46  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1906,  PART    I. 
DEVELOPMENT    AND    EQT  [PMENT. 
A  crosscut  tunnel  SSS  feet  long  reaches  the  ore  zone  about  '245 
feel  below  the  surface  and  continues  along  its  general  strike  for 
about  2,000  feet.  The  width  of  this  zone  is  from  SO  to  360  feet,  and 
it  has  been  explored  by  a  large  number  of  crosscuts  and  raises  from 
this  level.  There  is  an  engine  station  about  1,600  feet  from  the 
portal  of  the  main  adit  and  a  winze  from  which  levels  are  run  6fl 
140,  and  214  feet  befow  the  tunnel  level.  The  lowest  workings  are 
a  little  more  than  500  feel  below  the  surface.  Above  the  adit  three 
levels  are  run  from  shafts  now  abandoned,  and  these  workings  are 
connected  by  stopes  and  raises  with  those  below.  The  total  devel- 
opment by  crosscuts  and  drifts  is  about  7,500  feet. 
The  walls  stand  remarkably  well  and  very  little  timbering  is  nec- 
essary.  The  huge  cavities  from  which  the  ore  has  been  remove! 
have  remained  for  years  without  sign  of  approaching  collapse.  Of 
these  the  Cornish,  Square  Set,  and  Showers  stopes  are  above  the 
tunnel  level.  The  Cornish  stope  is  a  rudely  cylindrical  cavity  just 
above  the  engine  station,  inclined  toward  the  west  about  30°.  It  is 
about  50  feet  in  maximum  diameter,  125  feet  long,  and  its  top  is 
about  (I.")  feet  higher  than  its  base,  which  is  just  a  few  feet  above 
the  tunnel  level.  The  Square  Set  stope  is  east  of  and  above  the 
Cornish  stope,  with  the  top  of  which  its  base  is  connected.  Its  plan 
is  rudely  elliptical  and  it  extends  upward  within  .")()  feet  of  the  sur- 
face. The  Showers  stope  is  about  loo  feet  west  of  the  engine  sta- 
tion, its  base  being  that  <>\'  the  adit  level.  It  is  about  30  feet  lonj 
15  feet  wide,  and  20  feet  high.  The  Lake  stope  is  a  few  feet  north 
n\'  the  engine  station  and  is  a  long,  flat-lying  opening,  almost  cylin- 
drical in  shape.  Jt  is  320  feet  long,  40  feet  wide,  and  from  \^  to  30 
feet  high.  Its  roof  is  approximately  at  the  level  of  the  floor  of  the 
adit.  On  the  65-foot  level  there  is  a  large  stope  below  the  west  end 
of  the  Lake  stope  and  connected  with  it.  and  t  here  are  several  smaller 
stopes  on  the  lower  levels  both  east  and  west  of  the  hoist. 
The  mine  is  equipped  with  air  compressors,  that  furnish  power  for 
hoist,  pump,  and  drills.  Two  diamond  drills  are  operated  continu- 
ously, since  it  is  necessary  to  prospect  the  entire  ore  zone,  which  has 
an  average  width  of  about  200  feet.  The  cores,  which  aggregate 
several  thousand  feet,  are  kept  accessible  at  all  times  and  the  records 
are  carefully  plotted  in  the  office. 
The  mill  is  located  just  below  the  portal  of  the  tunnel  and  is 
equipped  with  two  Blake  crushers  and  thirty  Frazier  &  Chalmers 
stamps.  A  fair  saving  is  made  by  simple  amalgamation,  even  with 
the  sulphide  ores;  the  extraction  is  said  to  run  from  SO  to  DO  per  cent. 
In  the  autumn  of  1890  experiments  were  made  with  a  view  to  adding 
