English engineer and industrialist whose financial backing and ability to raise funds from others enabled James Watt to perfect his steam engine. In 1759 when his father died, Boulton inherited his father's silver business and over the next several years expanded it into the great Soho works. By the early 1770s he had partnered with Watt, who needed financial help. Boulton needed greater power at his factory than nearby streams could provide. The effort nearly bankrupted Boulton, but by the late 1780s Watt's engine had reached profitable production. Ten years later Boulton's factory began minting coins for the British government and various colonies.