﻿F. 
  H. 
  Bigelow 
  — 
  Solar 
  Corona. 
  5 
  

  

  172° 
  59' 
  

   173 
  56 
  

   175 
  23 
  

  

  Mean, 
  174° 
  6' 
  

  

  This 
  will 
  enable 
  us 
  to 
  compute 
  the 
  position 
  of 
  the 
  center 
  of 
  

   polarization 
  of 
  the 
  sun, 
  which 
  is 
  seen 
  to 
  be 
  considerably 
  eccen- 
  

   tric, 
  and 
  from 
  this 
  our 
  second 
  approximation 
  begins. 
  It 
  should 
  

   be 
  mentioned 
  that 
  although 
  the 
  existing 
  photographs 
  have 
  

   served 
  our 
  purpose, 
  and 
  given 
  results 
  more 
  satisfactory 
  than 
  

   was 
  anticipated, 
  yet 
  no 
  pains 
  should 
  be 
  spared 
  at 
  approaching 
  

   eclipses 
  to 
  produce 
  pictures 
  of 
  much 
  greater 
  power 
  than 
  those 
  

   we 
  now 
  possess. 
  For 
  this 
  subject 
  already 
  opens 
  up 
  a 
  vista 
  of 
  

   great 
  interest 
  in 
  studying 
  the 
  physical 
  nature 
  of 
  the 
  sun.* 
  

  

  From 
  the 
  results 
  that 
  have 
  been 
  quoted 
  we 
  may 
  draw 
  the 
  

   conclusion 
  that 
  the 
  axis 
  of 
  polarization 
  seems 
  to 
  be 
  fixed 
  in 
  the 
  

   body 
  of 
  the 
  sun, 
  the 
  difference 
  in 
  longitude 
  and 
  the 
  distance 
  

   measured 
  on 
  a 
  great 
  circle 
  being 
  constant, 
  within 
  the 
  errors 
  

   arising 
  from 
  the 
  measures, 
  for 
  epochs 
  extending 
  over 
  nearly 
  

   eleven 
  years. 
  Since 
  the 
  coordinates 
  of 
  position 
  of 
  the 
  poles 
  

   are 
  celestial, 
  we 
  have 
  only 
  to 
  compute 
  the 
  periodic 
  time 
  in 
  

   order 
  to 
  know 
  the 
  period 
  of 
  the 
  rotation 
  of 
  the 
  sun 
  at 
  a 
  

   distance 
  of 
  4J 
  degrees 
  from 
  the 
  axis 
  of 
  figure. 
  It 
  is 
  de- 
  

   sirable 
  that 
  this 
  should 
  be 
  done, 
  because 
  the 
  sun-spots, 
  from 
  

   which 
  such 
  a 
  period 
  is 
  obtained 
  for 
  the 
  equatorial 
  regions, 
  are 
  

   confined 
  to 
  about 
  35° 
  in 
  latitude, 
  and 
  we 
  shall 
  thus 
  be 
  able 
  to 
  

   pass 
  over 
  the 
  intervening 
  50° 
  to 
  the 
  neighborhood 
  of 
  the 
  solar 
  

   poles. 
  I 
  have 
  obtained 
  the 
  following 
  results 
  : 
  

  

  For 
  the 
  period 
  from 
  July 
  29, 
  1878 
  to 
  Jan. 
  1, 
  1889, 
  138 
  revolu- 
  

   tions 
  + 
  194°-69; 
  the 
  mean 
  daily 
  motion 
  is 
  13°*1353 
  in 
  longitude, 
  

  

  For 
  the 
  period 
  from 
  July 
  29, 
  1878 
  to 
  Dec. 
  22, 
  1889, 
  151 
  revolu 
  

   tions 
  +166°-68 
  ; 
  the 
  mean 
  daily 
  motion 
  is 
  13°*1312 
  in 
  longitude 
  

  

  For 
  the 
  period 
  from 
  Jan. 
  1, 
  1889 
  to 
  Dec. 
  22, 
  1889, 
  12 
  revolu- 
  

   tions 
  + 
  331 
  0, 
  99; 
  the 
  mean 
  daily 
  motion 
  is 
  13 
  o, 
  0876 
  in 
  longitude. 
  

  

  As 
  my 
  conditions 
  are 
  of 
  equal 
  weight 
  for 
  each 
  eclipse, 
  a 
  least 
  

   square 
  solution 
  gives 
  me 
  for 
  mean 
  daily 
  motion 
  in 
  longitude 
  

   13°-13307=788 
  / 
  , 
  at 
  latitude 
  85°-5. 
  

   This 
  gives 
  for 
  the 
  

  

  Siderial 
  Period, 
  27 
  d 
  '41171 
  = 
  27 
  da 
  ^ 
  s 
  9 
  h 
  52 
  m 
  52 
  s 
  , 
  

   Synodic 
  Period. 
  29 
  d, 
  63580 
  = 
  29 
  da 
  ^ 
  s 
  15 
  h 
  15 
  m 
  33 
  s 
  , 
  

  

  in 
  mean 
  solar 
  time. 
  I 
  propose 
  the 
  following 
  formula 
  for 
  the 
  

   rotation 
  period 
  of 
  the 
  solar 
  surface 
  at 
  different 
  latitudes, 
  as 
  

  

  * 
  A 
  paper 
  containing 
  the 
  details 
  of 
  the 
  work 
  by 
  which 
  these 
  results 
  were 
  ob- 
  

   tained, 
  will 
  be 
  found 
  in 
  the 
  Proceedings 
  of 
  the 
  Astronomical 
  Society 
  of 
  the 
  

   Pacific, 
  23 
  o. 
  17. 
  

  

  