In spite of their large over-all scale and the complication of the basic pattern imposed by the unique situation, the Otis elevators performed well and justified the original judgment and confidence which had prompted Eiffel to fight for their installation. Aside from the obvious advantage of simplicity when compared to the French machines, their operation was relatively quiet, and fast. The double car, traveling at 400 feet per minute, carried 40 persons, all seated because of the change of inclination. The main valve or distributor that controlled the flow of water to and from the driving cylinder was operated from the car by cables. The hydraulic head necessary to produce pressure within the cylinder was obtained from a large open reservoir on the second platform. After being exhausted from the cylinder, the water was pumped back up by two Girard pumps (fig. 31) in the engine room at the base of the Tower's south leg. THE SYSTEM OF ROUX, COMBALUZIER AND LEPAPE There can be little doubt that the French elevators placed in the east and west piers to carry visitors to the first stage of the Tower had the important secondary function of saving face. That an engineer of Eiffel's mechanical perception would have permitted their use, unless compelled to do so by the Exposition Commission, is unthinkable. Whatever the attitudes of the commissioners may have been, it must be said--recalling the Backmann system--that they did not fear innovation. The machinery installed by the firm of Roux, Combaluzier and Lepape was novel in every respect, but it was a product of misguided ingenuity and set no precedent. The system, never duplicated, was conceived, born, lived a brief and not overly creditable life, and died, entirely within the Tower. Basis of the French system was an endless chain of short, rigid, articulated links (fig. 35), to one point of which the car was attached. As the chain moved, the car was raised or lowered. Recalling the European distrust of suspended elevators, it is interesting to note that the car was pushed up by the links below, not drawn by those above, thus the active links were in compression. To prevent buckling of the column, the chain was enclosed in a conduit (fig. 36). Excessive friction was prevented by a pair of small rollers at each of the knuckle joints between the links. The system was, in fact, a duplicate one, with a chain on either side of the car. At the bottom of the run the chains passed around huge sprocket wheels, 12.80 feet in diameter, with pockets on their peripheries to engage the joints. Smaller wheels at the top guided the chains.