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the employment of a long cylinder Smeaton contemplated gaining other advantages, namely, every part of the steam being nearer the surface of the cylinder, would be more readily condensed; and, in consequence, that

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a less quantity of injection-water would serve the cylinder, which would itself be more heated.” Under these advantages Smeaton thought himself quite secure; " but how great," he writes, “ was my surprise and mortification to find, that instead of requiring less injection-water than common, although the injection-pump was calculated to afford as much injectionwater as usual, in proportion to the area of the cylinder, with a sufficient overplus to answer all imaginable wants, it was unable to support the engine with injection; and that two men were obliged to assist to raise the injection-water quicker by hand, to keep the engine in motion. At

the same time the cylinder was so cold I could keep my hand

upon any part of it, and bear it for a length of time in the hot well. By good fortune the engine performed the work it was appointed to do, as to the raising of water; but the coals by no means answered my calculation. The injection-pump being enlarged, the engine was in a state for doing business; and I tried many smaller experiments, but without any good effect, till I altered the fulcrum of the beam so much as reduced the load upon the piston from 107 lbs. to 84 lbs. per inch. Under this load, though it shortened the stroke at the pump-end, the engine went so much quicker, as not only to raise more water, but to consume less coals; took less injection-water, the cylinder became hot, and the injection-water came out at 180° of Fahrenheit; and the engine, in every respect, not only did its work better, but went more pleasantly. This at once convinced me that a considerable degree of condensation of the steam took place in entering the cylinder, and that I had lost more this way by the coldness of the cylinder than I had gained by the increase of load. In short, this single alteration seemed to have unfettered the engine. But in what degree this condensation took place under different circumstances of heat, and where to strike the medium, so as upon the whole to do the best, was still unknown to me.

But resolving, if possible, to make myself master of the subject, I immediately began to build a small fire-engine at home, that I could easily convert into different shapes for experiments, and which engine was set to work in 1769.". The result of the experiments conducted with this engine Smeaton carefully tabulated, and took as a guide to regulate his future practice. The engines of a large class which he afterwards erected fully verified by their performance the correctness of his assumptions, and evidenced the practical care with which he had, in this as in other matters, conducted his experiments. In 1772 he was employed to construct an engine at Long Benton Colliery, at Newcastle,-and in this he introduced the several improvements suggested by his experiments,-similar in construction to that introduced by Beighton; it was, however, " distinguished by juster proportions and greater nicety of detail than had yet been realised; and the innovations thus introduced were found to be highly beneficial in practice.” The engine erected by Smeaton, and known as the “ Chacewater Engine,” was the most celebrated of his performances. We give, in fig. 19, a diagram showing the arrangements, derived from a plate in Smeaton's Reports (vol. ii. plate 11; published by Walton and Maberly, Paternoster Row). The diameter of cylinder was 72 inches, length of stroke 9 feet; making 9 strokes per minute with its full load of 51 fathoms of pump; capable of turning out per hour, from working barrels full 164 inches, 800 hogsheads of water, with a consumption of 13 bushels of coal, London measure, per hour.

Calculated according to the modern formulæ, the power of this engine may be taken at 76 horses; but from Mr. Smeaton's statement, he estimated it at a higher rate. He says: “ This engine, though not the largest that has been built, will be of considerably greater power than

any I have seen; and, when worked at its full extent, will work with a power of 150 horses acting together; to keep which power throughout the twenty-four hours would require at least 450 horses to be maintained.” Although there is nothing in connexion with the improvement of the atmospheric engine which can be said to be the invention of Smeaton, still the high praise is due to him of giving the most perfect form and proportion

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to those materials supplied by his predecessors and contemporaries.” “ The improvements”—we quote from the Artizan treatise—“introduced by Smeaton chiefly resolve themselves into greater care in the construction of the

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engines, and a better proportion and arrangement of the boiler; and involve neither the application of any new principle, nor any great expenditure of ingenuity. Before Smeaton's time, the manufacture of the engines was in the hands of very ignorant mechanics, who did not know the difference between power and force; and their perpetual aspiration was to make the piston exert a great force, without taking into account the velocity of the movement necessary to make it operate effectively. It was very rarely the case that the engine was adequately supplied with steam ; and when an

; engine was found incompetent ito its work, in consequence of this inadequacy, it was generally provided with a larger cylinder, which only aggravated the evil. Then the cylinders were very ill-bored; and the conden

sation from the water lying on the top of the piston, as well as from water escaping past it, was very considerable ; while, at the same time, the piston rarely travelled a sufficient distance in the cylinder; and a great deal of steam was lost every stroke by filling a useless vacuity. The boilers, besides being too small, were generally badly set, the bottom being too far from the fire; and the firing was badly conducted, the coals being piled in a heap on the middle of the grate, instead of being spread evenly over it. The injection-cistern was generally set too low, by which means the water was not adequately dispersed within the cylinder; and the valve-gearing was for the most part so constructed that the regulator did not open fully, by which means the steam was throttled, and a heavy counter-weight was necessary to suck the steam into the cylinder, which of course had afterwards to be raised at an expenditure of power.” The correction of these faults was left for Mr. Smeaton to effect.

Such as we now leave it, was the degree of perfection to which the steam-engine had arrived. The principles of its action apparently precluded the attainment of a higher degree of practical usefulness; and it remained for a brighter genius and a more original mind, than was possessed by any of those who had hitherto directed their attention to the subject, to thoroughly grapple with, and to understand, its defects; and by opening up a new path of discovery, to place the steam-engine, as a social power of rare value, in the high position to which its wonder-working powers has fairly entitled it.





In the year 1736, at the little town of Greenock on the banks of the Clyde, Jarnes Watt was born, Of a slender form, sickly appearance, retiring and bashful in his manners, and bearing with him no evidence of an intellectual capacity superior to his fellows, this youth, unaided by family wealth or station, or even by the adventitious aids of an early liberal education, was destined, during a long and active life, to be the means of introducing a power which aided this country materially during a time of difficulty and danger, and to leave behind him a name world-wide in its reputation.

When about sixteen years of age, he became acquainted with an obscure mechanic in Glasgow, who, “ by turns a cutler and whitesmith, a repairer of fiddles and a tuner of spinnets,' was a useful man at almost every thing;" adding to this list of accomplishments "a knowledge of the construction of mathematical instruments and of spectacle-glasses,' he was dignified by the title of optician.'' To this individual Watt in his sixteenth year was apprenticed, chiefly, as is probable, more from the fact that it offered an easy calling suitable for his delicate health, than from


inducement it held out as that by which he could afterwards make a fair livelihood. After a short apprenticeship of less than two years, James Watt removed to London, where he succeeded in obtaining employment under a regular mathematical-instrument maker. Here he obtained that knowledge of business habits and processes which had been withheld from him in his earlier engagement. His stay in London was very limited; and probably from a severe cold which he caught while following his avocations, and the effects of which he felt for many years afterwards, he returned to his native town after an absence of little more than a year. He next endeavoured to raise a business of his own, and began to practise both in Greenock and Glasgow. In the latter place he met with an obstacle which threatened to put a sudden stop to his progress; this arose from the fact that he was not a “freeman,” or “burgess," of the town. One spot, however, existed, within the boundaries of which all such absurd laws and regulations were inoperative and harmless for evil;—this was the “College of Glasgow." By the kind offices of some of the dignitaries, Watt was appointed mathematical-instrument maker to the university; and a room was allotted him within its precincts, in which he could carry on his avocations without molestation. Thus was the apparently untoward circumstance amply compensated for. And it is by no means idle to conjecture what would have been the results on the future progress of the


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