and  the  Magnetic  Relations  of  the  Heavenly  Bodies.        497 
serrations  made  simultaneously  in  two  vertical  circles  with  the 
horizontal  pendulum,  and  their  comparison  with  the  readings 
of  magnetical  instruments,  will  supply  valuable  material.  Their 
discussion  will  elucidate  the  causes  of  the  close  relation  between 
the  mechanical,  electrical,  and  magnetical  phenomena  on  our 
planet.  "We  come  by  this  into  possession  of  an  exceedingly  rich 
language  of  signs,  the  explanation  of  which  will  perhaps  some  day 
give  us  as  clear  a  conception  of  the  occurrences  in  the  earth  as 
the  language  of  signs  of  the  senses,  chiefly  by  the  help  of  light, 
has  given  us  of  the  occurrences  on  its  surface. 
Appendix. 
In  conclusion  of  the  present  research  on  the  Origin  of  the 
Earth's  Magnetism  and  the  Magnetical  Relations  of  the  Hea- 
venly Bodies,  I  return  to  those  considerations  which  formed  the 
starting-point  of  my  views  of  the  physical  causes  of  the  electric 
currents  which  circulate  round  the  earth  from  east  to  west,  and 
thus  call  forth  the  magnetical  and  electrical  phenomena  on  the 
surface  of  the  earth.  The  reasons  developed  there,  by  which  I 
was  inclined  to  regard  the  connexion  between  electrical  cur- 
rents and  streaming  motion  of  liquids  as  a  fundamental  fact,  grew, 
in  the  course  of  the  whole  research,  into  such  a  conviction  that 
I  cherished  the  desire  to  show  the  existence  of  these  currents  di- 
rectly in  flowing  water. 
Before  going  to  the  description  of  the  simple  experiments 
which  seem  to  prove  indeed  the  existence  of  such  currents  of 
very  considerable  electromotive  force  in  streaming  water,  always 
in  the  same  direction  as  the  current  of  water,  I  may  mention 
here  those  observations  which  have  recently  proved  the  constant 
existence  of  electrical  currents  in  the  crust  of  the  earth.  The 
literature  on  these  earth-currents  is  already  voluminous;  its 
beginning  is  chiefly  from  the  year  1859,  when  strong  earth-cur- 
rents rendered  the  correspondence  by  telegraph  on  all  lines  im- 
possible on  the  occasion  of  an  aurora  taking  place  on  August  29 
with  rare  splendour,  which  I  myself  observed  in  Basle  until 
morning-dawn.  Through  the  acquaintance  of  a  telegraphist  I 
had  opportunity  to  convince  myself  on  the  following  morning  at 
7  o'clock  of  the  force  with  which  the  armature  of  the  electro- 
magnet still  remained  permanently  in  contact  with  the  ends  of 
the  horseshoe. 
In  the  year  1859  Lamont*  had  stretched  telegraph  wires  in 
the  observatory  of  Munich  from  east  to  west  and  south  to  north 
and  joined  them  to  end -plates.  The  electric  current  which  was 
constantly  flowing  was  during  a  long  time  observed  and  regis- 
tered hourly  in  the  observatory  by  means  of  galvanometers.     It 
*  The  Earth-current  and  its  Connexion  with  the  Magnetism  of  the 
Earth.     Leipzig,  1862,  pp.  1-74. 
Phil.  May.  S.  4.  No.  289.  Suppl.  Vol.  43.  2  K 
