After the debacle of the Panama Canal with Ferdinand De Lessups, Gustave Eiffel began to experiment with enterprises to prove the usefulness of his tower. He had begun to develop a passionate interest in that which, at the turn of the century, was considered avant-garde science: meteorology, radiotelegraphy and aerodynamics. In 1889, M. Eiffel began to fit the peak of the tower as an observation station to measure the speed of wind. He also encouraged several scientific experiments including Foucault's giant pendulum, a mercury barometer and the first experiment of radio transmission. In 1898, Eugene Ducretet at the Pantheon, received signals from the tower. After M. Eiffel had experimented in the field of meterology, he begun to look at the effects of wind and air resistance, the science that would later be termed aerodynamics, which has become a large part of both military and commerical aviation as well as rocket technology. Gustave Eiffel imagined an automatic device sliding along a cable that was stretched between the ground and the second floor of the Eiffel Tower. The limited capacity of the available measuring instruments, led M. Eiffel to a more sophisticated knowledge in aviation and, eventually, to wind tunnel experiments. He built a wind tunnel on the Champ de Mars, which was in use from 1909-1911. The tunnel was sufficient for lab experiments bit inadequate for the study of airplanes. However, with the help of several other engineers, Leon Rith, Lapresle, and Eiffel made over 5,000 tests in this lab. Almost all the pioneers of aviation tested in this wind tunnel.