An Overlooked Invention

William Rosen, via Ritholtz:

The sliding D-valve dramatically improved the steam-engine, and ushered in the age of incremental innovation. Source: Library of Congress

Lists of history’s great inventions always include the wheel, fire, the telephone, digital computing, the printing press, television, the automobile and (surprisingly frequently) the flush toilet. Depending on the archness of the list maker, you’ll also find the likes of the transistor radio, birth- control pills, eyeglasses, the Internet, WD-40, the push-up bra and the iPhone, which came in at No. 9 in a 2010 survey.
You won’t find the D-valve on any of them. However, almost every list is likely to include the steam engine, for which the sliding D-valve was invented by Murray in 1797. That’s because the steam engine is one of the most transformative machines in history -- the power behind the Industrial Revolution.
Yet the steam engine changed the world in a different way than we usually believe. For one thing, it didn’t actually drive the machines of the Industrial Revolution, at least not at first. Though Thomas Newcomen’s first engine appeared in 1712, it wasn’t until the middle of the 19th century that steam power overtook waterwheels as Britain’s foremost power source. This is why Murray’s 10-inch-long valve does a better job of illustrating the steam engine’s historical importance than Newcomen’s 40-foot behemoth.

The whole thing is worth reading, both for the history and the perspective.  A quick summary is that incremental changes add up to significant improvements over time.