'274  ;  lucena  T.  Crawford,  2  B.  &  P.  (z)    Wilson  v.  Boulter,  2  Str.  859;

N.  K.  269  ;  see  ante,  p.  369.  Hovil  v.  Back,   7  East,  166  ;  Brewer

(t)  Watson  V.  Swann,  11  C.  B.  N.  S.  v.  Sparrow,  7  B.  &  C.  510.
394


PRINCIPAL  AND  AGENT.
Past  II.    commission  and  for  his  charges  in  carrying  out  the  con-
tract (a).
Extent  of
authority.
Construc-
tion of
written
authority.
Powers  of
attorney.
The  nature  and  extent  of  authority  of  an  agent  is  defined
either  by  the  express  terms  in  which  it  is  given,  or  hy  the
circumstances  or  conduct  from  which  it  is  implied. — The
construction  of  a  power  of  attorney  and  of  all  written  autho-
rities is  for  the  Court ;  and  where  the  original  document  has
been  lost  and  secondary  evidence  given  of  the  contents,  the
construction  of  the  contents  so  proved  is  for  the  Court  {h).
An  authority  given  in  writing  is  presumptively  contained
exclusively  in  the  writing ;  and  the  general  rule  applies  that
no  extrinsic  evidence  is  admissible  to  vary  the  writing  (c). —
Powers  of  attorney  are  construed  with  reference  to  the  special
purpose  for  which  they  are  expressed  to  be  given ;  and
accordingly  terms  of  general  authority  are  taken  as  restricted
to  that  purpose  {d).  A  power  of  attorney  in  general  terms,
without  limitation  of  time,  was  construed  as  limited  by  the
recital  that  the  principal  was  going  abroad  and  desirous  of
appointing  an  attorney  during  his  absence  (e).  A  power  of
attorney  given  abroad  to  contract  in  England  must  be  con-
strued, as  to  the  authority  given,  according  to  English  law  (/).
