﻿JAN. 
  19, 
  1922 
  

  

  I^AMBHRT: 
  LATITUDE 
  OF 
  UKIAH 
  

  

  35 
  

  

  It 
  would 
  be 
  equally 
  legitimate 
  to 
  interchange 
  the 
  processes 
  by 
  which 
  

   the 
  two 
  periodic 
  portions 
  of 
  the 
  latitude 
  variation 
  were 
  eliminated. 
  

   Instead 
  of 
  taking 
  out 
  the 
  effect 
  of 
  the 
  annual 
  portion 
  by 
  computing 
  

   from 
  an 
  assumed 
  expression 
  for 
  it 
  in 
  the 
  form 
  of 
  an 
  harmonic 
  term, 
  

   we 
  could 
  take 
  out 
  the 
  14-month 
  component 
  by 
  assuming 
  it 
  to 
  be 
  ex- 
  

   pressed 
  by 
  a 
  harmonic 
  term 
  and 
  computing 
  the 
  necessary 
  values. 
  

   The 
  remaining 
  periodic 
  portion 
  of 
  the 
  variation 
  would 
  be 
  the 
  annual 
  

   portion 
  and 
  could 
  be 
  eliminated 
  by 
  taking 
  means 
  over 
  the 
  period 
  of 
  

   a 
  year. 
  These 
  means, 
  being 
  free 
  from 
  the 
  effects 
  of 
  periodic 
  terms, 
  

   should 
  bring 
  to 
  light 
  the 
  progressive 
  variation. 
  

  

  Both 
  methods 
  were 
  employed 
  and 
  the 
  two 
  rates 
  thus 
  obtained 
  for 
  

   the 
  progressive 
  change 
  of 
  latitude 
  at 
  a 
  station 
  agreed 
  well 
  in 
  all 
  cases. 
  

   There 
  appeared 
  to 
  be 
  some 
  reason 
  for 
  thinking 
  that 
  the 
  rate 
  of 
  change 
  

   might 
  be 
  different 
  for 
  the 
  later 
  years 
  ; 
  with 
  this 
  in 
  mind 
  the 
  experiment 
  

  

  

  ass 
  

  

  1900 
  

  

  1905 
  

  

  1910 
  

  

  191S 
  

  

  Fig. 
  4. 
  The 
  latitude 
  of 
  Mizusawa, 
  Japan 
  ; 
  means 
  by 
  calendar 
  years 
  and 
  lines 
  showing 
  adjusted 
  

   rates 
  of 
  change; 
  derived 
  from 
  the 
  latitudes 
  of 
  the 
  International 
  Latitude 
  Service. 
  

  

  was 
  tried 
  of 
  fitting 
  two 
  straight 
  lines 
  to 
  the 
  mean 
  latitudes 
  instead 
  of 
  

   only 
  a 
  single 
  line, 
  the 
  two 
  lines 
  to 
  show 
  the 
  same 
  latitude 
  at 
  a 
  pre- 
  

   determined 
  epoch. 
  This 
  epoch 
  was 
  taken 
  not 
  far 
  from 
  the 
  end 
  of 
  

   1911. 
  The 
  considerations 
  governing 
  this 
  choice 
  were 
  in 
  part 
  the 
  

   general 
  appearance 
  of 
  the 
  plotted 
  mean 
  latitudes 
  and 
  in 
  part 
  the 
  change 
  

   in 
  the 
  star 
  program 
  at 
  the 
  end 
  of 
  1911 
  already 
  referred 
  to 
  and 
  due 
  to 
  

   the 
  dropping 
  of 
  certain 
  stars. 
  

  

  