Figure 2.—Gustave Eiffel (1832-1923).
(From Gustave Eiffel, La Tour de Trois Cents Mètres,
Paris, 1900, frontispiece.)
There was, it is true, some inspiration to be found in the paper projects of several earlier designers—themselves inspired by that compulsion which throughout history seems to have driven men to attempt the erection of magnificently high structures.
One such inspiration was a proposal made in 1832 by the celebrated but eccentric Welsh engineer Richard Trevithick to erect a 1,000-foot, conical, cast-iron tower ([fig. 3]) to celebrate the passing of the Reform Bill. Of particular interest in light of the present discussion was Trevithick’s plan to raise visitors to the summit on a piston, driven upward within the structure’s hollow central tube by compressed air. It probably is fortunate for Trevithick’s reputation that his plan died shortly after this and the project was forgotten.
One project of genuine promise was a tower proposed by the eminent American engineering firm of Clarke, Reeves & Company to be erected at the Centennial Exhibition at Philadelphia in 1876. At the time, this firm was perhaps the leading designer and erector of iron structures in the United States, having executed such works as the Girard Avenue Bridge over the Schuylkill at Fairmount Park, and most of New York’s early elevated railway system. The company’s proposal ([fig. 4]) for a 1,000-foot shaft of wrought-iron columns braced by a continuous web of diagonals was based upon sound theoretical knowledge and practical experience. Nevertheless, the natural hesitation that the fair’s sponsors apparently felt in the face of so heroic a scheme could not be overcome, and this project also remained a vision.
Preparatory Work for the Tower
In the year 1885, the Eiffel firm, which also had an extensive background of experience in structural engineering, undertook a series of investigations of tall metallic piers based upon its recent experiences with several lofty railway viaducts and bridges. The most spectacular of these was the famous Garabit Viaduct (1880-1884), which carries a railroad some 400 feet above the valley of the Truyere in southern France. While the 200-foot height of the viaduct’s two greatest piers was not startling even at that period, the studies proved that piers of far greater height were entirely feasible in iron construction. This led to the design of a 395-foot pier, which, although never incorporated into a bridge, may be said to have been the direct basis for the Eiffel Tower.