Monday, August 4, 2008
The Eiffel Tower was built between 1887 and 1889 as the entrance arch to the International Paris Exhibition, held to celebrate the centenary of the French Revolution. Conceived in 1882 by Gustave Eiffel’s chief research engineers Maurice Koechlin and Emile Nouguier, and constructed in collaboration with architect Stephan Suavestre, the tower is a graceful and imaginative puddled iron lattice pylon. It soars to 1,020 feet (312 meters), the first building in almost 5,000 years to surpass the height of the Great Pyramid.
Preliminary sketches were made in June 1884 and in September Eiffel, suddenly interested in the project, registered a patent “for a new configuration allowing the construction of metal supports and pylons capable of exceeding a height of 300 meters.”
A careful and innovative assembly of over 18,000 small lightweight parts, the Eiffel Tower demonstrated to fullest advantage the structural possibilities of wrought iron. The world’s tallest structure until the Chrysler Building was constructed in 1929 in New York City, it became (and still is) a landmark synonymous with Paris. Intended as a temporary exhibit and scheduled for demolition in 1909, it was saved by its tourist potential and its usefulness as a communication antenna. A radio tower added in 1959 increased its height by 56 feet (20 meters).
Eiffel had specialized in metal construction during his studies at the École Centrale des Arts et Manufactures in Paris. Prior to the acceptance of his design for the tower, he had built in iron and steel, notably the Maria-Pia railway bridge over the Douro River in Oporto, Portugal; the Truyere Bridge near Carabit, France; locks on the Panama Canal; and the internal frame for the Statue of Liberty. Whilst the Parisian tower drew on the outcomes of these projects, it was nonetheless a unique scientific and engineering challenge: its great height meant that wind loads had to be calculated in the design as well as the effects of gravity, Eiffel chose open lattice and splayed legs so that the wind would pass through the structure. In gale-force winds the movement of the tower is estimated to be a mere 4.5 inches (11 centimeters). Speedy and safe transportation of workers and materials (and later of visitors) was another challenge. Eiffel installed elevators that ran on inclined tracks within the tower’s legs; the guide rails were used as tracks for climbing cranes during construction.
The Eiffel Tower weighs over 13,200 tons (11,180 tonnes), more than 70 percent of which is metal. Its 412-foot-square (126-meter) base is defined by the four huge masonry foundation piers set in bedrock; each supports a leg, and the legs converge to form the shaft. Eiffel employed a team of 50 engineers to prepare 5,300 drawings to his specifications, 100 workers to fabricate the components in the Eiffel factory at Levallois-Perret on the outskirts of Paris, and between 150 and 300 site laborers. His calculations were so precise that no revisions were required during construction. Work began on 1 July 1887 and the project was finished in a little over twenty-six months. Eiffel was awarded the French Legion of Honor.
On the tower’s completion, opposition to its erection was silenced. An earlier protest published in Le Temps had been signed by such illustrious Frenchmen as the writers Guy de Maupassant and Alexandre Dumas Jr. and the architect Charles Garnier. Others had described the proposal as a “truly tragic street lamp” and a “carcass waiting to be fleshed out with freestone or brick, a funnel-shaped grill, a hole-riddled suppository.” But it was an instantaneous popular success. In the last five months of 1889, over 1.9 million people visited it. Each paid an entrance fee to help defray the cost—a little under Fr 8 million (about U.S.$1.5 million).
Three viewing platforms—at 186, 376, and 900 feet (57, 115, and 276 meters)—were provided for visitors. At the first, where there were restaurants and a theater, arches linked the four legs; applied after the construction of the legs and platform, they were purely ornamental. Visitors were taken to the first and second platforms in double-deck, glass-enclosed hydraulic elevators. Stairs led to the third platform, and an elevator gave access to the top of the tower, where Eiffel originally had his studio and office (now restored). Each level offered a panoramic view of Paris and beyond for about 50 miles (80 kilometers). From the Eiffel Tower, people were afforded, for the first time, the unique opportunity of seeing the earth from far above.
When the Société de la Tour Eiffel’s original operating concession expired in 1980, the city of Paris assumed direct control of the tower through a company called Société Nouvelle d'Exploitation de la Tour Eiffel. From 1980 to 1984 it undertook a restoration and renovation program. The tower was reinforced in places, 1,560 tons (1,320 tonnes) of excrescences were removed, and the elevators were replaced. It requires regular maintenance, including painting every seven years. The Eiffel Tower continues to be a prime tourist attraction, with over 6 million visitors annually. Each of the viewing platforms is accessible and Eiffel’s office has been opened to tourists. The exclusive Le Jules Vernes restaurant occupies the second level. During the Paris millennium celebrations of 2000, the tower was covered with thousands of small lights that nightly illuminated the gracious “iron lady” of Paris.