The earliest pipe organs were water organs, which were powered by the flow of water, sometimes from a natural resource or using a pump. Later ones used foot pedals or hand cranks to pump a bellows, which in turn produces the air that goes through the pipes. These kinds of organs are still made today, and are called harmoniums. Today's pipe organs ones use an electric motor to move air, and some, like those in theaters, play different instruments as well. The Wurlitzer company was well known for making instruments that make different sounds.