g type used in the Otis system;
that is, the pressure was introduced behind the plungers, driving them
out. To the ends of the plungers were fixed smooth-faced sheaves, over
which were looped heavy quadruple-link pitch chains, one end of each being
solidly attached to the machine base. The free ends ran under the cylinder
and made another half-wrap around small sprockets keyed to the main drive
shaft. As the plungers were forced outward, the free ends of the chain
moved in the opposite direction, at twice the velocity and linear
displacement of the plungers. The drive sprockets were thereby revolved,
driving up the car. Descent was made simply by permitting the cylinders to
exhaust, the car dropping of its own weight. The over-all gear or ratio of
the system was the multiplication due to the double purchase of the
plunger sheaves times the ratio of the chain and drive sprocket diameters:
2(12.80/1.97) or about 13:1. To drive the car 218 feet to the first
platform of the Tower the plungers traveled only about 16.5 feet.

To penetrate the inventive rationale behind this strange machine is not
difficult. Aware of the fundamental dictum of absolute safety before all
else, the Roux engineers turned logically to the safest known elevator
type--the direct plunger. This type of elevator, being well suited to low
rises, formed the main body of European practice at the time, and in this
fact lay the further attraction of a system firmly based on tradition.
Since the piers between the ground and first platform could accommodate a
straight, although inclined run, the solution might obviously have been to
use an inclined, direct plunger. The only difficulty would have been that
of drilling a 220-foot, inclined well for the cylinder. While a difficult
problem, it would not have been insurmountable. What then was the reason
for using a design vastly more complex? The only reasonable answer that
presents itself is that the designers, working in a period before the
Otis bid had been accepted, were attempting to evolve an apparatus capable
of the complete service to the second platform. The use of a rigid direct
plunger thus precluded, it became necessary to transpose the basic idea in
order to adapt it to the curvature of the Tower leg, and at the same time
retain its inherent quality of safety. Continuing the conceptual sequence,
the idea of a plunger made in some manner flexible apparently suggested
itself, becoming the heart of the Rou