and  the  Magnetic  Relations  of  the  Heavenly  Bodies.        349 
inner  parts  of  a  heavenly  body,  according  to  the  principles  of 
the  conservation  of  energy,  this  change  in  the  vis  viva  of  the 
currents  must  be  accompanied  by  an  equivalent  change  in  the 
mean  temperature  of  the  system.  We  can  therefore  generally 
say : — Changes  in  the  mean  intensity  of  the  streaming  process  are 
accoynpanied  by  changes  in  the  mean  temperature  of  the  streaming 
masses,  and  the  masses  connected  with  them.  An  increase  in  the 
vis  viva  of  the  current  implies  a  decrease  in  the  temperature,  and 
vice  versa.  These  changes  must  necessarily  take  place  simultane- 
ously (at  least  only  retarded  by  the  conduction  of  the  solid  crust), 
as  the  first  phenomenon  is  only  another  expression  of  the  second  one, 
There  is  still  a  third  way  by  which  we  could  show  the  exist- 
ence of  these  currents — if  they  were  to  cause  disturbances  in  the 
electrical  equilibrium.  If  the  direction  of  the  electrical  currents, 
which  are  perhaps  produced,  were  to  depend  merely  upon  the 
direction  of  the  streaming  masses/  magnetic  phenomena  would 
take  place  on  the  surface  which  would  be  connected  by  certain 
laws  with  the  general  character  of  the  motion,  and  hence  also 
with  the  circles  and  points  whose  situation  depends  on  the  rota- 
tion of  the  earth. 
5. 
If  we  ask  whether  by  the  known  laws  of  electricity  we  have 
the  right  to  assume  that  electrical  currents  are  produced  by 
currents  of  liquids,  we  must  answer  in  the  affirmative.  We 
shall  see  that  we  may  positively  assert  that  wherever  a  streaming 
motion  of  conducting  and  chemically  decomposable  liquids  takes  place, 
electrical  currents  are  produced  which  are  connected  by  certain 
laws  with  these  streams.  The  observed  facts  by  which,  I  think, 
this  assumption  is  not  only  justified,  but,  according  to  the  laws 
of  logical  induction,  necessary,  are  the  electrical  currents  and 
their  reciprocal  phenomena  discovered  by  Quincke  in  the  year 
1859,  and  called  by  him  "diaphragmic  currents  "*. 
The  fundamental  fact  which  forms  the  starting-point  for 
Quincke's  researches  is  expressed  by  him  in  the  following 
words  : — 
"  If  pure  water  flows  through  a  porous  body,  an  electrical 
current  is  produced.  1  found  and  confirmed  this  fact  by  the 
following  experiments." 
The  direction  of  these  electric  currents  depends,  with  all 
liquids  which  have  been  hitherto  examined,  only  upon  the  direc- 
tion of  the  streaming  movement,  while  their  intensity  varies  a 
great  deal  with  qualitative  changes  of  the  liquid.  The  direc- 
tion of  the  positive  current  is  always  the  same  as  that  of  the 
*  G.  Quincke  "  On  a  New  Class  of  Electric  Currents,"  PoggendorfFs 
Annalen,  vol.  cvii.  pp.  1-47,  and  vol.  ex,  pp.  38-65. 
