Monday, August 4, 2008
Galerie des Machines (Gallery of Machines)
The Galerie des Machines was designed for the 1889 Paris International Exhibition—L’Exposition Tricolorée—by architect Ferdinand Dutert (1845–1906) in collaboration with engineer Victor Contamin (1840–1893). It was remarkable for its vast exhibition hall, made possible by exploiting a new structural innovation, the three-pin hinged or portal arch. Although used previously in bridge construction, this was the first application of the arch on such a large scale.
The concept of exhibiting to the world a nation’s resources and achievements in art, science, and industry has its origins in ancient times. According to the Bible, the fifth-century-b.c. Persian king Xerxes I showed the riches of his kingdom for five months. More recently, fine art exhibitions were mounted, but such shows gradually added inventions. Following the Industrial Revolution and the consequent rise of mechanization, expositions demonstrating industrial progress were held regularly. Before 1900, no fewer than thirteen were organized in the manufacturing centers and capitals of Europe. They were popular events and buildings were purpose-built for them; perhaps the most renowned was Joseph Paxton’s revolutionary Crystal Palace, built in London for the Great Exhibition of 1851. In turn, many of those structures became showpieces of structural and technological advances.
Following the celebrated success of the Great Exhibition and Britain’s abandonment of such shows after 1862, the French seized the opportunity to take center stage, so to speak. Between 1855 and 1900 five international exhibitions were presented in Paris, boasting of the progress of French industry and the country’s rapid transition from a predominantly agrarian to an industrial economy. By 1889 when L’Exposition Tricolorée commemorated the centenary of the French Revolution, the size and variety of machines and other items offered for display were so great that a range of special exhibition spaces was needed. A formal entrance structure was built—the famed Eiffel Tower—and two long galleries were dedicated to the fine and liberal arts and a third to clothing and furniture exhibits. Beyond them and behind the Dome Central that terminated the long axis of the showground rose the vast and impressive Galerie des Machines.
Built principally of iron and glass, the structure employed a three-hinged or portal arch spanning a phenomenal 375 feet (114 meters); the widest previously achieved was 242 feet (74 meters) in the train shed of St. Pancras Station, London, about 25 years earlier. The display hall was 1,270 feet (380 meters) long, and its colossal proportions provided the largest unobstructed floor area of any building in history—an ideal setting in which to show the world the massive engines, transformers, dynamos, and other wonders of the age. The 20 prefabricated wrought-iron trusses of the main span comprised two half-arches, hinged at their meeting point 143 feet (45 meters) above the floor. They curved and tapered to a slender wedgelike base, where their loads were distributed to the ground through a hinged joint. The apparent lightness with which they touched the ground defied the conventional, rational notion that the base was the principal load-bearing component of any structure; here that role was seemingly reversed. The hinges allowed small movements between the foot of the frames and the foundation but made the arches statically determinate. Thus, stresses and reactions at the supports could be calculated beforehand and were only slightly influenced by movements of the supports or thermally induced dimensional variations.
The iron frame of the galerie was exposed at each end in a frank display of its construction system. The walls were generally glazed, in part with colored glass. Paintings, mosaic, and ceramic bricks also formed part of the cladding. Elevated tracks on each side of the long axis carried mobile walkways above the exhibition space, allowing visitors to travel in carriages and to look down on the machines. The interior was lit by electric lights, invented only some seven years earlier. The galerie was more than just a place for displaying machinery; it was in itself, as one historian has observed, an “exhibiting machine.” It was enlarged for the 1900 Paris Exposition but demolished in 1910, because (so the reason was given) it spoiled the view of the church of Les Invalides. By then, the three-hinged arch was in wide use.