A MUSICAL FORK

If you pick one of the teeth of a fork^* with a knife, as shown, you will hear nothing. But if you press at once the end of the fork against a table, you will hear a musical noise. You may show this trick to your friends after dinner. But you must practise it first. You must pick one of the teeth of the fork, then hold the knife over an empty drinking glass. When the knife is over the glass, you move your other hand so that the end of the fork touches the table. Your friends must not notice it. They will look at the knife and think that the noise is coming from the glass. But when they try the trick, it won't work, because the noise comes from the table. Scientists call the noise "sympathetic vibration".^*

^*  pick one of the teeth of a fork — заденете один из зубьев вилки

^*  "sympathetic vibration" — ответная вибрация

MUSIC FROM A COAT-HANGER ^*

Do you know that you can hear musical noises from a coathanger? If you want to hear them, you must tie a metal coat-hanger to the centre of a piece of rope a metre and a half long, as shown in the picture. Now you understand what you must do next. You tie one end of the rope three or four times round your left finger, then the other end the same way round your right finger, and put the ends of your fingers into your ears. Now you come up to a chair and allow the coat-hanger to strike against it. You will hear with surprise some beautiful music, like the music of a large bell or of an old clock. You hear the music because the coat-hanger vibrates. The rope and your fingers bring the sound waves^* to your ears.

^* Music from a Coat-hanger — Музыку создает вeшалка (для платья)

^* the sound waves — звуковые волны

A MUSICAL GLASS OF WATER

Ask your friend if he can use a glass of water as a musical instrument. Of course, he can't. Then you take a glass of water. (Thin glasses work best.) You put your finger in the water and then move it slowly round the rim of the glass, as shown in the picture. Your finger must not be very wet, but it must not be dry. So you must try many times. At last you will hear clear music which comes from the glass. When your finger moves round the rim, it makes the glass vibrate and the glass makes a musical noise. The same principle makes the violin and its strings give music. The American scientist Benjamin Franklin made a musical instrument out of glass bowls. He used the same principle. He called his musical instrument an "armonica".