After this experiment, parachute descents became popular the world over, and have been repeated up to the present time substantially without change. A slight improvement in the construction was made by cutting away the top of the canvas, thus allowing the air to escape sufficiently to check the oscillations; but no radical change in the design has come into general use. It would seem easy to have transformed the craft into a traveling parachute gliding down the sky like a great bird on out-stretched wings. Such a device would enable the aëronaut to sail some miles and direct his course in the air. If fair skill had been acquired it might have hastened the advent of human flight twenty years, so far as it is practicable without the aid of the internal combustion motor. For two decades ago Maxim produced an abundantly powerful steam engine; but could find no one to furnish him a manageable glider on which to mount it. Now, indeed, such gliders are available; but they were developed by aviators, not by balloonists, or parachutists, who should have effected that advance many years ago. Curiously enough, Nature has furnished a traveling parachute which seems never to have been imitated by man, though not difficult to copy. It is a large two-winged seed, which when dropped in any poise, immediately rights itself, and glides gracefully through the air. The seeds grow on a tree in India, bearing the name _Zanonia Macrocarpa_, and when shaken from its branches look like so many sparrows sailing earthward in wide curves. Artificial gliders of this type are easy to construct, and would make interesting toys. However, if man has not copied such natural models, he has done much better, by making his gliders concave below instead of concave upward, as are the beautiful Indian seeds. An interesting model of a traveling parachute, quite as efficient as the gauzy-winged seed, is shown in the accompanying figure. It is a sheet of paper twenty inches long by four inches wide, having a quarter inch strip of tin folded in its forward margin, and having its rear margin turned upward slightly, to steer the little craft from a too steep descent. In order to improve the stability of the paper plane, its sides may be bent upward. The model when dropped in any attitude quickly rights itself, and sails down a gently sloping course, the rear margin functioning as a rudder or tail. [Illustration: FIG. 30.—PAPER TRAVELING PARACHUTE.]