﻿TOTAL 
  SOLAR 
  ECLIPSE 
  OF 
  1851. 
  50.9 
  

  

  to 
  do 
  too 
  much, 
  and 
  with 
  insufficient 
  means. 
  He 
  tried 
  to 
  give 
  an 
  account 
  of 
  all 
  

   the 
  prominences 
  all 
  round 
  the 
  sun's 
  limb, 
  as 
  well 
  as 
  to 
  observe 
  the 
  instants 
  of 
  

   beginning 
  and 
  ending 
  of 
  the 
  totality, 
  and 
  judge 
  of 
  darkness 
  over 
  the 
  landscape, 
  

   &c, 
  &c. 
  ; 
  — 
  his 
  main 
  instrument 
  being, 
  too, 
  a 
  small 
  telescope, 
  with 
  generally 
  some 
  

   inferior 
  style 
  of 
  altitude 
  azimuth 
  mounting. 
  

  

  Now, 
  a 
  little 
  experience 
  would 
  shew, 
  that 
  a 
  firm 
  and 
  clock-moved 
  equatorial, 
  

   with 
  micrometer 
  and 
  lamp 
  apparatus, 
  is 
  a 
  sine 
  qua 
  non 
  ; 
  and 
  that 
  with 
  this 
  appa- 
  

   ratus 
  an 
  observer 
  should 
  confine 
  himself 
  to 
  a 
  single 
  red 
  prominence, 
  and 
  get 
  a 
  

   numerous 
  series 
  of 
  measures 
  of 
  it 
  throughout 
  its 
  period 
  of 
  visibility. 
  On 
  the 
  

   records 
  of 
  such 
  measures 
  a 
  safe 
  theory 
  might 
  be 
  erected. 
  

  

  But, 
  if 
  we 
  are 
  never 
  to 
  see 
  these 
  red 
  prominences, 
  except 
  during 
  the 
  very 
  un 
  

   frequent 
  phenomenon 
  of 
  a 
  total 
  solar 
  eclipse, 
  ages 
  may 
  pass 
  away 
  before 
  we 
  know 
  

   much, 
  and 
  if 
  they 
  be 
  real, 
  they 
  must 
  play 
  some 
  important 
  part 
  in 
  the 
  great 
  

   mystery 
  of 
  the 
  economy 
  of 
  the 
  solar 
  light 
  and 
  heat. 
  Astronomers 
  are 
  bound, 
  there- 
  

   fore, 
  to 
  exert 
  themselves 
  to 
  the 
  utmost, 
  in 
  contriving 
  methods 
  which 
  shall 
  make 
  

   these 
  prominences 
  visible 
  at 
  all 
  times 
  ; 
  and 
  Mr 
  James 
  Nasmyth, 
  C.E., 
  having 
  sug- 
  

   gested 
  to 
  me 
  a 
  method 
  by 
  which 
  he 
  hoped 
  the 
  end 
  in 
  view 
  might 
  be 
  effected, 
  I 
  lost 
  

   no 
  time 
  in 
  putting 
  it 
  into 
  execution. 
  The 
  method 
  consisted 
  in 
  pointing 
  a 
  tele- 
  

   scope 
  to 
  the 
  sun 
  from 
  a 
  dark 
  room, 
  and 
  therein 
  receiving 
  the 
  image 
  of 
  the 
  field 
  

   of 
  view 
  on 
  the 
  top 
  of 
  a 
  box, 
  painted 
  black 
  inside. 
  A 
  circular 
  hole, 
  a 
  little 
  larger 
  

   than 
  the 
  sun's 
  image, 
  being 
  then 
  made 
  in 
  the 
  lid, 
  the 
  solar 
  light 
  passes 
  through, 
  

   is 
  completely 
  absorbed 
  on 
  the 
  sides 
  of 
  the 
  box, 
  and 
  the 
  picture 
  of 
  the 
  annular 
  por- 
  

   tion 
  of 
  the 
  field, 
  between 
  its 
  boundaries 
  and 
  the 
  sun's, 
  i.e., 
  the 
  blue 
  sky 
  adjacent 
  to 
  

   the 
  sun, 
  can 
  be 
  examined 
  at 
  leisure, 
  and 
  in 
  comparative 
  darkness, 
  so 
  that 
  a 
  faint 
  

   light 
  projecting 
  from 
  the 
  solar 
  orb, 
  anything 
  in 
  the 
  shape 
  of 
  a 
  ray 
  or 
  red 
  promi- 
  

   nence, 
  would 
  have 
  much 
  greater 
  chance 
  of 
  being 
  seen. 
  

  

  Mr 
  Nasmyth 
  having 
  no 
  means 
  at 
  command 
  to 
  try 
  his 
  proposed 
  experiment, 
  I 
  

   put 
  it 
  into 
  execution 
  myself 
  in 
  the 
  Edinburgh 
  Observatory. 
  The 
  shutters 
  in 
  the 
  

   dome 
  were 
  furnished 
  with 
  screens 
  and 
  tubes, 
  allowing 
  no 
  sunlight 
  to 
  enter 
  the 
  room, 
  

   but 
  what 
  passed 
  through 
  the 
  object-glass 
  of 
  the 
  telescope 
  ; 
  and 
  this 
  was 
  9 
  feet 
  

   long, 
  by 
  6 
  inches 
  in 
  diameter, 
  was 
  moved 
  by 
  clockwork, 
  and 
  carried 
  near 
  the 
  eye- 
  

   end, 
  on 
  an 
  adjustable 
  arm, 
  a 
  large 
  light 
  box 
  lined 
  with 
  black 
  velvet, 
  and 
  having 
  

   a 
  hole 
  in 
  the 
  top. 
  The 
  image 
  of 
  the 
  sky, 
  in 
  all 
  but 
  contact 
  with 
  the 
  sun, 
  was 
  

   then 
  received 
  and 
  examined 
  on 
  the 
  surface 
  of 
  the 
  lid 
  round 
  about 
  the 
  hole, 
  into 
  

   which 
  the 
  sun's 
  rays 
  passed 
  and 
  were 
  lost. 
  So 
  far 
  as 
  the 
  apparatus 
  was 
  con- 
  

   cerned, 
  everything 
  answered 
  to 
  admiration, 
  for 
  when 
  the 
  sun's 
  image 
  was 
  actually 
  

   thrown 
  into 
  the 
  dark 
  box, 
  the 
  general 
  illumination 
  of 
  the 
  room 
  was 
  certainly 
  

   much 
  fainter 
  than 
  that 
  of 
  the 
  air 
  during 
  the 
  total 
  eclipse. 
  

  

  But 
  notwithstanding 
  this, 
  and 
  though 
  I 
  have 
  tried 
  it 
  carefully 
  on 
  all 
  the 
  

   finest 
  days 
  of 
  the 
  autumn 
  of 
  1851, 
  and 
  the 
  summer 
  of 
  1852, 
  I 
  have 
  seen 
  nothing 
  

   of 
  any 
  prominent 
  matter 
  beyond 
  the 
  photosphere 
  of 
  the 
  sun. 
  The 
  same 
  negative 
  

  

  