sonants.  In  the  former  series  there  is  no  sound  while  the
organs  of  speech  are  closed ;  in  the  latter  there  is,  even  during
the  continuance  of  the  closure,  a  tone  produced  by  the  vibration
of  the  vocal  chords.  Herein  lies  the  fundamental  distinction
of  *  surd '  and  '  sonant '  sounds.  The  former  are  produced  by
unintonated  breath ;  the  latter  by  intonated  breath.  Surd
sounds  have  sometimes  been  called  by  other  names,  as  '  strong,'
*  hard,'  '  sharp' ;  and  sonant  sounds  have  been  called  by  other
corresponding  names,  as  '  weak,'  '  soft,'  '  flat ' ;  but  these  names
should  be  rejected,  and  the  terms  *  surd  '  and  '  sonant '  should
be  employed,  because  they  express  the  true  distinction.  In
Greek  and  Latin  the  surd  aspirated  mutes  are  often,  and
with  sufficient  propriety,  called  simply  aspirates.  Next  to
the  mutes  come  the  fricatives,  divided  into  two  sub-classes,
spirants  and  sibilants.  Then  come  the  nasals  (sometimes
called  resonants).
Beginning  now  at  the  other  extreme  with  the  open  vowel  a,
we  form  by  successive  degrees  of  approach  of  the  tongue  to  the
palate  the  series  of  palatal  sounds  represented  in  the  scheme  by
a,  05,  e,  i.  By  contraction  with  the  lips,  we  form  the  labial  series
represented  by  a,  JL,  o,  u.  The  semivowels  stand  nearly  on
the  dividing  line  between  vowels  and  consonants.  The  closest
of  the  vowels  are  i  and  u.  By  abbreviating  their  sounds  suffi-
ciently before  another  vowel-sound,  we  should  change  them
into  the  consonantal  sounds  of  3/  and  w.  With  them  belong
r  and  I,  which  are  in  many  languages  used  also  as  vowels.
