TABLE OF CONTENTS. 



Pago. 



Introduction 5 



Characteristics and properties of wood 11 



I. — Structure and appearance 11 



Classes of trees 11 



Wood of coniferous trees 12 



Bark and pith 13 



Sap and heart wood 13 



The annual or yearly ring 14 



Spring and summer wood 15 



Anatomical structure 16 



Wood of broad-leaved trees 18 



Minute structure 20 



Different grain of wood 21 



Color and odor 24 



Resonance 24 



II. — Weight of wood 25 



III. — Moisture in wood 29 



IV. — Shrinkage of wood 32 



V. — Mechanical properties of wood 37 



Stiffness 38 



Cross breaking or bending strength 41 



Tension and compression 43 



Shearing 45 



Influence of weight and moisture on strength 45 



Hardness and shearing across the grain 47 



Cleavability 48 



Flexibility 49 



Toughness 49 



Practical conclusions 50 



VI. — Chemical properties of wood 51 



VII. — Durability and decay 54 



How to distinguish the different kinds of wood 59 



How to use the key 62 



Key to the more irnportaut woods of North America 64 



I. — Non-porous woods (includes all coniferous woods) 64 



II. — Ring-porous woods 65 



III. — Diffuse-porous woods 69 



List of the more important woods of the United States 72 



A. — Coniferous woods 72 



B. — Broad-leaved woods (hardwoods) 76 



3 



