Editor's Note: Eric Jay Dolin is a writer with degrees in environmental science and environmental policy from Brown, Yale, and MIT. His most recent book is A Furious Sky: The Five-Hundred-Year History of America's Hurricanes (Liveright), from which this essay was adapted.
World War II
In 1933 the 68-year-old inventor Niels Christensen finally tackled a problem that had bothered him throughout his long career in hydraulics. His elegant and simple solution—the O-ring—would become such a ubiquitous part of so many technologies that it is present by the dozens in every home and car, and applied to everything from fountain pens and soap dispensers to hydraulic presses and bomb-bay doors.