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  XXXIV.— 
  On 
  the 
  Total 
  Solar 
  Eclipse 
  of 
  \8bl. 
  By 
  Professor 
  C. 
  Piazzi 
  Smyth. 
  

  

  (Read 
  December 
  1, 
  1851.) 
  

  

  Eclipses 
  are 
  still, 
  as 
  they 
  have 
  ever 
  been, 
  very 
  important 
  phenomena 
  for 
  the 
  

   astronomical 
  observer 
  ; 
  partly 
  on 
  account 
  of 
  the 
  crucial 
  test 
  which 
  they 
  afford 
  

   for 
  the 
  examination 
  of 
  the 
  truth 
  of 
  the 
  theory 
  and 
  calculation 
  of 
  the 
  motions, 
  real 
  

   and 
  apparent, 
  of 
  the 
  Sun 
  and 
  Moon, 
  partly 
  also 
  for 
  the 
  special 
  opportunities 
  

   which 
  they 
  furnish 
  of 
  inquiring 
  into 
  some 
  of 
  the 
  arcana 
  of 
  the 
  physical 
  charac- 
  

   teristics 
  of 
  those 
  bodies. 
  

  

  For 
  the 
  former 
  purpose, 
  a 
  partial 
  eclipse 
  will 
  serve 
  almost 
  as 
  well 
  as 
  a 
  total 
  

   one 
  ; 
  while 
  the 
  continued 
  improvement 
  of 
  the 
  observation 
  of 
  meridian 
  passages 
  

   is 
  now 
  raising 
  these 
  daily 
  measures 
  fully 
  to 
  the 
  importance 
  of 
  the 
  other 
  occasional 
  

   phenomena, 
  as 
  a 
  test 
  of 
  the 
  theory. 
  But 
  for 
  inquiry 
  into 
  the 
  physics 
  of 
  the 
  Sun, 
  

   a 
  perfectly 
  total 
  eclipse 
  of 
  that 
  body 
  is 
  necessary 
  ; 
  revelations 
  may 
  then 
  happily 
  

   be 
  procured, 
  which 
  no 
  observation 
  of 
  any 
  other 
  phenomena 
  at 
  any 
  other 
  time, 
  can 
  

   hope 
  to 
  afford 
  any 
  suspicion 
  of. 
  

  

  As 
  the 
  occurrence 
  however 
  of 
  a 
  total 
  eclipse 
  near 
  any 
  inhabited 
  and 
  civilised 
  

   region 
  of 
  the 
  earth, 
  is 
  very 
  rare 
  ; 
  and 
  as 
  even 
  when 
  it 
  does 
  occur, 
  the 
  observation 
  

   lasts 
  but 
  for 
  three 
  short 
  minutes, 
  — 
  the 
  utmost 
  extremity 
  of 
  importance 
  attaches 
  

   to 
  the 
  occasion 
  in 
  the 
  eyes 
  of 
  all 
  practical 
  astronomers. 
  So 
  many 
  circumstances, 
  

   too, 
  have 
  to 
  be 
  noted, 
  observed, 
  and 
  measured, 
  within 
  a 
  few 
  seconds, 
  that 
  it 
  is 
  

   necessary 
  to 
  adopt 
  some 
  systematic 
  division 
  of 
  labour 
  amongst 
  a 
  number 
  of 
  ob- 
  

   servers, 
  and 
  for 
  each 
  to 
  be 
  previously 
  practised 
  and 
  expert 
  in 
  his 
  particular 
  part. 
  

  

  Much 
  of 
  this 
  arrangement 
  was 
  organised 
  for 
  the 
  eclipse 
  of 
  July 
  28, 
  1851 
  ; 
  and 
  

   while 
  other 
  observers 
  were 
  distributing 
  themselves 
  along 
  various 
  parts 
  of 
  the 
  line 
  

   of 
  totality, 
  I 
  gladly 
  seized 
  the 
  opportunity 
  of 
  occupying, 
  in 
  company 
  with 
  the 
  

   Rev. 
  T. 
  R. 
  Robinson, 
  D.D., 
  the 
  western 
  coast 
  of 
  Norway, 
  where 
  the 
  path 
  of 
  the 
  

   moon's 
  shadow 
  first 
  entered 
  Europe. 
  On 
  the 
  importance 
  of 
  the 
  occasion 
  being 
  

   represented 
  to 
  the 
  Commissioners 
  of 
  Northern 
  Lighthouses, 
  then 
  sitting 
  in 
  Edin- 
  

   burgh, 
  that 
  Board, 
  who 
  can 
  so 
  well 
  appreciate 
  science, 
  and 
  who 
  have 
  introduced 
  

   so 
  many 
  of 
  its 
  more 
  recondite 
  appliances 
  into 
  their 
  admirable 
  establishments 
  on 
  

   the 
  coasts 
  of 
  Scotland, 
  — 
  finding 
  that 
  their 
  steam-vessel, 
  the 
  Pharos, 
  would 
  be 
  

   engaged 
  amongst 
  the 
  Shetland 
  Isles 
  about 
  the 
  time 
  of 
  the 
  eclipse, 
  most 
  liberally 
  

   undertook 
  to 
  convey 
  Dr 
  Robinson 
  and 
  myself 
  to 
  the 
  selected 
  part 
  of 
  the 
  Nor- 
  

   wegian 
  coast 
  ; 
  a 
  boon 
  of 
  so 
  much 
  the 
  more 
  importance, 
  as 
  that 
  portion 
  was 
  un- 
  

   visited, 
  so 
  far 
  as 
  we 
  could 
  learn, 
  by 
  any 
  sort 
  of 
  vessels 
  available 
  to 
  ordinary 
  

   passengers. 
  

  

  Being 
  taken 
  across 
  the 
  North 
  Sea, 
  then, 
  in 
  this 
  manner, 
  and 
  having 
  been 
  pro- 
  

  

  VOL. 
  XX. 
  PART 
  III. 
  6 
  U 
  

  

  