Rachel Carlson on Bats

Rachel Carlson writes an essay in Readers' Digest in which she talks about radar and sonar as a metaphor for the way bats fly. At the time she wrote the essay, radar, sonar, and echolocation were new technologies. These technologies provided a more accurate metaphor for the way bats fly then the metaphor of print. We know that bats don't actually have a radar device inside them, but this is the closest we can get right now to describing the way bats maneuver in the dark. Yes, it's very, VERY possible that this metaphor will change in the future with the developement of new technologies.

In the essays, she uses words that make references to radar, sonar, and echolocation. She uses words like "signals." This references directly to radar and sonar because these technologies use signals to sense objects and avoid running into them, the same way that bats use high-pitched sound waves to sense objects in front of them and avoid running into them.