In 1906, while many aviators in Europe were developing flyers, and cautiously testing them in various ways, by gliding above sand or water, or swinging from a high wire or traveling arm, Señor Alberto Santos-Dumont, of Brazil, brought forth in France the quaint and crude biplane shown in Plate XXII. Aërodynamically this was not a great improvement on the aëroplane of Sir George Cayley constructed 98 years earlier; but it had a petrol motor whose power and lightness would have astounded that talented pioneer in aviation. The motor was an eight-cylinder Antoinette, weighing 170 pounds and developing 50 horse power. The screw, formed of two aluminum blades, was of two meters diameter, one meter pitch, mounted on the engine shaft, and, at 1,500 revolutions a minute, gave a thrust of 330 pounds. The total lifting surface of the aëroplane was 650 square feet, and the weight, including pilot, 645 pounds. This bird-shaped craft ran tail foremost through the air, having the screw at the rear, and the rider in a small basket just before the wings. By means of a pilot-wheel and lever, he could operate the “tail,” i. e., the front rudder, sidewise and vertically, thus steering the craft in two directions. The lateral balance was preserved automatically by means of the dihedral inclination of the wings, aided sometimes by the rider swaying his weight to right or left. After some days of preliminary adjustment and trial, Santos-Dumont was ready for a dash in his new aëromobile. On August 22d, 1906, he made a brief tentative flight, the first witnessed in Europe since Ader’s surreptitious experiment. On October 23d, he ran this strange machine swiftly over the ground and glided boldly into the air, flying above the excited spectators at a speed of 25 miles an hour, and covering a distance of 200 feet, thus gaining the Archdeacon cup. Again on November 12th, 1906, he made four flights, the last one covering 220 meters in twenty-one seconds, thus gaining the prize of 1,500 francs offered by the Aëro Club of France for the first person who should fly 100 meters. The demonstration was made before the general public and technical witnesses, including an official committee of the Aëro Club of France, who reported that the aëroplane preserved good balance and a true soaring speed independent of the acquired momentum.