A Ferris wheel is an amusement ride consisting of an upright wheel with passenger gondolas around the rim. It is named after George Washington Gale Ferris, Jr., who designed a 75-meter (250-foot) wheel for the World Columbian Exposition in Chicago in 1893. The earliest ancestor of the Ferris wheel is the Ups-and-Downs, a crude, hand-turned device, which dates back at least to the 17th century and is still in use in some parts of the world.
Currently, the largest Ferris wheel is the London Eye, at 120 meters (393 feet). Another famous Ferris wheel, dating back to 1897, can be found in Vienna.
A list of Ferris wheel patents, with links to the U.S. Patent Office:
http://www.personal.psu.edu/faculty/v/a/vac3/flat2.html