As mentioned, the most serious problem confronting Edoux was the extremely high rise of 525 feet. The Trocadero elevator, then the highest plunger machine in the world, traveled only about 230 feet. A secondary difficulty was the esthetic undesirability of permitting a plunger cylinder to project downward a distance equal to such a rise, which would have carried it directly into the center of the open area beneath the first platform (fig. 6). Both problems were met by an ingenious modification of the basic system. The run was divided into two equal sections, each of 262 feet, and two cars were used. One operated from the bottom of the run at the second platform level to an intermediate platform half-way up, while the other operated from this point to the observation platform near the top of the Tower. The two sections were of course parallel, but offset. A central guide, on the Tower's center-line, running the entire 525 feet served both cars, with shorter guides on either side--one for the upper and one for the lower run. Thus, each car traveled only half the total distance. The two cars were connected, as in the Backmann system, by steel cables running over sheaves at the top, balancing each other and eliminating the need for counterweights. Two driving rams were used. By being placed beneath the upper car, their cylinders extended downward only the 262 feet to the second platform and so did not project beyond the confines of the system itself.[15] In making the upward or downward trip, the passengers had to change from one car to the other at the intermediate platform, where the two met and parted (fig. 39). This transfer was the only undesirable feature of what was, on the whole, a thoroughly efficient and well designed work of elevator engineering. [Illustration: Figure 32.--The Otis distributor, with valves shown in motionless, neutral position. Since the main valve at all times was subjected to the full operating pressure, it was necessary to drive this valve with a servo piston. The control cable operated only the servo piston's valve. (Adapted from Gustave Eiffel, _La Tour de Trois Cents Mètres_, Paris, 1900, p. 130.)] [Illustration: Figure 33.--General arrangement of the Roux Combaluzier and Lepape elevator.] [Illustration: Figure 34.--Roux, Combaluzier and Lepape machinery and cabin at the Tower's base. (From _La Nature_, Aug. 10, 1889, vol. 17, p. 168.)]