And so begin that hours-long vigil of quartering the stratosphere over the unmarked area which Jeter had set as a limit. Now and again Hadley spoke to Jeter. Yes, the demolitions were still continuing in Manhattan. Could all telescopes on the ground pick out their space ship? Yes, said Hadley, and a young scientist in New Jersey was constantly watching them. Were they, since sunrise, ever out of his sight? Only when clouds at comparatively low altitudes intervened. However, the sky was unusually clear and it was hoped to keep their plane in sight during the entire day.
"Hadley," Jeter almost whispered, "I'm satisfied we're above the area of force, else we'd have flown into the anti-gravitation field. Get in touch with that Jersey chap by direct personal wire or radiophone if he is equipped with it. See that his watch is set with yours, which is synchronised with ours. Got that?"
"Yes."
"When you've done that give him these instructions: He is never to take his eyes of us for more than a split second at a time—unless someone else takes his place. I doubt if, at this distance, this will work, but it may help us a little. If we become invisible for even the briefest of moments, he is to look at his watch and observe the exact time, even to split seconds. We shall try to follow a certain plan hereafter in quartering the stratosphere, and I shall mark our location on the navigational charts every minute until we hear from this chap, or until we decide nothing is to be accomplished by this trick. Understand?"
"You're hoping that the enemy, while invisible to all eyes, yet has substance...."
"Shut up!" snapped Jeter, but he was glad that Hadley had grasped the idea. It was a slim chance, but such as it was it was worth trying. If the plane were invisible for a time, then it would be proof of some opaque obstruction between the plane and the eye of the beholder on the surface of the Earth. Refraction had to be figured, perhaps. Oh, there were many arguments against it.
The fliers followed the very outer edge of the area above the world they had mapped out as their limit of exploration. This circuit completed, they banked inward, shortening their circuit by about a mile of space. A mile, seen at a distance of ninety thousand feet, would be little indeed.
It was almost midday when they had their first stroke of luck.
The buzzer sounded at the very moment Eyer uttered an ejaculation.