From Academic Kids
Boulton was born in Birmingham, where his father, Matthew Boulton the elder, was a "toymaker" (a manufacturer of small metal articles of various kinds). In 1749 he became a partner in his father's business (and the general manager), and in 1755 the Boultons acquired Sarehole Mill, which they used for rolling sheet metal. In 1756 Boulton married Mary Robinson, a distant cousin and heir to a large fortune, she died around 1760 and they had no children. Shortly after his father's death in 1759, Boulton went into partnership with John Fothergill and in 1762 they established the Soho Manufactory, two miles north of Birmingham. Here they undertook the manufacture of artistic objects in metal, as well as the reproduction of oil paintings by a mechanical process in which he was associated with Francis Eginton (1737-1805), who subsequently achieved a reputation as a worker in stained or enamelled glass. In this he was also encouraged by Robert Adam. Between 1762 and 1775 he established a strong reputation as a craftsmen; his works at Soho were widely known for excellent and artistic workmanship.
About 1767, Boulton, who was finding the need of improving the power supply for his machinery, made the acquaintance of James Watt, who on his side appreciated the advantages offered by the Soho works for the development of his steam-engine. He also married his late wife's sister Anne (Nancy) at about this time - the marriage was contrary to ecclesiastical law, being considered incestuous, so it was conducted in obscure circumstances. The Boultons had a daughter, Anne (died 1829), and a son, Matthew Robinson Boulton (1770-1842).
In 1772 Watt's partner, Dr John Roebuck, got into financial difficulties, and Boulton, to whom he owed £1200, accepted the two-thirds share in Watt's patent held by him in satisfaction of the debt. Three years later Boulton and Watt formally entered into partnership, and it was mainly through the energy and self-sacrifice of the former, who devoted all the capital he possessed or could borrow to the enterprise, that the steam engine was at length made a commercial success. It was also owing to Boulton that in 1775 an act of parliament was obtained extending the term of Watt's 1769 patent to 1799. In 1800 the two partners retired from the business, which they handed over to their sons, Matthew Robinson Boulton and James Watt junior.
In 1788 Boulton turned his attention to coining machinery, and erected at Soho a complete plant with which he struck coins for the Sierra Leone and East India companies and for Russia, and in 1797 produced a new copper coinage for Britain. In 1797 he took out a patent in connection with raising water on the principle of the hydraulic ram. He died at Birmingham on August 18 1809.