266  THE  CHINESE  EMPIRE
The  western  part  is  covered  with  mountain  chains  rising
to  heights  through  which  the  passes  are  over  8,000  feet  m
altitude,  with  steep  slopes  running  north  and  south,  the
valleys  containing  rivers  with  great  volumes  of  water,
formed  by  the  rains  and  melted  snows  of  Himalayan  ranges,
rushing  down  through  rocky  beds  which  themselves  are
several  thousand  feet  above  the  level  of  the  sea.  Th®
greater  part  of  the  eastern  portion  has  been  described
as  “an  elevated  broken  plateau,  having  an  average  height
of  5,000  feet  ”  ;  but  this  "  plateau  ”  is  so  broken  up  that
the  plains  cannot  be  discerned,  and  the  mountains  are  the
most  distinguishing  feature.  The  waterways  are  unavailable ­
  for  transport  within  the  province,  acting  with  their
deep  valleys  rather  as  barriers  to  trade  ;  and  the  paucity
of  the  population  forbids  the  use  of  human  porters,  making
the  pack-mule  and  horse,  supplemented  on  emergency  by
pack-cattle,  the  only  agency  of  transportation.  The  water
outlets  from  the  province  begin  only  on  its  borders,  and
those  available  for  the  major  operations  of  trade  are  three  •
the  Red  River  from  the  southern  border  into  Tonkin,  to
be  supplemented  by  the  railway  now  under  construction
to  Yunnanfu,  the  provincial  capital  ;  the  West  River  from
the  eastern  border,  leading  to  Canton  and  Hongkong  ;  and
the  Yangtze  from  the  northern  border,  leading  down  to
Hankow  and  Shanghai.  Of  the  agricultural  products  oi
the  province,  the  only  one  deserving  attention  is  opium,
which  is  considered  in  the  chapter  on  that  drug,  and  which
is  the  principal  means  by  which  Yunnan  pays  for  the
imports  which  it  consumes.  The  chief  wealth  of  the  province ­
  is  in  its  minerals,  of  which  there  are  known  to  exist
cinnabar,  coal,  copper,  gold,  iron,  lead,  orpiment,  salt,
silver,  tin,  and  zinc.  The  mining  industry  was  severely
crippled  by  the  Panthay  rebellion,  but  prior  to  that  date,
though  iron  ore  is  the  most  abundant,  copper  was  mined
on  a  much  larger  scale  in  order  to  provide  for  the  requirements ­
  of  the  mints  of  the  Empire,  which  formerly  were
almost  entirely  dependent  upon  the  Yunnan  mines  f° r
their  needs,  which  may  be  put  at  about  6,000  tons  annually-