The structural design of the Fabre monoplane was novel and unique, not to say radical. The wing framing consisted of a single Fabre trussed beam with ribs attached like the quills of a bird, over which was stretched the light sailcloth cover, then laced to the beam. The girder itself was formed of two ash planks eight inches wide by one-fourth inch thick trussed together by flat steel plates zigzagging trelliswise between them. As all parts of the beam cut the air edgewise it offered very little resistance, while at the same time being very strong. The ribs being attached only at one end allowed the sailcloth to be quickly slipped on and off for washing and proper care. The characteristic features of Fabre’s wing construction were adopted by Paulhan in his novel and picturesque biplane shown in Plate XXXI. Trussed beams were used for all parts requiring considerable stiffness, the longitudinal ones being covered with fabric to reduce the resistance. The wings whose solid ribs were fastened only at their front ends were quite elastic, a quality conducive to stability, as long taught by writers[55] on aviation. In addition to the front rudder, there was at the rear a horizontal rudder with a vertical one just before it. To reduce the air resistance further the pilot and passenger were to sit tandem in a torpedo-shaped car with the 50-horse Gnome engine and fuel tank back of them. Beneath the longitudinal girders were two Farman skids flanked with the usual wheels, elastically connected. The machine, besides flying well, was readily demountable. The wings could be quickly removed, thus allowing the biplane to enter a door fifteen feet wide. The entire machine could be packed in a case 15½ feet long by 3¼ feet square, the whole case cubing less than six solid yards. Hundreds of them, therefore, could be stowed away in an ocean cruiser. The flying quality of adequately designed flexible aëroplanes is well illustrated by the swallowlike monoplane shown in Fig. 43. This airy creation of the distinguished Austrian engineer, Igo Etrich, came into public prominence in the spring of 1910, though it had been developing privately for half a decade or more. On May 14th, near Vienna, it carried pilot Illner 84 kilometers in 80 minutes, at an elevation of 300 meters, thus surpassing all previous Austrian records for distance, duration and altitude. Its successor, _Etrich IV_, had wing tips still more turned up, and possessed such stability that during the meet at Johannisthal in October, Illner circled the pylons with his hands off the warping levers. At times he wheeled round curves of only ten meters radius, the whole machine tilted at an alarming angle, yet maintaining its poise with the natural ease and grace of a soaring albatross.