JAMES WATT, mechanician, engineer, and man of science, famous as the improver, and almost the inventor of the steam-engine, was born at Greenock, in Scotland, on the 19th of January, 1736. His father was a block-maker and general merchant at Greenock, was long a member of the council of that burgh, and for a time a magistrate.
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 teacher. What schooling he did get, he got in the schools of his native town. 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 was, at the age of eighteen, sent to London to learn the trade of a mathematical instrument maker. Ill health compelled him to return home about a year after, but he had made good use of his opportunities in London, and, on his health returning, he resolved to 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 premises within their precincts.
Living in the college at Glasgow, in constant intercourse with the professors of the university, with access to books, and with much unemployed time on his hands, Watt had been a diligent student of science and experimenter in the application of science to the arts. In 1761 or 1762, he made a series of experiments on the force of steam, using a Papin's Digester. These do not seem to have led to any results, and it was not till the winter of 1763-64, that he began the investigations which ended in his improvement of the steam engine. During that winter, 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. Watt 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 cf them. The Newcomen engine was still but little used, and only for pumping water out of mines. It was a cumbersome machine, and it required so much fuel that the expense of working it half restricted its use. It was not a steam engine at all. It was worked by means of the atmospheric pressure; steam being only used in producing, by its condensation, a vacuum in a cylinder, into which - the vacuum made - a piston was depressed by the pressure of the air. The steam issuing from a boiler, was admitted into the cylinder until it filled it, when the supply was cut off by a self-acting cock, and then the steam was condensed in the cylinder by means of a jet of water. The water so greatly cooled the cylinder, that the greater part of the steam at each stroke of the piston was wasted in heating its walls; and on the other hand, much of the injected water was heated to the boiling point, and gave off steam, which resisted the descent of the piston. Watt found that about four-fifths of the steam, and consequently of the fuel, was wasted; and he saw that to make it work economically, two apparently incompatible conditions must be obtained - first, that the walls of the cylinder must constantly be of the same temperature as the steam which came in contact with them, and second, that the injected water must never be heated up to 100°, the boiling point in vacuo. Constantly, from the end of 1763, occupied with the subject of steam, he at length, early in 1765, hit upon the expedient which solved all his difficulties - the separate condenser, an air-exhausted vessel, into which the steam was admitted from the cylinder and there condensed. The separate condenser at once prevented the loss of steam in the cylinder which had arisen in the process of condensation; and there was no difficulty in keeping it cool, so as to prevent the undue heating of the injection-water. He had now got a perfectly economical engine on Newcomen's principle, but he did not rest content with this - he resolved to make steam his motive power. Closing the cylinder at both top and bottom, and connecting the piston with the beam to which it was to communicate motion, by a piston-rod passing through a stuffing-box, he admitted the steam by suitable valves, alternately above and below the piston, to push it downwards and upwards in turn; and this done, his invention was substantially complete. He had at last made a real steam-engine, capable of being worked with a comparatively small expenditure of fuel, and of yielding any amount of power. Comparing his invention with the atmospheric engine of Newcomen, it must be admitted that it is not without justice that the popular voice has awarded him the name of inventor of the steam engine.
In 1773, Watt entered into a partnership with Matthew Boulton, of Soho, near Birmingham, when the manufacture of the new engines was commenced at the Soho Iron Works.
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 immense 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. In the years 1781, 1782, 1784, 1785, he obtained patents for a series of inventions - among them the sun and planet motion, the expansive principle, the double engine, the parallel motion, and the smokeless furnace, of most of which the chief purpose was to make steam-pressure available for turning machinery in mills. The accomplishment of this - extending the application of the new power to the arts - was of scarcely inferior importance to the invention of the steam-engine itself. The application to the steam-engine of the governors, was Watts' crowning improvement.
He retired from business in the year 1800, giving up to his two sons his interest in the extensive and prosperous business which Boulton had created at Soho. He died at Heathfield, in Staffordshire, on the 25th of August, 1819, in his eighty-fourth year.