Those pieces, little removed from the nature of pig-iron, were called ran, and thrown aside to be refined. The perfect plates were built into piles of 50 to 70 lbs. weight; and each pile was placed upon a tile stone, or fire clay plate, or incased in a large rough sort of crucible, called a balling furnace pot. When a sufficient number of these were in readiness, a batch was introduced into a large furnace, heated with flame of pit-coal. When the temperature had been sufficiently raised to weld the parts together, each ball or pile was removed from the furnace in succession, by a pair of tongs, carried to the hammer, and formed into a bloom, being a short thick bar of iron. These blooms were re-heated in a fire, called the chaffery, and put under a lighter and more active hammer, where they were drawn into their destined shape.

A considerable waste of iron was in these various processes sustained, amounting to ten or twelve hundred weight for every ton of bars that were finished; but the difference of the price of fuel compensated for this additional loss; and the necessity of the case, from the diminution of wood, and increased demand, had become imperious. The manufacture of bar iron remained subject to the stamping process many years, and the quality of the iron so made was strong, and generally tough; but the tardy finish of the hammer, and the arrangement of the whole, was not calculated speedily to overcome quantity; and it was considered a respectable establishment that could turn out, in one week, twenty tons of bars fit for the market. Refineries could not be multiplied without an additional increase of blast; and this, in general, could not be done without additional steam-engines; and, in short, the manufacture had become apparently stationary, when the genius of Mr Cort furnished the ardent minds of his countrymen with a new and interesting field for enterprise. When Mr

Cort laid before the public his new plans, so inadequate was this country to the supply of its own demands, that it imported from Russia and Sweden the enormous quantity of 70,000 tons of bar-iron annually. The object of Mr Cort's processes was to convert into malleable iron, cast or pig-iron, by means of the flame of pit-coal in a common air furnace; and to form the result into bars by the use of rollers in place of hammers. He made many experiments, and expended large sums of money, in the progress of establishing his inventions; but, so long as the various qualities of pig-iron only were the subject of operation, the results in the puddling furnace (his invention) were uncertain, attended with waste, and unequal in quality. These obstacles were at last removed by the operations of the coke-refinery, already alluded to. In refining grey or fusible iron, it was in common practice to tap the fusion, immediately upon its being smelted, into a flat-box. This plate of iron being so far refined, was again thrown up on the fire, and passed a second time before the blast. If still too fine to come into "nature" it was again put on the fire, to complete its decarbonization. Some of these plates being taken to the puddling furnace, were observed, in working, to possess properties, both as to facility and quality, very superior to the best pig-iron. It then occurred that the finery ought to be employed, not as formerly, to refine the iron to the extent of malleabilization, but merely to decarbonize it to a certain extent, and to fit it more properly for the operation of puddling. This gave rise to the very extensive practice of "running out," which gives complete certainty to the puddling process. In this new refinery, or "running out fire," the various qualities of pig-iron are, by the skill of the workman, mixed and reduced to a common standard, which is now called finer's metal. By this means, the operations of the puddler are rendered certain, and he can reckon, within a few minutes, the continuation of his operation. In the commencement of this, as in all new things, much difficulty and waste of iron was sustained, and only a limited quantity overcome. The loss now, when the refinement is carried on in one fire to the extent of sixty to eighty tons a-week, is estimated not to exceed 2½ cwt. per ton, or 12½ per cent.

The puddling furnace, for which the refined metal is thus prepared, is, in its general form and appearance, not unlike a founder's air furnace. It is heated by means of pit-coal, on a grate; and, as may be seen in the drawing, has a chimney of considerable height, in which there is a damper, to regulate the degree of heat while puddling. A considerable portion of the space between the grates and the chimney is formed flat, and covered with a peculiar sand, possessing the properties, when heated, of becoming very hard and infusible. On this space is placed 3 or 3½ cwts. of finer's metal, and the flame allowed to pass over it with the full force of the furnace. In twenty minutes, the iron assumes a yellowish white colour, and marks of fusion appear on the angles of the pieces; the puddler then turns up new surfaces to the flame, and keeps breaking those which have reached a softened state. This he

continues, at intervals, till the charge has subsided into a thick clotted sort of fusion. The furnace, at this period, is reduced to its lowest temperature; part of the furnace bars and fire are withdrawn, and the damper nearly shut; the puddler keeps stirring and moving the iron, backwards and forwards, which now begins to ferment and emit flashes of a bluish coloured flame (the carbon passing off in the state of carbonous oxyde). This operation is continued till these appearances pass off, and till the iron becomes less clotted, and begins, in the language of the workman, to dry. His exertions are redoubled, and soon the whole charge is reduced to the state of the finest saw-dust; it is now said to be dry, and so totally free from cohesion, that it may be moved about like as much sand. At this stage of the operation the grate bars are replaced; the fire repaired; the damper elevated; and the heat is in consequence increased, though gradually. The grains of iron become tipt with a snowy whiteness, resembling the welding of iron; they no longer repel each other, but begin to adhere in small masses; these increase in size as the temperature of the furnace is raised. When the charge begins to work heavy, the puddler selects a nucleus, and rolls it over and over upon the coalescing masses, till he has got it of the weight of 60 or 70 lbs.; he then places this on the flame side of the furnace, and anew he begins the operation of balling; repeating this till the whole charge is balled up. A heavy iron instrument, called a Dolly, is then introduced into the furnace, and with this the balls are in succession beat to give them more cohesion in rolling. When properly heated, they are removed by tongs from the furnace, and slid along iron plates to the rolling machine. Here the lumps or balls are each, in succession, passed through rollers, grooved diagonally, acquiring, as they pass, additional cohesion and firmness, and assuming the form of a bloom. This is then presented to another pair of rollers, with flat openings or grooves, and rolled into a bar of three or four inches in breadth, and from half an inch to three-fourths of an inch in thickness. The whole operation of rolling one of the balls is performed in a minute and a-half, and pleases, while it astonishes the observer, by the rapid change which is thus passed upon matter the most unshapely and refractory. The whole time taken up to complete a charge from the puddling furnace is only from two to two and a half hours; the loss sustained is from 10 to 12 per cent. One furnace will discharge five or six heats in twelve hours, and make in one week from ten to twelve tons of rough bars. A set of rollers, moved by a thirty horse power, will rough down in a week 200 tons of such iron, and keep twenty puddling furnaces at work, for which three or four refineries or running out fires will be necessary. The material thus produced is called mill bars, and require another operation before they are finished. For this purpose they are carried to a pair of large steel shears, and cut into regular lengths, proportionate to the bar ultimately intended to be made. These pieces are then piled on each other in reference to the required thickness, as the cutting was to the requisite lengths, and are introduced into the reheating furnace. A welding

heat, by the flame of pit coal, is here brought upon them in the space of twenty minutes; they are then, one by one, taken to another set of rollers, similar to the first, and in the diagonal grooves each pile is brought down to a certain size; they are then put into the finishing rollers, and rapidly formed into bars of the most perfect form, and most accurate dimensions. At one of the most perfect works in this or in any country, one bar of iron per minute is finished for hours in succession, and one set of rollers have finished, in twelve hours, twenty tons of bar iron of the most perfect form. This formerly would have been full work for a week in any large manufactory of iron.

Such has been the extension of the iron trade in this kingdom, mainly owing to the great facility presented by puddling and rolling. That the Cyfarthfa Iron Works alone manufacture annually double the quantity of pig and bar iron made in the whole kingdom between the years 1740 and 1750, and a quantity nearly equal to one half of the whole make as it stood so late as 1788. Several iron establishments, on a smaller scale, finish from 200 to 300 tons; and few there are which do not manufacture regularly 100 to 150 tons weekly. In South Wales alone, there are now made yearly upwards of 80,000 tons of bars; and, in the whole kingdom, besides, nearly 120,000 tons more, making in all 200,000 tons. One of the paramount advantages of the present system is the facility and cheapness of rolling. Iron of every possible size and form can now be obtained at the common price of bars. The labour of the smith, in forging and drawing, are now almost unknown, and the price of his work proportionally reduced.

It is painful to know that, incalculable as have been, and are likely to be, the national advantages derived from the puddling process, which has given England the command of the markets of the world, Mr Cort, the inventor, after expending an ample fortune in bringing the system to perfection, died, and a respectable family survives, without having received any public acknowledgment of his services, or compensation for his losses.

IRON ORES.

To comprehend fully the theory of the separation of iron from its ores, it is necessary to examine and operate upon them in a smaller scale than that of manufacture. Ores of iron are in general mixtures of oxides of iron with certain earths, in every possible proportion, which, if fused alone, without any addition, would be formed into glasses more or less dense, according to the quantity of iron they contained, and in which no trace of metallic iron would be found to exist. The simple principle, therefore, in reduction, is to add a substance to which the oxygen will unite, in preference to remaining with the iron, and such other substances, with which the earthy matters of the ore would combine, on the same principle. Carbonaceous matter is found essential to perform the former part of this operation; and opposing earths contrary to each other in their natures, are found sufficient for the latter. Thus, if a common ironstone of this country is fused alone, in a common clay crucible, the result is a black glass of

iron. If charcoal be added in proportion to the quantity, the iron becomes separated. As the iron separates, it forms itself into a small spherule, under the glass. When charcoal is added in excess, that is, to the extent of one-fifth or one-seventh, the weight of the ore, three-fourths of the iron, will be found revived. The deficient produce remains in the glass, or unites to the superfluous charcoal, forming a magnetic carburet of iron. If there has been an excess of clay in the ore, the glass will be found black, opaque, and concave on the surface. If of silex, deep bottle green, with brownish-coloured cells, around the metallic button.

If this experiment is repeated with one-third or one-fourth the weight of the ore of lime, other circumstances being alike, the carburet of iron will disappear, the glass will be found dense, comparatively transparent, and the produce in iron greatly increased. If the same ore alone was put into a crucible, mixed with carbonaceous matter in its texture, or into one chiefly composed of black lead, fully one-half the produce of the ore would be revived. Or, if masses of the same ore were deoxidated by a prolonged cementation with charcoal, their subsequent fusion, per se, even in a common crucible, would yield five-eighths the whole iron contained in the ore; and, if fused in a black lead crucible, seven-eighths of the whole iron would be reduced to a metallic state.

When the first portions of iron are extracted from an ore, with a minor proportion of charcoal, the resulting globule is always in the state of soft or ductile iron; as the dose of carbon is increased, the iron subsequently passes through various states of steel and common crude iron; and, if properly conducted, into that of the richest carburet of iron. The quantity of reduction performed by the charcoal is various at various stages. In the first place, all the charcoal is employed to unite with the oxygen, and a certain additional quantity beyond this must be used, before iron is produced. After this the rate of reduction is increased, till more than one-half the iron is revived; it then falls off, upon the well-known ground that the last portions are always most difficult to extract. Much larger doses of charcoal, in proportion, are necessary; and it is essential to perfect separation that not only all the oxygen be removed from the ores, but that the resulting iron itself should take up a considerable portion of the carbon so added. The table subjoined will more clearly illustrate these hitherto unknown facts.

If a calcareous ore is subjected to fusion in a clay crucible, it will melt with facility, in proportion to the quantity of iron united with the lime, and form a black shining lustrous glass. If charcoal is added, the iron will separate; but if it is added in excess, the ore will become refractory, and not melt. The same ore, thrown into a black lead crucible, will sink down into a rough mass, without any separation of iron. If an argillaceous substance is added, fusion and a fine glass will ensue; and if a proper quantity of charcoal is present, the same will be transparent. If the argillaceous earth is diminished without any change in the charcoal, a pure white porcelain will be obtained over the iron, similar to, though much

more perfect than the cruddley or limy cinder of the blast-furnace.

The fusion of a siliceous ore of iron, per se, affords a highly polished shining glass of iron, the fracture of which frequently decomposes light. On the addition of charcoal, an imperfect rosy fusion is obtained. The siliceous matter is then resolved into a deep brown or yellowish glass, streaked with glass of iron, and the separated iron thrown about the crucible in a state of small globules of a silvery colour, which are generally understood to be an alloy of iron and the metal of silex. When the silex exists in small quantities, compared with the oxyde of iron, as is the case with the Lancashire and Cumberland ores, the whole of the iron may be revived with charcoal alone, and the earthy matter remain unfused, but in an agglutinated state.

Ores of iron are in themselves frequently united with such a mixture of earths, as to render, with the proper dose of carbon, the most transparent glasses, and iron of the most perfect quality. If the ores are rich, an inconvenience is sustained, by the metallic button being on its upper surface exposed without a covering of glass. This not only tends to decarbonate the iron, but, if in a state of ebullition, allows it to be projected against the sides and cover of the crucible, and makes the product difficult to ascertain.

The following is a table or abstract of a set of experiments, made with a common blast-furnace ironstone, in which experiments, lime, deprived of its carbonic acid, predominated as a flux, but to which other substances were added, to prove their effect in facilitating or retarding, with the same or different proportions of charcoal, the reduction of the metal from the ore. The ore itself had been previously assayed for carbureted cast iron, and yielded 46 per cent.

Fig. 1, Represents the section of an air-bloomery furnace, similar to that used by the Africans, as stated by Mr Park in his Travels.

Fig. 2, A horizontal section of the same furnace across the openings, used for the admission of air, and discharging the furnace.

Fig. 3, Represents a section of the old blast-bloomery, with its bellows and lifters, which was universally used for the manufacture of malleable iron before the invention of the blast-furnace, and the discovery of the manufacture of pig-iron.

Fig. 4, A ground plan of the same furnace, showing the bellows and blast pipes, and A, the opening which was regularly broken down at the end of each heat, to remove the bloom of iron from the bottom to the hammer. These bellows were worked in a very simple manner, without the assistance of levers, by a man alternately depressing the upper board of each, by merely treading thereon, which, in its turn, was again elevated by means of the lifter and counter weight. The stream of air, in this way, was prolonged with but little pause or interval.

Fig. 5, Is a section of the building, and interior of the charcoal blast-furnace, about the time of its first application for the purpose of making pig-iron. The remains of a furnace similarly constructed were accidentally discovered, in making an excavation, about eight years ago, in Dean Forest. This furnace, along with many others in ancient times, belonged to the Crown, were called King's Furnaces, and were probably used for the purposes of smelting, with the cord-wood of the forest, the King's share of the iron ore obtained from the mines.

From its situation on the margin of a small stream, and the remains of the water course, the bellows must have been worked by means of a small water wheel. The height of this furnace, from A to B, judging by the dimensions of the hearth and boshes, which were found entire, could not have exceeded 20 feet. The height of the hearth, from A to C, 4 feet, and the height of the boshes, from C to D, 2½ feet. The length of the hearth, from e, the back wall, to f, the front of the dam-stone, 4 feet.

G, G, The lining, constructed of thin beds of an infusible species of sandstone.

H, The hearth, composed of stronger beds of the same species of sandstone, called land-stone.

Fig. 6, Is a section at right angles of that part of Fig. 5, comprising the space from D to A, in which the letters correspond, showing the blowing orifice called the twyre, the twyre-arch, and the three cast iron bearers called "sows," for supporting the same.

Fig. 7, Is a horizontal section of the same furnace at D, the top of the boshes, Figs. 5 and 6, showing the quadrangular form of the interior, which was common to charcoal furnaces at that time, and in which the letters of reference also correspond.

This furnace was destroyed at the commencement of the civil commotions in the reign of Charles the First, and was never afterwards rebuilt.

Fig. 1, Represents a section of one of the largest charcoal furnaces, such as are now in use, and which is also applicable to the making of coke pig-iron.

In this drawing the exterior building is omitted, and no more retained than is necessary to give a correct view of the interior of the furnace, and the arrangement of the blowing apparatus.

Fig. 2, Is a ground plan or horizontal section of the above furnace at the top of the twyre openings, exhibiting A, A, A, the twyre arches.

B, B, B, The blast pipes; the two dotted lines showing their communication with each other through the pillars of the furnace, and with the blowing machine.

C, The fold, fauld, or working-arch, by which the hearth is approached, and the operations of working, flowing the cinder, and tapping off the metal, are performed.

D, A longitudinal view of the hearth from the back-wall to the front of the dam stone.

E, The dam stone, about eighteen inches high, over which the cinder or scoria flows, and which closes up the front of the furnace, with the exception of the space at f, called the tapping-hole. This is opened from time to time to allow the metal to flow out. The letters in this plan correspond with those in the perpendicular section, Fig. 1.

Fig. 3, End view of the blowing machine, consisting of three cylinders, calculated to discharge the air both ways. The pistons are successively moved by means of three cast iron beams.

K, K, K, the three working beams (two of which only are seen), connected with a triple crank or lying shaft, I, I, I. To this crank-shaft is attached a small pinion wheel G, which is worked by the large spur wheel H, placed on the shaft of the water wheel.

Fig. 4, Is a ground plan of the former, showing the crank-shaft I. The tops of three blowing cylinders L, L, L, with the valve openings N, N, N, the main valve boxes and blast pipes M, M, M. The letters of reference correspond with those of Fig. 3.

Fig. 5, A view of a refinery furnace, or running-out-fire, with its blowing apparatus.

O, The general appearance of the furnace.

P, The front plate of the hearth, with the tapping holes.

Q, The cistern into which the water of the tue-irons empties itself.

R, A reservoir for the supply of the tue-irons with cold water.

S, The tue-iron pipe, which conveys a constant stream of water to prevent the tue-irons from burning. The tue-irons for this purpose being made double, leaving a hollow space all round for the water.

T, The nose-pipe, inflected for the purpose of discharging, when melted, a current of air upon the surface of the metal, to produce refinement or decarbonization.

U, The blast box, containing the valve for regulating the air.

V, The blowing cylinder.

W, The blast pipes for conveying the air into the inverted water regulating cistern X.

Y, Y, The space for the ascent and descent of the water, for restoring the equilibrium, giving smoothness to the motion of the engine, and rendering the current of air more equable throughout.

Fig. 6, Represents a ground plan of the blowing machinery, and two running-out-fires.

Z, Z, The hearths in which the iron is melted and refined.

t, t, t, t, The water tue-irons, two of which are necessary for each fire. The other letters of this plan correspond with those of Fig. 5.

Fig. 7, An enlarged section of the water tue-iron, with its pipes of supply and discharge, s and r.

Fig. 8, End view of the above tue-iron, showing the two holes for receiving the pipes s and r, and the size of the blowing orifice at the smaller end. It is the same with that referred to under the letter t, in Figs. 5 and 6.

Fig. 1, A section of a coke pig-iron furnace, with its twyres and twyre-arches, similar to what are at this present time used in South Wales, where upwards of one hundred tons of pig-iron have been produced weekly from one furnace. The extreme height of this surface from the bottom at A, to the filling place at B, is 50 feet. The height of the hearth, from A to C, 8½ feet; from C to the top of the boshes at D, 8½ feet. The diameter of the hearth, from A to C, increases from 3 feet to 3½ feet. The extreme width at the top of the boshes D, 18 feet. The diameter of the charging place, B, 6 feet.

E, E, E, E, The lining, composed of a double circle of fire bricks, about 15 inches long, each, with a space for an intermediate packing of sand.

F, F, The hearth, constructed of large blocks of breccia or plum-pudding stone, from over the mountain limestone measures.

G, G, The twyres or openings, by which the blast is discharged into the furnace.

Fig. 2, A view of a double power steam-engine for the purpose of blowing furnaces, the steam cy-

linder of which is 60 inches diameter, the blowing cylinder 100 inches diameter; length of the stroke, 9 feet; travels 12 double or 24 single strokes per minute.

This engine is capable of blowing four furnaces at the rate of 3000 cubic feet of air per minute for each, and making from 250 to 280 tons of pig-iron weekly.

A, The steam cylinder.

B, The blowing cylinder.

C, The cold water cistern, with its ends taken off to show the air-pump p, and condensing cylinder s.

D, The lever wall for supporting the cast-iron beam.

E, The working beam and parallel motions to which the steam and blowing piston rods are attached.

F, The steam cylinder pedestal of ashlar work.

G, The pedestal of the blowing cylinder, serving also to load the air receiver, x, beneath.

H, Spaces for the water to ascend when displaced by the compressed air within the inverted cistern, x. The difference of level, between the surface of the water in the interior and exterior of this cistern, when the engine is at work, will always be in the ratio of the density of the blast. In this instance, the surface of the outside water will be nearly seven feet higher than that of the water within the regulating cistern.

I, The branch blast pipe for communicating with the water regulator.

Fig. 3, A ground plan of the steam cylinder, pedestal, cold water cistern, air pump, condenser, and lever wall, the letters of which correspond with those in the elevation.

Fig. 4, Is a ground plan of the blowing cylinder, blast-pipes, pedestal, and water regulator.

K, K, K, K, Represent the openings or valve spaces in the top of the blowing cylinder, for admitting the air during the descent of the piston. A similar number of these openings with valves affixed, are placed in the bottom of the cylinder for admitting the air during the ascent of the piston.

L, The blast box, containing the upper main valve for preventing the return of the air during the descending stroke. A similar box, containing the lower main valve, may be seen at L, in the elevation (Fig. 3), for preventing the return of the air, during the ascending stroke. The other letters in this figure correspond to those in the elevation.

PLATE XCI.

Fig. 1. A ground-plan of a mill for rolling various sorts of iron.

A, The crank by which motion is communicated to the machine, when steam is the moving power.

B, The large spur-wheel, the teeth of which work into those of

C, The pinion wheel, to the axis of which the roller pinions are coupled.

D, The fly-wheel, of cast iron, 24 feet in diameter.

E, The small spur-wheel for imparting motion to

F, F, F, Three pinions, and their respective shafts, to which the rollers, or cutters, are occasionally coupled.

G, G, G, G, The main cills, which are heavy masses of cast iron.

H, The puddling or roughing-rolls for compressing into regular form the balls of iron from puddling furnace.

I, Rollers for finishing flat bars.

K, Rollers for forming square bars of iron.

L, Pinion and rollers for hoops or plate iron.

M, Pinion and cutters for slitting rod iron.

N, N, N, N, N, N, Roller and cutter cills made of cast iron.

O, O, Eccentric wheels for working the cutting sheers. P. (Fig. 2.)

Fig. 2, An elevation of that part of Fig. 1, comprising the crank-shaft, spur wheel, fly wheel, and cutting sheers, P; the other letters correspond to those in the ground plan.

Fig. 3, An elevation of that part of Fig. 1, including the small spur wheel, three adjoining pinions, fly wheel, and main cill. The letters correspond with those of the plan. (Fig. 1.)

Fig. 5, Rollers for sheet, plate, or hoop iron.

Fig. 13, An enlarged view of one of the roller housing frames, with the rollers, plummer blocks, brasses, and adjusting screw, corresponding to t, t, t, t, in Figs. 1 and 5, and Fig. 4, Plate XCII.

Fig. 15, Ground plan of a water wheel bar iron forge, with two hammers and anvils.

A, The water wheel and shaft.

B, Forge hammer, with a cast iron helve and supports, lifted by projecting pieces of cast iron, on the end of the water wheel shaft, called cams.

C, A forge hammer, with a wooden helve, lifted by similar means. Only one of the hammers can be worked at a time, and the latter only when the motion is reversed, and in cases where, instead of the water wheel, a steam-engine is the moving power.

Fig. 17, An elevation of the forge (Fig. 15), showing the water wheel, cam-ring, cams, standard, hammers, anvils, anvil blocks, and framing.

F, F, The anvil blocks and anvils.

G, The standard for supporting the end of the water wheel shaft.

H, The spring beam corresponding to Fig. 16, Plate XCII.

I, The cam-ring and cams. The other letters in this figure correspond to those on the ground plan.

PLATE XCII.

Fig. 4, An elevation of three different sets of rollers, with their pinions, housings, cills, and underground buildings.

a, Rollers for the extension of square bars.

b, Rollers for forming and finishing flat bars.

c, Rollers for making round or bolt iron.

Fig. 6, An enlarged view of the rollers, pillar-bed, and pillars, with their screws, which are broken off for the convenience of the plate. This figure is the same as that of r, r, Fig. 1, in Plate XCI. and of r, r, in the centre rollers, Fig. 4, Plate XCII.