Bat Experiments
The work of Italian and Swiss scientists in the late 1700s led to remarkable discoveries. One of the men stuffed cotton material into the ears of some bats , blocking their hearing. The other put small bags over their heads. Then the bats were let loose to fly through the air. However, in both cases, the bats could not navigate properly. Over a century later, in the 1930s, a Harvard University student used microphones to study bats. The student, Donald Griffin, detected ultrasonic signals produced by bats. Ultrasonic signals are tiny signals or sound waves that the human ear cannot detect. Griffin proved that bats used the echoes from the ultrasonic signals to navigate. He came up with the term"echolocation." Through years of research into the sensory system of bats. scientists now understand how bats fly through the air. Today, there is less 50 mystery about how these unique creatures of the night navigate.