Winding  in  great  folds  for  two  thousand  miles  at
the  lowest  level  of  the  depression  is  a  mighty  river —
the  main  trunk  on  which  all  the  branches  of  drainage
converge.  From  its  nature  it  is  in  its  upper  course
no  scurrying,  brawling  stream,  roaring  over  rapids,
and  making  mad  leaps  down  precipices.  Its  current
is  slow  and  majestic,  broad,  smooth,  deep,  and  even-
flowing,  and  capable  of  bearing  navies  of  merchant-
men on  its  wide  breast.  Sometimes  it  stands  still,
and  spreads  out  into  great  lakes,  from  whose  centre
an  ocean  horizon  surrounds  the  voyager.  Between
these  expansions  its  appearance  is  more  like  that  of
a  lake  than  a  river.  Its  breadth  is  rarely  less  than
one,  often  as  much  as  six  and  even  ten  miles.  Islands
miles  in  length  look  like  insignificant  clumps  of  ver-
dure from  its  banks,  and  the  inhabitants  have  rarely
communication  with  the  shore.  The  Nile  may  exceed
it  in  length,  but  it  is  no  more  comparable  with  it  in
bulk  and  volume  than  a  slender  palm-tree  is  to  the
massive  baobab,  or  than  the  scraggy  giraffe  is  to
the  lordly  elephant.  There  are  many  of  its  minor
branches  that  supply  more  water  than  all  the  rivers
of  Northern  Africa  put  together.  These  affluents
have  their  coui'ses,  like  the  main  stream,  through
rank  forest  wildernesses  for  many  hundreds  of  miles,
receive  in  their  turn  tributaries  which  would  be  rivers
of  the  first  rank  in  Europe,  expand  into  large  unvisited


140  A  XEGLECTED  PROBLEM.
lakes,  and  pass  by  the  dwellings  of  races  who  have
never  seen  and  probably  never  heard  of  the  white
man.
