<P> The arrangement of the lifts has been changed several times during the tower's history . Given the elasticity of the cables and the time taken to align the cars with the landings, each lift, in normal service, takes an average of 8 minutes and 50 seconds to do the round trip, spending an average of 1 minute and 15 seconds at each level . The average journey time between levels is 1 minute . The original hydraulic mechanism is on public display in a small museum at the base of the east and west legs . Because the mechanism requires frequent lubrication and maintenance, public access is often restricted . The rope mechanism of the north tower can be seen as visitors exit the lift . </P> <P> Gustave Eiffel engraved on the tower the names of 72 French scientists, engineers and mathematicians in recognition of their contributions to the building of the tower . Eiffel chose this "invocation of science" because of his concern over the artists' protest . At the beginning of the 20th century, the engravings were painted over, but they were restored in 1986--87 by the Société Nouvelle d'exploitation de la Tour Eiffel, a company operating the tower . </P> <P> The tower is painted in three shades: lighter at the top, getting progressively darker towards the bottom to complement the Parisian sky . It was originally reddish brown; this changed in 1968 to a bronze colour known as "Eiffel Tower Brown". </P> <P> The only non-structural elements are the four decorative grill - work arches, added in Sauvestre's sketches, which served to make the tower look more substantial and to make a more impressive entrance to the exposition . </P>

What color is the eiffel tower in paris