and  the  Magnetic  Relations  of  the  Heavenly  Bodies.        455 
of  Regents  of  the  Smithsonian  Institution  &c.  foi*  the  year  1865  ' 
(pp.  208-24$) .  This  compilation  is  the  more  important,  as 
Loomis  never  mentions  the  connexion  between  sun-spots  and 
magnetic  variations ;  the  researches  of  Wolf  were  at  any  rate 
not  known  to  him*.  Any  preconceived  opinion  was  therefore 
impossible,  and  the  connexion  between  the  two  phenomena  be- 
comes the  more  astouishing. 
In  the  following  Table  I  have  separated,  as  above,  the  years  of 
sun-spot  maxima  and  minima,  and  annexed,  in  place  of  the  mag- 
netic variations,  the  aurora-borealis  epochs  of  maxima  and  minima 
deduced  by  Loomis  from  European  observations  only  The  years 
deduced  from  American  observations  are  almost  identical  with 
those  given  below. 
Sun-spots  and  Aurora  Boreales. 
Maximum. 
| 
Minimum. 
Sun-spots. 
Aurora  borealis. 
Sun-spots. 
Aurora  borealis. 
1707 
1713 
1718 
1721 
1730 
1733 
1741 
1745 
17500 
1750 
1755-7 
1755 
1761-5 
1760 
1766-5 
1766 
17700 
1771 
1775-8 
1776 
1779-5 
1779 
1784-8 
1784 
1788-5 
1788 
1798-5 
1798 
1804-0 
1804 
1810-5 
1811 
1816-8 
1819 
1823-2 
1823 
1829-5 
1830 
1833-8 
1834 
1837-2 
1840 
1844-0 
1843 
1848-6 
1849 
1856-2 
1856 
These  observations  leave  no  doubt  as  to  the  connexion  between 
terrestrial  magnetism  and  the  occurrences  on  the  solar  surface ; 
and  I  only  add  that  my  theory  not  only  explains  the  existence 
but  also  the  nature  of  this  connexion.  Indeed,  if  the  only  ques- 
tion were,  to  confirm  its  existence,  it  would  not  have  mattered 
whether  a  maximum  of  sun-spots  coincided  with  a  maximum  or 
with  a  minimum  of  magnetic  disturbances ;  but,  according  to 
the  theory  developed  above,  the  coincidence  of  the  maxima  of 
the  two  phenomena  is  a  necessity.  For  at  the  time  of  maximum 
of  sun-spots  the  sun's  increased  magnetic  action  will  cause  an 
acceleration  in  the  glowing  streams  within  the  earth;  and  hence 
the  magnitude  of  the  magnetic  disturbance  will  increase,  just  as 
it  does,  in  higher  geographical  latitudes  (compare  §  10). 
*  Only  later,  in  Silliman's  Journal,  September  1870,  did  Loomis  lay 
stress  upon  these  connexions.  Compare  the  critique  of  his  paper  by  Wolf 
in  No.  28  of  his  Astronomische  Mittheilungen. 
