[9] Annales des Mines, vol. ix., 4th Series, 266.
CHAPTER VII.
THE INVENTIONS OF HENRY CORT.
"I have always found it in mine own experience an easier matter to devise manie and profitable inventions, than to dispose of one of them to the good of the author himself."—Sir Hugh Platt, 1589.
Henry Cort was born in 1740 at Lancaster, where his father carried on the trade of a builder and brickmaker. Nothing is known as to Henry's early history; but he seems to have raised himself by his own efforts to a respectable position. In 1765 we find him established in Surrey Street, Strand, carrying on the business of a navy agent, in which he is said to have realized considerable profits. It was while conducting this business that he became aware of the inferiority of British iron compared with that obtained from foreign countries. The English wrought iron was considered so bad that it was prohibited from all government supplies, while the cast iron was considered of too brittle a nature to be suited for general use.[1] Indeed the Russian government became so persuaded that the English nation could not carry on their manufactures without Russian iron, that in 1770 they ordered the price to be raised from 70 and 80 copecs per pood to 200 and 220 copecs per pood.[2]
Such being the case, Cort's attention became directed to the subject in connection with the supply of iron to the Navy, and he entered on a series of experiments with the object of improving the manufacture of English iron. What the particular experiments were, and by what steps he arrived at results of so much importance to the British iron trade, no one can now tell. All that is known is, that about the year 1775 he relinquished his business as a navy agent, and took a lease of certain premises at Fontley, near Fareham, at the north-western corner of Portsmouth Harbour, where he erected a forge and an iron mill. He was afterwards joined in partnership by Samuel Jellicoe (son of Adam Jellicoe, then Deputy-Paymaster of Seamen's Wages), which turned out, as will shortly appear, a most unfortunate connection for Cort.
As in the case of other inventions, Cort took up the manufacture of iron at the point to which his predecessors had brought it, carrying it still further, and improving upon their processes. We may here briefly recite the steps by which the manufacture of bar-iron by means of pit-coal had up to this time been advanced. In 1747, Mr. Ford succeeded at Coalbrookdale in smelting iron ore with pit-coal, after which it was refined in the usual way by means of coke and charcoal. In 1762, Dr. Roebuck (hereafter to be referred to) took out a patent for melting the cast or pig iron in a hearth heated with pit-coal by the blast of bellows, and then working the iron until it was reduced to nature, or metallized, as it was termed; after which it was exposed to the action of a hollow pit-coal fire urged by a blast, until it was reduced to a loop and drawn out into bar-iron under a common forge-hammer. Then the brothers Cranege, in 1766, adopted the reverberatory or air furnace, in which they placed the pig or cast iron, and without blast or the addition of anything more than common raw pit-coal, converted the same into good malleable iron, which being taken red hot from the reverberatory furnace to the forge hammer, was drawn into bars according to the will of the workman. Peter Onions of Merthyr Tydvil, in 1783, carried the manufacture a stage further, as described by him in his patent of that year. Having charged his furnace ("bound with iron work and well annealed") with pig or fused cast iron from the smelting furnace, it was closed up and the doors were luted with sand. The fire was urged by a blast admitted underneath, apparently for the purpose of keeping up the combustion of the fuel on the grate. Thus Onions' furnace was of the nature of a puddling furnace, the fire of which was urged by a blast. The fire was to be kept up until the metal became less fluid, and "thickened into a kind of froth, which the workman, by opening the door, must turn and stir with a bar or other iron instrument, and then close the aperture again, applying the blast and fire until there was a ferment in the metal." The patent further describes that "as the workman stirs the metal," the scoriae will separate, "and the particles of iron will adhere, which particles the workman must collect or gather into a mass or lump." This mass or lump was then to be raised to a white heat, and forged into malleable iron at the forge-hammer.
Such was the stage of advance reached in the manufacture of bar-iron, when Henry Cort published his patents in 1783 and 1784. In dispensing with a blast, he had been anticipated by the Craneges, and in the process of puddling by Onions; but he introduced so many improvements of an original character, with which he combined the inventions of his predecessors, as to establish quite a new era in the history of the iron manufacture, and, in the course of a few years, to raise it to the highest state of prosperity. As early as 1786, Lord Sheffield recognised the great national importance of Cort's improvements in the following words:—"If Mr. Cort's very ingenious and meritorious improvements in the art of making and working iron, the steam-engine of Boulton and Watt, and Lord Dundonald's discovery of making coke at half the present price, should all succeed, it is not asserting too much to say that the result will be more advantageous to Great Britain than the possession of the thirteen colonies (of America); for it will give the complete command of the iron trade to this country, with its vast advantages to navigation." It is scarcely necessary here to point out how completely the anticipations of Lord Sheffield have been fulfilled, sanguine though they might appear to be when uttered some seventy-six years ago.[3]
We will endeavour as briefly as possible to point out the important character of Mr. Cort's improvements, as embodied in his two patents of 1783 and 1784. In the first he states that, after "great study, labour, and expense, in trying a variety of experiments, and making many discoveries, he had invented and brought to perfection a peculiar method and process of preparing, welding, and working various sorts of iron, and of reducing the same into uses by machinery: a furnace, and other apparatus, adapted and applied to the said process." He first describes his method of making iron for "large uses," such as shanks, arms, rings, and palms of anchors, by the method of piling and faggoting, since become generally practised, by laying bars of iron of suitable lengths, forged on purpose, and tapering so as to be thinner at one end than the other, laid over one another in the manner of bricks in buildings, so that the ends should everywhere overlay each other. The faggots so prepared, to the amount of half a ton more or less, were then to be put into a common air or balling furnace, and brought to a welding heat, which was accomplished by his method in a much shorter time than in any hollow fire; and when the heat was perfect, the faggots were then brought under a forge-hammer of great size and weight, and welded into a solid mass. Mr. Cort alleges in the specification that iron for "larger uses" thus finished, is in all respect's possessed of the highest degree of perfection; and that the fire in the balling furnace is better suited, from its regularity and penetrating quality, to give the iron a perfect welding heat throughout its whole mass, without fusing in any part, than any fire blown by a blast. Another process employed by Mr. Cort for the purpose of cleansing the iron and producing a metal of purer grain, was that of working the faggots by passing them through rollers. "By this simple process," said he, "all the earthy particles are pressed out and the iron becomes at once free from dross, and what is usually called cinder, and is compressed into a fibrous and tough state." The objection has indeed been taken to the process of passing the iron through rollers, that the cinder is not so effectually got rid of as by passing it under a tilt hammer, and that much of it is squeezed into the bar and remains there, interrupting its fibre and impairing its strength.
It does not appear that there was any novelty in the use of rollers by Cort; for in his first specification he speaks of them as already well known.[4] His great merit consisted in apprehending the value of certain processes, as tested by his own and others' experience, and combining and applying them in a more effective practical form than had ever been done before. This power of apprehending the best methods, and embodying the details in one complete whole, marks the practical, clear-sighted man, and in certain cases amounts almost to a genius. The merit of combining the inventions of others in such forms as that they shall work to advantage, is as great in its way as that of the man who strikes out the inventions themselves, but who, for want of tact and experience, cannot carry them into practical effect.