278         CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,    1907,    PAET   II. 
The  drift  on  No.  7  bed  is  driven  on  the  strike  of  the  bed  and  is 
1 ,600  feet  in  length,  running  under  a  hill  from  one  canyon  to  the  next, 
and  open  at  both  ends.  The  rooms,  200  to  600  feet  in  length,  depend- 
ing on  the  distance  to  the  outcrop,  are  driven  at  right  angles  directly 
up  the  rise,  winch  is  about  4°.  They  are  40  feet  between  centers 
and  24  feet  wide,  with  a  10-foot  pillar,  which  is  left  until  the  rooms 
are  finished  and  brought  back,  allowing  the  roof  to  cave.  The  coal 
bed  is  from  6  feet  to  6  feet  5  inches  thick,  and  is  undermined  and 
shot  down. 
The  slope  opening  on  No.  7  bed  is  1,200  feet  long  and  has  an  average 
pitch  of  4°  N.  61°  E.  Coal  is  hoisted  out  by  cable  in  cars  of  3,500 
pounds  capacity.  It  is  a  fair  blacksmithing  coal  and  gives  a  reddish 
ash  without  clinker.  Large  horses  are  used  for  hauling  cars  on  entries 
and  up  into  the  rooms.  The  mine  is  ventilated  by  furnace  and  has 
no  water  or  gas.  Timber  is  used  in  the  rooms  to  keep  up  the  roof 
until  the  pillars  are  brought  back.  The  roof  is  a  sandy  shale  and  is 
regular  throughout  the  mine.  The  floor  is  composed  of  shale.  The 
coal  bed  is  clean  and  ranges  in  thickness  from  6  feet  to  6  feet  6  inches. 
The  opening  on  No.  1  bed  is  600  feet  long  and  is  similar  to  the  drift 
on  No.  7  bed.  The  coal  bed  is  8  feet  thick,  with  a  2-inch  band  of  bone 
about  1  foot  6  inches  from  the  roof.  Cars  handling  the  coal  from 
this  opening  go  to  the  same  dump  that  handles  the  coal  f^om  No.  7  bed. 
"b"  mine. 
Work  on  the  "B"  mine  started  in  April,  1906.  The  drift,  now  3,000 
feet  in  length,  followed  the  strike  of  a  very  thin  bed  of  coal  which 
widened  out  to  about  6^  feet  at  the  point  reached  in  July,  1907,  when 
shipping  began.  The  coal  was  dirty  and  not  workable  for  the  first 
1,800  feet;  beyond  that  point  there  is  from  7  to  8  feet  of  clean  coal 
overlying  a  shale  floor.  The  coal  is  the  same  as  that  at  the  lower 
openings  of  the  "A"  mine  and  is  mined  and  hauled  in  the  same  way, 
the  average  daily  output  being  about  200  tons.  It  is  necessary  to 
timber  the  mine,  as  the  roof  is  a  sandy  shale  that  will  not  stay  up  on 
more  than  10 -foot  spans. 
Work  on  the  slope  of  the  aC"  mine,  which  is  located  on  No.  1  bed, 
was  started  February  7,  1906,  in  coal  having  thick  bands  of  shale,  but 
no  coal  was  shipped  until  December  of  the  same  year.  The  slope  is 
1,650  feet  in  length  and  has  an  average  pitch  of  4°  N.  37°  E.  The 
room  and  pillar  system  is  employed,  the  rooms  being  driven  up  the 
rise  as  at  "A"  mine.  Timbers  are  used  in  all  rooms  and  in  entries 
where  the  roof  is  shale.  A  coal  roof  is  left  in  many  of  the  entries. 
The  coal  is  undermined  and  all  shot  down  in  the  rooms,  then  hauled 
by  horse  along  the  entries  to  the  slope,  where  it  is  hoisted  by  cable 
in  cars  of  3,500  pounds  capacity.     The  daily  output  averages  about 
