The wood is used for finishing, flooring, furniture, veneers, slack
    cooperage, boxes, and gun stocks.

[Illustration:  FIG. 152.—­Maple. (Magnified 25 times.)]

5.  Black or sweet birch, Fig. 151.  Rays variable in size but all rather
    indistinct.  Color brown, tinged with red, often deep and handsome. 
    Wood heavy, hard, and strong, straight-grained, readily worked.  Is
    darker in color and has less prominent rays than maple.

    The wood is used for furniture, cabinet work, finishing, and
    distillation.

6.  Cottonwood.  Rays extremely fine and scarcely visible even under lens. 
    Color pale dull brown or grayish brown.  Wood light, soft, not
    strong, straight-grained, fairly easy to work.  Cottonwood can be
    separated from other light and soft woods by the fineness of its
    rays, which is equaled only by willow, which it rather closely
    resembles.  The wood is largely used for boxes, general construction,
    lumber, and pulp.

How to judge the quality of wood:  To know the name of a piece of wood
    means, in a general way, to know certain qualities that are common
    to all other pieces of wood of that species, but it does not explain
    the special peculiarities of the piece in question or why that
    particular piece is more suitable or unsuitable for a particular
    purpose than another piece of the same species.  The mere
    identification of the wood does not explain why a particular piece
    is tougher, stronger or of darker color than another piece of the
    same species or even of the same tree.  The reason for these special
    differences lies in the fact that wood is not a homogeneous material
    like metal.  Within the same tree different parts vary in quality. 
    The heartwood is generally heavier and of deeper color than the
    sapwood.  The butt is superior to the top wood, and the manner in
    which the wood was sawed and dried will affect its quality.  Knots,
    splits, checks, and discoloration due to incipient decay are defects
    worth considering.  Wood that looks lusterless is usually defective,
    because the lack of luster is generally due to disease.  Woods that
    are hard wear best.  Hardness can be determined readily by striking
    the wood with a hammer and noting the sound produced.  A clear,
    ringing sound is a sign of hardness.  The strength of a piece of wood
    can be judged by its weight after it is well dried.  Heavy woods are
    usually strong.  A large amount of late wood is an indication of
    strength and the production of a clear sound when struck with a
    hammer is also an evidence of strength.

CHAPTER IX

AN OUTDOOR LESSON ON TREES