Q. _How fast does LIGHT TRAVEL?_ A. Light would go 8 times round the whole earth, while sound is going its 13 miles. Q. _Why are SOME things SONOROUS, and others NOT?_ A. The sonorous quality of any substance depends upon its _hardness and elasticity_. Q. _Why are COPPER and IRON SONOROUS, and not LEAD?_ A. Copper and iron are _hard and elastic_; but as lead is neither hard nor yet elastic, it is _not sonorous_. Q. _Of what is BELL-METAL made?_ A. Of _copper and tin_ in the following proportions:--In every 5 pounds of bell-metal, there should be 1 lb. of tin, and 4 lbs. of copper. Q. _Why is this mixture of tin and copper used for BELL-METAL?_ A. Because it is much _harder_ and more _elastic_ than either of the pure metals. Q. _Why is the SOUND of a bell STOPPED by TOUCHING the bell with our finger?_ A. The weight of the finger _stops the vibrations_ of the bell; and as soon as the bell _ceases to vibrate_, it ceases to make sound-waves in the air. Q. _Why does a SPLIT BELL make a HOARSE disagreeable sound?_ A. The _split_ of the bell causes a _double vibration_; and as the sound-waves _clash and jar_, they impede each other's motion, and produce discordant sounds. 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 GLASSES give sounds?_ A. Because the glasses _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 BASS and some TREBLE?_ A. _Slow_ vibrations produce _bass 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 passage 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.