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"dered counterfeits nearly impossible. The executions," [for the crime of false coining], "which in London and Birming"ham were every year till then unhappily of frequent occurrence, altogether ceased. It was on occasion of this that "Dr. Darwin exclaimed, in the notes to his 'Botanic Garden,' "If a civic crown was given in Rome for preserving the "life of one citizen, Mr. Boulton should be covered with garlands of oak!""

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The Soho mint was erected in 1788, and the copper coin which it manufactured from 1797 to 1808 amounted to no less than three thousand five hundred and thirty-one tons weight. Mr. Boulton also, at a later date, planned and directed the arrangement of the machinery for the British Royal Mint on Tower-hill, and executed that for the coining department; which now, after fifty years' constant employment, continues to work with as great perfection as when it left Soho. He did the same for the great national mints of Petersburg and Copenhagen; as his son afterwards did for the still more extensive and splendid establishments of the East India Company, the Calcutta and Bombay mints. Mr. Boulton struck several fine medals at Soho, commemorative of persons and events in the late war with France; and, in particular, a beautiful one of Lord Nelson, on the occasion of the victory of Trafalgar, 21st October, 1805; the reverse representing the British fleet bearing down into action in two lines, with the motto, "ENGLAND EXPECTS EVERY MAN WILL DO HIS DUTY." In a truly patriotic spirit, and with the consent and approbation of Government, he presented one to each officer, sailor, and marine engaged in that memorable action; and round the edge of the medal is the inscription, FROM MR. BOULTON TO THE HEROES OF TRAFALGAR."

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Mr. Watt's inspection of the Soho manufactory, and the knowledge he acquired, through Dr. Small's friendly offices, of the talent, enterprise, and success with which that great concern was conducted, seem to have led him greatly to desire that his steam-engine could meet with so happy a fate as to be sheltered and cared for like the other machines which he there saw at work. From the first letter that

remains from Dr. Small to Mr. Watt, (of 7 January, 1768), it is evident that some conversation had passed between them on the subject, and that Dr. S., while only informed of the ingenious discoveries recounted to him by Mr. Watt, and as yet ignorant of the precise nature of the connection between him and Roebuck, had formed a great esteem for his new acquaintance, had pressed him to settle at Birmingham, and had engaged, (which in any case he said they would most certainly do), that Mr. Boulton and he should both assist him in every possible way. "I have no kind of doubt "of your success," says Dr. S., "nor of your acquiring "fortune, if you proceed upon a proper plan as to the "manner of doing business, which if you do you will be "sole possessor of the affair, even after your patent has "expired. * * Whether it would be possible to manage "the wheel and reciprocating engines by separate partnerships, without their interfering, I am not certain; if it is, "Boulton and I would engage with you in either, provided "you will live here. I am, in haste, dear Watt, your affec"tionate humble servant, W. SMALL."

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They were evidently in greater doubt as to the expediency of forming any intimate business connection with Roebuck, some rumours of the dangerous extent of whose enterprises had probably reached Birmingham; although of him also, it is proper to add, Dr. Small writes, at the same date, "his integrity and generosity, everybody agrees, are "great."

In the earlier part of 1768, Mr. Watt, "close-working," as he terms it, actively renewed his experimental alterations and trials of both the wheel or circulating engine, and the reciprocating or condensing one. Putty and other lutings, intended to keep the complicated valves of the former tight, in reality hindered them from shutting, by being metamorphosed into "the form of little balls;" and contributed to make the completion of that machine,-what it always remained,—a sort of labour of Sisyphus. But in the latter, great progress was made; for, although "the mercury," (with which the piston was packed), "by an unforeseen accident

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"found its way into the cylinder, and played the devil with "the solder," yet the piston was made to act by steam above it, as well as by the vacuum below it; the cylinder was set wholly in a steam-case; the piston was "extremely tight, and might easily be made tighter still; made of pasteboard, "baked with linseed oil, and put on like the leather of a "pump-box." He further proposed making two exhausting barrels instead of one, and giving them each half of its stroke, thereby producing a more perfect vacuum;

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"that the strokes may be counted, and the water measured "that is boiled away. These things are in hand, and will

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soon be done." This was on the 29th of April, and by the 10th of May he had got the two new exhausting cylinders cast, bored, and partly turned, as well as new condensers made, and expected to have them going again by the end of the week.

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"The two cylinders stand side for side; the pipes at bottom "communicate with two condensers, which, by the pipe c, "communicate with the large cylinder. There is a valve at e "that prevents the air and water in the condenser from going "into the big cylinder at the return of the piston of the "exhauster, but obliges them to go out at the top of the con"denser through the pipe e, having a valve at bottom to prevent their return. This pipe e has another use, viz., to "measure accurately the quantity of water condensed [at] "each stroke, by observing what space it occupies in this tube. “I take this to be the best way of determining that article, "if we can make the pistons of the exhausters tight, so that "none may be introduced that way. As soon as I have got "it completed I will write you, that I may either come to and give you account of the success, or you come here "and see the machine go. I am uneasy till I know the "exact quantity of steam consumed; though from several "circumstances I think it will answer hopes. At any rate

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"the vacuum is good and sudden; the consumption undoubtedly the least possible.”

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After one or two trials which gave good promise, but left "several motions to adjust still," on the 24th of May he was at last able to send the following satisfactory report to Dr. Roebuck:

"I received yours, and would have answered it sooner if I "could have given you the satisfaction I now can. I this

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day had another trial of the engine with the double con"denser: the vacuum was as before, 14 lbs. on the inch, and "more readily formed, though this new apparatus is not perfectly air-tight. From some circumstances it was impossible "to measure the water condensed in the way I proposed, but "I found the engine could easily make twenty strokes per "minute and snift properly, when the steam was middling "strong. I filled the boiler to a certain mark, allowed it to "come a-boil, and boil one hour, in which time it wasted 300 "cubic inches: I repeated this experiment with the same "result nearly. Now 300, divided by 60, gives 5 inches in a "minute, or inch each stroke. Now, the cylinder is 71⁄2 inch

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diameter, squared is 56; deduct to give square inches : "42 multiplied by 12, the stroke, 504 cubic inches-about "3-part of a cubic foot; but this used only the of an inch "of steam. As we could not use all the steam, great part "went off at the loading-valve, and some was needlessly "expended from another cause, which I shall explain at

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meeting. Therefore I speak within bounds when I say that "every cubic foot of the contents of the cylinder will require "only one cubic inch of water to be evaporated. I am even "of opinion that, in a large engine, with a strong boiler and "a hot steam, the half of that quantity will be sufficient. "I intend to have the pleasure of seeing you at Kinneil on Saturday or Friday. I sincerely wish you joy of this suc"cessful result, and hope it will make you some return for "the obligations I ever will remain under to you."

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This result, of which he was too good a mechanician not fully to comprehend the vast importance and great promise

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in every way, seems quite to have decided Mr. Watt on at all events immediately securing his invention by patent. From a friendly letter written by Professor Jardine to Mr. Watt in 1768, (probably early in the summer), and dated from Kinneil, it is pretty apparent that the inventor had by that time become very doubtful of Dr. Roebuck's ability, under his evident embarrassments, to carry out the invention with the requisite vigour and resources. But, on the other hand, "the more," says Mr. Jardine, "Dr. Roebuck is convinced of "the practicability of the scheme, the keener he is of carrying it [in]to practice yourselves for your mutual advantage;" and, while strongly urging him to keep up his spirits and hopes, and recommending him to devote some months to putting up a new engine at Bo'ness, with every aid that the Doctor could furnish, he adds, with characteristic discernment; -"You are surely very near to something that will be much "to your advantage: the happiness, or at least the interest, "of your family,-your own ease and amusement,-that life ❝ of ingenious indolence which you have often figured out to yourself, are all within prospect;-not to mention the "honour of a discovery of so much importance, a circum"stance which few would think so moderately of as yourself."

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Mr. Watt being satisfied in his own mind of the value of his invention, went to London in August, 1768, to make arrangements for taking out a patent for it; only delaying the completion of that step till he should be able, if possible, to secure the aid of a fit associate in the execution of engines for sale, with an equitable adjustment of the chance of profit, or the risk of loss. Mr. Boulton had intended to have met him in town, but being detained at home, invited Mr. Watt to visit him at Soho,-at "l'Hôtel de l'Amitié sur Handsworth "Heath," as he called his own hospitable house; and there Mr. Watt stayed for a fortnight, to the great joy of Dr. Small, Dr. Darwin, and Mr. Keir, who were asked to meet him. Keir, "the wit, the man of the world, the finished gentleman, "who gave life and animation to the party," and whom Mr. Watt calls "a mighty chemist, and a very agreeable man,' was possessed of considerable literary as well as scientific

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