are  formed  in  the  Doric  mode,  if  lonic,  in  the  lonic  mode,  as  explained  in  the  description
of  portals  in  the  fourth  book.  The  breadth  of  the  light  of  the  impluvium  is  left  not  less  than
the  fourth,  nor  more  than  the  third  part  of  the  breadth  of  the  atrium;  the  length  is  such  as
the  proportion  of  the  atrium  may  occasion.
The  peristylium  is,  transversely,  a  third  part  longer  than  it  is  inwardly:  the  columns
are  as  high  as  the  porticus  is  broad;  the  intercolumns  of  the  peristyle  are  not  less  than  three,
nor  more  than  four  times  the  thickness  of  the  columns:  but  if  the  columns  of  the  peristyle
shall  be  in  the  Doric  mode,  modules  must  be  used,  as  mentioned  in  the  description  of  the
Doric  mode  at  the  fourth  book,  that  by  those  modules  the  distribution  of  the  triglyphs  may
be  properly  adjusted.

CHAPTER  V.
Of  the  Triclinium,  Œcus,  Exedra,  and  Pinacotheca.
WHATEVER  the  breadth  of  a  triclinium  may  be,  twice  so  much  should  be  the  length.
The  height  of  all  rooms  that  are  oblong  should  be  thus  regulated:  the  meafures  of  the
length  and  breadth  are  to  be  united,  and  the  half  of  that  sum,  whatever  it  may  be,  is  to  be

(6*)  The  impluvium,  from  this  passage,  and  from  the
words  of  Varro  (quoted  in  the  3d  note  of  chap.  3,  of
this  book),  we  may  conclude  was  the  opening  in  the
ceiling  or  roof  of  the  atrium,  through  which  the  light  was
admitted.  Nardini,  page  136,  and  some  other  authors,
have  supposed  it  was  the  court-yard  itself.
((75)  The  peristylium  was  a  large  area  surrounded  by
a  columnade,  as  we  learn  from  the  11th  chap.  of  the  sth
book.  Galiani  adds,  that  the  master's  apartments  were
disposed  around  it;  and  he  has  in  his  plan  so  dispoled
them:  but  in  the  third  chapter  foregoing  it  is  said  that

BO  O
K.

the  tricliniums  (which  were  the  master's  apartments)  received -
  their  light  from  the  cavaedium,  and  consequently
they  must  sometimes  at  least  have  been  disposed  around
the  cavaedium.
(15)  The  triclinium  or  triclinia  (as  at  the  8th  chap.
following)  was  the  dining  room;  the  word  is  sometimes
used  for  the  dining  table,  and  furrounding  couches  on
which  they  lay  to  eat  (see  chap.  6).  The  term  is  faid  to
have  arisen  from  there  being  usually  three  couches  on  the
three  sides  of  the  table,  the  fourth  side  being  left  for  the
attendance  of  the  servants.