t 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.

If by some motive force the wheel (fig. 33) were turned counterclockwise,
the lower half of the chain would be driven upward, carrying the car with
it. Slots on the inside faces of the lower guide trunks permitted passage
of the connection between the car and chain. Lead weights on certain links
of the chains' upper or return sections counterbalanced most of the car's
dead weight.

[Illustration: Figure 28.--Plan and section of the Otis system's movable
pulley assembly, or chariot. Piston rods are at left. (Adapted from _The
Engineer_ (London), July 19, 1889, vol. 68, p. 58.)]

Two horizontal cylinders rotated the driving sprockets through a mechanism
whose effect was similar to the rope-gearing of the standard hydraulic
elevator, but which might be described as chain gearing. The cylinders
were of the pushing rather than the pullin