and  the  Magnetic.  Relations  of  the  Heavenly  Bodies.       461 
at  series  of  numbers  which  show  increase  and  decrease  when 
compared  with  the  course  of  the  moon. 
"  Sabine  is  the  only  one  who  found  the  same  law  for  all  stations 
of  observation  and  in  differeDt  seasons." 
I  shall  confine  myself  in  the  following  to  considering  in  detail 
the  results  of  Sabine. 
His  first  paper  is  entitled  <(  On  the  Evidence  of  the  existence 
of  the  Decennial  Inequality  in  the  Solar-diurnal  Variations,  and 
its  non-existence  in  the  Lunar-diurnal  Variation  of  the  Magnetic 
Declination  at  Hobarton"*. 
In  this  memoir  the  hourly  observations  of  Toronto  are  divided 
into  several  periods,  and  the  lunar  influence  is  deduced  from  each 
of  these  periods.  All  the  individual  periods  lead  consistently 
to  the  following  results  : — 
1.  The  moon  manifests  its  influence  in  the  variation  of  all  the 
magnetic  elements ;  its  action  can  decidedly  be  shown  to  exist 
in  declination,  dip,  and  intensity. 
2.  The  lunar  influence  consists  of  a  regular  period  with  double 
maximum  and  double  minimum  ;  the  maxima  are,  for  the  decli- 
nation, 6  hours  and  18  hours,  for  dip  3  hours  and  14  hours,  and 
for  intensity  3  hours  and  16  hours,  after  the  upper  culmination  ; 
the  magnitude  of  the  periods  (difference  between  maximum  and 
minimum)  is,  for  declination,  0;,64',  for  inclination  0,#07,  for  total 
intensity  0'-000012. 
3.  These  movements  may  be  explained  by  the  hypothesis  that 
the  earth  induces  magnetism  in  the  moon. 
4.  The  lunar  influence  does  not  show  any  trace  of  a  decennial 
period. 
The  last-mentioned  result,  which  constitutes  a  characteristic 
difference  between  the  magnetic  influence  of  sun  and  moon, 
might  be  considered,  from  what  has  been  said  at  the  beginning 
of  this  section,  a  confirmation  of  the  conclusion  that  in  the  inner 
part  of  the  moon  no  glowing  liquid  mass  is  present  which  could 
give  rise  to  disturbances,  or  that,  if  these  currents  are  present, 
they  are  not  subjected  to  such  changes  as  those  on  the  solar 
surface  by  the  periodically  changing  quantity  of  sun-spots. 
A  second  paper  of  Sabine  has  the  title  "  On  the  Lunar-diurnal 
Variation  of  the  Magnetic  Declination  obtained  from  the  Kew 
Photograms  in  the  years  1858,  1859,  and  1860"+. 
In  this  paper  Sabine  deduces  the  influence  of  the  moon  from 
the  photographically  registered  observations  of  Kew,  and  shows 
that  there  exists  a  regular  period  with  two  maxima  and  two 
*  Proceedings  of  the  Roval  Societv,  vol.  viii.  p.  314  (1857);  Phil.  Trans. 
1857,  pp.  WJ.  ' 
t  Proceedings  of  the  Royal  Society,  vol.  xi.  pp.  73-80.  Phil.  Mag.  1861, 
Ser.  4.  vol.  xxii.  p.  4/9^-485. 
