﻿ANNUAL 
  RINGS 
  OF 
  TREES 
  — 
  DOUGLASS. 
  229 
  

  

  character 
  is 
  somewhat 
  different. 
  To 
  get 
  a 
  satisfactory 
  representa- 
  

   tion 
  through 
  several 
  centuries, 
  therefore, 
  it 
  is 
  better 
  to 
  combine- 
  

   younger 
  trees 
  with 
  older 
  ones 
  to 
  get 
  a 
  more 
  even 
  and 
  constant 
  record 
  

   of 
  climatic 
  conditions. 
  

  

  The 
  third 
  thought 
  is 
  this. 
  The 
  spreading 
  of 
  a 
  certain 
  character 
  

   over 
  many 
  miles 
  of 
  country 
  stamps 
  it 
  in 
  almost 
  every 
  case 
  as 
  climatic 
  

   in 
  origin, 
  because 
  climate 
  is 
  the 
  common 
  environment 
  over 
  large 
  

   areas. 
  

  

  III. 
  NUMBER 
  AND 
  LOCATION 
  OF 
  TREES. 
  

  

  The 
  whole 
  number 
  of 
  trees 
  used 
  is 
  nearly 
  450 
  and 
  includes 
  cone- 
  

   bearing 
  trees 
  from 
  Oregon, 
  California, 
  Arizona, 
  New 
  Mexico, 
  Colo- 
  

   rado, 
  Vermont, 
  England, 
  Norway, 
  Sweden, 
  Germany, 
  and 
  Bohemia. 
  

   The 
  total 
  number 
  of 
  rings 
  dated 
  and 
  measured 
  is 
  well 
  over 
  100,000. 
  

   The 
  average 
  ages 
  found 
  in 
  these 
  various 
  trees 
  are 
  very 
  interesting. 
  

   The 
  European 
  groups 
  reach 
  for 
  the 
  most 
  part 
  about 
  90 
  years, 
  al- 
  

   though 
  one 
  tree 
  in 
  Norway 
  showed 
  400 
  years 
  of 
  age, 
  and 
  15 
  were 
  

   found 
  beginning 
  as 
  early 
  as 
  1740. 
  The 
  Oregon 
  group 
  of 
  Douglas 
  firs 
  

   goes 
  back 
  to 
  about 
  1710, 
  the 
  Vermont 
  hemlocks 
  reach 
  1654, 
  the 
  

   Flagstaff 
  yellow 
  pines 
  give 
  a 
  number 
  of 
  admirable 
  records 
  from 
  

   about 
  1400. 
  

  

  The 
  oldest 
  trees, 
  of 
  course, 
  were 
  the 
  great 
  sequoias 
  from 
  the 
  Sierra 
  

   Nevada 
  Mountains 
  in 
  California. 
  They 
  were 
  found 
  to 
  have 
  ages 
  

   that 
  formed 
  natural 
  groups, 
  showing 
  probably 
  a 
  climatic 
  effect. 
  

   There 
  are 
  very 
  few 
  under 
  700 
  years 
  old 
  (except 
  the 
  young 
  ones 
  which 
  

   have 
  started 
  since 
  the 
  cutting 
  of 
  the 
  Big 
  Trees). 
  A 
  number 
  had 
  

   about 
  that 
  age. 
  The 
  majority 
  of 
  the 
  trees 
  scatter 
  along 
  in 
  age 
  from 
  

   1,200 
  up 
  to 
  about 
  2,200 
  years, 
  at 
  which 
  age 
  a 
  large 
  number 
  were 
  

   found. 
  One 
  or 
  two 
  were 
  found 
  of 
  2,500 
  years, 
  one 
  of 
  2,800, 
  one 
  of 
  

   3,000, 
  one 
  at 
  just 
  under 
  3,100, 
  and 
  the 
  oldest 
  of 
  all 
  just 
  over 
  3,200. 
  

   The 
  determination 
  of 
  this 
  age 
  of 
  the 
  older 
  sequoias 
  in 
  the 
  present 
  

   instance 
  is 
  not 
  merely 
  a 
  matter 
  of 
  ring 
  counting, 
  but 
  depends 
  

   upon 
  the 
  intercomparison 
  of 
  some 
  55,000 
  rings 
  in 
  35 
  trees. 
  In 
  

   1919 
  a 
  special 
  trip 
  was 
  made 
  to 
  the 
  Big 
  Trees 
  and 
  samples 
  from 
  a 
  

   dozen 
  extra 
  trees 
  obtained 
  in 
  order 
  to 
  decide 
  the 
  case 
  of 
  a 
  single 
  

   ring, 
  1580 
  A. 
  D., 
  about 
  which 
  there 
  was 
  some 
  doubt, 
  and 
  it 
  was 
  

   apparent 
  that 
  the 
  ring 
  in 
  question 
  stood 
  for 
  an 
  extra 
  year. 
  This 
  was 
  

   corrected 
  and 
  it 
  now 
  seems 
  likely 
  that 
  there 
  is 
  no 
  mistake 
  in 
  dating 
  

   through 
  the 
  entire 
  sequence 
  of 
  years, 
  but 
  if 
  not 
  correct 
  the 
  error 
  is 
  

   certainly 
  very 
  small. 
  

  

  IV. 
  TOPOGRAPHY. 
  

  

  The 
  late 
  Prof. 
  W. 
  R. 
  Dudley, 
  of 
  Stanford 
  University, 
  in 
  his 
  charm- 
  

   ing 
  essay 
  on 
  the 
  "Vitality 
  of 
  the 
  Sequoia" 
  refers 
  to 
  the 
  fact 
  that 
  the 
  

   growth 
  of 
  the 
  Big 
  Trees 
  depends 
  in 
  a 
  measure 
  on 
  the 
  presence 
  of 
  a 
  

   55379—24 
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