Excerpt
The 1,000-foot tower that formed the focal point and central feature of the Universal Exposition of 1889 at Paris has become one of the best known of man’s works. It was among the most outstanding technological achievements of an age which was itself remarkable for such achievements.
Second to the interest shown in the tower’s structural aspects was the interest in its mechanical organs. Of these, the most exceptional were the three separate elevator systems by which the upper levels were made accessible to the Exposition visitors. The design of these systems involved problems far greater than had been encountered in previous elevator work anywhere in the world. The basis of these difficulties was the amplification of the two conditions that were the normal determinants in elevator design—passenger capacity and height of rise. In addition, there was the problem, totally new, of fitting elevator shafts to the curvature of the Tower’s legs. The study of the various solutions to these problems presents a concise view of the capabilities of the elevator art just prior to the beginning of the most recent phase of its development, marked by the entry of electricity into the field.
The great confidence of the Tower’s builder in his own engineering ability can be fully appreciated, however, only when notice is taken of one exceptional way in which the project differed from works of earlier periods as well as from contemporary ones. In almost every case, these other works had evolved, in a natural and progressive way, from a fundamental concept firmly based upon precedent. This was true of such notable structures of the time as the Brooklyn Bridge and, to a lesser extent, the Forth Bridge. For the design of his tower, there was virtually no experience in structural history from which Eiffel could draw other than a series of high piers that his own firm had designed earlier for railway bridges. It was these designs that led Eiffel to consider the practicality of iron structures of extreme height.
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Figure 1.—The Eiffel Tower at the time of theUniversal Exposition of 1889 at Paris.(From La Nature, June 29, 1889, vol. 17, p. 73.)
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 () 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....