Inside, carefully wrapped in shock-absorbing tissue, was a fragile contrivance of many tubes and wires, and a tiny parabolic mirror. It had a brand new Elecorp 210 volt battery, and it needed every volt of that tremendous power. Tate made the connections, his hands trembling slightly, and set it up on a telescoping tripod. Syme watched him closely, his big body tensed with expectation.
The field was before them, shimmering faintly in the starlight. It looked unsubstantial as the stuff of dreams, but both men knew that no power man possessed, unless it was the thing Tate held, could penetrate that screen.
Tate set the mechanism up close to the field, aimed it very delicately, and closed a minute switch. After a long second, he opened it again.
Nothing happened.
The screen was still there, as unsubstantial and as solid as ever. There was no change.
Tate looked worriedly at his wiring, a deep wrinkle appearing between his pale, serious eyes. Syme stood stock-still but quivering with repressed energy, scowling like a thundercloud.
"It must be capable of working," Tate told himself querulously. "The Martians knew—they wouldn't have tried to stop us if—Wait a minute." He paced back and forth, biting his lip. Syme watched him with catlike eyes, clenching and unclenching his great fists.
Tate paused. "I think I have it," he said slowly. "I haven't enough power to hetrodyne the whole screen, although that's theoretically possible. But there must be weaker portions of the field—doors—set to open on the impact of a beam like this one. But I've only got power enough for two more tries. Jones, where would you put an entrance, if you'd built Kal-Jmar?"
Syme's eyes widened, and he stared around slowly. "A thousand years ago?" he muttered. "Two thousand? These hills were raised in five hundred. We can't go by topography.