Scientific Facts

Eiffel tower at night

From the time of his project proposal in 1886, Gustave Eiffel knew that the Tower’s service to science alone could protect it from its enemies and extend its life span. At the beginning it was meant to last 20 years and then be destroyed! Eiffel therefore spelled out the uses he had in mind: meteorological and astronomical observation, experimentation in physics, a strategic observation post, a communications base for signaling, a beacon for electric light and wind studies. He said: “It will be an observatory and a laboratory such as science has never had at its disposal. That’s why, from Day 1, all our scientists have encouraged me with such strong fellow feeling.” In fact from 1889 onward, the Eiffel Tower was used as a laboratory for scientiic measurements and experiments. Much scientiic equipment was installed (barometers, wind gauges, lightning conductors, etc.). Gustave Eiffel even built himself an office on the third floor to carry out astronomy and physiology observations.

Why the Eiffel Tower is made of iron

What are the advantages of iron? Gustave Eiffel himself gives the answer: “First of all, its resistance. From the viewpoint of loads one or the other of these materials can support, we know that for any given surface area, iron is ten times more resistant than wood and 20 times more resistant than stone.” He points out: “It’s above all in the large constructions that the metal’s resistance makes it superior to other materials. The relative lightness of metal constructions also allows for smaller supports and foundations.” And he concludes: “To give just one example, that of the Exhibition Tower, I astonished more than one person who was worried about the load on the floor of the foundations, by saying that the load wouldn’t be any greater than that of a house in Paris.”

The scientific experiments

The day after the Tower was inaugurated, Gustave Eiffel installed a meteorology lab on the third floor. He also had a passion for aerodynamics and performed a series of observations on falling bodies (dedicated equipment was installed from 1903 to 1905). He then imagined “an automatic device sliding the length of a stretched cable between the second level of the Tower and the ground”. He had a small wind tunnel built at the foot of the tower. From August to December 1909 he carried out ive thousand tests. In addition, Gustave Eiffel encouraged others to perform experiments on the Tower: Foucault’s pendulum, the mercury manometer, physiology studies and radio contact (1898).

Movement of the Tower top

The Tower sways slightly in the wind. During the storm of 1999, it moved approximately 13 centimeters from its initial position. But the Tower is also affected by heat. When the temperature is high, that portion of the structure exposed to the sun expands more than the portion in the shade. To “get out of the sun”, the Tower can lean as much as 18 centimeters.

Gazing through fog
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