The Life of James Watt

"to specify only what was his invention, and to leave any mechanical improvements he might make, to be secured by "other patents, if worthy of them.

"His idea, then, was to apply his invention to the steam"engines as they existed. For this purpose there was nothing "else necessary than to shut up the snift, to apply a regulator or valve to the opening of the eduction-pipe within the cylinder, an air-pump to the outer end of that pipe, and to inject into the upper end of the eduction-pipe. If, at the "same time, the cylinder was defended from the cold of "the atmosphere, the engine would thus be complete, if the weight of the atmosphere were to be employed as the acting power; for all the regulators could be easily opened "and shut by the then existing contrivances, and the airpump rod could be suspended from the working beam.

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If, however, the engine was wanted to receive all the advantages of the invention, the cylinder was to be placed "in a case containing steam, with access for that fluid to the "upper side of the piston, so that it might act upon it as the

atmosphere acted in common engines, or in the case just "stated. And in this latter manner were the engines made "which he constructed in the beginning of the business; that "is to say, the cylinders were fixed in a case containing steam, with which fluid they were wholly surrounded; and, "their mouths being open within the case, the steam had always access to the upper side of the piston, and was "admitted to the part below the piston only when the piston was rising. The opening from the cylinder into the eduction-pipe was shut by a valve while the piston was rising, "but when it was required to descend, the valve was opened. "Those valves were of the sliding kind used in Newcomen's engines. The injection was made into the eduction-pipe; " and the air-pumps, which drew out the water as well as the air, were fixed to the bottom of the eduction-pipe, which "had a valve to prevent regress as usual. There was some"times one pump, and sometimes there were two or three, as "circumstances or the fancy of the moment directed. The "working beams and working gear were made in the usual

"manner, or nearly so; and in cases where there were boilers "fixed for the common engine, which was superseded, they "were used without alteration.

"These engines, then, differed in nothing from the ancient ones, except in the application of W.'s principles as set "forth in his specification.

"It was found that the external cylinder, or steam-case, "was very expensive. The method of covering the cylinder itself with a lid or cover, (which had been used in some of "the models), and conveying the steam to the lower end of "the cylinder by a pipe, was adopted, and a less expensive " method of applying the envelope of steam was used. Other "kinds of regulators were invented, and the whole mechanism "of the engine was gradually improved, and these improve"ments have been progressive for the last twenty-one years. "Some of them W. has secured by other patents, but many "of the most essential he has left free, and by means of them "Newcomen's engines have been improved to his loss.

"It will now, it is hoped, appear to the candid that W. has "not wilfully concealed his invention by a false specification, "but has set forth the nature of the same, and the means of "performing it. He has told what he had invented; and it "could not have been expected that he should have described "mechanism already known to all practitioners, or not then "invented.

"W.'s invention is merely a contrivance to prevent cooling "the cylinder, and to make the vacuum more perfect by con"densing the steam in a vessel distinct from the cylinder itself; "this is the nature of the invention. The means of keeping "the cylinder warm,-the substitution of the powers of steam "for those of the atmosphere,-of grease, &c., in place of "water to keep the piston tight,—and the drawing out the "air, &c., by means of pumps, are merely aids in performing "the principal object. This ought to be kept in view in "judging of the specification; also that W. supposed it to "be addressed to mechanics and philosophers, and not to the "ignorant."

CHAPTER VIII.

DR. BLACK'S AND PROFESSOR ROBISON'S ACCOUNT OF MR. WATT'S INTRODUCTION TO DR. ROEBUCK ENTIRE ORIGINALITY OF MR. WATT'S INVENTION -CONFIRMED BY DR. ROEBUCK WILCKE'S AIR-PUMP ACTING BY THE CONDENSATION OF STEAM SUBSEQUENT TO MR. WATT'S INVENTION OF THE SEPARATE CONDENSER HUMPHRY GAINSBOROUGH.

WITH regard to the model of Newcomen's engine belonging to the College of Glasgow, and which has attained so great a celebrity by the results which it was instrumental in producing, we find two entries in the records of that University; the first is as follows :-" University meeting, 25th June, "1760. Mr. Anderson is allowed to lay out a sum, not exceeding two pounds sterling, to recover the steam-engine "from Mr. Sisson,* instrument-maker at London."

Mr. John Anderson in 1757 succeeded Dr. Dick as Professor of Natural Philosophy in the College; he filled that chair for the long period of thirty-nine years, and was the founder of the Andersonian Institution in Glasgow, which he designed "for Lectures in Natural Philosophy, and in every "branch of knowledge ;" and which was endowed by him with valuable philosophical apparatus, a museum, and library. We have already seen from the account given by Dr. Robison, that Mr. Anderson, although "much more popular” than his predecessor, was considered to have "infinitely less knowledge;" a circumstance which may perhaps account for the nearly total oblivion of his name in any of the records connected with the life of Watt. But it appears that he was a

*Of this skilful artificer the learned M. Delambre writes:-"Sisson fit "le quart de cercle de Greenwich, un autre pour l'Observatoire par"ticulier du Roi d'Angleterre, et le quart de cercle que Lemonnier

"rendit mobile. Sisson soutint à "cet égard l'honneur et la pré"éminence de l'Angleterre." -Delambre, Histoire de l'Astronomie dixhuitième Siècle,' p. 237,

'au 1827.

native of Greenock, and brother of one of Mr. Watt's schoolcompanions, and, having been Professor of Hebrew from 1754 to 1757, he doubtless aided in that act of kindly patronage by which Mr. Watt was, at a critical period of his life, protected and encouraged. His employment of the young artisan to repair the little machine which suggested a train of thought leading to the greatest inventions of modern days, certainly gives Mr. Anderson a further claim, even if it be but an accidental one, to have his name associated with the "natural philosophy" of the steam-engine and of Glasgow College.

The model, (as will presently appear), never having worked well, had been sent to London in a vain endeavour to have its faulty construction amended. Whether Mr. Watt had seen it, during his stay there, in the workshop of Sisson, or how far he may have advised it being brought back to Glasgow, as a subject for further consideration and study, we know not. But the next entry concerning it, in the same records, appears to be this:-"University "meeting, 10th June, 1766. An account was given in by “Mr. James Watt for repairing and altering the steamengine, with copper pipes and cisterns, amounting to 57. 118. "The said machine being the property of the College, and "having been in such a situation that it did not answer the "end for which it was made, the Principal is appointed to "grant a precept for payment of the said account, which is "to be stated upon the fund for buying instruments to the "College." *

This, it will be remembered, was after the idea of the separate condenser had "occurred," which was "early in "1765;" and by the repairs and alterations of the "copper "pipes and cisterns" of the machine, its fault of not answering the end for which it was made,-(one grievous enough, no

doubt, but appertaining to many other machines, both animate and inanimate, in common with it),—had in all probability been effectually corrected. That interesting little model, as altered by the hand of Watt, and preserved in all safety and honour within the precincts of its ancient birth-place, was once appropriately placed beside the noble statue of the Engineer, in the Hunterian Museum;-a sacred relic worthy of such a shrine, and there visited by many a worshipping pilgrim. Such had been, in former years, the felicitous arrangement. But on revisiting the College of Glasgow in January, 1854, one morn we miss'd" the model from its apposite home. On inquiry, we found that it had been placed among the apparatus attached to the Natural Philosophy Lecture-room, where, it was alleged, it had dwelt nearly a century ago. As the model, however, belongs to "the College," we hope that this seclusion, so disappointing to the public eye, may be only temporary; and that what might now be fairly said to be "meant for mankind," may not permanently be imprisoned where it can be open to the inspection of comparatively only a few.

None of the different accounts which thus remain to us of the date of this, Mr. Watt's greatest invention, fix the precise day on which, to use Dr. Black's happy expression, "this "capital improvement flashed on his mind at once, and filled "it with rapture." According to Robison's recollection, thirty-one years afterwards, it was somewhere about 1765. Dr. Black, writing after the same interval of time, states it as having been "in the beginning of the year 1765." Mr. Watt himself, in his notes on Robison, says "early in 1765;" and the nearest approximation that we can make, from other documentary evidence, to any more precise date, is, that it must have been previous to the 29th of April in that year, as on that day Mr. Watt writes to his friend Dr. Lind, "I have "now almost a certainty of the facturum of the fire-engine, having determined the following particulars: the quantity "of steam produced; the ultimatum of the lever engine; the quantity of steam destroyed by the cold of its cylinder; the quantity destroyed in mine: and if there is not some devil

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The Life of James Watt: With Selections from His Correspondence