A Guide To The Scientific Knowledge Of Things Familiar - novelonlinefull.com
You’re read light novel A Guide To The Scientific Knowledge Of Things Familiar Part 91 online at NovelOnlineFull.com. Please use the follow button to get notification about the latest chapter next time when you visit NovelOnlineFull.com. Use F11 button to read novel in full-screen(PC only). Drop by anytime you want to read free – fast – latest novel. It’s great if you could leave a comment, share your opinion about the new chapters, new novel with others on the internet. We’ll do our best to bring you the finest, latest novel everyday. Enjoy
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.
Q. _Why can we HEAR distant clocks MOST distinctly in CLEAR COLD weather?_
A. Because the air is most _uniform_ then: there are not _two currents of air_ (one up and one down) to interrupt the sound-waves.
Q. _Why can persons hear the VOICES of men in conversation for a MILE distant, near the POLES, in winter time?_
A. Because the air is very _cold and very clear_; in consequence of which, there are not _two currents of air_ (one up and one down) to interrupt the sound-waves.
Captain Ross heard the voices of his men in conversation, a mile and a half from the spot where they stood.
Q. _Why are not SOUNDS (such as distant church bells) heard so distinctly on a HOT DAY as in FROSTY weather?_
A. Because there are _two currents of air_; the current of _hot_ air _ascending from the earth_, and the current of _colder_ air _falling towards_ the earth; and these two currents _break up the sound-waves_.
Q. _Why can we not hear SOUNDS (such as distant clocks) so distinctly in a thick MIST or HAZE, as in a CLEAR night?_
A. Because the mist _diminishes the velocity_ of the sound-waves, and (by overburdening them with vapour) _limits their length_.
Q. _Why do we hear SOUNDS better by NIGHT than by DAY?_
A. 1st--Night air is _more uniform_, because the ascending currents of air (raised by the action of the sun's rays) _cease_ as the evening advances; and
2ndly--Night is more _still_ from the suspension of business, and the cessation of the hum of men.
Q. _How should PARt.i.tION WALLS be made to PREVENT the voices in adjoining rooms from being HEARD?_
A. The s.p.a.ce between the laths (or canva.s.s) should be filled with _shavings or saw-dust_; and then no sound would ever pa.s.s from one room to another.
Q. _Why would SHAVINGS or saw-dust PREVENT the transmission of sound from room to room?_
A. Because there would be _several different media_ for the sound to pa.s.s through: 1st--the air;
2ndly--the laths and paper;
3rdly--the saw-dust or shavings;
4thly--the air again: and every _variety_ diminishes the _strength of the sound-waves_.
