192
whenever  it  was  required  to  prolong  the  vibrations,  or  to
increase  the  powers  of  the  voice,  the  orchestra  was  strewn
with  sand  or  saw-dust;  by  which  means  the  voice  being
directed  to  the  body  of  the  house,  the  sounds  were  carried
along  the  walls  so  long  as  there  was  no  impediment  to
obstruct  their  course.  Pliny  in  describing  this  mode  of
building,  might  have  had  our  author  in  view;  whose  mention
of  vases  received  a  degree  of  confirmation  from  the  fact  that
earthen  vessels  were  sometimes  inserted  in  the  masonry  of
ancient  buildings.  An  instance  in  which  this  practice  has  been
adopted,  occurs  in  the  circus  of  Caracalla.  Vases  are  found
regularly  distributed  in  the  stone-work  above  the  crown  of
the  arches  which  were  constructed  for  the  purpose  of  giving
a  proper  degree  of  elevation  to  the  seats  of  the  spectators.
The  object  of  their  introduction  seems  to  have  been  the
diminution  of  weight.  Vitruvius  confesses  that  there  was
no  theatre  at  Rome  which  had  vases  for  such  a  purpose;
although  he  states  them  to  have  been  in  use  in  the  provinces
of  Italy,  and  in  most  of  the  cities  of  Greece.  It  is  certain,
however,  that  in  the  various  theatres  which  have  fallen
within  our  observation,  no  provision  has  been  made  for
the  reception  of  vases  in  the  situation  which  Vitruvius  assigns
to  them.
Lucius  Mummius  is  said  by  some  authors  to  have
brought  away  brazen  vases  from  the  theatre  of  Corinth.
This  fact  is  adduced  by  Vitruvius  in  corroboration  of  the
application  of  his  principle  to  practice.  But  the  purpose  to
which  these  vessels  were  previously  applied  is  not  mentioned.
Strabo  gives  an  account  of  some  Corinthian  vases  which