Construction of an annexe gallery for the 1878 Universal Exposition

Henri de Dion devised an economical metallic structure composed of lattice half-arches anchored in the ground. Although he arrived late in the construction of the 1878 Exposition, for the Machines Hall he succeeded in replacing the Polonceau trusses initially planned with his system. The calculations he had just published showed that further economising on materials was possible. When, a few months before the opening, it was discovered that the Machines Hall was not big enough to contain all the planned exhibits, the construction of an annexe gave the engineer an opportunity to put his new theory into practice. Sadly, he died before the exhibition’s opening and never saw his project completed. The builders of this construction, the Moisant company, had this scale model made. It was shown in the civil engineering section of the Exposition then donated to the Conservatoire.