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  Hubert 
  Anson 
  Newton. 
  

  

  that 
  time 
  far 
  surpassed 
  all 
  other 
  meteoric 
  streams 
  in 
  interest. 
  

   One 
  of 
  his 
  later 
  studies 
  related 
  to 
  another 
  stream 
  which 
  in 
  the 
  

   mean 
  time 
  had 
  acquired 
  great 
  importance. 
  The 
  identification 
  

   of 
  the 
  orbit 
  of 
  the 
  Andromed 
  meteors 
  with 
  that 
  of 
  Biela's 
  

   comet, 
  which 
  we 
  have 
  already 
  mentioned, 
  gave 
  these 
  bodies 
  a 
  

   unique 
  interest, 
  as 
  the 
  comet 
  had 
  been 
  seen 
  to 
  break 
  up 
  under 
  

   the 
  influence 
  of 
  the 
  sun. 
  Here 
  the 
  evolution 
  of 
  meteoroids 
  was 
  

   taking 
  place 
  before 
  our 
  eyes 
  ; 
  and 
  this 
  interest 
  was 
  heightened 
  

   by 
  the 
  showers 
  of 
  1872 
  and 
  1885, 
  which 
  in 
  Europe 
  seem 
  to 
  

   have 
  been 
  unsurpassed 
  in 
  brilliancy 
  by 
  any 
  which 
  have 
  

   occurred 
  in 
  this 
  century. 
  

  

  The 
  phenomena 
  of 
  each 
  of 
  these 
  showers 
  were 
  carefully 
  dis- 
  

   cussed 
  by 
  Professor 
  Newton. 
  Among 
  the 
  principal 
  results 
  of 
  

   his 
  paper 
  on 
  the 
  latter 
  shower 
  are 
  the 
  following 
  :* 
  

  

  The 
  time 
  of 
  the 
  maximum 
  frequency 
  of 
  meteors 
  was 
  Nov. 
  

   27, 
  1885, 
  6 
  h 
  15 
  m 
  Gr. 
  m. 
  t, 
  The 
  estimated 
  number 
  per 
  hour 
  

   visible 
  at 
  one 
  place 
  was 
  then 
  75,000. 
  This 
  gives 
  a 
  density 
  of 
  

   the 
  meteoroids 
  in 
  space 
  represented 
  by 
  one 
  to 
  a 
  cube 
  of 
  twenty 
  

   miles 
  edge. 
  Three 
  hours 
  later 
  the 
  frequency 
  had 
  fallen 
  to 
  

   one-tenth 
  of 
  the 
  maximum 
  value. 
  The 
  really 
  dense 
  portion 
  of 
  

   the 
  stream 
  through 
  which 
  we 
  passed 
  was 
  less 
  than 
  100,000 
  

   miles 
  in 
  thickness, 
  and 
  nearly 
  all 
  would 
  be 
  included 
  in 
  a 
  thick- 
  

   ness 
  of 
  200,000 
  miles. 
  

  

  A 
  formula 
  is 
  given 
  to 
  express 
  the 
  effect 
  of 
  the 
  earth's 
  

   attraction 
  on 
  the 
  approaching 
  meteoroids 
  in 
  altering 
  the 
  posi- 
  

   tion 
  of 
  the 
  radiant. 
  This 
  is 
  technically 
  known 
  as 
  the 
  zenithal 
  

   attraction, 
  and 
  is 
  quite 
  important 
  in 
  the 
  case 
  of 
  these 
  meteors 
  

   on 
  account 
  of 
  their 
  small 
  relative 
  velocity. 
  The 
  significance 
  

   of 
  the 
  formula 
  may 
  be 
  roughly 
  expressed 
  by 
  saying 
  that 
  the 
  

   earth's 
  attraction 
  changes 
  the 
  radiant 
  of 
  the 
  Biela 
  meteors, 
  

   toward 
  the 
  vertical 
  of 
  the 
  observer, 
  one-tenth 
  of 
  the 
  observed 
  

   zenith 
  distance 
  of 
  the 
  radiant, 
  or 
  more 
  briefly, 
  that 
  the 
  zenithal 
  

   attraction 
  for 
  these 
  meteors 
  is 
  one-tenth 
  of 
  the 
  observed 
  zenith 
  

   distance. 
  The 
  radiant 
  even 
  after 
  the 
  correction 
  for 
  zenithal 
  

   attraction, 
  and 
  another 
  for 
  the 
  rotation 
  of 
  the 
  earth 
  on 
  its 
  axis, 
  

   is 
  not 
  a 
  point 
  but 
  an 
  area 
  of 
  several 
  degrees 
  diameter. 
  The 
  

   same 
  has 
  been 
  observed 
  in 
  regard 
  to 
  other 
  showers, 
  but 
  the 
  

   result 
  comes 
  out 
  more 
  distinctly 
  in 
  the 
  present 
  case 
  because 
  the 
  

   meteors 
  were 
  so 
  numerous 
  and 
  the 
  shower 
  so 
  carefully 
  

   observed. 
  

  

  This 
  implies 
  a 
  want 
  of 
  parallelism 
  in 
  the 
  paths 
  of 
  the 
  

   meteors, 
  and 
  it 
  is 
  a 
  very 
  important 
  question 
  whether 
  it 
  exists 
  

   before 
  the 
  meteoroids 
  enter 
  our 
  atmosphere, 
  or 
  whether 
  it 
  is 
  

   due 
  to 
  the 
  action 
  of 
  the 
  atmosphere. 
  

  

  Professor 
  Newton 
  shows 
  that 
  it 
  is 
  difficult 
  to 
  account 
  for 
  so 
  

   large 
  a 
  difference 
  in 
  the 
  original 
  motions 
  of 
  the 
  meteoroids, 
  and 
  

  

  * 
  This 
  Journal, 
  III, 
  xxxi, 
  p. 
  409. 
  

  

  