[The  numbers  of  these  notes  correspond  with  those  in  the  first  column  of  the  preceding  table.]

1.  Pine  and  some  hard  woods  used.  Oak  makes  the  best  charcoal  that  we  get.  The
yield  is  about  1,500  bushels  to  the  acre,  and  20,000  acres  are  sufficient  for  a  permanent
supply.  Lauds  cut  over  are  reserved  for  growing  another  crop,  and  the  furnace  now
has  4,000  acres  of  young  trees.  When  8  years  old  they  should  be  thinned  out,  getting
10  per  cent,  and  leaving  the  rest  in  better  condition  for  growing.  Some  attempts  have
been  made  at  planting  black  walnuts  around  pasture-fields,  but  to  no  great  extent.
Charcoal  burnt  in  open  air  better  than  in  kilns,  although  the  percentage  of  yield  is  less.
2.  Oak  and  hickory  regarded  the  best  kinds  of  timber  for  making  hard  carboniferous
coal.    Gum  and  poplar  make  soft  coal,  of  much  less  value.    Charcoal  made  under  soil


126  USE   OP   CHARCOAL   IN   IRON   MANUFACTURE.
is  cheapest  and  best.  Ilavo  made  some  in  brick  ovens,  but  it  was  no  better  and  much
more  expensive,  on  account  of  hauling  wood  instead  of  coal.  The  yield  is  about  1,400
bushels  to  the  acre.  About  10,440  acres  would  yield  a  permanent  sflpply  if  no  acci-
dent, such  as  fires,  happened  to  the  growing  timber.  Many  furnaces  in  Kentucky  have
large  tracts  of  woodland  for  growing  new  supplies.  They  are  cut  off  once  in  28  to  30
years.
