garding  all  these  shocks  as  so  many  isolated
disturbances,  having  no  connection  the  one  with
the  other,  while  others  regard  them  all  as  part  of
one  whole,  I  share  the  opinion  of  the  latter,  on
the  ground  that  whole  localities,  districts  and
regions,  situated  between  Lisbon  and  these
extreme  points,  were  disturbed  at  the  same  time.
Between  Sweden  and  Portugal  there  were  earth-
quake shocks  in  France,  Switzerland  and
Germany  ;  while,  between  Portugal  and  America,
the  bed  of  the  ocean  was  felt  to  rock,  as  well  as
the  island  of  Madeira.  Although  vast  regions
remained  motionless,  in  the  very  centre  of  the
zone  which  was  disturbed,  it  is  none  the  less  true
that  the  shocks  felt  north,  south,  and  west  were
so  many  links  connecting  these  extreme  points
with  the  centre  of  disturbance.  Is  it  not,  there-
fore, natural  and  even  compulsory,  to  recognize
the  close  connection  of  all  these  disturbances,  and
to  consider  the  whole  phenomenon  as  one  single
earthquake,  extending  over  a  considerable  part  of
the  terrestrial  surface  ?

But  it  sometimes  happens,  too,  that  shocks
occur  simultaneously  at  two  points  of  the  globe,
very  far  from  each  other,  without  there  being
anything  to  show,  by  way  of  a  link  between  the
two  commotions,  that  other  countries  have  been
disturbed  at  the  same  time.
EARTHQUAKES.  173

The  earthquake  which  ravaged  New  Granada
in  1827  is  a  remarkable  instance  of  the  simul-
taneousness  in  question,  for  upon  the  i6th  of  No-
vember the  terrible  scourge  desolated  the  whole
of  the  splendid  table-land  of  Santa  Fe  de  Bogota,
and  at  the  same  hour  several  violent  shocks  were
felt  at  Ochotok,  in  Siberia,  at  a  distance  of  more
than  /jooo  miles.  Let  me  give  a  second  instance.
