energy and liberality. He applied for and obtained an act of parliament, whereby, on the ground that seven years of the term of Watt's patent had elapsed without its producing any profit, that term was extended to the year 1800. Boulton and Watt then entered into partnership, and set up a steam-engine work at Soho, where Watt now fixed his residence, Boulton supplying the capital, and managing the commercial part of the business, while Watt conducted the scientific and mechanical part. Their undertaking, though it had many difficulties to struggle with, was in the end completely successful, and realized large fortunes for both partners, and for their successors in the firm. They began by applying Watt's inventions to the existing pumping-engines of mines on condition of receiving one-third of the sum saved in cost of coals; but through the enterprise and activity of Boulton, and through a series of successive inventions by Watt, the most remarkable that ever have been made by one man, the applications of the steam-engine were gradually extended until they reached their present scope. In 1769 Watt had invented the cutting off the admission of steam, so as to make it work expansively, as appears from a letter of his to his friend Dr. Small. He began to use that invention in 1776, but did not publish it till 1782, when he patented it along with his invention of the double-acting engine, the first form of steam-engine which gave rotatory motion to machinery. In 1784, Watt patented and published his inventions of the parallel motion, the counter for recording the strokes of engines, the throttle-valve, the governor for regulating the speed, and the indicator for ascertaining the power, and also a locomotive engine, which last, however, he did not put in practice. The improvements in the steam-engine since the time of Watt have chiefly related either to the boiler and furnace, to the details of the mechanism, to the more full development of Watt's principle of using the expansive force of the steam to drive the piston, or to the means of applying the steam-engine to the propulsion of carriages and ships; in its essential principles the steam-engine continues to be wholly Watt's. New discoveries have since been made in the general science of the relations between heat and motive power; they have all confirmed the soundness of Watt's main principles. Few patents have had their validity more obstinately contested than those of Watt's inventions; and the successful results of the trials of which they were subjects have greatly contributed to ascertain and fix the interpretation of the patent laws. In the most important of those trials Watt received most valuable assistance from the evidence of Black and Robison as to the early history of his principal invention. (See Robison.) In 1800, on the expiry of the term of the original patent. Watt and Boulton retired from the active conduct of their business, which they handed over to their sons, Matthew Robinson Boulton, and James and Gregory Watt. Being gifted with a mind versatile as well as powerful, Watt acquired a very extensive and varied knowledge of science, literature and art, and occupied his leisure in many different pursuits. In 1783, having taken into consideration the experiments of Priestley on the combustion of "inflammable air" or "phlogiston" (as hydrogen was then called), he arrived at the conclusion that water is a compound of that gas with "dephlogisticated air" (now called oxygen). In the course of the same year he communicated that conclusion, the greatest chemical discovery of the age, to the Royal Society of London. The same discovery was made independently by Cavendish, but he did not publish it till the beginning of 1784. Watt was elected a fellow of the Royal Society of Edinburgh in 1784, and of the Royal Society of London in 1785. In 1806 he received the honorary degree of LL.D. from the university of Glasgow. He paid some short visits to France, and became well-known and highly esteemed amongst the leading men of science in that country. During one of those visits, in 1787, he learned from Berthollet the use of chlorine for bleaching, and communicated it to his father-in-law, Macgregor, by whom it was first practised in Britain. In 1808 he was appointed a corresponding member of the Institute, and in 1814 one of its eight foreign associates. In 1808 he evinced his gratitude to the university of Glasgow, by founding a prize for essays on various branches of natural philosophy, to be competed for annually. About the same time he was consulted by the promoters of an undertaking for supplying Glasgow with water, as to the means of conveying it across the River Clyde; and he contrived a jointed pipe, which worked with perfect efficiency until the works were superseded by a supply from a new source. In 1816 he endowed in his native town of Greenock a library and institute, which are known by his name. Amongst the mechanical pursuits of the later years of Watt's life, was the inventing and perfecting a machine for copying sculpture. His health, which in childhood and early life had been delicate, recovered after he had been relieved of the cares of business; and he passed his old age cheerfully in scientific and literary study, domestic and social enjoyment, and works of beneficence, retaining his wonderful mental faculties unimpaired until his death in his eighty-fourth year. His moral character was as excellent as his mental powers were vast; and to quote the words of Scott (who saw him during a brief visit to Scotland about a year before his death)—"This potent commander of the elements, . . . was one of the best and kindest of human beings." His body was buried in the church of Handsworth, near his mansion of Heathfield. In 1824 a monumental statue by Chantrey, with a remarkable inscription by Lord Brougham, was erected to his memory in Westminster abbey. Watt was twice married; his first wife has been already mentioned; to his second wife, the daughter of his friend Macgregor, he was married in 1775.
James Watt the younger, his son by his first wife, inherited much of his father's talent. During his youth he passed some time in Paris, and was for a while captivated by the principles of the Revolution; but becoming disgusted by the terrorists, he returned to England about 1792, and gave his assistance in carrying on the business of the firm of Boulton and Watt, of which, on the retirement of his father and the elder Boulton in 1800, he became one of the leading partners; and much of the subsequent success of the firm is to be ascribed to his ability, as well as to that of the younger Boulton. They furnished the engines for Fulton's first steamboat, and thereafter turned much of their attention to the improvement of marine steam-engines. In 1817 and 1818, James Watt the younger, having bought a vessel called the Caledonia, and fitted her with engines, passed a long time at sea in making experiments on her performance, which afterwards proved of great practical utility in establishing principles for the adaptation of steam-engines to ships. He died childless at his mansion of Aston Hall, near Birmingham, in 1848. Owing to the great diffidence of his character his name was less known and his merit less appreciated than they deserved. The elder Watt's son by his second wife, Gregory Watt, a youth of great promise, was prematurely cut off in 1804.—W. J. M. R.
* WATT, James Henry, an eminent line engraver, was born in London in 1799. At the age of sixteen he was articled to Mr. Charles Heath. His first important independent plate was the Procession of the Flitch of Bacon, after Stothard, which became extremely popular. A print rivalling it in popularity, and showing more varied mastery of the burin, was his large engraving from Landseer's Drovers Departing for the South, the finest line engraving that was made after Landseer, and of its class perhaps the most brilliant print of the modern school of English line engraving. Mr. Watt's other principal plates include Landseer's Courtyard in the Olden Time; Leslie's May-Day in the reign of Elizabeth; and his latest work, Christ blessing Little Children, after Eastlake. Mr. Watt has likewise engraved some smaller plates in a very charming manner.—J. T—e.
WATT, Robert, M.D., the author of the "Bibliotheca Britannica," was the child of poor parents and born in the parish of Stewarton, Ayrshire, in May, 1774. During his boyhood, although he worked as a ploughboy and as a helper of "stone-dykers" in Dumfriesshire, he lost no opportunity of acquiring such knowledge as lay within his reach. At eighteen he entered the Glasgow university, and supported himself whilst pursuing his medical studies by public and private teaching. In 1799 he went to Edinburgh to complete his professional education, and then commenced practice at Paisley. In 1808 he published "Cases of Diabetes, Consumption, &c., with observations on the history and treatment of disease in general," 8vo, Paisley, 1808. Two years afterwards he removed to Glasgow, where he commenced a course of lectures on the theory and practice of medicine. In 1812 he published an "Address to medical students on the best method of prosecuting their studies." In the following year he produced a treatise on chincough, with cases and dissections, and a statistical inquiry into the mortality of children in Glasgow under ten years of age from different diseases, during the previous thirty years. In 1814 he published "Rules of
