﻿TIMBER; 
  FORESTRY 
  

  

  109 
  

  

  u.r 
  

  

  The 
  structure 
  of 
  coniferous 
  wood 
  - 
  - 
  as 
  seen, 
  for 
  example, 
  on 
  

   the 
  end 
  of 
  a 
  beam 
  cut 
  off 
  squarely, 
  or 
  011 
  a 
  new 
  lead 
  pencil 
  

   is 
  in 
  one 
  respect 
  less 
  complex 
  than 
  that 
  of 
  most 
  hard 
  woods 
  : 
  

   the 
  wood 
  is 
  chiefly 
  composed 
  of 
  tracheids 
  - 
  - 
  long, 
  tubular 
  cells 
  

   with 
  tapering 
  ends 
  -and 
  contains 
  no 
  continuous 
  ducts, 
  though 
  

   it 
  may 
  contain 
  resin 
  pas- 
  

   sages. 
  The 
  rings 
  plainly 
  

   seen 
  on 
  the 
  cross 
  sections 
  

   of 
  some 
  kinds 
  are 
  due 
  to 
  

   the 
  difference 
  in 
  diameter 
  

   between 
  the 
  tracheids 
  

   formed 
  in 
  early 
  spring 
  and 
  

   the 
  later 
  ones 
  (fig. 
  91). 
  

  

  103. 
  Hardwoods. 
  Most 
  

   of 
  the 
  hard 
  wood 
  used 
  for 
  

   all 
  kinds 
  of 
  construction 
  

   in 
  this 
  country 
  is 
  fur- 
  

   nished 
  by 
  native 
  trees. 
  

   Of 
  these 
  we 
  have 
  about 
  

   eighty 
  kinds, 
  the 
  most 
  im- 
  

   portant 
  ones 
  being 
  the 
  oaks 
  

   (of 
  about 
  nineteen 
  species). 
  

  

  a.i 
  

  

  u.r 
  

  

  FIG. 
  91. 
  Cross 
  section 
  of 
  white 
  pine, 
  a 
  

  

  typical 
  coniferous 
  wood 
  

  

  a.r, 
  boundaries 
  between 
  one 
  year's 
  growth, 
  

   or 
  annual 
  ring, 
  and 
  the 
  next. 
  The 
  <arge, 
  

   roundish 
  white 
  spots 
  are 
  resin 
  passages 
  that 
  

   have 
  been 
  cut 
  off. 
  Magnified 
  15 
  diameters. 
  

   Photomicrograph 
  by 
  R. 
  B. 
  Hough 
  ! 
  

  

  These 
  furnish 
  more 
  than 
  

   half 
  of 
  our 
  supply 
  of 
  

   hard-wood 
  timber. 
  Tulip- 
  

   wood, 
  or 
  yellow 
  poplar 
  

   (I/iriodendroTi), 
  is 
  used 
  in 
  

   great 
  quantities 
  for 
  the 
  interior 
  finish 
  of 
  houses 
  and 
  in 
  the 
  

   manufacture 
  of 
  wooden 
  ware. 
  The 
  wood 
  is 
  soft, 
  free 
  from 
  

   knots, 
  and 
  furnishes 
  very 
  wide 
  boards. 
  It 
  is 
  not 
  durable 
  when 
  

   exposed 
  to 
  the 
  weather. 
  

  

  Other 
  important 
  hard 
  woods 
  are 
  ash, 
  beech, 
  birch, 
  chestnut, 
  

   elm, 
  maple, 
  red 
  gum, 
  and 
  sycamore. 
  Each 
  of 
  these 
  woods 
  has 
  

   its 
  valuable 
  qualities 
  and 
  its 
  defects, 
  well 
  known 
  to 
  builders 
  

  

  1 
  From 
  " 
  Handbook 
  of 
  the 
  Trees 
  of 
  the 
  Northern 
  States 
  and 
  Canada," 
  

   written 
  and 
  published 
  by 
  Romeyn 
  B. 
  Hough, 
  Lowville, 
  New 
  York. 
  

  

  