A Ferris wheel (also known as an observation wheel or big wheel), named after George Washington Gale Ferris, Jr., is a nonbuilding structure consisting of a rotating upright wheel with multiple passenger-carrying components (commonly referred to as passenger cars, cabins, capsules, gondolas, or pods) attached to the rim in such a way that as the wheel turns, they are kept upright, usually by gravity.
Some of the largest modern Ferris wheels have cars mounted on the outside of the rim, with electric motors to independently rotate each car to keep it upright. These wheels are sometimes referred to as observation wheels, and their cars referred to as capsules. These alternative names are sometimes used for wheels with conventional gravity-oriented cars.
"Pleasure wheels", whose passengers rode in chairs suspended from large wooden rings turned by strong men, may have originated in 17th-century Bulgaria.
The travels of Peter Mundy in Europe and Asia, 1608-1667 describes and illustrates "severall Sorts of Swinginge used in their Publique rejoyceings att their Feast of Biram" on 17 May 1620 at Philippopolis in the OttomanBalkans. Among means "lesse dangerous and troublesome" was one:
...like a Craine wheele att Customhowse Key and turned in that Manner, whereon Children sitt on little seats hunge round about in severall parts thereof, And though it turne right upp and downe, and that the Children are sometymes on the upper part of the wheele, and sometymes on the lower, yett they alwaies sitt upright.
Five years earlier, in 1615, Pietro Della Valle, a Roman traveller who sent letters from Constantinople, Persia, and India, attended a Ramadan festival in Constantinople. He describes the fireworks, floats, and great swings, then comments on riding the Great Wheel:
I was delighted to find myself swept upwards and downwards at such speed. But the wheel turned round so rapidly that a Greek who was sitting near me couldn't bear it any longer, and shouted out "soni! soni!" (enough! enough!)
Similar wheels also appeared in England in the 17th century, and subsequently elsewhere around the world, including India, Romania, and Siberia.
A Frenchman, Antonio Manguino, introduced the idea to America in 1848, when he constructed a wooden pleasure wheel to attract visitors to his start-up fair in Walton Spring, Georgia.
Ferris was a graduate of Rensselaer Polytechnic Institute and a Pittsburgh, Pennsylvania, bridge-builder. He began his career in the railroad industry and then pursued an interest in bridge building. Ferris understood the growing need for structural steel and founded G.W.G. Ferris & Co. in Pittsburgh, a firm that tested and inspected metals for railroads and bridge builders.
The wheel rotated on a 71-ton, 45.5-foot axle comprising what was at that time the world's largest hollow forging, manufactured in Pittsburgh by the Bethlehem Iron Company and weighing 89,320 pounds, together with two 16-foot-diameter (4.9 m) cast-iron spiders weighing 53,031 pounds.
There were 36 cars, each fitted with 40 revolving chairs and able to accommodate up to 60 people, giving a total capacity of 2,160. The wheel carried some 38,000 passengers daily and took 20 minutes to complete two revolutions, the first involving six stops to allow passengers to exit and enter and the second a nine-minute non-stop rotation, for which the ticket holder paid 50 cents.
The Exposition ended in October 1893, and the wheel closed in April 1894 and was dismantled and stored until the following year. It was then rebuilt on Chicago's North Side, near Lincoln Park, next to an exclusive neighborhood. This prompted William D. Boyce, then a local resident, to file a Circuit Court action against the owners of the wheel to have it removed, but without success. It operated there from October 1895 until 1903, when it was again dismantled, then transported by rail to St. Louis for the 1904 World's Fair and finally destroyed by controlled demolition using dynamite on May 11, 1906.
Antique Ferris wheels
Wiener Riesenrad, Vienna, built in 1897, originally had 30 passenger cabins but was rebuilt with 15 cabins following a fire in 1944
The Wiener Riesenrad (German for "Viennese Giant Wheel") is a surviving example of nineteenth-century Ferris wheels. Erected in 1897 in the Wurstelprater section of Prater public park in the Leopoldstadt district of Vienna, Austria, to celebrate Emperor Franz Josef I's Golden Jubilee, it has a height of 64.75 metres (212 ft) and originally had 30 passenger cars. A demolition permit for the Riesenrad was issued in 1916, but due to a lack to funds with which to carry out the destruction, it survived.
Following the demolition of the 100-metre (328 ft) Grande Roue de Paris in 1920, the Riesenrad became the world's tallest extant Ferris wheel. In 1944 it burnt down, but was rebuilt the following year with 15 passenger cars, and remained the world's tallest extant wheel until its 97th year, when the 85-metre (279 ft) Technocosmos was constructed for Expo '85, at Tsukuba, Ibaraki, Japan.
1895: the Great Wheel was built for the Empire of India Exhibition at Earls Court, London, UK, and was 94 metres (308 ft) tall. Construction began in March 1894 and it opened to the public on July 17, 1895. It stayed in service until 1906 and was demolished in 1907, having carried over 2.5 million passengers.
1989: the Cosmo Clock 21 was built for the YES '89 Yokohama Exposition at Minato Mirai 21, Yokohama, Japan. Originally constructed with a height of 107.5 metres (353 ft), it was dismantled in 1997 and then in 1999 relocated onto a taller base which increased its overall height to 112.5 metres (369 ft).
2000: the London Eye, in London, UK, is 135 metres (443 ft) tall. Although officially opened on December 31, 1999, it did not open to the public until March 2000, because of technical problems. It is still the tallest wheel in Europe and the Western Hemisphere.
Following the huge success of the 135-metre (443 ft) London Eye since it opened in 2000, giant Ferris wheels have been proposed for many other world-class cities, however a large number of these projects have stalled or failed.
Erection currently in progress
The 167.6 m  (550 ft) High Roller is currently nearing completion on the Las Vegas Strip in Nevada, US. The last of its 28 cabins was installed on 3 December 2013, completing the structure of the wheel. Due to open in February 2014, it is 2.6 metres (9 ft) taller than the Singapore Flyer, the world's tallest operational Ferris wheel.
The Orlando Eye has been reported to be both 129.6 m (425 ft) and 137.1 m (450 ft) tall. Jointly developed by Merlin Entertainments, Unicorp National Developments, and Circle Entertainment, the wheel was reported to be in the early stages of planning in March 2011, with completion due in the summer of 2014, and was approved by county commissioners in September 2012. In January 2013 it was reported that the expected opening date had been pushed back to "by Thanksgiving [November] 2014". Erection of the main support structure began in December 2013.
Erection yet to begin
The 210 m (689 ft) Dubai Eye was announced in February 2013, with construction planned to begin at Bluewaters Island in the United Arab Emirates in June 2013, and will cost US$1.6 billion. Design and construction are to be undertaken by Hyundai Contracting and Starneth Engineering.
Wheels for which no completion date has been announced, or whose original completion date has already passed:
Erection begun but delayed, stalled, or abandoned
The Skyvue Las Vegas Super Wheel (or SkyVue - the official website uses both), was originally announced as being 145 m (476 ft) tall, but has since been reported to be 150 m (492 ft) and 152.4 m  (500 ft). Approved by Clark County Commission in March 2011, it is now under construction on the Las Vegas Strip. Announced at a media event and groundbreaking ceremony in May 2011 by Howard Bulloch of Compass Investments, who stated "We expect it to be up and running in time for New Year's 2012", the completion date has since been put back several times. In July 2012 it was reported that the opening was scheduled for New Year's Eve, 2013. As of September 2013, the projected opening has been delayed until mid-2015.
The 89-metre (292 ft) Turn of Fortune has been under construction in Changzhou, Jiangsu, China, since 2009. The 84-metre (276 ft) diameter structure could supersede the 60-metre (197 ft) Big O, in Tokyo, Japan, as the world's tallest centreless Ferris wheel, but completion has been repeatedly delayed.
Erection not begun
The 220 m (722 ft) Moscow View, proposed in 2011, would feature 48 monorail-mounted passenger capsules, each able to carry 48 passengers, travelling round a centreless non-rotating rim. At that time, the timeframe for its construction was unknown and its site within Moscow had yet to be selected, though candidates were said to include the All-Russia Exhibition Centre, Gorky Park, Prospekt Vernadskogo, and Sparrow Hills. In December 2011 the project was reported to be stalled due to lack of City Hall approval.
The 198 m (650 ft) Baghdad Eye was proposed for Baghdad, Iraq, in August 2008. At that time, three possible locations had been identified, but no estimates of cost or completion date were given. In October 2008, it was reported that Al-Zawraa Park was expected to be the site, and a 55 m (180 ft) wheel was installed there in March 2011.
The 185 m (607 ft) Great Dubai Wheel proposed for Dubailand, Dubai, United Arab Emirates, was granted planning permission in 2006 and expected to open in 2009, but it has since been announced that the Great Dubai Wheel will not be built. It was one of at least five Great Wheel Corporation giant Ferris wheel projects which failed between 2007 and 2010.
The 183 m (600 ft) Voyager has been proposed several times for Las Vegas, Nevada.
Artist's impression of the 175 m Great Berlin Wheel, a project originally due for completion in 2008, but which stalled after encountering financial obstacles
The 175 m (574 ft) Great Berlin Wheel was originally planned to open in 2008 but the project encountered financial obstacles. It was one of at least five Great Wheel Corporation giant Ferris wheel projects which failed between 2007 and 2010.
The 150 m (492 ft) Jeddah Eye was proposed in 2008, as part of a development scheduled to open in 2012 in Saudi Arabia. Construction was to have begun in 2009, but there were no subsequent announcements. It was one of at least five Great Wheel Corporation giant Ferris wheel projects which failed between 2007 and 2010.
The 101-metre (331 ft) Eye on Malaysia, a Chinese-manufactured wheel with 54 passenger gondolas, was scheduled to begin operating in April 2013 at Malacca Island, Malaysia. In November 2012, Chief Minister of the state of Malacca Datuk Seri Mohd Ali Rustam stated that the installation of piles had brought the RM40 million wheel to 15 per cent of completion, and that "the installation of the wheel structure will begin in February ." Mohd Ali Rustam had previously announced the Malaysia Eye, which conflicting reports stated would be 85 metres (279 ft) or 88 metres (289 ft) tall, also to be sourced from China and located at Malacca Island, and to have 54 air-conditioned gondolas, each able to carry six people. It was scheduled to open on December 1, 2011, but was never built.
The 87 m (285 ft) Pepsi Globe was proposed for the planned Meadowlands complex in New Jersey in February 2008 and originally due to open in 2009, then put on hold until 2010. It has since been further delayed, and construction of the host complex, originally due to be completed in 2007, has been stalled since 2009 due to financing problems.
Nippon Moon, described as a "giant observation wheel" by its designers, was reported in September 2013 to be "currently in development". At that time, its height was "currently undisclosed", but "almost twice the scale of the wheel in London." Its location, an unspecified Japanese city, was "currently under wraps", and its funding had "yet to be entirely secured." Commissioned by Ferris Wheel Investment Co., Ltd., and designed by UNStudio in collaboration with Arup, Mitsubishi Heavy Industries, and Experientia, it was expected to have 32 individually-themed capsules and take 40 minutes to rotate once.
The Shanghai Star, initially planned as a 200-metre (656 ft) tall wheel to be built by 2005, was revised to 170 metres (558 ft), with a completion date set in 2007, but then cancelled in 2006 due to "political incorrectness". An earlier proposal for a 250-metre (820 ft) structure, the Shanghai Kiss, with capsules ascending and descending a pair of towers which met at their peaks instead of a wheel, was deemed too expensive at £100m.
The Singapore Flyer, world's tallest Ferris wheel since 2008, has 28 air-conditioned passenger capsules, each able to carry 28 people
The London Eye's 32 ovoidal air-conditioned passenger capsules each weigh 10 tonnes (11 short tons) and can carry 25 people
Observation wheel is an alternative name for Ferris wheel. In 1892, when the incorporation papers for the Ferris Wheel Company (constructors of the original 1893 Chicago Ferris Wheel) were filed, the purpose of the company was stated as: [construction and operation of] "...wheels of the Ferris or other types for the purpose of observation or amusement".
Some Ferris wheels are marketed as observation wheels, any distinction between the two names being at the discretion of the operator, however the wheels whose operators reject the term Ferris wheel are often those having most in common with the original 1893 Chicago Ferris Wheel, especially in terms of scale and being an iconic landmark for a city or event.
Wheels with passenger cars mounted external to the rim and independently rotated by electric motors, as opposed to wheels with cars suspended from the rim and kept upright by gravity, are those most commonly referred to as observation wheels, and their cars are often referred to as capsules. However, these alternative names are also sometimes used for wheels with conventional gravity-oriented cars.
Currently, only four Ferris wheels with motorised capsules exist.
The 135 m (443 ft) London Eye, typically described as a "giant Ferris wheel" by the media, has ovoidal externally-mounted motorised capsules and is the "world's tallest cantilevered observation wheel" according to its operators, who claim "The London Eye is often mistakenly called a Ferris wheel. This is not the case: first, the passenger capsules are completely enclosed and are climate controlled; secondly, the capsules are positioned on the outside of the wheel structure and are fully motorised; and third, the entire structure is supported by an A-frame on one side only." The Singapore Flyer, which is supported on both sides, bills itself as the "world's largest observation wheel".
The 120 m (394 ft) Melbourne Star (previously the Southern Star) in Australia, has ovoidal externally-mounted motorised capsules and is described by its operators as "the only observation wheel in the southern hemisphere", but also as a Ferris wheel by the media.
Official conceptual renderings of the proposed 190.5 m (625 ft) New York Wheel, due to begin construction in 2014, also show a wheel equipped with externally-mounted motorised capsules.
Transportable Ferris wheels are designed to be operated at multiple locations, as opposed to fixed wheels which are usually intended for permanent installation. Small transportable designs may be permanently mounted on trailers, and can be moved intact. Larger transportable wheels are designed to be repeatedly dismantled and rebuilt, some using water ballast instead of the permanent foundations of their fixed counterparts.
Roue de Paris is a Ronald Bussink series R60 design using 40,000 litres (8,800 imperial gallons; 11,000 US gallons) of water ballast to provide a stable base. The R60 weighs 365 tonnes (402 short tons), and can be erected in 72 hours and dismantled in 60 hours by a specialist team. Transport requires seven 20-foot container lorries, ten open trailer lorries, and one closed trailer lorry. Its 42 passenger cars can be loaded either 3 or 6 at a time, and each car can carry 8 people. Bussink R60 wheels have operated in Australia (Brisbane), Canada (Niagara Falls), France (Paris), Malaysia (Kuala Lumpur & Malacca), UK (Belfast, Birmingham, Manchester, Sheffield), US (Myrtle Beach), and elsewhere.
Other notable transportable wheels include the 60-metre (197 ft) Steiger Ferris Wheel, which was the world's tallest transportable wheel when it began operating in 1980. It has 42 passenger cars, and weighs 450 tons. On October 11, 2010, it collapsed at the Kramermarkt in Oldenburg, Germany, during deconstruction.
Swiss manufacturer Intamin produced a series of rides comprising a vertical column supporting multiple horizontal arms, with each arm supporting a Ferris wheel. Custom designed for the Marriott Corporation, each ride had three main components: the wheels with their passenger cars; a set of supporting arms; and a single central supporting column. Each wheel rotated about the end of its own supporting arm. The arms in turn would either pivot or rotate together as a single unit about the top of the supporting column. The axis about which the rotating arms turned was offset from vertical, so that as the arms rotated, each arm and its corresponding wheel was raised and lowered. This allowed one wheel to be horizontal at ground level, and brought to a standstill for simultaneous loading and unloading of all its passenger cars, while the other wheel(s) continued to rotate vertically at considerable height.
The first such ride was Astrowheel, which had two arms and wheels with 8 passenger cars each, and operated at the former Six Flags Astroworld, Houston, Texas, from 1968 until 1980.
Eccentric wheels (sometimes called sliding wheels or coaster wheels) differ from conventional Ferris wheels in that some or all of the passenger cars are not fixed directly to the rim of the wheel, but instead slide on rails between the hub and the rim as the wheel rotates.
Mickey's Fun Wheel is 48.8 metres (160 ft) tall and has 24 fully enclosed passenger cars, each able to carry 6 passengers. 16 of the cars slide inward and outward as the wheel rotates, the remainder are fixed to the rim. There are separate boarding queues for sliding and fixed cars, so that passengers may choose between the two. Inspired by Coney Island's 1920 Wonder Wheel, it was designed by Walt Disney Imagineering and Waagner Biro, completed in 2001 as the Sun Wheel, and later refurbished and reopened in 2009 as Mickey's Fun Wheel.
Wonder Wheel was built in 1920, is 45.7 metres (150 ft) tall, and can carry 144 people.
Major designers, manufacturers, and operators
Seattle Wheel (debuted 1962): 16 cars, 2 passengers per car
Sky Wheel (debuted 1939; also manufactured by Chance Rides): a double wheel, with the wheels rotating about opposite ends of a pair of parallel beams, and the beams rotating about their centres; 8 cars per wheel, 2 passengers per car