National Geographic : 1961 Apr
One-fifth of a second later, the moth is clenched in the bat's jaws their way about. Biologists belittled, then forgot, the experiments; they were inclined to credit the bat with some sixth sense or with a highly developed sense of touch. The role of the ears was not understood, because there seemed to be nothing for the bat to hear. But in 1938 Donald Griffin, then an under graduate at Harvard, showed with electronic equipment that bats emit short ultrasonic cries and guide themselves by means of the echoes. Since then, tests for the U. S. Navy have shown that porpoises are skilled at echoloca tion. Cornell University experiments have proved that even humans sense obstructions by means of echoes-the blind more expertly than those who can see. So, too, modern man-made echo sounders detect submarines, schools of fish, and sea mounts. But the bat's sonar is much more discriminating than these instruments. In lab oratory tests, bats have successfully dodged hanging wires only a few times thicker than a human hair.