﻿RED 
  PROMINENCES 
  SEEN 
  DURING 
  TOTAL 
  ECLIPSES 
  OF 
  THE 
  SUN. 
  463 
  

  

  through 
  apertures, 
  such 
  as 
  i 
  k 
  fig. 
  10, 
  in 
  a 
  luminous 
  envelope, 
  a 
  b, 
  which 
  surrounds 
  

   him 
  ; 
  and 
  Sir 
  William 
  Herschel,* 
  to 
  explain 
  the 
  penumbra 
  which 
  generally 
  en- 
  

   circles 
  a 
  solar 
  spot, 
  considers 
  the 
  luminous 
  strata 
  to 
  be 
  sustained 
  far 
  above 
  the 
  

   level 
  of 
  the 
  sun's 
  solid 
  body, 
  by 
  a 
  transparent 
  elastic 
  medium, 
  carrying 
  on 
  its 
  

   upper 
  surface 
  (or 
  rather 
  at 
  some 
  considerably 
  lower 
  level 
  within 
  its 
  depth) 
  a 
  cloudy 
  

   stratum 
  c 
  d, 
  which 
  being 
  strongly 
  illuminated 
  from 
  above, 
  reflects 
  a 
  considerable 
  

   portion 
  of 
  light 
  to 
  our 
  eyes, 
  and 
  forms 
  the 
  penumbra, 
  while 
  the 
  solid 
  body 
  shaded 
  by 
  

   the 
  clouds 
  reflects 
  none. 
  The 
  temporary 
  removal 
  of 
  both 
  strata, 
  but 
  more 
  of 
  the 
  

   upper 
  than 
  the 
  lower, 
  as 
  represented 
  in 
  the 
  figure, 
  he 
  supposes 
  effected 
  by 
  power- 
  

   ful 
  upward 
  currents 
  of 
  the 
  atmosphere, 
  arising, 
  perhaps, 
  from 
  spiracles 
  in 
  the 
  

   body, 
  or 
  from 
  local 
  agitations. 
  f 
  

  

  Since, 
  then, 
  it 
  has 
  been 
  shewn 
  to 
  be 
  highly 
  probable 
  that 
  the 
  matter 
  compos- 
  

   ing 
  the 
  red 
  prominences 
  is 
  distributed 
  with 
  little 
  interruption 
  all 
  round 
  the 
  sun, 
  

   we 
  may 
  conceive 
  the 
  luminous 
  strata 
  of 
  the 
  solar 
  atmosphere 
  to 
  be 
  surmounted 
  

   by 
  an 
  envelope 
  (e/,) 
  of 
  clouds, 
  of 
  which 
  only 
  the 
  higher 
  portions 
  are 
  visible 
  beyond 
  

   the 
  moon's 
  limb, 
  at 
  the 
  central 
  phase 
  of 
  a 
  total 
  eclipse 
  ; 
  and 
  which 
  then 
  consti- 
  

   tute 
  the 
  red 
  prominences. 
  If 
  it 
  be 
  thought 
  that 
  the 
  hypothesis 
  of 
  two 
  envelopes 
  

   of 
  cloud, 
  one 
  above 
  and 
  another 
  below 
  the 
  luminous 
  strata 
  of 
  the 
  sun's 
  atmo- 
  

   sphere, 
  introduces 
  too 
  great 
  complication, 
  we 
  may 
  avoid 
  the 
  objection, 
  by 
  sup- 
  

   posing 
  that 
  the 
  envelope 
  which 
  occasions 
  the 
  penumbrae 
  around 
  the 
  spots 
  pene- 
  

   trates 
  the 
  luminous 
  stratum, 
  and 
  exists, 
  although 
  in 
  greatly 
  different 
  degrees 
  of 
  

   density, 
  both 
  above 
  and 
  below 
  it. 
  

  

  If, 
  then, 
  we 
  conceive 
  that 
  a 
  stratum 
  of 
  cloudy 
  matter 
  surrounds 
  the 
  sun, 
  of 
  

   which 
  the 
  red 
  prominences 
  are 
  the 
  higher 
  portions, 
  the 
  serrated 
  appearance 
  of 
  

   the 
  long 
  range 
  of 
  prominences, 
  seen 
  by 
  Mr 
  Dawes 
  and 
  Mr 
  Hind, 
  sufficiently 
  indi- 
  

   cates 
  that 
  its 
  general 
  surface 
  is 
  exceedingly 
  uneven, 
  presenting 
  the 
  appearance 
  of 
  

   being 
  covered 
  with 
  numerous 
  eminences 
  or 
  ridges. 
  But 
  these 
  irregularities 
  are 
  

   small 
  when 
  compared 
  with 
  the 
  large 
  hook-shaped 
  prominence, 
  and 
  its 
  companion 
  

   the 
  detached 
  cloud, 
  which 
  were 
  seen 
  by 
  most 
  of 
  the 
  observers 
  of 
  the 
  eclipse. 
  The 
  

   altitude 
  of 
  the 
  hook-shaped 
  prominence 
  has 
  been 
  variously 
  estimated 
  at 
  from 
  1*5 
  

   to 
  3'; 
  and, 
  by 
  actual 
  micrometrical 
  measurement, 
  it 
  was 
  found 
  to 
  be 
  1' 
  41"-5 
  just 
  

   before 
  the 
  sun 
  reappeared.;!: 
  Adopting 
  this 
  measurement, 
  its 
  actual 
  height 
  must 
  

   have 
  exceeded 
  47,000 
  miles, 
  or 
  about 
  six 
  times 
  the 
  diameter 
  of 
  the 
  earth. 
  The 
  

   existence 
  of 
  bodies 
  of 
  such 
  magnitude 
  indicates 
  some 
  immense 
  local 
  disturbance 
  in 
  

   the 
  sun's 
  atmosphere, 
  but 
  not 
  greater 
  than 
  that 
  indicated 
  by 
  the 
  solar 
  spots, 
  some 
  

   of 
  which 
  Sir 
  John 
  Herschel 
  states 
  to 
  have 
  been 
  observed, 
  " 
  whose 
  linear 
  dia- 
  

   meter 
  has 
  been 
  upwards 
  of 
  45,000 
  miles, 
  and 
  even, 
  if 
  some 
  records 
  are 
  to 
  be 
  

  

  * 
  Philosophical 
  Transactions, 
  1801. 
  f 
  Herschel's 
  Outlines 
  of 
  Astronomy, 
  par. 
  389. 
  

  

  J 
  This 
  is 
  the 
  mean 
  of 
  observations 
  by 
  Mr 
  Williams 
  and 
  Mr 
  Stannistreet. 
  Notice 
  of 
  R. 
  Ast, 
  

   Soc. 
  for 
  January 
  1852, 
  pp. 
  54, 
  55. 
  

  

  