﻿38 
  JOURNAL 
  OF 
  TH© 
  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  VOL. 
  12, 
  NO. 
  2 
  

  

  of 
  the 
  assumed 
  annual 
  shift 
  of 
  the 
  North 
  Pole 
  towards 
  the 
  Equator 
  

   along 
  the 
  meridians 
  of 
  Greenwich 
  and 
  of 
  90 
  ° 
  W, 
  respectively 
  ; 
  let 
  w 
  

   denote 
  the 
  annual 
  increase 
  in 
  latitude 
  common 
  to 
  all 
  stations 
  and 
  due 
  

   to 
  erroneous 
  declinations; 
  then 
  the 
  observation 
  equations 
  have 
  the 
  

   form 
  

  

  u 
  cos 
  \ 
  -{- 
  V 
  sin 
  \ 
  -{- 
  w 
  = 
  observed 
  annual 
  rate, 
  

  

  where 
  X 
  is 
  the 
  west 
  longitude 
  of 
  the 
  station 
  in 
  question. 
  

  

  Various 
  least-square 
  solutions 
  were 
  tried 
  with 
  different 
  weights 
  for 
  

   the 
  several 
  stations 
  and 
  different 
  sets 
  of 
  annual 
  rates. 
  Full 
  details 
  

   will 
  be 
  given 
  in 
  the 
  longer 
  publication. 
  The 
  results 
  were 
  fairly 
  con- 
  

   sistent 
  and 
  the 
  adopted 
  result 
  was 
  a 
  motion 
  of 
  the 
  North 
  Pole 
  southward 
  

   along 
  the 
  meridian 
  of 
  77° 
  West 
  of 
  Greenwich 
  at 
  a 
  rate 
  of 
  about 
  0".0050 
  

   a 
  year. 
  The 
  values 
  of 
  w 
  depend 
  on 
  the 
  star 
  program 
  and 
  represent 
  

   mean 
  cumulative 
  corrections 
  to 
  the 
  declinations 
  for 
  the 
  period 
  

   covered; 
  they 
  might 
  therefore 
  be 
  expected 
  to 
  dififer 
  according 
  to 
  the 
  

   set 
  of 
  rates 
  used, 
  even 
  if 
  the 
  components 
  of 
  the 
  polar 
  motion 
  remained 
  

   constant. 
  This 
  was 
  found 
  to 
  be 
  the 
  case, 
  the 
  values 
  of 
  w 
  ranging 
  from 
  

   +0".0013to+0".0050. 
  

  

  This 
  then 
  is 
  the 
  interpretation 
  I 
  would 
  offer 
  of 
  the 
  apparent 
  increase 
  

   in 
  latitude 
  at 
  Ukiah; 
  cumulative 
  errors 
  in 
  the 
  declinations 
  combined 
  

   with 
  a 
  shifting 
  of 
  the 
  North 
  Pole 
  towards 
  the 
  American 
  continent. 
  

   There 
  might 
  be 
  also 
  the 
  surface 
  creep 
  which 
  Professor 
  Lawson 
  offers 
  

   as 
  the 
  all-sufficient 
  explanation, 
  but 
  I 
  believe 
  that 
  if 
  this 
  creep 
  

   exists, 
  its 
  contribution 
  to 
  the 
  increase 
  in 
  latitude 
  is 
  quite 
  subordinate 
  

   to 
  the 
  contributions 
  of 
  the 
  other 
  causes. 
  

  

  The 
  suggestion 
  of 
  a 
  displacement 
  of 
  the 
  Pole 
  towards 
  the 
  American 
  

   continent 
  has 
  been 
  made 
  before. 
  Wanach,^° 
  the 
  successor 
  to 
  Albrecht 
  

   in 
  the 
  work 
  of 
  the 
  International 
  Latitude 
  Service, 
  found 
  from 
  the 
  

   observations 
  of 
  the 
  Service 
  from 
  1900 
  to 
  1911, 
  inclusive, 
  a 
  displacement 
  

   of 
  the 
  North 
  Pole 
  at 
  the 
  rate 
  of 
  not 
  more 
  than 
  0".0030 
  a 
  year 
  and 
  in 
  

   the 
  general 
  direction 
  of 
  Newfoundland, 
  say 
  along 
  the 
  meridian 
  of 
  

   56 
  ° 
  West. 
  The 
  period 
  of 
  time 
  covered 
  is 
  different, 
  likewise 
  the 
  method 
  

   of 
  treatment 
  and 
  the 
  weights 
  assigned 
  to 
  Tschardjui 
  and 
  Cincinnati. 
  

   The 
  differences 
  doubtless 
  explain 
  the 
  differences 
  in 
  the 
  results, 
  differ- 
  

   ences 
  not 
  particularly 
  large 
  in 
  view 
  of 
  the 
  difficulties 
  of 
  the 
  subject. 
  

  

  It 
  is 
  evident 
  that 
  the 
  burden 
  of 
  proof 
  for 
  this 
  explanation 
  of 
  the 
  

   change 
  of 
  latitude 
  at 
  Ukiah 
  by 
  a 
  shifting 
  of 
  the 
  Pole 
  rests 
  chiefly 
  on 
  the 
  

   results 
  at 
  Gaithersburg, 
  for 
  Ukiah 
  is 
  suspected 
  of 
  being 
  on 
  unstable 
  

  

  " 
  B. 
  Wanach. 
  ResuUate 
  des 
  Internationalen 
  Breitendienstes 
  5: 
  219. 
  1916. 
  

  

  