Part 91 (1/2)
Q. _Why does a FIDDLE-STRING give a musical sound?_
A. The bow drawn across the string _causes it to vibrate_, and this vibration of the string _sets in motion the sound-waves of the air_, and produces musical notes.
Q. _Why does a DRUM sound?_
A. The parchment head of the drum _vibrates_ from the blow of the drum-stick, and sets in motion the sound-waves of the air.
Q. _Why do MUSICAL GLa.s.sES give sounds?_
A. Because the gla.s.ses _vibrate_ as soon as they are struck, and set in motion the sound-waves of the air.
Q. _Why do FLUTES, &c. produce musical sounds?_
A. The breath of the performer causes the _air in the flute to vibrate_, and sets in motion the sound-waves of the air.
Q. _Why do PIANO-FORTES produce musical sounds?_
A. The _keys of the piano_ (being struck with the finger) lift up a little hammer which _knocks against a string_; and the vibration thus produced, sets in motion the sound-waves of the air.
Q. _Why are SOME notes Ba.s.s and some TREBLE?_
A. _Slow_ vibrations produce _ba.s.s or deep sounds_; whereas, _quick_ vibrations produce _shrill or treble sounds_.
Q. _Why is an instrument FLAT when the STRINGS are UNSTRUNG?_
A. Because the vibrations are _too slow_; in consequence of which, the sounds produced are not _shrill_ or _sharp_ enough.
Q. _Why can persons living a mile or two from_
_a town HEAR the BELLS of the town-church SOME TIMES, and not at OTHERS?_
A. Fogs, rain, and snow, obstruct the pa.s.sage of sound; but when the air is _cold and clear_, sound is propagated more easily.
Q. _Why can we NOT hear sounds (as distant church bells) in RAINY weather, so well as in FINE weather?_
A. Because the falling rain _interferes with the undulations of the sound-waves_, and breaks them up.
Q. _Why can we not hear sounds (as distant church bells) in SNOWY weather, so well as in FINE weather?_
A. Because the falling snow _interferes with the undulations of the sound-waves_, and stops their progress.