Eiffel Tower In 1909, a permanent underground radio centre was built near the south pillar, which still exists today. On 20 November 1913, the Paris Observatory, using the Eiffel Tower as an aerial, exchanged wireless signals with the United States Naval Observatory, which used an aerial in Arlington, Virginia. The object of the transmissions was to measure the difference in longitude between Paris and Washington, D.C. Today, radio and digital television signals are transmitted from the Eiffel Tower. A television antenna was first installed on the tower in 1957, increasing its height by 18.7 m (61.4 ft). Work carried out in 2000
Gustave Eiffel Using this Eiffel definitely established that the air resistance of a body was very closely related to the square of the airspeed. He then built a laboratory on the Champ de Mars at the foot of the tower in 1905, building his first wind tunnel there in 1909. The wind tunnel was used to investigate the characteristics of the airfoil sections used by the early pioneers of aviation such as the Wright Brothers, Gabriel Voisin and Louis Blériot. Eiffel established that the lift produced by an airfoil was the result of a reduction of air pressure above the wing rather