When Eiffel was called upon by Bartholdi in early 1880, he had been deeply engaged in the design and the start-up of site construction for the Garabit bridge, but he immediately recognized the potential publicity that he could garner from being involved in such an international project. Eiffel’s experience was such that he would fundamentally change Viollet-le-Duc’s intended structure. He replaced Viollet-le-Duc’s mass with geometric stiffness by simply inserting an iron pylon, similar to those that he was designing for the Garabit Bridge, into the inside of the hollow sculpture.
The 92′ tall central spine or pylon upon which the copper skin of the statue would be hung consisted of four columns made of riveted (laminated) wrought iron plates. These were connected with diagonal bracing that gave the pylon its stiffness against the wind. A secondary system of wrought iron braces was built from the pylon that roughly estimated the actual shape of the sculpture. This system’s role was to support each copper plate independent of the others, primarily to avoid the accumulation of the weight from the plates above, and to permit thermal movement in the copper to freely occur so that the statue would not tear itself apart as the seasons changed from summer expansion to winter contraction. Each copper plate was, therefore, joined to the secondary braces by a system of custom-fitted iron straps, that were not directly attached to the copper plates, but were slotted into copper sheathes that were riveted to the copper plates, again to allow each metal to move independent of the other. In the Statue of Liberty, Eiffel had reworked James Bogardus’ technique of using an iron frame to support its masonry curtain wall in order to support Bartholdi’s copper curtain wall. The point here is that sheathing an iron frame in a non-loadbearing envelope (be it masonry or metal or glass-the cast iron front) had been in use since 1855 (earlier if we count the cast iron front). It would be up to American architects to apply this concept to the exterior of a skyscraper.
Typical of Eiffel’s precision, the statue was first erected piece by piece to make sure everything fit like a glove, at the Monduit workshop in Paris where the copper plates were being fabricated. Erection of the iron pier began in October 1881, which meant that the iron, more than likely, was fabricated by Eiffel prior to the start of his fabricating the iron for the Garabit project. By December 1882, the construction had reached a height that it was visible above the rooftops of the neighboring houses in Paris. Meanwhile, the hand and torch in New York were disassembled, packed, and shipped back to Paris. By January 1884, Lady Liberty could be seen from all over Paris where she spent the summer sunning herself.
FURTHER READING:
Loyrette, Henri. Gustave Eiffel. New York: Rizzoli, 1985.
Trachtenburg, Marvin. The Statue of Liberty. New York: Penguin, 1977.
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The Architecture Professor 