That wasn’t the only innovative use of the Paris landmark, however. Eiffel also installed a drop test machine to measure the drag and velocity of bodies dropped from the tower. As well as proving the concept of relative motion, this cutting-edge device was also invaluable for early aviators, as was the wind tunnel he built at the tower's base.
When Eiffel had to move his equipment from the Tower, he was encouraged by his aeronautical associates to set up a new laboratory in order to continue these tests.
Opened in 1912 in Auteuil, the aerodynamic laboratory and its wind tunnel are still operating today – and as I discovered when I had the luck to visit, there are signs of its rich past throughout the building.
Unassuming premises in a quiet Paris street don’t give much of a clue as to the extraordinary machinery within.
Most of the space is taken up by a wind tunnel which runs the length of the building. The intake is 4m in diameter, narrowing to 2m at the experiment chamber end. At the other side of the chamber is a 2m-long diffuser with 23-blade fan, which pulls air through the wind tunnel.
Although the original engines are still present, modern electric ones are now used to power the wind tunnel. However, the original equipment otherwise remains in use.
To answer an obvious question about such a facility in the middle of a residential area, it is surprisingly quiet. The neighbours are not disturbed.
Marble-backed instrument panels are still in situ, although many have been superceded by modern technology. This is still very much a working lab, even if laptops have taken the place of paper records.
The laboratory is full of models used for aerodynamic testing throughout its history. They range from the propellors of early aeroplanes to modern buildings. There is a workshop on site, with a specialist model-maker.
Other reminders of the building's long and special history include graphs and publications. They evidence Eiffel's wider interests too, which included meteorology.
In his late seventies when the laboratory opened, Eiffel nonetheless took an active interest in its activities; his desk is still there today. By the time of his death in 1923, the wind tunnel had become a pattern for others throughout the world.
Anemometer used by Eiffel to measure wind speed