Portland,  to  haul  coal  from  Kilmarnock  to  Troon,  which
cost  £750,  and,  with  some  interruptions,  this  engine  worked
on  that  line  until  1848,  when  it  was  broken  up.  On  Novem-
ber 18,  1822,  the  Hetton  Railway,  near  Sunderland,  was
opened.  George  Stephenson  was  the  engineer  of  the  line — a
short  track,  8  miles  long,  built  from  the  Hetton  Colliery  to
the  docks  on  the  bank  of  the  river  Wear.  On  this  line  he
put  in  five  of  the  "  self-acting  inclines  " — two  inclines  worked
by  stationary  engines,  the  gradients  being  too  heavy  for
locomotives — and  used  five  locomotive-engines  of  his  own
design,  which  were  called  by  the  people  of  the  neighbor-
hood, possibly  for  the  first  time,  "  the  iron  horses."  These
engines  were  quite  similar  to  the  Killingworth  engine.
They  drew  a  train  of  IT  coal-cars — a  total  load  of  64  tons
— about  4  miles  an  hour.  Meantime,  also,  in  1823,  Ste-
phenson had  been  made  engineer  of  the  Stockton  &  Dar-
lington Railroad,  which  had  been  projected  for  the  purpose
of  securing  transportation  to  tide-water  for  the  valuable
coal-lands  of  Durham.  This  road  was  built  without  an  ex-
pectation on  the  part  of  any  of  its  promoters,  Stephenson
excepted,  that  steam  would  be  used  as  a  motor  to  the  ex-
clusion of  horses.
