and  the  Magnetic  Relations  of  the  Heavenly  Bodies.        453 
magnetism ;  and  the  former  gentleman  has  since  succeeded,  with 
great  zeal  and  trouble,  in  establishing  this  relation  as  an  un- 
doubted fact. 
In  proof  of  this  assertion  I  cite  some  passages  from  a  paper 
of  Wolf,  "On  the  Eleven-years  period  of  the  Sun-spots  and 
Magnetical  Variations  w*  : — 
"  When  I  showed,  in  the  year  1852,  that  there  exists  a 
period  of  11 J  years  in  the  frequency  of  sun-spots  which  could  be 
followed  backward  as  far  as  the  discovery  of  sun-spots,  I  had, 
besides  the  series  of  Hofrath  Schwabe,  which  already  then  ex- 
tended over  twenty-six  years,  nothing  at  my  disposal  but  a 
certain  number  of  short  series  of  observations  and  separate  state- 
ments; the  proof  therefore  only  layin  the  two  facts,  that  Schwabe's 
series  showed  such  a  period,  and  that  the  assumption  of  a 
period  extending  over  11 J  years  was  not  contradicted  by  any 
of  the  statements  found.  Now  it  is  otherwise.  The  dis- 
covery of  observations  made  by  Staudacher,  Flangergues,  Tevel, 
Adams,  &c.  renders  it  possible  to  me  to  express  by  relative 
numbers  the  mean  frequency  of  sun-spots  for  a  series  of  112 
years  as  found  from  20,000  observations.  I  give  these  numbers 
in  full,  adding,  as  far  as  space  permits,  the  mean  yearly  varia- 
tion in  declination." 
As  regards  the  above-mentioned  complete  reproduction  of  the 
observations,  I  refer  to  the  paper  itself,  and  only  give  the  re- 
sults of  Wolf  in  his  own  words  (/.  c.  p.  505)  : — 
"  The  above  Table  shows  at  first  sight  the  periodical  change 
of  the  frequency  of  sun-spots  as  well  as  in  the  magnitude  of  mag- 
netical variations  in  declination.  The  following  periods  result 
from  it : — 
Sun-spots  and  Magnetism  of  the  Earth. 
Maximum. 
Minimum. 
Sun-spots. 
Magnetic 
variations. 
Sun-spots. 
Magnetic 
variations. 
1750  0+10 
1761-5+0-5 
1770-0+0-5 
1779-5  +  0-5 
1788  5  +  0  5 
18040  +  1  0 
1816-8  +  0-5 
1829-5+0  5 
1837-2  +  05 
1848-6+05 
1860-2  + 
17872 +  10 
1803-5  +  10 
1817-5  +  10 
1829-7+0-5 
18377+0-5 
1848-9+0-3 
18600+0-3 
1755-7+05 
1766  5+0-5 
!     1775-8+0-5 
;     1784-8  +  0-5 
1798-5+0  5 
1810-5+0-5 
1823-2  +  0-5 
1833-8+0-2 
1844-8+0-2 
1856-2  +  0-2 
1 
1784-5+0-5 
17990+2-0 
1823-8  +  1-0 
1844-2  +  0-5 
18563+0-3 
u  If  we  consider,  first,  the  epochs  corresponding  to  the  sim- 
l'ogg.  Ann*  vol.  cxvii.  \).  502  (1862). 
