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

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

  

  (Read 
  April 
  19, 
  1852.) 
  

  

  In 
  the 
  first 
  part 
  of 
  this 
  paper, 
  I 
  have 
  endeavoured 
  to 
  prove, 
  that 
  the 
  red 
  pro- 
  

   minences 
  seen 
  during 
  total 
  solar 
  eclipses, 
  exist 
  in 
  the 
  sun 
  ; 
  and 
  I 
  now 
  propose 
  to 
  

   state 
  some 
  views 
  which 
  have 
  occurred 
  to 
  me 
  as 
  to 
  the 
  nature 
  of 
  those 
  remarkable 
  

   objects, 
  and 
  their 
  possible 
  connexion 
  with 
  other 
  solar 
  phenomena. 
  It 
  is 
  not, 
  

   however, 
  without 
  great 
  misgivings 
  that 
  I 
  venture 
  on 
  this 
  subject 
  ; 
  for 
  we 
  know 
  so 
  

   little 
  of 
  the 
  sun, 
  that 
  any 
  hypothesis 
  regarding 
  the 
  constitution 
  of 
  his 
  atmosphere, 
  

   can 
  amount 
  only 
  to 
  a 
  conjecture, 
  possessing 
  more 
  or 
  less 
  probability 
  according 
  to 
  

   the 
  variety 
  of 
  the 
  appearances 
  it 
  serves 
  to 
  explain, 
  and 
  the 
  exactness 
  with 
  which 
  

   theory 
  and 
  observation 
  correspond 
  in 
  each 
  case 
  : 
  and 
  I 
  am 
  well 
  aware 
  that 
  views 
  

   which 
  may 
  seem 
  probable 
  to 
  myself 
  may 
  not 
  appear 
  equally 
  so 
  to 
  others, 
  whose 
  

   greater 
  experience 
  in 
  observing 
  the 
  sun 
  constitutes 
  them 
  better 
  judges 
  of 
  such 
  

   questions. 
  

  

  1. 
  On 
  the 
  Nature 
  of 
  the 
  Red 
  Prominences, 
  and 
  their 
  Mode 
  of 
  Distribution 
  in 
  the 
  Solar 
  

  

  Atmosphere. 
  

  

  For 
  the 
  reasons 
  stated 
  in 
  the 
  first 
  part 
  of 
  this 
  paper, 
  I 
  shall 
  assume 
  that 
  the 
  

   red 
  prominences 
  exist 
  in 
  the 
  sun's 
  atmosphere. 
  They 
  must, 
  then, 
  to 
  use 
  the 
  words 
  

   of 
  Sir 
  John 
  Herschel, 
  be 
  " 
  cloudy 
  masses, 
  of 
  the 
  most 
  excessive 
  tenuity 
  ;" 
  * 
  for 
  being 
  

   placed 
  so 
  near 
  the 
  sun, 
  if 
  their 
  density 
  approached 
  that 
  of 
  the 
  rarest 
  terrestrial 
  

   clouds, 
  they 
  could 
  not 
  fail 
  to 
  reflect 
  an 
  intensely 
  brilliant 
  light. 
  Now 
  this 
  is 
  far 
  

   from 
  being 
  the 
  case 
  ; 
  for 
  although 
  they 
  are 
  by 
  no 
  means 
  faint 
  objects, 
  neither 
  are 
  

   they 
  very 
  bright 
  ones. 
  

  

  Another 
  circumstance, 
  which 
  proves 
  that 
  the 
  red 
  prominences 
  are 
  gaseous 
  and 
  

   not 
  solid 
  bodies, 
  is 
  the 
  overhanging 
  form 
  sometimes 
  assumed 
  by 
  them, 
  which, 
  in 
  

   the 
  case 
  of 
  solid 
  bodies, 
  would 
  result 
  in 
  the 
  impending 
  portions 
  breaking 
  off, 
  and 
  

   falling 
  under 
  the 
  action 
  of 
  the 
  sun's 
  gravitation 
  ; 
  and 
  the 
  same 
  conclusion 
  follows 
  

   inevitably 
  from 
  the 
  appearance, 
  at 
  the 
  late 
  eclipse, 
  of 
  a 
  red 
  mass 
  completely 
  de- 
  

   tached 
  from 
  the 
  moon's 
  limb, 
  and 
  therefore 
  evidently 
  floating 
  in 
  the 
  sun's 
  atmo- 
  

   sphere, 
  f 
  

  

  The 
  red 
  prominences 
  being 
  thus 
  obviously 
  vaporous 
  masses, 
  I 
  shall 
  inquire, 
  

   first, 
  into 
  the 
  manner 
  of 
  their 
  distribution 
  in 
  the 
  solar 
  atmosphere. 
  Now 
  the 
  ob- 
  

  

  * 
  Herschel's 
  Outlines 
  of 
  Astronomy, 
  par. 
  395. 
  

  

  f 
  M. 
  Arago 
  reasons 
  in 
  the 
  same 
  manner, 
  in 
  the 
  Annuaire 
  for 
  1852, 
  p. 
  344. 
  

  

  VOL. 
  XX. 
  PART 
  III. 
  6 
  H 
  

  

  