Did James Watt invent the steam engine?

James Watt did not invent the steam engine. He did, however, improve the engine apparatus. In 1764 Watt observed a flaw in the Newcomen steam engine: it wasted a lot of steam. Watt deduced that the waste resulted from the steam engine’s single-cylinder design. In 1765 Watt conceived of a separate condenser—a device to reduce the amount of waste produced by the Newcomen steam engine. Watt patented the device in 1769. In 1776 Watt and his business partner, Matthew Boulton, installed two steam engines with separate condensers. The modified steam engines not only reduced waste but also cut fuel costs. Watt spent the next several years improving his design, adding to it the “sun-and-planet” gear (1781), the double-acting engine (1782), the parallel motion (1784), a flywheel (1788), and a pressure gauge (1790).