﻿660 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  used, 
  but 
  each 
  pit 
  in 
  this 
  case 
  holds 
  enough 
  material 
  for 
  the 
  daily 
  

   use 
  of 
  two 
  machines. 
  

  

  Pug 
  mill. 
  This 
  machine, 
  like 
  the 
  ring 
  pit 
  just 
  described, 
  is 
  used 
  

   for 
  thoroughly 
  mixing 
  the 
  clay, 
  or 
  clay 
  and 
  sand 
  as 
  the 
  case 
  may 
  

   be, 
  before 
  introducing 
  it 
  into 
  the 
  machine. 
  It 
  consists 
  essentially 
  

   o'f 
  a 
  semi-cylindric 
  trough, 
  6 
  to 
  10 
  feet 
  long, 
  in 
  which 
  revolves 
  

   a 
  shaft, 
  beiaring 
  knives 
  set 
  spirally 
  around 
  it, 
  or 
  a 
  worm 
  screw 
  6 
  

   or 
  more 
  inches 
  wide. 
  The 
  material 
  is 
  put 
  in 
  at 
  one 
  end, 
  and 
  the 
  

   knives 
  or 
  thread 
  mix 
  it 
  up. 
  At 
  the 
  same 
  time 
  it 
  is 
  worked 
  along 
  

   to 
  the 
  other 
  end 
  of 
  the 
  trough, 
  from 
  which 
  it 
  is 
  discharged 
  into 
  the 
  

   machine. 
  The 
  pug 
  mill 
  may 
  be 
  closed 
  or 
  open 
  ; 
  the 
  former 
  is 
  better 
  

   as 
  there 
  is 
  a 
  more 
  uniform 
  pressure 
  on 
  the 
  clay 
  while 
  it 
  is 
  being 
  

   tempered, 
  and 
  a 
  more 
  thorough 
  mixing 
  results. 
  Water 
  is 
  also 
  added 
  

   from 
  a 
  faucet 
  at 
  the 
  upper 
  end 
  of 
  the 
  trough 
  till 
  the 
  clay 
  is 
  in 
  the 
  

   right 
  condition. 
  The 
  angle 
  of 
  the 
  knives 
  with 
  relation 
  to 
  the 
  shaft 
  

   can 
  be 
  changed 
  so 
  that 
  the 
  clay 
  can 
  be 
  moved 
  along 
  slower 
  or 
  

   faster 
  as 
  desired. 
  The 
  trough 
  of 
  the 
  pug 
  mill 
  is 
  of 
  iron 
  or 
  wood, 
  

   usually 
  the 
  former. 
  A 
  pug 
  mill, 
  according 
  to 
  its 
  size, 
  will 
  in 
  10 
  

   hours 
  temper 
  clay 
  enough 
  for 
  from 
  25,000' 
  to 
  60,000> 
  brick. 
  Pug 
  

   mills 
  take 
  up 
  less 
  room 
  than 
  ring 
  pits 
  and 
  do 
  not 
  require 
  as 
  much 
  

   power 
  to 
  operate 
  them. 
  They 
  will 
  also, 
  if 
  desired, 
  discharge 
  the 
  

   clay 
  directly 
  into 
  the 
  molding 
  machine. 
  They 
  are 
  used 
  chiefly 
  with 
  

   stiff 
  mud 
  machines. 
  

  

  In 
  some 
  works 
  a 
  double 
  form 
  of 
  pug 
  mill 
  is 
  used. 
  This 
  has 
  two 
  

   axles 
  bearing 
  knives, 
  instead 
  of 
  one. 
  They 
  revolve 
  in 
  opposite 
  di- 
  

   rections, 
  (pi. 
  106^^) 
  

  

  Screens 
  

  

  "When 
  clay 
  is 
  molded 
  in 
  the 
  dry 
  condition, 
  or 
  when 
  shale 
  is 
  used 
  

   instead 
  of 
  soft, 
  plastic 
  clay, 
  it 
  is 
  important 
  that 
  the 
  material 
  be 
  first 
  

   ground 
  to 
  the 
  proper 
  degree 
  of 
  fineness. 
  

  

  As 
  the 
  material 
  comes 
  from 
  the 
  dry 
  pan 
  or 
  other 
  apparatus 
  used 
  

   to 
  pulverize 
  it, 
  it 
  is 
  carried 
  to 
  screens, 
  which 
  allow 
  the 
  sufficiently 
  

   fine 
  material 
  to 
  pass 
  through 
  while 
  those 
  particles 
  which 
  are 
  too 
  

   coarse 
  go 
  back 
  to 
  the 
  crushing 
  machine. 
  

  

  Three 
  general 
  types 
  of 
  machine 
  are 
  used, 
  inclined, 
  rotary, 
  and 
  

  

  