﻿JAN. 
  19, 
  1922 
  LAMBERT: 
  LATITUDE 
  OP 
  UKIAH 
  29 
  

  

  His 
  thesis 
  is 
  that 
  there 
  are 
  slow 
  movements 
  of 
  the 
  surface 
  as 
  a 
  result 
  

   of 
  stresses 
  arising 
  from 
  a 
  subcrustal 
  flow 
  that 
  carries 
  the 
  surface 
  with 
  it. 
  

   In 
  time 
  these 
  stresses 
  increase 
  to 
  the 
  breaking 
  point; 
  there 
  is 
  then 
  

   rupture 
  with 
  attendant 
  seismic 
  shocks 
  and 
  a 
  rebound 
  toward 
  the 
  

   original 
  position. 
  

  

  In 
  support 
  of 
  this 
  thesis 
  Professor 
  Lawson 
  adduces 
  the 
  triangulation 
  

   executed 
  by 
  the 
  Coast 
  and 
  Geodetic 
  Survey^ 
  in 
  California 
  at 
  various 
  

   times 
  before 
  the 
  earthquake 
  of 
  1906 
  and 
  during 
  the 
  months 
  immedi- 
  

   ately 
  following. 
  He 
  adduces 
  also 
  the 
  observed 
  astronomic 
  latitudes 
  

   at 
  the 
  Ukiah 
  latitude 
  station, 
  one 
  of 
  the 
  stations 
  of 
  the 
  International 
  

   Latitude 
  Service 
  maintained 
  for 
  the 
  study 
  of 
  the 
  variation 
  of 
  latitude 
  

   and 
  the 
  motion 
  of 
  the 
  Pole. 
  It 
  should 
  be 
  stated 
  that 
  Ukiah 
  lies 
  outside 
  

   of 
  the 
  area 
  that 
  was 
  treated 
  as 
  potentially 
  movable 
  in 
  the 
  discussion 
  

   of 
  the 
  triangulation. 
  The 
  line 
  of 
  greatest 
  disturbance 
  during 
  this 
  

   earthquake 
  runs 
  along 
  the 
  San 
  Andreas 
  fault 
  ; 
  the 
  nearest 
  point 
  of 
  this 
  

   fault 
  is 
  some 
  30 
  miles 
  from 
  Ukiah 
  and 
  not 
  far 
  from 
  the 
  point 
  where 
  the 
  

   fault 
  itself 
  runs 
  out 
  to 
  sea 
  in 
  a 
  northwesterly 
  direction. 
  

  

  It 
  is 
  not 
  the 
  purpose 
  of 
  this 
  paper 
  to 
  interpret 
  the 
  evidence 
  from 
  the 
  

   triangulation, 
  but 
  solely 
  to 
  consider 
  the 
  meaning 
  of 
  the 
  astronomic 
  

   latitudes 
  at 
  Ukiah, 
  which 
  constitute 
  a 
  problem 
  quite 
  independent 
  of 
  the 
  

   problem 
  presented 
  by 
  the 
  triangulation. 
  

  

  The 
  latitude 
  of 
  Ukiah 
  appears 
  to 
  be 
  increasing 
  with 
  some 
  regularity 
  

   at 
  a 
  rate 
  not 
  much 
  smaller 
  than 
  0.01 
  second 
  per 
  year, 
  that 
  is, 
  a 
  dis- 
  

   placement 
  of 
  almost 
  1 
  foot 
  or 
  30 
  cm. 
  per 
  year. 
  This 
  deduction 
  was 
  

   made 
  by 
  Professor 
  Lawson 
  from 
  curves 
  given 
  in 
  an 
  article 
  by 
  Sir 
  

   Frank 
  Dyson, 
  ^ 
  Astronomer 
  Royal 
  of 
  England. 
  It 
  should 
  be 
  said 
  that 
  

   the 
  curves 
  are 
  used 
  by 
  Dyson 
  for 
  quite 
  a 
  different 
  purpose, 
  and 
  that 
  

   this 
  increase 
  in 
  latitude 
  is 
  not 
  mentioned 
  by 
  him, 
  nor 
  would 
  its 
  exis- 
  

   tence 
  affect 
  his 
  results 
  to 
  any 
  perceptible 
  degree. 
  It 
  should 
  be 
  said 
  on 
  

   the 
  other 
  hand 
  that 
  an 
  apparent 
  increase 
  of 
  this 
  sort 
  is 
  very 
  evident 
  

   from 
  a 
  mere 
  inspection 
  of 
  the 
  curve 
  for 
  Ukiah, 
  which 
  is 
  shown 
  in 
  figure 
  1 
  . 
  

  

  As 
  is 
  well 
  known, 
  the 
  two 
  principal 
  periodic 
  terms 
  in 
  the 
  expression 
  

   for 
  the 
  variation 
  of 
  latitude 
  have 
  periods 
  of 
  one 
  year 
  and 
  of 
  about 
  14 
  

   months. 
  The 
  curve 
  shows 
  the 
  observed 
  variation 
  of 
  latitude 
  with 
  the 
  

   effect 
  of 
  the 
  annual 
  term 
  removed 
  by 
  computation. 
  The 
  annual 
  term 
  

   was 
  deduced 
  by 
  harmonic 
  analysis 
  from 
  the 
  observed 
  latitudes 
  at 
  

   Ukiah 
  only 
  and 
  is 
  therefore 
  independent 
  of 
  any 
  assumption 
  as 
  to 
  the 
  

  

  ^ 
  J. 
  F. 
  Hayford 
  and 
  A. 
  L. 
  Baldwin, 
  The 
  earth 
  movements 
  in 
  the 
  California 
  earthquake 
  of 
  

   1906. 
  U. 
  S. 
  Coast 
  and 
  Geod. 
  Surv. 
  Ann. 
  Rept. 
  1907, 
  App. 
  4. 
  

   * 
  F. 
  W. 
  Dyson. 
  Month. 
  Not. 
  Roy. 
  Astr. 
  Soc. 
  78: 
  452. 
  1918. 
  

  

  