354     M.  F.  Zollner  on  the  Origin  of  the  Earth3 s  Magnetism, 
seven  hundred  years  round  the  earth.  It  is  easily  seen  that 
nothing  is  gained  by  hypotheses  which  are  neither  supported  by 
analogy  nor  facts,  and  at  present  the  best  thing  is  to  confess 
that  we  cannot  make  any  acceptable  supposition  about  these 
mysterious  phenomena." 
We  see  from  this  that  just  that  peculiarity  which  formed  the 
most  difficult  problem  for  all  explanations  hitherto  given  is 
almost  self  evident,  looking  at  it  from  the  point  of  view  of  the 
above  suppositions. 
If  the  general  direction  of  the  glowing  liquid  streams  agrees, 
as  already  said,  with  the  conditions  given  by  the  position  of  the 
magnetic  needle* ;  certain  physical  consequences  may  be  drawn 
from  my  theory  for  particular  conditions  by  which  the  streams 
or  their  beds  may  be  modified.  We  shall  consider  now  more 
closely  these  consequences. 
It  is  clear  that  the  configuration  and  nature  of  the  outer  sur- 
face of  the  earth  is  in  some  connexion  with  the  nature  of  its 
inner  surface,  although  perhaps  only  within  wide  limits. 
The  ice  which  covers  a  lake  or  the  sea  while  it  is  agitated  by 
manifold  movements  and  currents,  is  characterized  on  its  sur- 
face by  manifold  inequalities,  which  in  part  correspond  to  similar 
inequalities  on  the  inner  side ;  and  so  may  be  the  inner  sur- 
face of  the  earth's  crust.  Where  mighty  mountains  of  heavy 
stones  come  forth  on  the  upper  surface,  similar  projections  will 
probably  appear  on  the  inner  surface;  and  these  inequalities 
projecting  deeply  into  the  streams  must  have  an  influence  on 
them,  as  the  mountains  at  the  bottom  of  the  sea  have  an  in- 
fluence on  the  currents  of  the  sea,  or  the  mountains  on  the 
earth  on  the  currents  in  the  atmosphere. 
8. 
If  these  views  are  confirmed  by  nature,  and  if  the  solid 
crust  covering  our  planet  is  not  yet  thick  enough  to  cause 
these  influences  to  disappear,  we  shall  expect  that  the  situa- 
tion and  configuration  of  large  chains  of  mountains  influence 
the  direction  in  which  the  magnetic  needle  points,  as  they  in- 
fluence the  direction  of  the  pendulum. 
Lamont,  after  having  mentioned  the  subterranean  experiments 
of  Reich  in  Freiberg  f  and  his  own  magnetic  observations  made 
on  high  mountains,  says,  with  regard  to  this  question  : — 
"On  this  occasion  1  may  remark  that  I  have  confirmed  by  my 
*  If  we  look  at  the  position  of  the  isoclinic  lines,  or  those  of  equal  hori- 
zontal intensity,  or  the  lines  of  equal  total  magnetic  intensity,  all  of  them 
have,  as  regards  direction,  the  character  of  strongly  deviated  equato- 
rial currents  in  the  sea  or  in  the  atmosphere. 
f  Reich  "On  Electrical  Currents  in  Lodes,"  Pogg.  Ann.  xlviii.  1839. 
