CHAPTER  III.
OF  BRICKS.
1  SHALL  first  treat  of  bricks,  and  the  earth  of  which  they
ought  to  be  made.  Gravelly,  pebbly,  and  sandy  clay  are
unfit  for  that  purpose  ;  for  if  made  of  either  of  these
sorts  of  earth,  they  are  not  only  too  ponderous,  but  walls
built  of  them,  when  exposed  to  the  rain,  moulder  away,
and  are  soon  decomposed,  and  the  straw,  also,  with  which
they  are  mixed,  will  not  sufficiently  bind  the  earth  together, -
  because  of  its  rough  quality.  They  should  be  made
of  earth  of  a  red  or  white  chalky,  or  a  strong  sandy  nature. -
  These  sorts  of  earth  are  ductile  and  cohesive,
and  not  being  heavy,  bricks  made  of  them  are  more
easily  handled  in  carrying  up  the  work.  The  proper
seasons  for  brick-making  are  the  spring  and  autumn,
because  they  then  dry  more  equably.  Those  made  in
the  summer  solstice  are  defective,  because  the  heat  of  the
sun  soon  imparts  to  their  external  surfaces  an  appearance
of  sufficient  dryness,  whilst  the  internal  parts  of  them  are
in  a  very  different  state;  hence,  when  thoroughly  dry,
they  shrink  and  break  those  parts  which  were  dry  in  the
first  instance;  and  thus  broken,  their  strength  is  gone.
Those  are  best  that  have  been  made  at  least  two  years;
for  in  a  period  less  than  that  they  will  not  dry  thoroughly.
When  plastering  is  laid  and  set  hard  on  bricks  which  are
not  perfectly  dry,  the  bricks,  which  will  naturally  shrink,
and  consequently  occupy  a  less  space  than  the  plastering, -
  will  thus  leave  the  latter  to  stand  of  itself.  From  its