The  Wilson  Producer. — This  is  the  best  known  and  most
widely  used  of  all  the  solid-bottom  producers.  It  was
patented  by  Messrs.  Brook  &  Wilson  in  1876.  The
original  producer  was  square,  but  as  now  used  it  is  always
circular.  It  consists  of  a  shell  of  firebrick  cased
with  iron  (Fig.  14),  the  internal  diameter  being
usually  about  8ft.  The  air  and  steam  are  supplied
by  a  blower  into  a  conical  tube  which  opens  into  a
brick  passage  running  across  the  producer  and  com-
municating with  the  interior  by  a  series  of  rectangular
openings.  On  each  side  of  this  air  passage  is  a
cleaning  door  for  the  removal  of  the  ashes,  and  narrow
doors  are  placed  a  little  above  the  level  of  the  air
passage,  so  that  a  line  joining  them  is  at  right  angles  to
it.  Clinker  can  be  allowed  to  accumulate  to  any  height
that  may  be  desired,  and  the  air  and  steam  passing
through  this  on  its  way  upward  becomes  hot.  The  air
and  steam,  as  will  be  seen,  are  delivered  into  the  centre
of  the  contents  of  the  producer,  and  combustioi-i  is  very
perfect.  The  maximum  size  which  such  a  producer  can
be  made  depends  on  the  power  of  the  air  to  reach  the
circumference,  as,  should  it  fail  to  do  so,  fuel  would  escape
combustion  and  would  be  lost  in  the  ashes.  These
producers  are  made  up  to  12ft.  in  diameter,  and  a  con-
sumption of  401bs.  of  fuel  per  square  foot  of  bottom  can
be  obtained.  The  gas  is  also  usually  richer  than  that
made  in  bar-bottom  producers.
