The  Cumana  earthquake  of  November  4,  1799,
was  preceded,  accompanied,  and  followed  by
extraordinary  atmospheric  phenomena.  A  reddish
light  had  been  seen  in  the  sky  during  the  whole
of  the  previous  night,  and  a  strong  gust  of  wind,
followed  by  a  thunderstorm,  followed  instantane-
ously this  first  subterranean  shock,  which,  with  an
upward  direction,  created  great  terror  among  the
population.  After  this  first  shock  the  red  light
was  again  seen  for  several  nights,  and  each  day  at
the  same  hour  there  were  shocks  as  violent  as
that  which  occurred  on  the  first  day.  Finally,
upon  the  seventh  night,  a  countless  number  of
meteors  and  bolids  shot  through  the  sky,  and  after
this  night  the  mysterious  light  disappeared,  and
there  were  no  more  shocks.
The  dreadful  shock  in  the  valley  of  Viege  in
1855  occurred  simultaneously  with  the  most
severe  thunderstorm  ever  felt  in  the  Valois.
And,  coming  down  to  more  recent  times,  severe
thunderstorms  accompanied  the  earthquake
shocks  in  Andalusia,  especially  at  Granada,
which  was  the  centre  of  the  disturbance,  while  an
immense  quantity  of  ozone  found  its  way  into  the
atmosphere.
316  EARTHQUAKES.
Ozone  is  a  most  singular  substance,  of  which
we  know  neither  the  origin,  nor  the  physical
properties,  though  it  is  generally  considered  to  be
a  transformation  of  oxygen  effected  by  means  of
electrical  effluvia,  while  recent  researches  of  a
very  ingenious  kind  have  taught  us  that  in  colour
it  is  azure  blue  like  the  sky.  Although  the
sudden  appearance  of  ozone  during  earthquakes
had  often  been  reported,  the  fact  was  regarded  by
men  of  science  as  improbable,  but  there  could  be
no  mistake  about  it  this  time,  as  the  shocks  had
scarcely  ceased  in  Andalusia  when  its  presence
was  noticed  all  over  the  scene  of  the  catastrophe.
