goods,  to  be  delivered  upon  the  request  of  the  buyer,  and
afterwards  sells  and  delivers  the  same  goods  to  another  person,
he  dispenses  with  the  request  of  the  former  as  a  condition  of
delivery  (r) .  And  if  a  man  promises  to  marry  one  person  and
afterwards  marries  another,  he  thereby  dispenses  with  all
conditions,  as  to  time  or  request  or  otherwise,  which  might
have  been  precedent  to  his  liability  to  the  former  (s).
Contracts  may  provide,  .expressly  or  impliedly,  for  termina-  Conditions
tion  by  lapse  of  time,  or  by  notice,  or  by  other  events ;  which  quent.
then  operate  as  conditions  subsequent.  It  is  said  "  that  prima
facie  every  contract  is  permanent  and  irrevocable,  and  that  it
lies  upon  a  person  who  says  that  it  is  revocable  or  determin-
able to  show  either  some  expression  in  the  contract  itself,  or
something  in  the  nature  of  the  contract,  from  which  it  is
reasonably  to  be  implied  that  it  was  not  intended  to  be  per-
manent and  perpetual,  but  was  to  be  in  some  way  or  other
subject  to  determination"  [t).  Accordingly,  where  a  contract
was  made  between  two  railway  companies  for  giving  to  one
of  them  running  power  over  the  lines  of  the  other,  but  with-
out mentioning  any  limit  of  time  or  any  mode  of  terminating
the  power ;  it  was  held  that,  considering  the  perpetuity  of
the  contracting  parties  and  of  the  subject-matter,  the  contract
must  have  an  indefinite  duration,  according  to  the  prima  facie
construction  of  its  terms ;  and  that  there  was  no  implied  con-
dition to  terminate  it  by  notice  or  othervsrise  {u).
