The Fives-Lilles equipment reflected the advance of European elevator engineering in this short time. The machines were rope-geared and incorporated the elegant feature of self-leveling cabins which compensated for the varying track inclination. For the 1900 fair, the Otis elevator in the south pier was also removed and a wide stairway to the first platform built in its place. In 1912, 25 years after Backmann's startling proposal to use electricity for his system, the remaining Otis elevator was replaced by a small electric one. This innovation was reluctantly introduced solely for the purpose of accommodating visitors in the winter when the hydraulic systems were shut down due to freezing weather. The electric elevator had a short life, being removed in 1922 when the number of winter visitors increased far beyond its capacity. However, the two hydraulic systems were modified to operate in freezing temperatures--presumably by the simple expedient of adding an antifreezing chemical to the water--and operation was placed on a year-round basis. Today the two Fives-Lilles hydraulic systems remain in full use; and visitors reach the Tower's summit by Edoux's elevator (fig. 41), which is all that remains of the original installation. BALANCE OF THE THREE ELEVATOR SYSTEMS _The Otis System_ Negative effect Weight of cabin: 23,900 lb. × sin 78°9' (incline of upper run) 23,390 lb. Live load: 40 persons @150 lb. = 6,000 × sin 78°9' 5,872 ------ -- 29,262 lb. Positive effect Counterweight: 55,000 × sin 54°35' (incline of lower run) ------------------------------------------ 3 (rope gear ratio) 14,940 lb. Weight of piston and chariot: 33,060 × sin 54°35' ------------------ 12 (ratio) 2,245 Power: 156 p.s.i. × 1,134 sq. in. (piston area) ---------------------------------------- 12 (ratio) 14,742 31,927 lb. Excess to overcome friction 2,665 lb. _The Roux, Combaluzier and Lepape System_ Negative effect Weight of cabin: 14,100 × sin 54°35' 11,500 lb. Live load: 100 persons @150 lb. = 15,000 × sin 54°35' 12,220 ------ -- 23,720 lb. Positive effect Counterweight: 6,600 × sin 54°35' 5,380 Power: 156 p.s.i. × 2 (pistons) × 1,341.5 sq. in. (piston area) ------------------------------------------ 13 (ratio) 32,196 37,576 lb. ------ ---------- Excess to overcome friction 13,856 lb.