456 
A  KEW  PLASTER-SPREADING  APPARATUS. 
"cheeks  "  (ad)  placed  at  right  angles  with  the  bottom.  These 
cheeks  form  the  ends  of  the  trough.  The  interior  of  each  has 
two  grooves  in  which  two  wrought-iron  plates  (5  and  e)  fit  so  as 
to  allow  of  their  being  raised  or  lowered  as  required.  The 
grooves  of  the  back  plate  [c)  are  at  an  angle  of  60°  with  the 
bottom,  and  in  them  the  plate  wwks  of  its  own  free  gravity. 
The  grooves  of  the  front  plate  {h)  are  at  an  angle  of  75°. 
The  "  play  "  of  this  plate  is  regulated  as  will  be  described.  The 
edges  of  the  plates  at  the  bottom  where  they  press  upon  the 
cloth  are  slightly  bevelled.  These  two  plates  and  the  cheeks 
above  mentioned  form  the  sides  and  ends  of  the  trough ;  the 
cloth  (d)  forms  the  bottom,  as  it  passes  through  over  an  iron 
support  {e).  This  support  is  in  the  shape  of  the  section  of  a 
wedge,  the  acute  end  of  which  is  terminated  by  an  arc.  The 
arc  forms  its  upper  surface  over  which  the  cloth  is  drawn ;  the 
support,  as  is  shown  in  the  figure,  projects  a  little  through  each 
cheek,  and  is  fitted  accurately  into  its  position  by  two  keys 
placed  under  it,  and  resting  on  the  cheeks,  the  borings  through 
which  correspond  with  its  wedge-shape.  It  is  covered  with 
fustian,  which  gives  it  a  yielding  surface  for  the  iron  plates  to 
press  the  cloth  against  whilst  being  drawn  through.  By  these 
arrangements  leakage  from  the  trough  is  entirely  prevented. 
The  play  of  the  front  plate  (5),  as  has  been  stated,  requires 
regulating  for  different  plasters,  and  when  they  are  required  to 
be  spread  of  difierent  degrees  of  thickness ;  this  is  done  by 
means  of  two  screws  (//)  working  in  nuts  [gg)  which  are  riveted 
to  the  plate  ;  the  heads  {lih)  of  these  screws  work  against  thread- 
less  nuts  [U)  attached  to  the  cheeks  {aa).  By  screwing  or  un- 
screwing these,  the  plate  can  be  adjusted  to  spread  any  thick- 
ness of  plaster.  It  will  be  observed  that  the  screws  can  prevent 
the  plate  falling  below  any  given  depth,  yet  allow  it  to  be  raised 
to  permit  any  inequality  in  the  cloth,  etc.,  to  pass  under  it  and 
again  to  resume  its  position.  To  assist  it  to  do  this,  two  levers 
{kh\  with  moveable  weights  [11)  attached,  press  upon  the  heads 
(Jih)  of  the  screws,  and  indirectly  the  pressure  is  exerted  upon 
the  plate,  or  the  nuts  (zV).  For  common  strapping  and  plasters, 
which  require  to  be  thinly  spread,  the  bolts  are  unscrewed  so 
far  that  the  heads  of  the  screws  do  not  rest  on  the  threadless 
