Watt, JAMES, improver, and almost inventor, of the modern steam-engine, was born at Greenock in Scotland on the 19th of January 1736. His father, a general merchant at Greenock, was long a member of the council of that burgh, and for a time a magistrate. His mother, Agnes Muirhead, was a woman of superior endowments. Two members of James Watt's family—his grandfather and an uncle—possessed some local reputation for scientific or engineering ability. The former was a teacher of mathematics, surveying, and navigation at Crawfordsdyke near Greenock; the latter was a land-surveyor and engineer. James Watt was very weakly as a child, and, being unable to go to school with regularity, he became to a great extent his own instructor. His mother taught him reading, and his father writing and arithmetic. He early manifested a turn for mathematics and calculations, and a great interest in machines, and accordingly—his father's business, for which he had been destined, having greatly declined—he came to Glasgow in June 1754 to learn the trade of a mathematical instrument maker. After a year in Glasgow he went to London, but ill-health compelled him to return home about a year after; he had however made good use of his opportunities, and after his return he set up as a mathematical instrument maker in Glasgow. The incorporation of hammermen of that city put difficulties in his way; but the authorities of the university took him by the hand, appointed him mathematical instrument maker to the university, and gave him the use of premisses within their precincts. He occupied these premises from 1757 to 1763, when he set up a place of business in the town. In 1767 he was employed to make the surveys and prepare the estimates for a canal projected to unite the Forth and the Clyde. He made surveys for various canals, for the improvement of the harbours of Ayr, Port-Glasgow, and Greenock, and for the deepening of the Forth, the Clyde, and other rivers. He was also employed on a survey for the Caledonian Canal (q.v.). In this and in other surveys, the accuracy of which was borne witness to by Telford, he made use of a new micrometer, and a machine, also of his own invention, for drawing in perspective.
As early as 1759 Watt's attention had been directed to the capabilities of steam as a motive-force by Mr Robison (q.v.), afterwards professor of Natural Philosophy in the university of Edinburgh, who was then a student in Glasgow. In 1761–62 Watt made a series of experiments on the force of steam, using a Papin's Digester (q.v.); but it was not till the winter of 1763–64 that he began the investigations which ended in his improvement of the steam-engine. A working model of the Newcomen engine, kept for the use of the natural philosophy class in the college, was sent to him to be put in repair. He quickly found out what was wrong with the model, and easily put it into order; but in doing this he became greatly impressed with the defects of the machine, and with the importance of getting rid of them. The result was that he hit upon the expedient of the separate condenser, which prevented the loss of steam in the cylinder. See STEAM-ENGINE, where his other important inventions, the use of the 'air-pump,' steam-jacket for cylinder, double-acting engine, &c., are described.
Watt, soon after perfecting his model, formed a partnership with Dr Roebuck, then of the Carron Ironworks, for the construction of engines on a scale adapted to practical uses; and an engine was erected at Kinneil, near Borrowstounness. But Roebuck got into difficulties; and nothing further was done until, in 1774, Watt entered into a partnership with Matthew Boulton (q.v.) of Soho near Birmingham, when, Roebuck's interest having been repurchased, the manufacture of the new engine was commenced at the Soho Ironworks. A patent for his invention had been taken by Watt in 1769, and a prolongation of his patent for twenty-five years was secured in 1775. This partnership was a fortunate one for Watt—Boulton was bold and enterprising; Watt was timid and shrank from the commercial side of affairs. The advantages of the new engine were in no long time found out by the proprietors of mines; and it soon superseded Newcomen's machine as a pumping-engine. Watt afterwards made numerous improvements in its construction, and in conjunction with his partner Boulton he immensely improved the quality of the workmanship employed in building engines and other machines. Between 1781 and 1785 he obtained patents for a series of inventions—among them the sun and planet motion, the expansion principle, the double engine, the parallel motion, and a smokeless furnace. The application to the steam-engine of the governor was Watt's crowning improvement. He described a steam-locomotive in one of his patents (1784), but did not prosecute it further, neither did he encourage his chief assistant Murdock (q.v.) in his experiments. He also invented a letter-copying press, machines for copying sculpture, and numerous devices unconnected with the steam-engine, several of which he patented. It is curious to recall that Boulton and Watt attempted to secure an act of parliament forbidding the use of high-pressure engines; Watt persisted in the use of steam at low pressure. Watt's claims to be the first discoverer of the composition of water were long and strenuously maintained (see WATER, p. 565).
He retired from business in the year 1800, giving up to his two sons, James and Gregory, his interest in the extensive and prosperous business which Boulton had created at Soho. He showed the same alert and active mind after his retirement. The attic room at Heathfield Hall, his house near Birmingham, where he used to work alone, is still preserved, in its old condition. Here he was perfectly happy, working with his turning-lathe, and amongst his tools and models. In the earlier portion of his life he suffered much from ill-health. He had quickness of apprehension, a powerful memory, and an immense store of well-digested miscellaneous information outside his own domain. In conversation his utterance was slow and unimpassioned, with a quiet, grave humour, while his manners were gentle, modest, and unassuming. He died at Heathfield on 19th August 1819 in his eighty-fourth year. There are many monuments to Watt; the inscription on that in Westminster Abbey is from the pen of Lord Brougham. Watt stands at the head of all inventors, and the honours paid to his memory and to himself in his later years appear to have been deserved by his personal qualities, no less than by the immeasurable benefits which his inventive talents have conferred upon the human race.
See J. P. Muirhead, Origin and Progress of the Mechanical Inventions of James Watt (3 vols. 1854), comprising a memoir, letters, and patent specifications; Muirhead's Life, abridged from his larger work (1 vol. 2d ed. 1859); Smiles, Lives of Boulton and Watt; Williamson, Memorials of the Lincage of Watt (1856); Cowper in Proc. Inst. Mech. Engineers, Nov. 1883.