"No. Listen closely and you'll hear any whirlybird--especially hospital ambulances--go _rackety-rackety-rack groundhog_, _rackety-rack groundhog_!--a reminder to people that they belong on the ground, one may assume. Picture a microphone attached outside the bird and wired to your transmitter. The radio waves go out in all directions through the air. Suppose your air is all of the same density, and so forth--then all the waves peter out at a constant radius and form a perfect sphere going _rackety-rackety-rack groundhog_! "Now compressed waves travel a certain number of feet--theoretically, the number of foot-pounds of work the power input could perform modified by a constant value called 'e'--and at that point they revert to ordinary radio waves. This forms a sphere of compressed or supra-short waves. Do you understand that?" "No," said Miss Knox. "Well, anyway, where two spheres overlap, you get the Barger effect. And they can vary or limit the effect in interesting ways. Just move one or both projectors so that the waves intersect each other in different phases--" "That's a fascinating way to back me into a corner of the room, Dr. Brooks. Now will you please let me look at my patient?" Mr. Barger's body convulsed and twitched, and the disordered bedclothes exposed the pink, swollen layers of his throat. Only the face slept. Miss Knox reduced the feed on the water envelope, and with her palm brushed drops of moisture from the burning, out-of-focus pink skin. The drops were sticky and warm. She wiped her hands on a piece of cotton and started to prepare the blood transfusion. "Before you get out of here," she said to Dr. Brooks, "let me thank you." "For the information? You'll only forget it." "No, for the crack about my age." Slumping his eyebrows, he went to the door and stepped through almost before it could slide open. "Wait!" she commanded in a stage whisper. He appeared, the door sliding back harmlessly against his shoulder before it changed direction. "What's so terrible?" she asked. "You talk as though that radiocompressor on the Silvertongue roof were going to destroy the American home, at the very least." "They don't just have to transmit within the factory," he said. "Suppose they wanted you arrested. Say they didn't like brunettes. Well, first they get some dame to call police and say she's going to do a strip in front of the Psychiatric Pavilion wall. Then they go across First Avenue and set up a subliminal movie sequence of some stripper in action and focus it on the wall from their car. They set up two portable wave projectors and adjust their phasing to achieve the Barger effect in that one place. Then they wait for you to pass that spot on your way to church. Very little power is required; the actual radiocompression takes place across the river."