458     M.  ¥.  Zollner  on  the  Origin  of  the  Earth's  Magnetism, 
changes  in  the  streams  in  our  earth,  and  by  this  generate  varia- 
tions in  the  terrestrial  magnetism.  Until  now  we  have,  how- 
ever, only  considered  those  causes  of  changes  in  the  streams  of 
the  solar  surface  which  are  produced  by  the  periodical  number 
of  sun-spots.  Let  us  now  see  whether  we  can  find  other  pro- 
cesses on  the  sun,  of  a  more  accidental  and  local  nature,  which, 
similar  to  earthquakes  or  volcanic  eruptions,  could  mechanically 
produce  sudden  changes  in  the  velocity  of  the  glowing  streams. 
Just  as  the  purely  mechanical  causes  produce  a  disturbance  in  the 
whole  magnetic  force  of  the  earth,  they  must  have,  if  sufficiently 
intense,  the  same  effect  on  the  sun,  and  produce  there  changes 
which  in  their  turn  may  be  accompanied  by  all  the  phenomena 
observed  in  consequence  of  magnetic  disturbances. 
The  spectroscope  has  discovered  such  a  richness  of  mighty 
volcanic  eruptions  on  the  solar  surface  that  a  mechanical  reac- 
tion on  the  glowing  streams  seems  to  be  a  natural  supposition. 
Such  reactions  would  chiefly  manifest  themselves  at  the  great 
changes  and  sudden  ruptures  of  the  immense  slag-like  masses 
which  we  observe  in  the  sun-spots. 
The  observations  show  indeed  the  very  same  connexion  be- 
tween local  processes  on  the  sun's  surface  as  was  deduced  by  our 
theory. 
I  give  here  the  most  remarkable  of  these  observations  known 
to  me.  They  date,  of  course,  only  from  the  time  when  the 
solar  surface  was  first  made  the  subject  of  careful  researches. 
PoggendorfPs  Annalen,  vol.  cix.  p.  190  (January  1860),  con- 
tains an  extract  of  a  letter  from  Major-General  Sabine  to  Professor 
Dove,  under  the  title  of  "An  Observation  of  Sun-spots."  It  runs 
as  follows : — 
"  Mr.  Carrington  being  engaged  in  the  morning  of  the  1st 
of  September  last  year  in  taking  his  daily  observations  on  the  form 
and  position  of  the  sun-spots,  saw,  to  his  great  surprise,  a  white 
light  which  was  breaking  forth  from  the  middle  of  a  large  spot 
which  had  already  during  several  days  been  the  subject  of  general 
attention ;  this  white  light  was  more  intense  than  the  rest  of  the 
solar  surface.  It  lasted  somewhat  longer  than  five  minutes ;  and 
when  it  had  disappeared,  the  large  spot  seemed  to  be  unchanged. 
This  phenomenon  was  also  seen  by  Mr.  Hodgson  at  Highgate, 
at  a  distance  of  some  miles  from  Red  Hill,  the  observatory  of 
Mr.  Carrington.  Both  observers  agree  in  fixing  the  time  of 
appearance  and  disappearance  (right  within  a  few  seconds)  at 
llh  18m  and  llh  23m  Greenwich  mean  time.  A  few  days 
afterwards  Mr.  Carrington  had  occasion  to  visit  the  Meteorolo- 
gical Observatory  in  Kew ;  and  talking  about  the  phenomenon, 
he  looked  at  the  photographical  records  made  there  by  the  three 
magnetical  elements.     In  each  of  them  he  observed  a  great  dis- 
