Figure 30.—Upperworks and passenger platforms of the Otis system at second level.
(From La Nature, Aug. 10, 1889, vol. 17, p. 169.)
The Roux and the Otis systems both drew their water supply from the same tanks; also, each system used similar distributing valves ([fig. 32]) operated from the cars. Although no reports have been found of actual controlled tests comparing the efficiencies of the Otis and Roux systems, a general quantitative comparison may be made from the balance figures given for each (p. [40]), where it is seen that 2,665 pounds of excess tractive effort were allowed to overcome the friction of the Otis machinery against 13,856 pounds for the Roux.
THE EDOUX SYSTEM
The section of the Tower presenting the least difficulty to elevator installation was that above the juncture of the four legs—from the second platform to the third, or observation, enclosure. There was no question that French equipment could perform this service. The run being perfectly straight and vertical, the only unusual demand upon contemporary elevator technology was the length of rise—525 feet.
The system ultimately selected ([fig. 37]) appealed to the Commission largely because of a similar one that had been installed in one tower of the famous Trocadero[13] and which had been operating successfully for 10 years. It was the direct plunger system of Leon Edoux, and was, for the time, far more rationally contrived than Backmann’s helicoidal system. Edoux, an old schoolmate of Eiffel’s, had built thousands of elevators in France and was possibly the country’s most successful inventor and manufacturer in the field. It is likely that he did not attempt to obtain the contract for the elevator equipment in the Tower legs, as his experience was based almost entirely on plunger systems, a type, as we have seen, not readily adaptable to that situation. What is puzzling was the failure of the Commission’s members to recognize sooner Edoux’s obvious ability to provide equipment for the upper run. It may have been due to their inexplicable confidence in Backmann.
Figure 31.—The French Girard pumps that supplied the Otis and Roux systems.
(From La Nature, Oct. 5, 1889, vol. 17, p. 292.)