Figure 34. — Roux, Combaluzier and Lepape machinery and cabin 

 at the Tower's base. (From La Nature, Aug. 10, 1889, vol. 17, p. 

 168.) 



length was buoyed by the water within the cylinders, 

 increasing their effective weight. These two factors 

 were, however, exactly compensated for by the 

 lengthening of the cables on the other side of the 

 pulleys as the lower car descended. Perfect balance 

 of the system's dead load for any position of the cabins 

 was, therefore, a quality inherent in its design. How- 

 ever, there were two extreme conditions of live loading 

 which required consideration: the lower car full and 

 the upper empty, or vice versa. To permit the upper 

 car to descend under the first condition, the plungers 

 were made sufficiently heavy, by the addition of cast 

 iron at their lower ends, to overbalance the weight 



of a capacity load in the lower car. The second 

 condition demanded simply that the system be power- 

 ful enough to Hft the unbalanced weight of the plungers 

 plus the weight of passengers in the upper car. 



As in the other systems, safety was a matter of prime 

 importance. In this case, the element of risk lay 

 in the possibility of the suspended car falling. The 

 upper car, resting on the rams, was virtually free of 

 such danger. Here again the influence of Backmann 

 was felt — a brake of his design was applied (fig. 38). 

 It was, true to form, a throwback, similar safety devices 

 having proven unsuccessful much earlier. Attached 

 to the lower car were two helically threaded vertical 



PAPER 19: ELEVATOR SYSTEMS OF THE EIFFEL TOWER 



35 



