Watt's Steam Engine
James Watt patented the separate condenser in January 1769, and it is the single most consequential improvement to the steam engine. Newcomen's atmospheric engine had been pumping water out of mines since 1712 and worked by condensing steam inside the cylinder to create a vacuum, which meant that the cylinder had to be cooled with a spray of water on every stroke and then reheated by the next admission of steam. Watt was repairing a working model at Glasgow University in 1763 and calculated how much of the fuel was going into reheating metal rather than into work. His answer, which he said came to him on a Sunday walk on Glasgow Green in 1765, was to condense the steam in a separate vessel kept permanently cold, so that the cylinder could be kept permanently hot. Fuel consumption fell by something like three-quarters. It took him another eleven years to build one that worked reliably, because nobody could bore a cylinder accurately enough. John Wilkinson's cannon-boring machine of 1774 solved it, and the partnership with Matthew Boulton at Soho from 1775 supplied the capital and the manufacturing. Watt then added rotary motion through the sun-and-planet gear, the double-acting cylinder, the centrifugal governor and the parallel motion, which took the engine out of the pumping house and into mills and factories. The patent was extended to 1800 and Watt defended it aggressively, which is argued to have delayed high-pressure engines by two decades. The unit of power is named for him.
- Year: 1769 CE
- Category: Scientific
