Sound-waves  chase  one  another  up  and  down  through
the  air,  superposed  in  entangled  pulsations,  yet  a  cyl-
inder not  larger  than  a  quill  conveys  them  to  the
ear,  and  each  string  of  that  wonderful  harp  selects
its  appropriate  sound,  and  repeats  the  music  to  the
soul.  Though  a  thousand  instruments  be  played  at
once,  there  is  no  confusion,  but  each  is  heard,  and
all  blend  in  harmony,  f

*  To  this,  however,  there  are  remarkable  exceptions.  The  author  knows
a  lady  who  is  insensible  to  the  higher  tones  of  the  voice,  but  acutely  sensi-
tive to  the  lower  ones.  Thus,  on  one  occasion,  being  in  a  distant  room,  she
did  not  notice  the  ringing  of  the  bell  announcing  dinner,  but  heard  the
noise  the  bell  made  when  returned  to  its  place  on  the  shelf.  v

t  "Is  not  the  ear  the  most  perfect  sense?  A  needle-woman  will  distin-
guish by  the  sound  whether  it  is  silk  or  cotton  that  is  torn.  Blind  people
recognize  the  age  of  persons  by  their  voices.  An  architect,  comparing  the
length  of  two  lines  separated  from  each  other,  if  he  estimate  within  ^,  we
deem  very  accurate ;  but  a  musician  would  not  be  considered  very  precise
who  estimated  within  a  quarter  of  a  note  (128  -4-  30  =  4  nearly).  In  a  large
orchestra,  the  leader  will  distinguish  each  note  of  each  instrument.  We
recognize  an  old-time  friend  by  the  sound  of  his  voice,  when  the  other
senses  utterly  fail  to  recall  him.  The  musician  carries  in  his  ear  the  idea
of  the  musical  key  and  every  tone  in  the  scale,  though  he  is  constantly
hearing  a  multitude  of  sounds,"


184  ACOUSTICS.
'   PRACTICAL     QUESTIONS.
