In his time an electrical and mechanical genius, the engineer Ader innovated in a number of domains. He originally studied electrical engineering, and in 1878 improved the telephone, recently invented by Alexander Graham Bell. He refined the invention and established the first telephone network in Paris in 1880. In 1881, he invented the theater-phone, a system of telephonic transmisssion where two channels allowed binaural hearing and gave listeners an exact idea of the respective positions of the actors on a set; it was this invention which gave the first transmission in stereo of the spectacles of the Opera, over a distance of 2 miles (1881).
Following this he turned towards mechanical flight, and here concentrated, until the end of his life, all of his time and money. Using the studies of Louis Mouillard (1834-1837) on the flight of birds, he constructed his first flying machine in 1886, the Éole, a bat-like design run by a lightweight steam engine of his own invention (4 cylinders developing 20 horsepower, the weight no more than 7 pounds per horsepower) and driving a four-blade propeller. The wings, with a span of 14 yards, were equipped with a system of warping and all together weighed 650 pounds. Witnesses claimed to have seen it fly a short distance, but it was wrecked in the attempt.
In August 1890, a second version of the Éole was built, on October 9 at Armainvilliers (Seine-et-Marne), before witnesses, the airplane managed to take off into the sky flying a distance of more than 40 yards. This modest leap would be followed by others, often unfruitful. In August 1892, the Éole II accomplished a feat of 200 yards at a field in Satory, and managed to excite the interest of the minister of war Freycinet.
Ader then constructed Éole III which he baptised with a name destined for good luck: the Avion, a term showing up for the first time in his patent. The Avion was like an enormous bat of linen and wood, of 16 yards in wingspan, equipped with two puller propellers of four blades, each powered by a steam engine of 30 hp. On October 14, 1897, at Satory, the Avion rolled, took off towards the sky and, before the official commission, flew a distance of more than 300 yards, the first verified mechanical flight, and made its inventor "the father of aviation", but the meteorological conditions were bad, and Ader evidently did not have much notion of piloting; the Avion could not completely travel the circular course which the commission required, the flying machine left the runway and was damaged. At this point the French government withdrew its funding, but kept the results secret, only reporting them as successful flights after the Wright brothers made their flight.
Abandoning everything and in particular public demonstrations, the "father of aviation" died in Toulouse, in obscurity. His Avion is still displayed at the museum of the Conservatory of Arts and Industry in Paris. Aviation historians now discredit any claims of priority, since the flights all ended in crashes, but Ader was still admired for his efforts; in 1938 France issued a postage stamp honoring him.