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means of obtaining cast iron; an addition being then made to the quantity of charcoal consumed. On other occasions the same furnace was employed, like the Stückofen, for the production of malleable iron or of steel.

Iron-foundries are, it is true, spoken of by early writers as existing above 300 years ago. From the context, however, it seems clear that the term, notwithstanding its obvious derivation, was not applied, as it is in our own day, to the running of the metal in a state of fusion, into moulds, but was employed to designate establishments for forging or working up malleable iron, merely softened by heat obtained in the hearths already described.

In the work of Agricola, bearing the date of 1556, there is no allusion to the Blast-furnace; the only arrangement described for obtaining iron being a kind of Catalan hearth, in which the product, as we have already seen, is malleable and not cast iron. About 1618, as we learn from Dud Dudley's Metallum Martis, this unfortunate pioneer in the manufacture of iron was engaged in his attempts to substitute pit coal for charcoal; and, as he distinctly mentions mottled and grey iron, there is no doubt that, anterior to his time, the blast furnace was in existence. The writings of these two authors, Agricola and Dudley, appear, therefore, to fix the date of its introduction at somewhere about the beginning of the sixteenth century.

Seeing that the date and precise manner of the introduction of the blast furnace itself are so uncertain, it is needless to consider, with any minuteness, the circumstances which led to the making of cast iron the first stage in the manufacture of the malleable metal. Without the faintest glimmer of scientific knowledge to guide them as to the fundamental difference between the two forms of iron, it is nevertheless easy to comprehend that the forge owners of the period would be led to apply the same treatment to the crude metal, which had been found successful with the ore. This much is quite certain, that a hearth, not differing greatly in construction from the Catalan fire, remained, until near the close of the last century, the only means of producing malleable metal from pig iron: indeed, for the finer kinds of bars, the process is still practised in Sweden, Russia and elsewhere, one modification being known as the Lancashire hearth.

The product of the first blast furnaces, so long at least as they were of small dimensions, would be white cast iron: and this, being useless for the founder, would doubtless all be converted into the malleable form of the metal, and hammered in the way still pursued in the small forges of the countries above mentioned.

Down to the end of the sixteenth century, the only combustible employed in iron works was that afforded by the forests of the day; but the demands upon the resources of the latter became so large that regard for other requirements compelled legislative enactments to be passed in England regulating the felling of timber. Such a state of things naturally led to the consideration of the fitness of mineral coal as a substitute for charcoal; and towards the middle of the seventeenth century we find Dudley engaged in perfecting plans for "making of iron, and melting, extracting and refining all minerals and metals with pit coal, sea coal, peat and turf."

This early adventurer in the iron trade had many difficulties to contend with. Floods swept away his works, unscrupulous competitors destroyed his machinery, and dishonest partners completed his ruin. It would not, however, appear that very marked success had attended his efforts, if it be true that seven tons was the outside weekly product of his furnaces; being only about half that usually obtained from the charcoal furnaces of his time.

It is very probable that mechanical science, as it existed in the seventeenth century, although capable of contriving means of blowing a charcoal furnace, was unable readily to devise appliances adapted to forcing the air through pit coal, which was used just as it came from the mine. The effect of heat in charring coal, so as to convert it into coke, must have been known at that time; for in Plot's "History of Staffordshire" we learn that "Cokes for melting and refining of iron cannot be brought to do, though attempted by the most cunning and curious artists."

For something like half a century the idea, which had proved the ruin of Dud Dudley, slept. It was then revived by Abraham Darby, a name deservedly held in high esteem among the promoters of industrial science. Not only was the invention of his predecessor brought to a successful issue by his perseverance, but he did much at the begin

ing of the last century to spread the use of cast iron for foundry purposes. It was about the year 1733 that, in spite of the failures of "the most cunning and curious artists," this distinguished man succeeded in using charred coal or coke in his iron furnaces. Notwithstanding the importance of the discovery, circumstances were such that the annual make of pig iron gradually fell off; so that, in 1740, of 300 furnaces which had been blowing in the middle of the previous century, only 59 were in blast. Their production in that year was only 17,350 tons, and this very small yield, due probably to interruptions in their work, left 30,000 tons to be imported to meet the wants of the country. The march of improvement seems to have been but languid, for, with the aid of the steam engine and the substitution of iron cylinders for leathern bellows, the average weekly make in 1788 of the 85 furnaces in the kingdom was scarcely 15 tons per furnace. Of the total annual quantity produced-viz., 68,500 tons-about fourfifths was smelted with coke, and the remainder with charcoal.

Such were the insignificant proportions of a trade, now so vast, when, about the year 1784, another inventor, Henry Cort, rendered as important service to the manufacture of malleable iron as Abraham Darby had afforded to the smelting of the ore. To his ingenuity we owe the grooved rolls and the puddling process of our iron works; and it is no exaggeration to say that to these two inventions we are mainly indebted for those changes, which separate so sharply the last 40 or 50 years from the world's previous social history. With no better implement than the hearth and the forge hammer, as they are used to this day in Sweden, it would have been practically impossible to produce a railway bar or a ship plate; and who can set a limit to the aid these two articles have afforded to the unprecedented strides which have been made during the period referred to?

A more recent invention may possibly complete the revolution in the manufacture of iron, of which the beginning has just been described, by superseding the puddling furnace in its turn; but the facts as stated will remain unaltered. Indeed, admitting that steel or ingot iron will ultimately occupy the place of puddled iron, there seems but little likelihood of a rail of either material being obtained without the assistance. of a rolling mill, for which we owe so much to the inventor of puddling.

The absence of all continous records of our industry prevents our doing more than estimating, in a very rude way, the statistical progress made in the manufacture of iron by the assistance of the puddling furnace of Cort. Within seven years of its introduction, however, evidence was given before the Commissioners of the Navy that 50,000 tons of pig iron were annually converted by means of the process he had devised. If this statement be correct, it would appear that its value was quickly acknowledged by those interested in its application; although some refused to reward the inventor, who, from circumstances for which he was not personally responsible, was allowed to die without reaping any benefit from the undoubted service he had rendered to mankind.

Some thirty-two years after the first introduction of the puddling furnace―viz., in 1816-another unrequited discoverer, Samuel Baldwyn Rogers, greatly added to its value by substituting, for the sand. bottom of Cort, one of iron, protected by a coating of oxide of iron. The very great importance of this change will be more conveniently indicated when the process itself is described; suffice it now to say that it added greatly to the durability of the furnace, as well as to the quality of the product.

The introduction of successive minor improvements in the development of the blast furnace, the invention of the puddling process, and the employment of mineral fuel instead of charcoal, both in smelting the ore and converting the pig into malleable metal, were followed by marked economy in both operations. An extended use of cast and wrought iron was the natural result of reductions in price. It will be remembered that in the year 1788 the weekly make of the blast furnaces then in existence averaged 15 tons; and although I have been unable to obtain any exact figures as to the make, it is highly improbable that the total annual production at that period exceeded, if it even reached, 70,000 tons. In 1796 the annual make per furnace in Great Britain is given at 1,032 tons, or just within 20 tons per week. In the event of the 121 furnaces, mentioned as having been in existence at this period, being in blast, the make would have amounted to 125,000 tons for the year.

As nearly as can be made out by reference to Scrivenor and other authorities, the following figures shew the weekly average make of the British blast furnaces, when in blast, at the above mentioned dates:

1788.-15 tons, using ordinary clay ironstone.

The subjoined values of English pig iron, for each fourth year, are taken from Tooke's History of Prices:

It has thus been made manifest what a wonderful change the forty years ending 1828 had effected in the iron trade of this kingdom. During this period, the weekly make of a furnace was more than doubled; and the total annual production rose from 70,000 tons to 700,000 tons. We shall subsequently see how, during the succeeding forty years, the 35 tons run weekly from a furnace came to exceed 400, and how the yearly make of 700,000 tons approached very closely to 7 millions.2

In 1828, under the condition of things just described, it occurred to the mind of James Beaumont Neilson that heating the air before it

This refers to such furnaces only as were using ordinary clayband ironstone; the make, when the mineral was the rich black band of Scotland, being very much higher.

2 Since this was written, the returns for 1881 give the quantity of pig iron made in that year as having reached 8,352,623 tons.