One invention alone is responsible for the modern city full of skyscrapers that twinkle in the night sky: the elevator.
Before the elevator, buildings could be no higher than the number of stairs that people were willing to climb. It turns out that in the 1800s, that height was about six stories.
Enter the elevator. In the 1830s and 1840s, platform elevators helped lift freight, but they had a bad reputation. The lifting cables regularly broke and sent the car (and its contents) plummeting to the ground. People weren't eager to be on such a lift.
But things changed in 1854, when the American engineer Elisha Graves Otis devised an ingenious safety brake. He attached a strong-bow-shaped spring to the top of the platform, and when the platform cable was pulled up, the spring arched and slid smoothly along the elevator guide rails. Otis showed that when he cut the lift cable, the spring simply flexed back and its ends jammed inside guard rail notches, halting the elevator's fall.
Today, with some modifications, elevators use the same safety system that Otis invented and demonstrated in 1854.
Otis Worldwide is 171 years old and still installs elevators across the globe, including in the 88-story Petronas Twin Towers in Malaysia, the original World Trade Center in New York City, and the Eiffel Tower.
