﻿478 
  G. 
  C. 
  Oomstock 
  — 
  The 
  Secular 
  Variation 
  of 
  Latitudes. 
  

  

  were 
  reduced 
  and 
  from 
  this 
  comparison 
  and 
  a 
  similar 
  compari- 
  

   son 
  with 
  Boss's 
  declination 
  I 
  have 
  derived 
  the 
  following 
  values 
  

   of 
  the 
  latitude 
  : 
  

  

  Ann. 
  Var. 
  

  

  Epoch. 
  

  

  No. 
  of 
  Obs. 
  

  

  Seconds 
  of 
  Latitude. 
  

   Auwers. 
  Boss. 
  

  

  1847-2 
  

   1864-5 
  

  

  1883-5 
  

  

  192 
  

   436 
  

   123 
  

  

  37 
  // 
  *26 
  37 
  // 
  -64 
  

   38-]3 
  38-17 
  

   38-90 
  38'51 
  

  

  + 
  // 
  '050 
  +0-031 
  

  

  + 
  -041 
  + 
  -018 
  

  

  The 
  progressive 
  character 
  of 
  the 
  results 
  is 
  here 
  unmistakable 
  

   and 
  the 
  Madison 
  variation 
  is 
  confirmed. 
  But 
  in 
  order 
  that 
  my 
  

   conclusions 
  may 
  not 
  be 
  open 
  to 
  the 
  objection 
  of 
  resting 
  upon 
  

   an 
  assumed 
  proper 
  motion 
  of 
  a 
  single 
  star, 
  I 
  have 
  derived 
  a 
  

   value 
  of 
  the 
  latitude 
  for 
  the 
  several 
  epochs 
  from 
  all 
  of 
  the 
  

   observations 
  of 
  fundamental 
  stars 
  {Berliner 
  Jahrbueh) 
  which 
  

   are 
  available 
  for 
  this 
  purpose 
  with 
  the 
  following 
  result 
  : 
  

  

  Epoch. 
  No. 
  of 
  Stars. 
  No. 
  of 
  Obs. 
  Seconds 
  of 
  Lat. 
  Ann. 
  Var. 
  

  

  1847-0 
  41 
  461 
  37 
  // 
  '31 
  db 
  0**03 
  n 
  // 
  -04'7 
  

  

  1864-5 
  1 
  436 
  38'13 
  ± 
  '06 
  "Yn-fm 
  

  

  1883-5 
  9 
  306 
  38'83 
  ± 
  .05 
  + 
  

  

  Auwers* 
  proper 
  motions 
  have 
  been 
  employed 
  in 
  this 
  com- 
  

   parison, 
  but 
  it 
  should 
  be 
  stated 
  here 
  that 
  there 
  is 
  some 
  uncer- 
  

   tainty 
  in 
  regard 
  to 
  the 
  proper 
  motions 
  employed 
  by 
  the 
  

   observers 
  in 
  reducing 
  the 
  observed 
  declinations 
  to 
  a 
  mean 
  

   equinox, 
  since 
  the 
  printed 
  volumes 
  contain 
  no 
  indication 
  of 
  

   these. 
  It 
  is 
  stated 
  in 
  connection 
  with 
  the 
  mural 
  circle 
  obser- 
  

   vations 
  that 
  the 
  proper 
  motions 
  there 
  employed 
  for 
  this 
  pur- 
  

   pose 
  were 
  taken 
  from 
  the 
  Nautical 
  Almanac 
  for 
  1848, 
  and 
  I 
  

   have 
  assumed 
  that 
  the 
  same 
  practice 
  prevailed 
  with 
  the 
  prime 
  

   vertical 
  transit 
  and 
  have 
  corrected 
  the 
  printed 
  results 
  by 
  the 
  

   product 
  of 
  the 
  difference 
  between 
  these 
  proper 
  motions 
  and 
  

   those 
  of 
  Auwers, 
  multiplied 
  by 
  the 
  time 
  interval 
  between 
  the 
  

   date 
  of 
  observation 
  and 
  the 
  equinox 
  to 
  which 
  the 
  observations 
  

   were 
  reduced. 
  There 
  is 
  probably 
  a 
  certain 
  amount 
  of 
  error 
  

   introduced 
  by 
  this 
  process 
  into 
  the 
  latitude 
  for 
  1847 
  but 
  its 
  

   total 
  amount 
  must 
  be 
  exceedingly 
  small 
  since 
  in 
  no 
  case 
  were 
  

   the 
  observations 
  reduced 
  to 
  an 
  equinox 
  more 
  than 
  five 
  years 
  

   removed 
  from 
  the 
  date 
  of 
  observation. 
  

  

  The 
  data 
  furnished 
  by 
  the 
  prime 
  vertical 
  transit 
  may 
  be 
  

   presented 
  in 
  another 
  form 
  which 
  eliminates 
  the 
  declinations 
  of 
  

   the 
  stars 
  and 
  involves 
  only 
  their 
  proper 
  motions. 
  There 
  are 
  

   nine 
  stars 
  common 
  to 
  the 
  observations 
  of 
  1847 
  and 
  1883 
  

   which 
  are 
  also 
  contained 
  in 
  Auwers' 
  Fundamental 
  Catalog. 
  

   A 
  comparison 
  of 
  the 
  corrections 
  to 
  Auwers' 
  declinations 
  furn- 
  

   ished 
  by 
  the 
  observations 
  of 
  1847 
  and 
  1883 
  is 
  contained 
  in 
  the 
  

  

  