"Stop your ears!" snapped Thorn.
The racking concussion-wave of hexynitrate will break human eardrums at an incredible distance. But no sound came, though the seconds went by.... Then, two miles away, there was a second gigantic flash.... Then a third.... But there was no sound at all. The quiet of the hills remained unbroken, though Thorn knew that such cataclysmic detonations should be audible at twenty miles or more. Then lights flashed on above. Two—three—six of them. They wavered all about, darting here and there.... Then one of the flying searchlights vanished utterly in a fourth terrific flash of green.
"The watch planes are going up!" said Thorn dazedly. "Blowing up! And we can't hear the explosions!"
Behind him the G.C. speaker barked his call. He raced to get its message.
"The Watch planes we sent to join you," said a curt voice he recognized as that of the Commanding General of the United Nations, "have located an invisible barrier by their sonic altimeters. Four of them seem to have rammed it and exploded without destroying it. What have you to report?"
"I've seen the flashes, sir," said Thorn unsteadily, "but they made no noise. And there's no wind, sir. Not a breath since the blue flash I reported."
A pause.
"Your statement bears out their report," said the G.C. speaker harshly. "The barrier seems to be hemispherical. No such barrier is known on Earth. These must be Martians, as the Com-Pubs said. You will wait until morning and try to make peaceful contact with them. This barrier may be merely a precaution on their part. You will try to convince them that we wish to be friendly."
"I don't believe they're Martians, sir—"