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  XXIX. 
  — 
  On 
  the 
  Red 
  Prominences 
  seen 
  during 
  Total 
  Eclipses 
  of 
  the 
  Sun. 
  

   Part 
  I. 
  By 
  William 
  Swan, 
  F.R.S.E. 
  

  

  (Read 
  April 
  5, 
  1852.) 
  

  

  The 
  red 
  prominences 
  seen 
  during 
  total 
  solar 
  eclipses, 
  are 
  conspicuous 
  rose- 
  

   coloured 
  objects 
  which 
  appear 
  round 
  the 
  dark 
  edge 
  of 
  the 
  moon, 
  as 
  soon 
  as 
  the 
  last 
  

   rays 
  of 
  the 
  sun 
  have 
  disappeared. 
  In 
  preparing 
  my 
  account 
  of 
  the 
  total 
  eclipse 
  of 
  

   the 
  28th 
  July 
  1851, 
  it 
  was 
  at 
  first 
  my 
  intention 
  to 
  have 
  stated 
  some 
  hypothetical 
  

   views 
  which 
  I 
  had 
  formed 
  regarding 
  those 
  remarkable 
  objects, 
  and 
  other 
  appear- 
  

   ances 
  I 
  had 
  observed 
  during 
  the 
  total 
  phase 
  of 
  the 
  eclipse. 
  I 
  found, 
  however, 
  that 
  

   the 
  mere 
  description 
  of 
  phenomena 
  extended 
  to 
  so 
  great 
  a 
  length, 
  as 
  to 
  render 
  

   such 
  a 
  course 
  inexpedient 
  ; 
  and 
  I 
  have 
  since 
  delayed 
  resuming 
  the 
  subject, 
  in 
  

   order 
  that 
  by 
  comparing 
  a 
  number 
  of 
  other 
  observations 
  with 
  my 
  own, 
  I 
  might 
  

   be 
  enabled, 
  either 
  to 
  confirm 
  or 
  to 
  modify 
  my 
  views. 
  

  

  The 
  object 
  of 
  the 
  first 
  part 
  of 
  this 
  paper 
  is, 
  To 
  discuss 
  the 
  evidence 
  afforded 
  

   by 
  the 
  observations 
  of 
  the 
  late 
  eclipse 
  to 
  which 
  I 
  have 
  obtained 
  access, 
  as 
  to 
  the 
  

   nature 
  and 
  locality 
  of 
  the 
  red 
  prominences 
  ; 
  and, 
  of 
  the 
  second 
  part, 
  To 
  state 
  the 
  

   views 
  which 
  I 
  have 
  been 
  led 
  to 
  form 
  regarding 
  the 
  cause 
  of 
  those 
  singular 
  objects, 
  

   and 
  their 
  probable 
  connexion 
  with 
  other 
  solar 
  phenomena. 
  

  

  In 
  inquiring 
  into 
  the 
  nature 
  of 
  the 
  red 
  prominences, 
  I 
  shall 
  examine 
  in 
  suc- 
  

   cession 
  different 
  opinions, 
  which 
  have 
  either 
  been 
  formally 
  announced, 
  or 
  are 
  

   likely 
  to 
  be 
  entertained, 
  regarding 
  them, 
  in 
  order 
  to 
  ascertain 
  which 
  of 
  those 
  hypo- 
  

   theses 
  is 
  most 
  accordant 
  with 
  actual 
  observation. 
  The 
  hypotheses 
  I 
  shall 
  discuss 
  

   are 
  the 
  following, 
  namely, 
  1st, 
  That 
  the 
  prominences 
  are 
  optical 
  phenomena, 
  caused 
  

   by 
  the 
  telescope 
  used 
  in 
  viewing 
  the 
  eclipse, 
  — 
  by 
  the 
  unequally 
  heated 
  state 
  of 
  

   the 
  earth's 
  atmosphere, 
  — 
  or 
  by 
  the 
  action 
  of 
  the 
  moon's 
  edge 
  on 
  the 
  rays 
  of 
  light; 
  

   and, 
  2d, 
  That 
  they 
  are 
  material 
  objects, 
  existing 
  in 
  the 
  sun 
  or 
  in 
  the 
  moon. 
  

  

  I. 
  On 
  the 
  Hypothesis 
  that 
  the 
  Med 
  Prominences 
  are 
  Optical 
  Phenomena. 
  

  

  1 
  . 
  On 
  the 
  Visibility 
  of 
  the 
  Red 
  Prominences 
  to 
  the 
  Naked 
  Eye. 
  

  

  1. 
  It 
  may 
  be 
  supposed 
  that 
  the 
  red 
  prominences 
  are 
  optical 
  phenomena 
  caused 
  

   by 
  the 
  telescope 
  used 
  in 
  viewing 
  the 
  eclipse 
  ; 
  but 
  this 
  opinion 
  is 
  at 
  once 
  disproved 
  

   by 
  the 
  fact, 
  that 
  they 
  are 
  visible 
  to 
  the 
  naked 
  eye. 
  At 
  the 
  late 
  eclipse, 
  although 
  

   I 
  was 
  unable 
  to 
  distinguish 
  the 
  forms 
  of 
  the 
  prominences 
  with 
  the 
  naked 
  eye, 
  

   I 
  had 
  no 
  difficulty 
  in 
  seeing 
  the 
  position 
  of 
  at 
  least 
  one 
  of 
  them, 
  by 
  the 
  strong 
  

   red 
  tinge 
  it 
  imparted 
  to 
  the 
  adjacent 
  portions 
  of 
  the 
  corona. 
  It 
  was 
  also 
  seen 
  by 
  

   Mr 
  Lane, 
  who 
  observed 
  the 
  eclipse 
  along 
  with 
  me. 
  Mr 
  Adie 
  saw 
  the 
  same 
  pro- 
  

  

  VOL. 
  XX. 
  PART 
  III. 
  6 
  D 
  

  

  