﻿RED 
  PROMINENCES 
  SEEN 
  DURING 
  TOTAL 
  ECLIPSES 
  OF 
  THE 
  SUN. 
  449 
  

  

  3. 
  On 
  the 
  Hypothesis 
  which 
  would 
  refer 
  the 
  Phenomenon 
  of 
  the 
  Red 
  Prominences 
  to 
  the 
  

   Action 
  of 
  the 
  Moons 
  Limb 
  on 
  the 
  Sim's 
  Rays. 
  

  

  If 
  we 
  suppose 
  the 
  prominences 
  to 
  be 
  caused 
  by 
  some 
  action 
  of 
  the 
  moon's 
  limb 
  

   on 
  the 
  rays 
  of 
  light, 
  whatever 
  hypothesis 
  we 
  form 
  regarding 
  the 
  precise 
  nature 
  of 
  

   that 
  action, 
  it 
  is 
  evident, 
  that 
  the 
  effect 
  produced 
  will 
  depend 
  in 
  some 
  way 
  upon 
  

   the 
  relative 
  positions 
  of 
  the 
  luminous 
  object, 
  — 
  of 
  the 
  body 
  acting 
  on 
  its 
  light, 
  — 
  and 
  

   of 
  the 
  observer' 
  s 
  eye. 
  Any 
  change 
  in 
  the 
  position 
  of 
  the 
  observer 
  relatively 
  to 
  

   the 
  sun 
  and 
  moon, 
  would 
  seem 
  to 
  necessitate 
  some 
  change 
  in 
  the 
  appearance 
  of 
  

   the 
  red 
  prominences, 
  supposing 
  them 
  optical 
  phenomena 
  of 
  the 
  nature 
  of 
  reflexion 
  

   or 
  diffraction 
  ; 
  and 
  these 
  are 
  the 
  only 
  known 
  species 
  of 
  phenomena 
  which 
  the 
  

   action 
  of 
  the 
  moon's 
  limb 
  on 
  the 
  sun's 
  light 
  would 
  occasion. 
  

  

  Now, 
  as 
  the 
  moon 
  and 
  earth 
  are 
  in 
  rapid 
  motion, 
  the 
  position 
  of 
  an 
  observer 
  

   relatively 
  to 
  the 
  line 
  joining 
  their 
  centres 
  is 
  continually 
  changing 
  ; 
  and 
  in 
  order 
  

   to 
  see 
  the 
  supposed 
  optical 
  phenomena 
  always 
  from 
  the 
  same 
  point 
  of 
  view, 
  it 
  

   would 
  literally 
  become 
  necessary 
  for 
  him 
  to 
  run 
  a 
  race 
  with 
  the 
  moon's 
  shadow. 
  

   It 
  thus 
  seems 
  difficult 
  to 
  avoid 
  the 
  conclusion, 
  that 
  if 
  the 
  red 
  prominences 
  

   were 
  caused 
  by 
  the 
  action 
  of 
  the 
  moon's 
  limb 
  on 
  the 
  sun's 
  light, 
  their 
  appearance 
  

   should 
  rapidly 
  change 
  during 
  the 
  progress 
  of 
  the 
  eclipse. 
  But 
  it 
  has 
  already 
  been 
  

   seen, 
  that 
  their 
  forms 
  remained 
  unaltered 
  ; 
  and 
  it 
  is 
  therefore 
  in 
  the 
  last 
  degree 
  

   improbable 
  that 
  they 
  are 
  optical 
  phenomena, 
  caused 
  by 
  the 
  action 
  of 
  the 
  moon's 
  

   limb 
  on 
  the 
  sun's 
  light. 
  

  

  II. 
  On 
  the 
  Hypothesis 
  that 
  the 
  Med 
  Prominences 
  exist 
  in 
  the 
  Sun 
  or 
  Moon. 
  

  

  On 
  these 
  grounds 
  it 
  seems 
  impossible 
  to 
  regard 
  the 
  prominences 
  as 
  mere 
  

   optical 
  phenomena. 
  Let 
  us 
  now 
  inquire 
  whether 
  equal 
  difficulties 
  attend 
  the 
  sup- 
  

   position 
  that 
  they 
  are 
  objects 
  really 
  existing 
  in 
  the 
  sun 
  or 
  moon. 
  

  

  1 
  . 
  On 
  the 
  Discrepancies 
  in 
  the 
  Observed 
  Positions 
  of 
  the 
  Red 
  Prominences. 
  

  

  The 
  observers 
  of 
  the 
  late 
  eclipse 
  seem 
  frequently 
  to 
  have 
  adopted 
  no 
  better 
  

   means 
  of 
  ascertaining 
  the 
  angles 
  of 
  position 
  of 
  the 
  red 
  prominences, 
  than 
  estima- 
  

   tion 
  by 
  the 
  eye, 
  with 
  reference 
  either 
  to 
  the 
  sun's 
  vertex 
  or 
  north 
  point 
  ; 
  and 
  in 
  

   many 
  cases 
  the 
  point 
  of 
  reference 
  is 
  confessedly 
  only 
  roughly 
  estimated. 
  In 
  some 
  

   instances 
  also, 
  the 
  angles 
  have 
  been 
  merely 
  guessed 
  by 
  the 
  editor 
  of 
  the 
  Royal 
  

   Astronomical 
  Society's 
  Transactions, 
  from 
  the 
  drawings 
  furnished 
  by 
  the 
  ob- 
  

   servers 
  ;* 
  and 
  in 
  such 
  circumstances, 
  we 
  may 
  be 
  prepared 
  to 
  expect 
  notable 
  dis- 
  

   crepancies 
  in 
  the 
  observations. 
  

  

  In 
  other 
  cases, 
  however, 
  greater 
  care 
  was 
  taken 
  to 
  ensure 
  accuracy. 
  Thus 
  Mr 
  

   Dawes 
  observed 
  the 
  eclipse 
  with 
  a 
  telescope 
  equatorially 
  mounted, 
  having 
  cross 
  

  

  * 
  Royal 
  Ast. 
  Soc. 
  Notice, 
  p. 
  43. 
  

   VOL 
  XX. 
  PART 
  III. 
  6 
  E 
  

  

  