At once the monoplane began climbing, ascending in great spirals. Frank was absorbed by the sensation. He found that he could see the ground receding without feeling any qualms, and said so.
"You're lucky," said Greene, briefly. "Made me feel queer first few times I tried it, I can tell you. You're probably a born flyer—and the chances are you'll never do much of it, I suppose! Always the way!"
Frank, looking down, saw that they were moving away from the woods which they were to reconnoitre, and mentioned it.
"Got to," said Greene, briefly. "Then we'll fly back. We can't climb in a straight line. When I went out for altitude once, I made twelve thousand feet, and when I finished climbing I was nearly fifteen miles, in a straight line, from where I started. Let's see. Got that flashlight I gave you? Play it right on the board there till I tell you to stop."
Frank obeyed, shooting the little spear of light on the various instruments in front of the aviator.
"All right. Hold it there. My barograph, you see. Gives me my height by showing the change in atmospheric pressure. That's how we calculate height. Not very exact, because all sorts of things vary the pressure. But it's near enough. A thousand feet! That's good enough. I don't believe they're looking for us. We don't usually scout behind our own lines."
Now he brought the monoplane around in a great sweep and flew straight over the woods. But, though Frank looked down through powerful navy night glasses, of the sort that are used for look-out duty at sea, he could see nothing.
"Clasp them around my head—so," said Greene. "See the trick? All right! Now I'll have a look. There's another pair in my pocket—use those for yourself."
But if the Germans were there, they were concealing their presence with a good deal of care and skill.
"Have to go lower, then," decided Greene. "Get ready! We'll shoot the chutes now."