﻿6 
  F. 
  II. 
  Bigelow 
  — 
  Solar 
  Corona. 
  

  

  derived 
  from 
  the 
  mean 
  daily 
  motion 
  in 
  longitude 
  given 
  by 
  

   observations 
  of 
  the 
  sun-spots 
  and 
  by 
  computation 
  at 
  the 
  coronal 
  

   pole. 
  

  

  X 
  = 
  862' 
  — 
  76' 
  sin/, 
  where 
  X 
  is 
  the 
  mean 
  daily 
  motion 
  in 
  

   minutes 
  and 
  I 
  is 
  the 
  solar 
  latitude. 
  

  

  Other 
  formula 
  have 
  been 
  given 
  : 
  

  

  Faye, 
  X 
  = 
  862 
  — 
  186 
  sin 
  2 
  I. 
  

  

  Tisserand, 
  =857-6 
  — 
  157 
  "3 
  sin 
  2 
  I. 
  

   Spoerer, 
  =1011—203 
  sin 
  (41 
  6 
  -f-/). 
  

  

  Latitude. 
  

  

  Faye. 
  

  

  Tisserand. 
  

  

  Spoerer. 
  

  

  Bigelow. 
  

  

  Siderial 
  Period 
  

   in 
  days. 
  

  

  0° 
  

  

  863' 
  

  

  S58' 
  

  

  878 
  

  

  862-0 
  

  

  25-0577 
  

  

  10 
  

  

  857 
  

  

  853 
  

  

  853 
  

  

  848-8 
  

  

  25-4470 
  

  

  20 
  

  

  841 
  

  

  839 
  

  

  833 
  

  

  836-0 
  

  

  25-8370 
  

  

  30 
  

  

  816 
  

  

  818 
  

  

  819 
  

  

  824-0 
  

  

  26-2131 
  

  

  40 
  

  

  786 
  

  

  793 
  

  

  810 
  

  

  813-2 
  ■ 
  

  

  26-5613 
  

  

  50 
  

  

  754 
  

  

  765 
  

  

  808 
  

  

  803-8 
  

  

  26-8729 
  

  

  60 
  

  

  723 
  

  

  740 
  

  

  812 
  

  

  796-2 
  

  

  27*1288 
  

  

  70 
  

  

  699 
  

  

  719 
  

  

  821 
  

  

  790-6 
  

  

  27-3206 
  

  

  80 
  

  

  683 
  

  

  705 
  

  

  837 
  

  

  787*2 
  

  

  27-4386 
  

  

  90 
  

  

  677 
  

  

  700 
  

  

  858 
  

  

  786-0 
  

  

  27-4806 
  

  

  If 
  we 
  compute 
  back 
  to 
  the 
  epoch 
  1878*0 
  we 
  find 
  the 
  residuals 
  

   in 
  longitude 
  for 
  the 
  three 
  coronas, 
  

  

  North 
  Pole. 
  South 
  Pole. 
  

   July 
  29, 
  1878, 
  — 
  0°-9 
  + 
  0°*5 
  

  

  Jan. 
  1, 
  1889, 
  + 
  7 
  '9 
  +8'4 
  

  

  Doc. 
  22, 
  1889, 
  —7 
  '0 
  —8 
  -9 
  

  

  I 
  adopt 
  a 
  c 
  the 
  longitude 
  for 
  1878*0, 
  

  

  North 
  Pole, 
  201°*2. 
  

   South 
  Pole, 
  301°*6. 
  

  

  days. 
  

  

  Siderial 
  Period, 
  27*41171. 
  

  

  We 
  can 
  now 
  readily 
  locate 
  the 
  position 
  of 
  the 
  coronal 
  poles 
  

   at 
  any 
  epoch, 
  and 
  I 
  have 
  done 
  so 
  for 
  several 
  past 
  eclipses 
  in 
  

   order 
  that 
  comparison 
  may 
  be 
  made 
  between 
  a 
  model 
  and 
  the 
  

   pictures 
  obtained 
  during 
  the 
  totalities 
  of 
  the 
  eclipses. 
  The 
  

   model 
  was 
  constructed 
  in 
  the 
  following 
  manner. 
  The 
  body 
  of 
  

   the 
  sun 
  is 
  represented 
  by 
  a 
  five-inch 
  globe. 
  In 
  the 
  region 
  of 
  

   the 
  coronal 
  zones 
  three 
  parallels 
  of 
  coronal 
  polar 
  distance 
  are 
  

   taken, 
  29°, 
  34°, 
  39°, 
  and 
  on 
  these 
  somewhat 
  at 
  random, 
  are 
  in- 
  

   serted 
  wires 
  having 
  the 
  proper 
  form. 
  Their 
  curvature 
  and 
  

   their 
  inclination 
  to 
  the 
  normals 
  of 
  the 
  sphere 
  were 
  calculated 
  

   from 
  the 
  formulae, 
  a 
  graphic 
  representation 
  of 
  the 
  locus 
  of 
  the 
  

   curves 
  made 
  for 
  a 
  pattern, 
  and 
  the 
  wires 
  bent 
  accordingly. 
  

  

  