﻿510 
  PROFESSOR 
  PIAZZI 
  SMYTH 
  ON 
  THE 
  

  

  result 
  was 
  obtained 
  when 
  a 
  circular 
  plate 
  was 
  made 
  to 
  eclipse 
  the 
  sun's 
  image 
  in 
  

   the 
  focus 
  of 
  the 
  telescope, 
  and 
  I 
  looked 
  directly 
  into 
  the 
  eyepiece. 
  But 
  hardly 
  

   any 
  other 
  result 
  could 
  well 
  be 
  expected, 
  as 
  however 
  dark 
  the 
  room 
  might 
  be 
  

   kept 
  by 
  the 
  apparatus 
  employed, 
  that 
  in 
  no 
  wise 
  checked 
  the 
  illumination 
  of 
  the 
  

   atmosphere 
  outside, 
  in 
  the 
  apparent 
  neighbourhood 
  of 
  the 
  sun, 
  the 
  daylight, 
  in 
  

   fact 
  ; 
  and 
  this 
  was 
  always 
  so 
  bright, 
  that 
  no 
  object 
  of 
  the 
  reputed 
  faintness 
  of 
  

   these 
  red 
  prominences 
  could 
  well 
  appear 
  on 
  so 
  luminous 
  a 
  background. 
  

  

  There 
  is 
  only 
  one 
  way 
  of 
  getting 
  over 
  this 
  difficulty 
  ; 
  i. 
  e., 
  taking 
  the 
  telescope 
  

   to 
  the 
  top 
  of 
  a 
  high 
  mountain, 
  above 
  all 
  grosser 
  parts 
  of 
  the 
  atmosphere. 
  Other 
  

   circumstances 
  have 
  lately 
  compelled 
  me 
  to 
  request 
  leave 
  from 
  Government 
  to 
  

   take 
  the 
  Edinburgh 
  Equatorial 
  temporarily 
  to 
  the 
  top 
  of 
  the 
  Peak 
  of 
  Teneriffe 
  ; 
  and 
  

   if 
  allowed 
  to 
  do 
  so, 
  it 
  shall 
  be 
  one 
  of 
  my 
  first 
  cares 
  to 
  repeat 
  this 
  experiment. 
  

  

  This 
  mode 
  undoubtedly 
  would 
  not 
  be 
  perfect, 
  none 
  would 
  unless 
  tried 
  alto- 
  

   gether 
  above 
  the 
  limits 
  of 
  the 
  atmosphere 
  ; 
  but 
  it 
  would 
  certainly 
  be 
  a 
  great 
  im- 
  

   provement 
  on 
  anything 
  done 
  on 
  the 
  surface 
  of 
  the 
  earth 
  at 
  the 
  level 
  of 
  the 
  sea, 
  

   and 
  might 
  perhaps 
  be 
  found 
  sufficient 
  for 
  the 
  object 
  in 
  view. 
  All 
  travellers 
  who 
  

   have 
  ascended 
  high 
  mountains, 
  combine 
  in 
  speaking 
  of 
  the 
  greater 
  blackness 
  of 
  

   the 
  sky 
  witnessed 
  in 
  those 
  elevated 
  regions, 
  as 
  well 
  as 
  of 
  the 
  sun 
  becoming 
  

   more 
  luminous 
  and 
  more 
  concentrated 
  as 
  to 
  his 
  rays, 
  and 
  of 
  stars 
  becoming 
  

   visible 
  to 
  the 
  naked 
  eye 
  by 
  day. 
  Captain 
  Hodges, 
  at 
  the 
  height 
  of 
  15,000 
  feet 
  

   on 
  the 
  Himalayas, 
  saw, 
  with 
  a 
  two-inch 
  object-glass, 
  stars 
  of 
  the 
  fifth 
  magnitude 
  

   in 
  the 
  open 
  sunshine 
  : 
  but 
  on 
  the 
  Calton 
  Hill, 
  with 
  the 
  smoke 
  of 
  Edinburgh 
  more 
  

   or 
  less 
  diffused 
  through 
  the 
  air, 
  stars 
  of 
  the 
  first 
  magnitude 
  are 
  frequently 
  in- 
  

   visible, 
  in 
  our 
  pale 
  blue 
  sky, 
  to 
  a 
  six-inch 
  object-glass; 
  thus 
  making 
  a 
  difference 
  

   in 
  favour 
  of 
  the 
  mountain 
  station, 
  of 
  at 
  least 
  100 
  to 
  1. 
  I 
  have 
  not 
  myself 
  had 
  

   experience 
  of 
  such 
  great 
  heights, 
  but 
  have 
  observed 
  for 
  months 
  at 
  the 
  altitude 
  

   of 
  6000 
  feet, 
  and 
  from 
  the 
  improvement 
  in 
  the 
  transparency 
  of 
  the 
  atmosphere 
  

   up 
  to 
  that 
  point, 
  can 
  well 
  believe 
  what 
  has 
  been 
  related 
  of 
  the 
  higher 
  station. 
  

  

  Thus 
  far 
  I 
  have 
  gone 
  on 
  the 
  supposition 
  that 
  it 
  was 
  right 
  and 
  proper 
  to 
  attach 
  

   great 
  importance 
  to 
  the 
  conclusions 
  of 
  the 
  actual 
  observers, 
  that 
  the 
  red 
  promi- 
  

   nences 
  were 
  actual 
  material 
  bodies. 
  This, 
  however, 
  has 
  not 
  been 
  proved 
  ; 
  and 
  

   we 
  cannot 
  be 
  too 
  careful 
  in 
  guarding 
  against 
  the 
  deceptive 
  effects 
  of 
  objects 
  close 
  

   by. 
  Now 
  it 
  is 
  not 
  difficult 
  to 
  suppose 
  some 
  partial 
  diffractions 
  of 
  the 
  sun's 
  light 
  

   amongst 
  the 
  craggy 
  mountains 
  of 
  the 
  moon, 
  during 
  the 
  total 
  eclipse, 
  which 
  might 
  

   make 
  some 
  rays 
  diverge, 
  and 
  become 
  visible 
  in 
  an 
  anomalous 
  manner. 
  Accord- 
  

   ingly, 
  I 
  introduced 
  into 
  the 
  focus 
  of 
  the 
  object-glass 
  a 
  small 
  sphere, 
  which 
  was 
  

   made 
  to 
  pass 
  before 
  and 
  so 
  eclipse 
  the 
  sun's 
  image, 
  as 
  in 
  the 
  natural 
  pheno- 
  

   menon. 
  

  

  The 
  results 
  were, 
  that 
  light 
  of 
  a 
  pink 
  colour 
  was 
  thrown 
  off 
  from 
  the 
  edge 
  of 
  

   the 
  sphere, 
  and 
  in 
  greater 
  quantity 
  as 
  the 
  polish 
  of 
  the 
  surface 
  was 
  higher 
  ; 
  in 
  a 
  

   complete 
  ring 
  if 
  the 
  surface 
  was 
  smooth, 
  and 
  in 
  detached 
  portions 
  if 
  the 
  surface 
  

  

  