Exhibition buildings also presented designers with opportunities to explore the potential of iron and steel.
The national and international exhibitions held in Europe from the end of the eighteenth century generated a spirit of rivalry "a desire to equal or improve on the last exhibition". This rivalry applied to both what was on display and the buildings housing the displays. The buildings had to be impressive, and they usually had to be rapidly demountable and remountable. The new material, iron, had found an obvious home.
The series of Galerie des Machines for four successive Paris exhibitions was particularly important.
The French exhibitions in Paris were particularly influential and the first international exhibition held there was in 1855. A building of note at this, and the subsequent Paris exhibitions, was the Galerie des Machines. The same, or similar, names have been used to describe buildings at the 1867, 1878 and 1889 exhibitions.
The 1855 Galerie incorporated wrought iron latticed arches to span 48m, the outward thrusts from these arches being resisted by massive masonry buttressing.
For the 1878 exhibition the engineer de Dion designed a kind of trussed portal frame assembled from prefabricated elements. In between each of the frames spanned trussed iron purlins. De Dion realised that the rigid skeleton created by the purlins and the frames would be subject to considerable thermal movement and to allow for this he introduced movement joints every 60m. These consisted of bolts in oval holes, a problem and solution still used in long span steel structures today.
Two structures at the Paris exhibition of 1889 notable for both their appearance and technical innovation were the Tour de 300 Metres (Eiffel Tower) - more notable for its height than span - and the Galerie de Machines.
When the Galerie des Machines is mentioned it is usually the 1889 building which is being referred to. There were, in fact, two structures at the Paris exhibition of 1889 that attracted wide attention, for both their appearance and technical innovation: one was the Tour de 300 Metres (now commonly known as the Eiffel Tower) and the other the Galerie de Machines (also referred to as the Palais de Machines). Both were massive celebrations of iron as a structural material
The Tour de 300 Metres was clearly more notable for its vertical proportions than for any horizontal spans (though the square base of the tower is 125m corner to corner): but it did play an important role in supporting the credibility of iron as a major load carrying material.
The design of the Tower by Nougier, Koechlin and Sauvestre is a good example of fruitful architect/engineer collaboration since it was only after the architect Sauvestre had made modifications to the initial design that Eiffel became interested in the scheme.
There are two further points of interest relating to the Eiffel tower. First, the idea of an iron tower was not new. Trevethick, the Englishman who played an important part in the development of the steam engine, proposed the building of a 1000 ft. (305m) high cast iron tower as early as 1833. And for the New York Exhibition of 1853, James Bogard, a specialist in cast iron frame buildings, envisaged a 90m high iron tower. Second, the tower was not designed by Eiffel. It was Koechlin and Nougier, engineers working in Eiffel's office, who had the idea for a tower and produced the early drawings and calculations. When shown the project Eiffel said that he was not interested in a tower design but allowed Koechlin and Nougier to carry on developing the project. It was Stephen Sauvestre, an architect, also working at the Eiffel office, who made the important changes to the initial scheme. He joined the first level and the four main columns with monumental arches to give a stronger impression of stability to the tower and to form entrance gateways to the exhibition. He also added a hall with windows to the first floor and facade ornamentation to the second floor.
Eiffel later bought the patent for the tower design from his colleagues and defended it against a critical onslaught.
Eiffel's important roles were in building the tower, accepting all responsibility for the safety of the tower and giving financial guarantees to cover any accident or damage.>He also had to defend the scheme vigorously against those who thought the tower to be ugly or dangerous or both. Famous artists and writers including Guy de Maupassant, Alexandre Dumas and Charles Gounod officially complained about 'this offence to French good taste....this monstrous Eiffel Tower' Prince Charles might well have signed the letter if he had been around then. Eiffel believed all of such criticism to be misplaced. For him the tower was purely rational and abstract, in keeping with the laws of science and ethics, "a symbol of a vanquished difficulty".
The Galerie de Machines was, like the Eiffel Tower,similarly symbolic in demonstrating the particular qualities offered by iron as a structural material.
One of the three prize winners for the 1889 exhibition (along with the Eiffel Tower and Formige's Palace of Fine Arts and Liberal Arts) the Galerie was designed by the architect Dutert with the aid of the engineers Contamin, Pierron and Charton. Built in regular bays this long span, three-pinned, trussed Portal Frame, this innovative design was a clear progenitor of many steel industrial and exhibition buildings of the twentieth century: a most appropriate building to house an exhibition of recent industrial inventions.
Dutert submitted his project to the Paris Exposition competition in 1886. Although Dutert did work closely with Contamin et. al. in developing the scheme it is clear from contemporary accounts that the idea of enclosing the Galerie with a single span structure was his. It is interesting to note that up to the time when Dutert was awarded the commission for the Galerie he had had no other major commissions. There is an interesting parallel here with the Centre Pompidou (Beauborg) built in Paris around a hundred years later: a major exhibition building in steel designed by architects with no major commission beforehand, in this case Piano and Rogers.
The Galerie de Machines, like the Eiffel tower, was fabricated from many small sections and plates riveted together.
The pinned frame had feet made as large rocking steel shoes, and tapered towards the feet and crown in response to the low bending moments in these regions (zero at the pins). Internally the frames and trussed purlins which spanned between them were not decorated; ornamentation was left to the external faces. Sadly the building was demolished in 1910.