How to stop elevators safely.

How to move people up and down.

How to build tall buildings in cities.

How to move heavy things from floor to floor.

elevators did not have safe brakes.

elevators could only move heavy things.

elevators did not always go up and down.

elevators were not strong enough to hold people.

helping them move more quickly.

helping them stop at each floor.

making them able to go to the top floor.

making them able to hold more people.

He was always interested in how things worked.

This invention was used in buildings to lift heavy things from one floor up to another floor.

Later in life, Otis started an elevator business.

Otis had the idea to build a good brake system for elevators.