He also learned that the convex outside curve of wings allowed the wind to escape over them, while the under side, being concave, held every breath. Thus the upward stroke did not simply counterbalance the downward and keep him stationary. Moreover, she showed him how the feathers underlapped each other so that the downward stroke pressed them closely together to hold the wind, whereas in the upward stroke they opened and separated, letting the air slip easily through them, thus offering less resistance to the atmosphere. By the end of a week Jimbo had practised so hard that he could keep himself off the floor in mid-air for half an hour at a time, and even then without feeling any great fatigue. His excitement became intense; and, meanwhile, in his body on the nursery bed, though he did not know it, the fever was reaching its crisis. He could think of nothing else but the joys of flying, and what the first, awful plunge would be like, and when Miss Lake came up to him one afternoon and whispered something in his ear, he was so wildly happy that he hugged her for several minutes without the slightest coaxing. "It's bright and clear," she explained, "and Fright will not come after us, for he fears the light, and can only fly on dark and gloomy nights." "So we can start----?" he stammered joyfully. "To-night," she answered, "for our first practice-flight." CHAPTER X THE PLUNGE To enter the world of wings is to enter a new state of existence. The apparent loss of weight; the ability to attain full speed in a few seconds, and to stop suddenly in a headlong rush without fear of collapse; the power to steer instantly in any direction by merely changing the angle of the body; the altered and enormous view of the green world below--looking down upon forests, seas and clouds; the easy voluptuous rhythm of rising and falling in long, swinging undulations; and a hundred other things that simply defy description and can be appreciated only by actual experience, these are some of the delights of the new world of wings and flying. And the fearful joy of very high speed, especially when the exhilaration of escape is added to it, means a condition little short of real ecstasy. Yet Jimbo's first flight, the governess had been careful to tell him, could not be the flight of final escape; for, even if the wings proved equal to a prolonged effort, escape was impossible until there was somewhere safe to escape to. So it was understood that the practice flights might be long, or might be short; the important thing, meanwhile, was to learn to fly as well as possible. For skilled flying is very different to mere headlong rushing, and both courage and perseverance are necessary to acquire it.