﻿40 
  JOURNAL 
  OF 
  the; 
  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  VOL. 
  12, 
  NO. 
  2 
  

  

  ical 
  period 
  as 
  meaning 
  a 
  million 
  years/^ 
  which 
  corresponds 
  to 
  one 
  

   estimate 
  of 
  the 
  duration 
  of 
  the 
  entire 
  glacial 
  epoch, 
  including 
  all 
  the 
  

   various 
  periods 
  of 
  glaciation 
  and 
  the 
  interglacial 
  periods 
  between 
  them, 
  

   then 
  a 
  shift 
  of 
  0". 
  0050 
  a 
  year 
  would 
  mean 
  a 
  change 
  of 
  1 
  ° 
  23' 
  in 
  the 
  posi- 
  

   tion 
  of 
  the 
  Poles 
  during 
  the 
  glacial 
  epoch, 
  a 
  quantity 
  within 
  Darwin's 
  

   limits. 
  

  

  Now 
  the 
  fact 
  that 
  the 
  shifting 
  of 
  the 
  North 
  Pole 
  towards 
  the 
  Amer- 
  

   ican 
  continent 
  appears 
  to 
  have 
  continued 
  for 
  the 
  18 
  years 
  from 
  1900 
  to 
  

   1917, 
  inclusive, 
  does 
  not 
  oblige 
  us 
  to 
  suppose 
  that 
  it 
  has 
  continued 
  in 
  the 
  

   past 
  or 
  will 
  continue 
  in 
  the 
  future. 
  Indeed, 
  very 
  recent 
  observations 
  

   at 
  Ukiah 
  would 
  indicate, 
  if 
  taken 
  at 
  their 
  face 
  value, 
  that 
  the 
  mean 
  

   latitude 
  of 
  Ukiah 
  is 
  decreasing, 
  that 
  is, 
  that 
  the 
  Pole 
  is 
  moving 
  back 
  

   again. 
  No 
  satisfactory 
  conclusions 
  can 
  be 
  reached, 
  however, 
  until 
  the 
  

   observations 
  at 
  the 
  other 
  latitude 
  stations 
  become 
  available. 
  There 
  is 
  

   some 
  evidence 
  of 
  certain 
  periodic 
  effects 
  in 
  the 
  variation 
  of 
  latitude 
  

   other 
  than 
  those 
  represented 
  by 
  the 
  annual 
  and 
  the 
  14-month 
  terms, 
  

   effects 
  whose 
  periods 
  are 
  three 
  years 
  or 
  more 
  and 
  which 
  may 
  be 
  

   connected 
  with 
  the 
  periods 
  of 
  the 
  still 
  obscure 
  meteorological 
  and 
  

   climatic 
  cycles. 
  The 
  shifting 
  of 
  the 
  Pole 
  may 
  represent 
  chiefly 
  the 
  

   combined 
  effect 
  of 
  meteorological 
  causes 
  running 
  their 
  courses 
  in 
  

   periods 
  of 
  a 
  few 
  years 
  or 
  a 
  few 
  decades 
  and 
  be 
  due 
  only 
  in 
  very 
  small 
  

   part 
  to 
  elevations 
  or 
  subsidences 
  of 
  the 
  crust. 
  

  

  Some 
  of 
  the 
  by-products 
  of 
  the 
  investigation 
  may 
  now 
  be 
  men- 
  

   tioned. 
  The 
  calculations 
  necessary 
  to 
  derive 
  the 
  foregoing 
  conclusions 
  

   were 
  quite 
  extensive 
  and 
  made 
  it 
  possible 
  to 
  obtain 
  with 
  but 
  little 
  

   additional 
  labor 
  other 
  results 
  of 
  interest 
  in 
  connection 
  with 
  the 
  general 
  

   problem 
  of 
  the 
  variation 
  of 
  latitude. 
  Fuller 
  details 
  will 
  be 
  given 
  in 
  

   the 
  larger 
  publication 
  already 
  referred 
  to. 
  

  

  An 
  examination 
  was 
  made 
  with 
  a 
  view 
  to 
  detecting 
  terms 
  in 
  the 
  

   variation 
  with 
  periods 
  of 
  three 
  and 
  six 
  years. 
  Terms 
  of 
  these 
  periods 
  

   in 
  the 
  distribution 
  of 
  barometric 
  pressure 
  over 
  the 
  earth 
  were 
  found 
  

   by 
  Angenheister;^^ 
  the 
  magnitudes 
  of 
  the 
  fluctuations 
  of 
  pressure 
  

   appeared 
  to 
  be 
  probably 
  sufficient 
  to 
  affect 
  the 
  motion 
  of 
  the 
  Pole 
  

   perceptibly. 
  Harmonic 
  constants 
  were 
  deduced 
  from 
  the 
  observations 
  

  

  13 
  Cited 
  by 
  M. 
  P. 
  Rudzki 
  in 
  his 
  Physik 
  der 
  Erde 
  (Leipzig, 
  1911), 
  p. 
  552, 
  as 
  the 
  estimate 
  

   of 
  Penck 
  and 
  Bruckner 
  for 
  the 
  duration 
  of 
  the 
  glacial 
  epoch. 
  

  

  1* 
  G. 
  Angenheister. 
  tjher 
  die 
  dreijdhrige 
  Lujtdrnckschwayikung 
  und 
  ihren 
  Zusamtnen- 
  

   hang 
  mit 
  Polschwankungen. 
  Nachr. 
  kon. 
  Ges. 
  Wiss. 
  Gottingen, 
  Math-phys. 
  Kl. 
  1914: 
  1. 
  

   The 
  paper 
  is 
  described 
  as 
  a 
  preliminary 
  communication 
  but 
  nothing 
  further 
  from 
  Angen- 
  

   heister 
  on 
  the 
  subject 
  has 
  come 
  to 
  the 
  author's 
  attention. 
  

  

  