At the time, elevators that operated on a cable system were considered unreliable and dangerous, because, if the ropes broke, the elevator plummeted to the bottom. Freight could be damaged, but, more importantly, passengers were often killed by the fall. The person who found a solution to this problem revolutionized the concept of the elevator. But was it Elisha Otis, or Otis Tufts?
While working in a factory in 1852, Elisha Otis and his sons came up with an elevator design that employed a safety device. A wooden frame at the top of the platform would snap out against the sides of the elevator shaft if the ropes broke, essentially functioning as a brake. Otis called it the "safety hoist" and dramatically demonstrated this design at the 1854 New York World's Fair. He rode the platform high into the air and then had the rope cut, but, thanks to the brake, it only fell a few inches before stopping. Otis founded an elevator company, Otis Brothers, which installed the first public elevator in a five-story New York department store in 1874. Electric elevators came about in the 1880s.
This means that Elisha Otis is the inventor of the modern passenger elevator, right? It depends on who you ask. Until the World's Fair demonstration, Otis hadn't had much luck selling elevators, and his initial elevator patent in 1861 was for a freight elevator -- the open platform kind -- not an enclosed passenger one. For this reason, some think of another Otis, Otis Tufts, as the actual inventor of the modern passenger elevator. Two years before Elisha Otis, Tufts patented an elevator design that had benches inside an enclosed car, with doors that opened and closed automatically.
There's a key reason why Elisha Otis gets the credit and not Tufts. Tufts' design did away with the typical rope and pulley system due to safety concerns. Instead, he used the concept of a nut threading up and down a screw. The elevator car was the nut, threaded onto a giant steel screw that extended the entire length of the shaft. While it was very safe, it was also expensive and impractical -- especially for very tall buildings. Tufts did sell a few of his elevators, but his design wasn't widely adopted.
The Otis Brothers Company (today known as the Otis Elevator Company) continued to make improvements in elevator safety and efficiency. Today, it's the world's largest manufacturer of elevators and escalators, while Tufts is known more for his inventions of the steam-powered printing press and the steam-powered pile driver.