Barbara Plaza, age 11' of Somerville, Mass., for her question

  How can a bat fly in the dark?

Thousands of bats can mill around a dark, crowded cave without colliding vrith each other. Experiments showed that the furry little fellows can even fly blind folded through a tangle of hanging ropes. The bat, then, does not depend upon his eyesight to guide him in flight. Further experiments showed that he uses his voice and his large leafy ears. For, with ears covered and mouth sealed, he blunders and flounders.

The bat, it seems, has his own built in radar system. It works with echoes, just as our mechanical radar screens work. In flight, the furry flier is constantly sending out twittering cries which echo back from any object in his path. The sound, however, is supersonic, too high pitched for the human ear to hear.

The echoes from the solid objects in the bat's path are caught by his big ears. Sensitive nerves send these messages to the brain and the brain sends flight information to the leathery wings. All this happens so fast that the bat can fly at full speed through a tangle of twigs or a maze of hanging ropes.

In a small fraction of a second, the bat sends out his supersonic cry, the echo from a hanging bough bounces back to his leafy ears, the ears send the message to the brain, the brain sends out flight information, the wings and tail change course to dodge the obstacle. This radar operation has been going on in the bat world for thousands of years. The little brown bat, it seems, invented this means of communication long before mankind discovered how to make a mechanical radar.

Some people are scared silly by a little bat dodging this way and that. Actually, he is nothing to fsar and he is most certainly one of our friends. While he is dodging through the dusk, he is catching insects. Nothing makes him happier than a cloud of mosquitoes   for they are among his favorite foods. He flies with mouth open, catching all he can$ and during a summer season he may devour countless numbers of pesky flies and other insects.

Long before sunrise, the bat has gone to bed. He finds a hollow tree or a shady cave and hangs upside down to wait for the dim twilight. Some people think that the little fellow is quite blind, but this is not so. His eyesight is not good in the bright light of day. But in the dim light of dusk, he can see about as well as we can. The bat is a mammal, which means that the babies are born alive and fed on mother's milk. Close up, the little animal looks rather like a flying mouse. The bones of his arms, hands and long fingers are covered with fine skin which acts like a parachute when he takes to the air.