Because he wanted something that would be safe for the passangers that would go into the elevator
Elevator Safety Brake
The elevator ('lift' in the UK). He did not invent the elevator(lift). He invented the elevator brake system.
1923
in 1852 by Elisha Graves Otis.
Here is what I could find on the subject: "Elisha Otis invented the "Improvement in Hoisting Apparatus." Elisha Otis didn't actually invent the elevator, he invented the brake used in modern elevators. His brakes made skyscrapers a practical reality. (above illustration - patent drawing of the Elisha Otis elevator) " What he did was invent a device that would stop the elevator if the main lifting cable broke. Copy and paste link http://inventors.about.com/library/inventors/blelevator.htm
I do not believe you are correct in attributing the invention of the safety lamp to Elisha Otis, it was Sir Humphry Davy who did that (hence the name the "Davy Lamp"). However, Elisha Otis was an inventive genius and his most famous invention is the safety device that prevents elevators from falling if the hoisting cable fails. (aka "Otis Lifts"). I have made a link for you to follow explaining what he did.
Yonkers, New York Incorrect question being asked, Elisha did not invent the elevator, he invented the safety break system. As welll as invented an automatic bread baking oven.
In 1852
"Elisha Otis invented a safety device that prevented elevators from falling if the hoisting cable broke. He worked on this device while living in Yonkers, New York in 1852, and had a finished product in 1854." (www.wikipedia.com)
in 1850!
He created the safety brake in elevators. Without him new york city would be two stories high
elisha was American and was the actual inventor of the elevator break in 1850