and  the  Magnetic  Relations  of  the  Heavenly  Bodies.       499 
secured  from  all  chemical  influence;  and  as  precautions  were 
taken  to  keep  the  amalgamated  plates  at  the  same  temperature, 
Matteucci  expresses  his  conviction  that  there  could  not  have 
been  any  thermoelectric  currents.  The  observations  made 
during  one  month  gave  the  following  results  : — 
1.  Currents  were  almost  always  present. 
2.  Deeper  ditches  and  wet  weather  gave  an  increase  of  the 
currents. 
3.  With  the  original  depth  of  the  ditches  an  increase  in  the 
dimensions  of  the  porous  vessel  or  the  zinc  plates  did  not  cause 
a  stronger  current. 
4.  In  the  line  running  from  north  to  south  the  direction  of 
the  current  was  always  constant,  and  was  flowing  in  the  stretched 
wire  from  south  to  north.  The  intensity  of  this  current  showed 
a  daily  period  with  two  maxima  and  two  minima :  the  minima 
take  place  at  noon  and  midnight  (an  hour  sooner  or  later) ;  the 
maxima  take  place  at  5-7h  in  the  morning,  and  3-7h  in  the 
afternoon. 
5.  The  line  running  from  east  to  west  shows  great  incon- 
stancy in  the  intensity  of  the  current  (according  to  the  galva- 
nometer from  0°  to  ±15°)  as  well  as  in  its  direction;  the  direc- 
tion from  wrest  to  east  in  the  wire,  however,  is  the  most  common. 
6.  The  connexion  of  the  northern  or  southern  plate  with  the 
eastern  or  western  gave  generally  a  current  which  was  equal  to 
the  current  in  the  south-north  line. 
7.  The  direction  and  intensity  of  the  north-south  current  was 
independent  of  the  temperature  of  the  air,  which  varied  between 
0°  and  +18°;  it  was  independent  of  the  humidity  of  the  air; 
neither  storms  nor  thunderstorms  had  any  influence. 
8.  Nothing  was  changed  in  the  results  when  the  wires  which 
were  covered  with  gutta  percha  were  taken  o£F  the  telegraph- 
posts  and  laid  upon  the  earth. 
AVhat,  asks  now  Matteucci,  is  the  cause  of  these  currents  ? 
He  declares  that  he  is  not  able  to  give  any  decisive  answer.  But 
he  is  inclined  to  assume  a  close  connexion  with  the  terrestrial  mag- 
net  ism. 
A  not  less  interesting  fact  of  observation  is  communicated  by 
Matteucci  in  a  second  paper*.  A  constant  and  very  remarkable 
connexion  between  the  direction  of  the  current  and  the  difference 
in  level  of  the  two  zinc  plates.  Every  wire  which  is  connected 
with  the  ground  at  points  of  which  one  is  deeper  than  the  other, 
shows  a  pretty  constant  current  which  goes  in  the  wire  from  the 
deeper  to  the  higher  station,and  which  at  every  atmospheric  discharge 
receives  a  sudden  increase,  which,  however,  only  lasts  for  an  instant. 
The  experiments  were  made  on  four  different  lines,  of  a  length 
*  Comptes  Rendus,  tome  lix.  p.  511-516. 
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