The helicopter went down like a stone. A propeller shrieked away into space. Metalwork up aloft glowed dully red. Then there were whipping, lashing branches closing swiftly all around the helicopter. A jerk. A crash. Stillness. The smell of growing things all about. "Well?" said the 'copter pilot. "They turned it on us--whatever it is," said Sergeant Walpole. "They near got us, too." * * * * * A match scratched. A cigarette glowed. The Sergeant fumbled for a smoke for himself. "I'm waiting for that metal to cool off," said the helicopter pilot. "Maybe we can take off again. They located us with a loop while I was sending your stuff. Damn! I see what they've got!" "What?" "A way of transmitting real power in a radio beam," said the 'copter man. "You've seen eddy-current stoves. Everybody cooks with 'em nowadays. A coil with a high-frequency current. You can stick your hand in it and nothing happens. But you stick an iron pan down in the coil and it gets hot and cooks things. Hysteresis. The same thing that used to make transformer-cores get hot. The same thing happens near any beam transmitter, only you have to measure the heating effect with a thermo-couple. The iron absorbs the radio waves and gets hot. The chaps in the Wabbly can probably put ten thousand horsepower in a damned beam. We can't. But any iron in the way will get hot. It blows up a ship at once. Your monocycle and your rifle too. Damn!" He knocked the ash off his cigarette. "Scientific, those chaps. I'll see if that metal's cool." Something whined overhead, rising swiftly to a shriek as it descended. Sergeant Walpole cowered, with his hands to his ears. But it was not an earth-shaking concussion. It was an explosion, yes, but subtly different from the rending snap of hexynitrate. "Gas," said the Sergeant dully, and fumbled for his mask. "No good," said the 'copter man briefly. "Vesicatory. Smell it? I guess they've got us. No sag-suits. Not even sag-paste." The Sergeant lit a match. The flame bent a little from the vertical. "There's a wind. We got a chance." "Get going, then," said the 'copter man. "Run upwind." * * * * * Sergeant Walpole slid over the side and ran. A hundred yards. Two hundred. Pine-woods have little undergrowth. He heard the helicopter's engines start. The ship tried to lift. He redoubled his speed. Presently he broke out into open ploughed land. In the starlight he saw a barn, and he raced toward that. Someone else plunged out of the woods toward him. The helicopter-engine was still roaring faintly in the distance. Then a thin whine came down from aloft.... When the echoes of the explosion died away the pilot was grinning queerly. The helicopter's engine was still. "I said it could be done! Pack of fat-heads at Headquarters!" "Huh?"