246

CARRON WORKS.

Britain, and the scene of many memorable events in Scottish history, a bleak and steril tract, was chosen as the site of a stupendous experiment. It offered an abundant supply of water to impel machinery; in its neighbourhood were inexhaustible mines of coal, and quarries of ironstone, and lime; and its position on the strip of land that separates the estuaries of the Forth and Clyde, opened an easy water-communication to every market on the German and Atlantic oceans. Here, by the assistance of a little band of relations and friends, who intrusted their fortunes to his judgment and honour, he began his operations on a scale of magnitude, at that time unknown in commercial adventure. The Carron Works

ments that his services to the country should be estimated, but other things necessarily connected with them; and among others, by creating a spirit of enterprise and industry before his time not known in Scotland, which soon pervaded other departments of labour, and gave birth to many other useful projects.

The taste for classical studies which he carried with him and improved in every period and every situation, became his favourite resource, and one of the chief enjoyments of his life. Possessing the happy talent of turning his mind froin serious and fatiguing to elegant and recreating pursuits, he returned from the laboratory or coal pit, and drew relaxation and solace from the stores of classical learning. The amiable disposition of sensibility, humanity, and generosity, which strongly marked his character in the general intercourse of society, were peculiarly preserved and exercised in the bosom of his family, and in the circle of his friends. In the various relations of husband, father, friend, or master, it would not be easy to do justice to his character, or to determine in which of them he most excelled. Nor must it be forgot, for it reflected much honour on his benevolent heart, that his workmen not only found him at all times a kind and indulgent master, but a skilful and compassionate physician, who cheerfully visited the humblest abodes of poverty, and who attached them to his service by multiplied acts of kindness and generosity.-Memoir by Jardine.

appeared like the immense arsenal of a great nation, rather than a manufactory erected by a few individuals in the prosecution of an experiment to introduce an improvement into the smelting of

iron.

The successful termination of this undertaking left him to seek a fresh field for his exertions; and if the one which quickly presented itself was pregnant with danger and surrounded with difficulties, it held out a more splendid reward than any even of those in which he had so triumphantly succeeded.

The estate of Kinneil, a few miles from Carron, contained extensive beds of coal, in which mines had been sunk, and worked for generations; but they had seldom produced any thing to the noble house of Hamilton, who were lords of the domain; and the adventurers who from time to time attempted to explore them, had as often desisted from the undertaking with loss. Roebuck was satisfied that the quality of the coal was superior to any in the district; he knew how much success in projects of this kind depended on the possession of ample means; and his inimitable tact of operat ing on a vigorous and steady system, was almost in itself sufficient to inspire him with more than his usual confidence of good-fortune in an enterprise in which he traced the failure of others who had preceded him, to their not possessing his accidental advantages. His presence at Kinneil, to which he removed from Carron, quickly infused a new spirit into every thing around him.

Watt, who had become known to Roebuck as a surveyor, appears to have reserved his invention for his patronage-to have looked to him as the only person whose experience enabled him to judge of the value of his improvement-who

knew the importance of the mechanism it was made upon-who had the means, and wanted not the spirit to expend them in bringing his invention, if it were practicable, to a bearing. Roebuck consented to be at the expense of an experimental machine, on a large scale, and Watt accepted of his invitation to construct it under his inspection.

In the winter of 1768, in one of the out-houses of the mansion, Watt, with Gardiner his assistant, began the formation of his third model. In this the cylinder was eighteen inches in diameter, and formed of block-tin. As might be expected, the greatest difficulty he experienced was the packing of the piston, so as to be steam tight, as it did not admit of water laying upon it as in the old engines. The condensation of the steam was produced by a jet of cold water in the eduction pipe. The cocks and sliding valves by which he regulated the steam and injection, were constructed in the same manner as those employed by Newcomen's and Savery's.

During the eight months which its ingenious inventor devoted to its erection, it was successively altered and improved, until it was brought to a considerable degree of perfection. And it cannot be a matter of surprise, that owing to its imperfect workmanship-to the material of which the cylinder was formed-to the want of experience in the proportions of the parts-and to its leaks that the vacuum of the engine, on which depended its power, should be very imperfect. This however was not attributed to the right cause, but to the air which was introduced into the internal parts by the injection water.

Upon trial at a coal mine a few hundred yards from Kinneil, notwithstanding its imperfections,

WATT'S PATENT.

249

Watt had the gratification of seeing his labour rewarded by the engine operating as he had anticipated. With all its faults, when compared with the common engines, the economy of fuel was prodigious; and what was then considered to be almost as great a point gained, the economy of water for condensation was not to be compared with that in the common ones. But above all it was important to Watt, as his patron was satisfied; and becoming a partner in the invention, he supplied the necessary funds to procure a patent," for a saving of fuel in Fire Engines," and thus placed the invention beyond the reach of piracy. No drawing, however, accompanied the brief and vague description, which appears to have been drawn up from the experience gained in these experiments; and its distinguished author closed his career without giving to the public any details either of its subordinate mechanism or arrange

ment.

From this document we only learn, that "during the entire time the engine is kept at work, the cylinder is to be kept as hot as the steam which enters it, by a casing of wood, or by surrounding it by steam; and as a general rule not to suffer any substance colder than the air to touch it. In engines which were to be moved wholly or partially by the condensation of the steam, the steam is to be condensed in vessels distinct from the cylinder, though occasionally communicating with it, and these which he called the condenser, is always to be kept as cold, at least, as the air in its neighbourhood, by water or other cold bodies," and that the expansive power of the steam is to be used to press on the piston, in the same manner as the pressure of the atmosphere in Newcomen's engine. And he also said, “that in other

250

HIGH-PRESSURE ENGINE.

cases he intended to apply a degree of cold to the steam, not capable of reducing it to water, but of contracting it considerably, so that the engine shall be worked by the alternate contraction and expansion of the steam." But this excrescence appears to have been a mere thought, introduced probably to prevent an evasion.

Three other methods of employing steam are given in the same description. The first seems to have been suggested by his experiment with Papin's digester. And he merely says the vapour "which is to act on a piston, is to be discharged into the open air after it has done its office." No mechanism or further description is referred to. His scheme for procuring a rotary motion, although of the least value, is described with the greatest minuteness. This was a steam wheel in the "form of hollow rings or circular channels, with proper inlets and outlets for the steam, mounted on horizontal axles like the wheels of a water mill. Within them were placed a number of valves, that suffer any body to go round the channel in one direction only; in these steam vessels were placed weights, so fitted to them, as entirely to fill up a part or portion of their channels, yet rendered capable of moving freely in them. When the steam is admitted between these weights and the valves, it acts equally on both, so as to raise the weight to one side of the wheel, and by the reaction on the valves successively gives a circular motion to the wheel, as the valves open in the direction in which the weights are pressed, but not in the contrary. As the wheel moves round, it is supplied with steam from the boiler, and the vapour which has performed its office, may either be discharged by means of condensers, or into the open air." Of this mecha