﻿ANNUAL 
  RINGS 
  OF 
  TREES 
  — 
  DOUGLASS. 
  231 
  

  

  desired 
  and 
  are 
  believed 
  to 
  depend 
  in 
  part 
  on 
  the 
  relative 
  response 
  

   of 
  the 
  trees 
  to 
  climatic 
  influences. 
  The 
  great 
  sensitiveness 
  of 
  the 
  

   yellow 
  pines 
  as 
  compared 
  with 
  the 
  best 
  sequoias 
  is 
  evident 
  in 
  any 
  

   brief 
  comparison 
  of 
  dated 
  specimens. 
  

  

  V. 
  INSTRUMENTS. 
  

  

  In 
  the 
  course 
  of 
  this 
  long 
  attention 
  to 
  the 
  rings 
  of 
  trees 
  and 
  in 
  

   studying 
  such 
  a 
  vast 
  number 
  of 
  them, 
  special 
  tools 
  to 
  secure 
  ma- 
  

   terial 
  and 
  to 
  improve 
  and 
  hasten 
  the 
  results 
  have 
  very 
  naturally 
  

   been 
  adopted 
  or 
  developed. 
  One 
  goes 
  into 
  the 
  field 
  well-armed, 
  

   carrying 
  a 
  flooring 
  saw 
  with 
  its 
  curved 
  edge 
  for 
  sawing 
  half 
  across 
  

   the 
  tops 
  of 
  stumps, 
  a 
  chisel 
  for 
  making 
  numbers, 
  numerous 
  paper 
  

   bags 
  for 
  holding 
  fragments 
  cut 
  from 
  individual 
  trees, 
  a 
  recording 
  

   notebook, 
  crayon, 
  a 
  shoulder 
  bag, 
  camera, 
  and 
  especially 
  a 
  kindly, 
  

   strong 
  - 
  armed 
  friend 
  to 
  help 
  in 
  the 
  sawing. 
  In 
  the 
  last 
  18 
  

   months 
  the 
  Swedish 
  increment 
  borer 
  has 
  been 
  used 
  extensively 
  to 
  

   get 
  records 
  from 
  living 
  pine 
  trees. 
  Hardwoods 
  and 
  juniper 
  are 
  

   too 
  tough. 
  It 
  has 
  previously 
  been 
  considered 
  that 
  the 
  little 
  slender 
  

   cores, 
  smaller 
  than 
  a 
  pencil, 
  so 
  obtained, 
  would 
  hardly 
  be 
  worth 
  

   working 
  on. 
  But 
  the 
  method 
  of 
  mounting 
  them 
  has 
  been 
  raised 
  

   to 
  such 
  a 
  degree 
  of 
  efficiency, 
  and 
  the 
  collection 
  of 
  material 
  be- 
  

   comes 
  so 
  rapid 
  that 
  the 
  deficient 
  length 
  and 
  the 
  occasional 
  worth- 
  

   less 
  specimen 
  are 
  counterbalanced. 
  Besides, 
  it 
  is 
  often 
  easy 
  to 
  sup- 
  

   plement 
  a 
  group 
  of 
  increment 
  cores 
  by 
  some 
  other 
  form 
  of 
  speci- 
  

   men 
  extending 
  back 
  to 
  greater 
  age. 
  The 
  Mount 
  Lemmon 
  group, 
  

   near 
  Tucson, 
  has 
  eight 
  cores 
  giving 
  a 
  good 
  record 
  from 
  about 
  1725 
  

   to 
  the 
  present 
  time; 
  a 
  saw-cutting 
  from 
  a 
  large 
  stump 
  in 
  Summer- 
  

   haven 
  carries 
  the 
  record 
  back 
  150 
  years 
  earlier. 
  It 
  should, 
  however, 
  

   be 
  supported 
  by 
  at 
  least 
  one 
  more 
  long 
  record 
  and 
  this 
  can 
  be 
  done 
  

   by 
  the 
  tubular 
  borer 
  described 
  next. 
  

  

  The 
  tubular 
  borer 
  was 
  designed 
  especially 
  for 
  the 
  dried 
  and 
  

   sometimes 
  very 
  hard 
  logs 
  in 
  the 
  prehistoric 
  ruins. 
  It 
  works 
  well 
  

   on 
  pine 
  trees 
  and 
  junipers. 
  It 
  gives 
  a 
  core 
  an 
  inch 
  in 
  diameter, 
  

   which 
  means 
  a 
  far 
  better 
  chance 
  of 
  locating 
  difficult 
  rings 
  than 
  in 
  

   the 
  increment 
  borer 
  cores 
  which 
  are 
  only 
  one-fifth 
  of 
  that 
  diameter. 
  

   The 
  borer 
  is 
  a 
  1-inch 
  steel 
  tube 
  with 
  small 
  saw 
  teeth 
  on 
  one 
  end 
  

   and 
  a 
  projection 
  at 
  the 
  other 
  for 
  insertion 
  in 
  a 
  common 
  brace. 
  A 
  

   chain 
  drill 
  attachment 
  is 
  also 
  provided 
  to 
  help 
  in 
  forcing 
  the 
  drill 
  

   into 
  the 
  wood. 
  The 
  difficulty 
  with 
  this 
  borer 
  is 
  the 
  disposal 
  of 
  saw- 
  

   dust 
  and 
  the 
  extraction 
  of 
  the 
  core. 
  For 
  the 
  former, 
  a 
  separate 
  

   hole 
  is 
  bored 
  with 
  a 
  common 
  auger 
  just 
  below 
  the 
  core 
  (if 
  in 
  an 
  

   upright 
  tree) 
  and 
  in 
  advance 
  of 
  it 
  to 
  catch 
  the 
  sawdust. 
  The 
  core 
  is 
  

   broken 
  off 
  every 
  three 
  inches 
  and 
  pulled 
  out 
  to 
  make 
  more 
  room 
  for 
  

   the 
  sawdust. 
  To 
  extract 
  the 
  core 
  a 
  small 
  steel 
  rod 
  is 
  provided 
  with 
  

  

  