WOOD AND OTHER ORGANIC STRUCTURAL MATERIALS PUBLISHERS OF BOOKS F O R_, Coal Age ^ Electric Railway Journal Electrical World v Engineering News -Record Railway Age Gazette * American Machinist Electrical Merchandising v The Contractor Engineering 8 Mining Journal ^ Power Metallurgical & Chemical Engineering WOOD AND OTHER ORGANIC STRUCTURAL MATERIALS BY CHARLES HENRY SNOW, C. E., Sc. D. DEAN OF THE SCHOOL OF APPLIED SCIENCE, NEW YORK UNIVERSITY MEMBER OF THE AMERICAN SOCIETY OF CIVIL ENGINEERS, ETC. FIRST EDITION McGRAW-HILL BOOK COMPANY, INC. 239 WEST 39TH STREET. NEW YORK LONDON: HILL PUBLISHING CO., LTD. 6 & 8 BOUVERIE ST., E. C. 1917 A<\ COPYRIGHT, 1917, BY THE MCGRAW-HILL BOOK COMPANY, INC. f f f - ' . *> * *" \ THE MAPLE PRESS YORK PA PREFACE The purpose of this book is to present general as well as phys- ical characteristics of a group of structural materials, most of which are of organic origin. Among the materials thus described are woods, paints and varnishes with their associated oils, pig- ments, gums, and resins glues, creosotes, and indiarubber. As stated, most of these materials are of organic origin. Those that are not, such as pigments and creosotes, have been added because of their close practical association with the others. The book is designed for engineers, architects, students in schools of technology, teachers of manual training and others who use the materials described or who are interested in their properties. A statement of the reasons for separating structural materials along the line of organic and inorganic origin, seems to be in order. First, this basis is convenient: in fact, so many of the important organic materials are used in connection with one another that most of the present book might easily appear under such a title as "Properties of Woods and Associated Materials of Construction"; and, in the same way, the principal inorganic materials, steel, stone and concrete, are commonly associated. Second, the basis suggested is logical: organic materials are fundamentally different from inorganic materials, for the former are results of physiological processes and have within them the influence of life; these materials may manifest variations and special traits which do not appear in the more homogeneous and constant materials of the inorganic group. Assuming that some form of classification is desirable, where subject matter is as ex- tensive as that within the present field, the writer ventures to urge the merits of the one now employed. Also, a book devoted especially to the materials here considered seems warranted. It is true that the inorganic materials, metals, stones, and concrete, upon which principal attention is so often bestowed in text-books, do predominate in the larger engineering structures; but it is equally true that the organic material wood predominates in other structures, and that some of the materials now considered v 365844 vi PREFACE are used in practically all structures with which the engineer has to do. The opportunity is taken to criticise the degree of emphasis often laid in text-books upon those properties of structural mate- rials which relate to strength. That this phase of the subject should be given precedence is beyond all question, but that it should ever be emphasized so greatly as to diminish or more or less replace attention which might otherwise be given to other features, such as durability, is questioned. In other words, it is regarded as pedagogically unfortunate when the whole story can- not be at least outlined to the student, when one part is detailed to such an extent that the other parts cannot be detailed at all. The belief is expressed that many students in schools of tech- nology do not realize as early as they should, how real, live, and practical the subject " Properties of Structural Materials" is, and how greatly knowledge of it will influence works which they may later design and construct, and that one cause for this, in the case of some students, is the slight or omission here referred to. The printed sources of information employed are acknowledged in footnotes throughout the text, and in a bibliography arranged for those who wish further information on any of the parts in question. In addition to these printed sources of information, the writer is deeply indebted to some who have assisted him with special information and with criticisms and now acknowledges assistance thus received from Professors W. Kendrick Hatt, Hermann von Schrenk, C. Stuart Gager, Charles P. Sigerfoos, Edgar W. Olive, Alvah H. Sabin, the late Charles E. Bessey, and the late Mr. Octave Chanute, past president of the American Society of Civil Engineers. He also thanks, among others, Mr. C. D. Mell, Acting Dendrologist of the United States Forest Service, Mr. Charles A. Hexamer of the National Board of Fire Underwriters, Mr. Norman Taylor of the Brooklyn Botanic Gar- den, Mr. Edward A. Hewitt, late chemist of the Cooper Glue Company, Dr. Lothar E. Weber, of the Boston Indiarubber Labo- ratory, and several of his colleagues in New York University. CHABLES H. SNOW. UNIVERSITY HEIGHTS, BRONX, NEW YORK CITY, June 1, 1917. TABLE OF CONTENTS PAGE PREFACE v INTRODUCTION Practical Value of Subject "Properties of Materials." Materials Divided into Organic Materials and Inorganic Materials; Basis for this Division. Conservation. Relation of Organic Materials to Conservation xvii CHAPTER I WOODS COMPARED WITH STONES AND METALS. NOMENCLATURE. FUNDAMENTAL CLASSIFICATIONS Comparisons. Consumption of Wood. Reasons for Preferring Wood. Uses of Wood. Common and Botanical Names. Classifications: Botanical Classification of Trees and Woods; Gymnosperms (Coni- ferse) and Angiosperms (Monocotyledons, Dicotyledons) ; Practical Classification of Trees and Woods; Banded Trunks and Woods (Coniferous Series, Broadleaf Series); Non-Banded Trunks and Woods . 1 CHAPTER II TREES. PHYSIOLOGY OF TREES. VALUE OF FORESTS. FORESTRY Trees Considered as Sources from which Woods are Derived. Physi- ology of Trees: The Root System; The Leaves; The Trunk (Length- Growth, Thickness-Growth, The Cambium, Sap Movement, In- fluence of Sunlight). Value of Forests (Humus, -Influence of Forests on Streamflow, Influence of Forests on Erosion). For- estry vii viii TABLE OF CONTENTS CHAPTER III PAGE WOODS. CHARACTER AND ARRANGEMENT OF WOOD-ELEMENTS. IN- FLUENCE OF CELLULAR STRUCTURE UPON CHEMICAL COMPOSITION AND PHYSICAL PROPERTIES OF WOODS. IDENTIFICATIONS. STATEMENT OF WEIGHTS AND MODULI EMPLOYED IN TABULAR DESCRIPTIONS OF SPECIES Definitions. Cellular Structure of Wood. Importance of Subject. Wood-Elements: General; Wood-Fibers; Tracheids; Vessels; Wood- Parenchyma Fibers; Pith-Rays (Forms, Functions); Resin-Canals (Resins) ; Arrangement of Wood-Elements; Associated Compounds; Influence of Cellular Structure upon Chemical and Physical Properties of Woods. Identifications. Statement of Weights and Moduli Employed in Tabular Descriptions of Species 17 CHAPTER IV BANDED TRUNKS AND WOODS. GENERAL. (Conifers and Dicotyledons) General. Parts of the Trunk: Wood-Elements; Annual Layers (Spring and Summer Deposits, Means of Determining Age, Means of Identification); Bark (Inner Bark, Living Bark, Corky Layer, Epidermis): Sapwood; Heartwood; Pith. Development (Cross, Radial, and Tangential Surfaces, Grain or Figure, Definitions). Defects (Shakes, Checks, Knots, Disease, Manufacturers' Stand- ards). Sub-Divisions: Coniferous, Needleleaf or Softwood Series; Non-Coniferous, Broadleaf or Hardwood Series . . . 34 CHAPTER V BANDED TRUNKS AND WOODS (Continued) Coniferous or Needleleaf Series (Conifers) General and Introductory. Pine: The Soft Pines and Hard Pines (White Pine, Sugar Pine, Georgia Pine, Cuban Pine, Shortleaf Pine, Loblolly Pine, Bull Pine, Norway Pine, Pitch Pine, Northern Pine, etc., etc.). Kauri Pine (Kauri Pine). Spruce (Black Spruce, White Spruce, Sitka Spruce, etc.). Douglas Spruce (Douglas Spruce). Fir (Balsam Fir, Great Silver Fir, Red Fir, White Fir, Noble Fir). Hemlock, (Hemlock Western Hemlock). Larch or Tamarack (Larch). Cedar (Red Cedar, Juniper, White Cedar, Canoe Cedar, Port Orford Cedar, Yellow Cedar, Incense Cedar, etc.). Cypress (Bald Cypress). Redwood (Redwood, Giant Redwood) . 44 TABLE OF CONTENTS ix CHAPTER VI BANDED TRUNKS AND WOODS (Continued) Broadleaf Series, Part One (Dicotyledons) PAGE General, Definitions. Oak (White Oak, Cow Oak, Chestnut Oak, Post Oak, Bur Oak, Western White Oak, Red Oak, Pin Oak, Spanish Oak, Black Oak, Live Oak, California Live Oak, English Oak, etc.). Ash (White Ash, Red Ash, Blue Ash, Black Ash, Green Ash, Oregon Ash, etc.). Elm (White Elm, Cork Elm, Slip- pery Elm, Wing Elm, etc.). Maple (Sugar Maple, Silver Maple, Red Maple, Oregon Maple, Box-elder, etc.). Walnut (Circassian Walnut, Black Walnut, White Walnut, etc.). Hickory (Shagbark Hickory, Pignut, Mocker Nut, Pecan, etc.). Chestnut, Chinqua- pin (Chestnut, Chinquapin, etc.). Beech, Iron wood (Beech, Iron- wood, Hop Hornbeam, etc.). Sycamore (Sycamore, California Sycamore, etc.). Birch (White Birch, Paper Birch, Red Birch, Yellow Birch, Sweet Birch, etc.). Locust, Mesquite (Black Locust, Honey Locust, Mesquite, etc.) 102 CHAPTER VII BANDED TRUNKS AND WOODS (Continued) Broadleaf Series, Part Two (Dicotyledons) White wood Group (Tulip Tree, Poplar, Cottonwood, Black Cotton- wood, Cucumber-tree, Basswood, etc.); Willow (Black Willow, White Willow, etc.); Catalpa (Hardy Catalpa, Catalpa, etc.); Mulberry (Red Mulberry, etc.); Horse Chestnut. Buckeye (Ohio Buckeye, Sweet Buckeye, etc.); Gum (Sweet Gum, Tupelo Gum, Sour Gum); Holly. Boxwood. Lignumvitse (Holly, Dog- wood, Lignumvitse, etc.); Laurel (California Laurel, Madrona, etc.); Sassafras. Camphor (Sassafras); Greenheart (Greenheart) ; Persimmon. Ebony (Persimmon) ; Osage Orange. Cherry (Osage Orange, Wild Black Cherry) ; Mahogany (Mahogany, Spanish Cedar, White Mahogany); Satinwood; Teak (Teak); Some Tropical Species (Sabicu, Sissoo, Rubber Tree, California Pepper, China- berry, Rosewood, Sandalwood) ; Eucalyptus (Blue Gum, Red Gum, Jarrah, Karri, Tuart, Sugar Gum, Giant Eucalypt, Manna Gum, Stringybark, Red Mahogany, etc.) 169 CHAPTER VIII NON-BANDED TRUNKS AND WOODS (Monocotyledons) General and Introductory. Parts of the Trunk. Wood-Elements. Uses. Sub-Divisions. Palm (Washington Palm, Date Palm, Cabbage Palmetto, etc.); Yucca (Joshua-tree); Bamboo (Bamboo, etc.) .224 TABLE OF CONTENTS CHAPTER IX PAGE SPECIAL PROPERTIES OF WOODS DUE TO THEIR ORGANIC ORIGIN. CHEMICAL COMPOSITION OF WOODS. PHYSICAL PROPERTIES OF WOODS: DESCRIPTIONS OF WEIGHTS AND MODULI EMPLOYED. MOISTURE IN WOODS; INFLUENCE OF MOISTURE, ANTISEPTICS, AND HEAT UPON THE PHYSICAL PROPERTIES OF WOODS General and Introductory. Special Properties due to Organic Origin. Chemical Composition: Chemical Elements; Organic Compounds (Cellulose, Lignin, Associated Materials); Inorganic Compounds. Physical Properties: Descriptions of Physical Properties; Strength, Rigidity, Elasticity, Resilience, Hardness, Ability to Hold Fasten- ings, Weight, Specific Gravity and Density, Porosity, Conduc- tivity, Resonance. Measurements of Physical Properties (Diffi- culties, Selection and Preparation of Test-Pieces, Sizes of Test- Pieces, Standards for Moisture, Woods Compared with Stones and Metals, Existing Experiments Separated into Groups). Descrip- tions of Weights and Moduli Employed. Influence of 'Moisture, Antiseptics, and Heat upon Physical Properties : Moisture in Wood (Quantity of Moisture, Distribution of Moisture, Influence of Moisture upon Decay, Influence of Moisture upon Physical Prop- erties, Influence of Moisture upon Distortion). Influence of Anti- septics upon Physical Properties. Influence of Heat upon Physical Properties . . 233 CHAPTER X FAILURE OF WOOD BECAUSE OF USE, EXPOSURE, AGE, AND DECAY General and Introductory. Failure of Wood because of Use. Failure of Wood because of Exposure. Failure of Wood because of Age. Fungous Diseases: Fungi (Descriptions, Conditions under which Fungi Act); Fungous Diseases of Trees (Diseases of Foliage, Dis- eases of Roots, Diseases of Trunks) ; Fungous Diseases of Structural Woods (Life of Fungi Influenced by Position or Exposure of Wood, First Exposure, Second Exposure, Third Exposure, Influence of Top-Soil, etc., Fourth Exposure, Evidence of Disease, Methods of Treatment, Methods of Protection) 267 TABLE OF CONTENTS xi CHAPTER XI FAILURE OF WOOD BECAUSE OF FIRE. WOOD AS AN AGENT IN CONFLAGRATIONS. FIRE PROTECTION PAGE General and Introductory. Fire Losses in the United States. Com- parison of Losses with those in Other Countries. A Principal Cause for Excessive Fire Losses in the United States. Wood as an Agent in Conflagrations: The Burning of Wood; Attempts to Pre- vent Wood from Burning; Internal Protection (Fire-Retarding Materials, Processes for Introducing Fire-Retarding Materials within Woods, Preparation of Woods to Receive Fire-Retarding Materials) ; External Protection (Materials, Fireproof Paints, Metals, etc., Methods used to Apply Materials, Preparation of Woods to Receive Materials); Methods of Testing "Protected" Woods; Methods used to Extinguish Burning Woods; Materials (Water, Carbon Dioxide, Carbon Tetrachloride, etc.); Devices for Applying Materials (Fire Engines, Chemical Engines, Extin- guishers) ; Organizations. Some Principles of Fire Protection : His- torical and Introductory; Burning Buildings (Inside Fires, Outside Fires, Temperatures in Burning Buildings); Methods by which Buildings are Prevented from Burning; Materials (Metals, Natural Stones, Artificial Stones, Combinations); Influence of Design, Special Devices, etc. (Fireproof Construction, Roofs, Door Open- ings, Fire-Doors, Window Openings, Fire-Shutters, Wired-Glass, Automatic Sprinklers, Signals) ; Care or Maintenance of Structures (Inflammable Stores, Watchmen's Recorders) 277 CHAPTER XII FAILURE OF WOOD BECAUSE OF ANIMAL LIFE. MARINE AND TER- RESTRIAL WOODBORERS. METHODS OF PROTECTION Introductory. Marine Woodborers: The Shipworm; Form, Physiology, Reproduction, and Development, Influence of Temperature and Water, Method of Attack, Size of Borings, Rapidity of Work, Field of Attack, Woods Subject to Attack: The Limnoria; Form and Physiology, Influence of Temperature and Water, Method of Attack, Character of Excavation, Size of Borings, Rapidity of Work, Field of Attack, Woods Subject to Attack: The Chelura; Form and Physiology, Method of Attack, Character of Excavation, Size of Borings, Field of Attack : Miscellaneous ; Fresh Water Borers, Stone Borers, Barnacles. Methods of Protection: Removal during the Breeding Season; Change of Water; Use of Selected Woods; External Coatings (Bark, Planks, Metals, Teredo Nails, Paraffin, Tar, Paints, Reinforced Coatings, Cement, Sand, Natural Protection); Preservatives Applied within Woods (Creosotes); Substitution. Terrestrial Woodborers: General; Beetles (Char- acteristics, Summary); Moths and Butterflies (Characteristics, Summary); Termites or White Ants (Characteristics, Protection, Summary); Black Carpenter Ant; Carpenter Bee. Methods of Protection . xii TABLE OF CONTENTS CHAPTER XIII PROTECTIVE METHODS SEASONING PAGE General and Introductory. Natural Seasoning. Water Seasoning. Kiln Seasoning (General, Influence of Temperature, Influence of Moisture, Air-currents, Forms of Kilns, Operation of Kilns, Diffi- culties, Time Required). Protection of Seasoned Woods .... 326 CHAPTER XIV PROTECTIVE METHODS INTERNAL TREATMENT. PRESERVA- TIVE COMPOUNDS APPLIED WITHIN WOODS General and Introductory. Materials: Tannin; Copper Sulphate; Mercury Bichloride; Zinc Chloride; Creosote (General, Definitions, Specifications, Analyses, Required Quantities, Distribution, etc.); Miscellaneous Materials (Carbolineum). Processes Used to Intro- duce Antiseptics within Woods; Superficial Processes (Dipping, Soaking, Brush Applications); Non-Pressure Processes (The Kyan and Open-Tank Processes); Pressure Processes (Use of Cylinders, Pressure, Heat and Vacuum, Full Cell, Empty Cell, Bethell, Hay- ford, Burnett, Rutgers, Card, Allardyce, Rueping, Lowry, Boiling, Wellhouse, Creo-Resinate, Creoair, Boucherie, Charring, Vulcan- izing, Robbins, Seeley, Powell, Thilmany, Hasselmann, and Ferrell Processes) ; Woods that are to Receive Treatment 335 CHAPTER XV PROTECTIVE METHODS EXTERNAL TREATMENT. OILS, PAINTS, VARNISHES, AND OTHER COATINGS. THEIR APPLICATION TO SURFACES OF WOODS General and Introductory. Materials: Oils (Solidifying or Drying Oils and Driers, Non-Solidifying Oils, Volatile Oils and Spirits); Pig- ments and Fillers (White Lead, Zinc White, Barium Sulphate, Red Lead, Iron Oxides, Carbon Paints, Fillers); Gums, Resins, and Varnishes (Amber, Copal, Anime, Zanzibar, Kauri, Shellac, Sanda- rach, Dammar, Mastic, Rosin, Varnishes); Miscellaneous Mate- rials (Stains, Whitewash, Kalsomine, Cold Water Paints, etc.). Methods of Application: The Application of Paint; Influence of Application upon Durability; The Application of Varnish (Plain Varnished Surfaces, Polished Surfaces, Varnish Paint or Enamelled Surfaces). Preparation of Woods to Receive Paints and Var- nishes. Other Coatings (Metals, etc., etc.) 377 TABLE OF CONTENTS xiii CHAPTER, XVI ADHESIVES. CATTLE GLUES. FISH GLUES. SELECTION, TESTING - AND APPLICATION OF GLUES PAGE General and Introductory. Cattle Glues: Sources; Manufacture; Properties (Foreign and Domestic Glues, Influence of Heat and Moisture, etc.); Selection; Application (Dissolving the Glue, Pre- paring the Wood, Completing the Joint); Protection of Joints (Resistance to Heat, Resistance to Moisture, Influence of Forma- lin); Durability of Joints. Fish Glues: Sources; Manufacture; Properties; Selection; Application. Methods of Testing Glues: Cattle Glues (Standards, Samples, Appearance, Fracture, Odor, Acidity, Grease, Viscosity, Foam, Strength); Fish Glues. Some Uses: Veneers (Reasons for Preferring Veneered Work, Prepara- tion and Uses of Veneered Work) ...;....,...... 403 CHAPTER XVII INDIARUBBER AS A STRUCTURAL AND MACHINE MATERIAL. SOURCES, PREPARATION, PROPERTIES, AND USES OF INDIARUBBER General and Introductory. Indiarubber. Rubber Latex; Collection of Latex, Rubber obtained from Latex. Geographical and Botan- ical Classifications of Rubber; Crude and Refined Rubber, Fresh and Reclaimed Rubber, Wild and Plantation Rubber. Purification and Preparation of Rubber. Vulcanization. Properties of Pure Rubber and Vulcanized Rubber. Synthetic Rubber. Uses of Rubber 421 BIBLIOGRAPHY 437 INDEX. . 447 LIST OF PLATES FACING PLATE PAGE I Arrangement of Wood Elements Cross Sections 18 II Arrangement of Wood Elements Tangential Sections .... 22 III Arrangement of Wood Elements Radial Sections ..... 28 IV Influence of Wind upon Trees at Timber Line ....... 42 V Fungous Diseases of Wood 268 VI Portion of Floor Beam after Attack by Dry Rot Fungus . . . 274 VII Appearance of Fire Doors after Fire ; . 286 VIII Details of Tin Clad Fire Door. . ", . . . . . . 296 IX Work of the Shipworm ... . . . . , . . . . . % 302 X Work of Shipworm Large Borings ' . ,' 308 XI Work of the Limnoria . . . ... ............ 312 XII Work of the Chelura. 314 XIII Work of Larvae of Beetles. "Bookworms". ........ 318 XIV Work of Large Carpenter Ant. . . . ." ..... . . ... 322 XV High Power Spraying Apparatus in Action 324 XVI Trough Employed in Kyan Process 354 XVII Open Tank Process Applied to Butt Treatment of Poles . . . 358 XVIII Steel Cylinders Designed for Treating Wood 362 XIX Plant for Creosoting Lumber 370 XX Application of Glue in Large Curved Joint 416 xv INTRODUCTION A knowledge of the properties of the substances used in con- struction gives confidence to those who employ them and permits smaller margins beyond calculated requirements than otherwise would be possible. Wood is one of the primary materials of construction. The others are stone and iron. These fundamental materials possess distinguishing properties, and each as a class includes a series of individuals or varieties, which are again distinguishable from one another by certain minor or specific properties. All structural materials may be divided as they are organic and inorganic. Wood and other organic structural materials are characterized by qualities due to life processes, age, and other physiological causes. Stone, iron, and other inorganic materials are not distinguished in this way; these materials are more simple, homogeneous, and constant. What is now known as " conservation " has been defined 1 as "the greatest good to the greatest number and that for the longest time." The idea of conservation includes the reduction of waste. The future as well as the present is regarded. The broader needs of the nation are placed before the immediate needs of the individual; and, whenever possible, resources are considered more as they produce yearly incomes and less as though they were fixed sums to be drawn upon directly and thus exhausted ultimately. Woods and other organic materials respond more completely than metals and stones to the application of the principles of con- servation because they can be reproduced. The development of a forest requires time, but such development is possible, and once established the forest can be maintained so as to yield for in" definite periods. On the other hand, inorganic materials exist in fixed and final quantities. The more the materials of the 1 Van Hise in "The Conservation of Natural Resources in the United States." See also "The Fight for Conservation," Pinchot; "Conservation of Water by Storage," Swain (Yale University Press); etc., etc. xvii xviii INTRODUCTION inorganic group are used, the more quickly they will become exhausted, and once exhausted these materials cannot be reproduced. Wood is the principal organic structural material but it is not the only one. The oils that are used in paints, varnish-resins, glues, indiarubber and other materials are of this series. WOOD AND OTHER ORGANIC STRUCTURAL MATERIALS CHAPTER I WOODS COMPARED WITH STONES AND METALS. COMMON AND BOTANICAL NAMES. FUNDAMENTAL CLASSIFICATIONS Information relating to the general properties of wood compares in importance with information relating to the general properties of steel, stone, and cement. Engineers use more wood than any other set of men, yet general facts about wood, aside from those relating to its strength, are often relegated to the consideration of the botanist or the forester. The consumption of wood has never decreased, although metals and stones have been substituted for it in many positions. In England, the consumption per capita more than doubled in the fifty years preceding 1895, in spite of the fact that nearly all of the wood used in that country had to be imported. In 1905, the total yearly mill value of wood products in the United States was over nine times as great as the combined product of gold and silver, and twice as great as the value of the wheat crops. 1 The importance of wood as a material of construction is well expressed in the quotation that follows : 2 "Wood is an indispensable part of the material structure upon which civilization rests; and it is to be remembered always that the immense increase of the use of iron and substitutes for wood in many structures, 1 A conservative estimate places the yearly mill value of wood products in the United States alone at $1, 100,000.000. The spring and winter wheat crops of 1905 were together valued at $518,372,727. The production of gold and silver during the year 1904 was valued at $112,871,026. See also "Forest Resources of the World," Zon (United States Forest Service Bulletin, No. 83). 2 Credited to the Honorable Theodore Roosevelt. 1 2 ORGANIC STRUCTURAL MATERIALS while it has meant a relative decrease in the amount of wood used, has been accompanied by an absolute increase in the amount of wood used. More wood is used than ever before in our history." Wood is preferred because it is easily worked and light in weight. In many positions, it is as durable as iron. When dry it is a poor conductor of heat and electricity and is stronger than is commonly supposed. The tensile strength of a bar of hickory may exceed the tensile strength of a similar bar of wrought iron of the same length and weight. 1 However, wood is not homo- geneous like metal and most of the stones that are used for build- ing, but is so variable that several parts of the same tree often exhibit widely different qualities. Most wood is used in construction; that is, in mines, railways, houses, and ships where size or quantity is required and where finish and appearance are less important. Much wood is used in cabinet work and in positions where appearance, appropriateness, and finish are important. Such woods are more in evidence, but the amounts used are actually very much smaller than the amounts used in construction. Some wood is required for turnery, carv- ings, and implements that demand exact qualities that can be secured in small pieces only. Some wood is used indirectly, and in the manufacture of paper-pulp, gunpowder, and chemicals. There are also by-products of trees, such as tanbark, turpentine, resin, and sugar. Common and Botanical Names. Woods appear to be more numerous than they actually are, because more than one name is so often applied to the same species. Supplies are often brought from far distant places when woods of the same kind are available nearby, but are not recognized because they are called by differ- ent names. One species, the Southern, Yellow, Georgia, or Longleaf Pine (Pinus palustris), has nearly thirty local names. Such confusion can be avoided only by regarding the recognized botanical nomenclature. Not only is it true that several names are often applied to the same wood, but, strange as it may seem, a fairly constant single product is sometimes derived from several unrelated species. The single name cedar is thus applied to several species of durable characteristically scented woods, which have similar anatomical features and which are derived from species that are not closely related to one another. 1 United States Department of Agriculture, Yearbook, 1896, p. 392, Roth. NOMENCLA TURECLASSIFICA TIONS 3 The botanical name of a plant is made up of terms denoting genus and species. For example, Quercus is the generic name that includes all the species of oak, while alba and rubra are specific names that apply to two particular species of the genus Oak. Quercus alba and Quercus rubra are completed names. The names of species are not fixed, but differ with authorities so that it is often best to add the abbreviated name of the botanist responsible for the name employed. Illustrations would be Quercus alba Linn., Quercus rubra Linn., and Ulmus fulva Michx. A genus may be defined as a collection of related species, and a species may be regarded as a collection of individuals that might easily have sprung from some single stem. Genera are grouped into families, and both genera and families differ with authorities. The term " variety" is applied to individuals that differ less from one another than do species. Quercus robur var. pedunculata indicates a variety (var. pedunculata) of a certain species (robur) of Oak (Quercus). It should be noted that the variety of one botanical authority is sometimes regarded as a distinct species by another botanical authority. About five hundred species of trees grow in the United States 1 and many other species grow in other countries, yet, the great mass of wood that is used in construction comes from compara- tively few of these species. Sudworth excludes all but one hundred sources in his "Trees of the United States Important to Forestry," while a United States Treasury Department Sum- mary contains the statement that but sixteen (16) kinds of hard- wood were quoted in the Chicago markets on the first day of September of the year 1900. 2 The statement is also made in the source referred to, that the prin- cipal timbers of commerce in the United States are the genera known popularly as pine, fir, oak, hickory, hemlock, ash, poplar, maple, cypress, spruce, cedar and walnut. Conditions are changing. The original forests are much smaller than in former years. Many woods that were once common are now scarce, while other woods that were once unfamiliar are now employed. 1 Fernow credits four hundred and ninety-five species to the United States (Introduction to United States Forestry Bulletin No. 17); Sargent, counting species only and excluding varieties, notes four hundred and twenty-two species (Silva of North America). 2 1900, p. 1081. 4 ORGANIC STRUCTURAL MATERIALS Botanical Classification of Trees and Their Woods. Botanists group trees as they do other seed-bearing plants, mainly upon the characteristics of parts other than the trunks. In such groups, the flowers, fruit, and leaves are fundamentally important. A general classification is as follows : I. GYMNOSPERMS. The seeds are naked, that is, they are not enclosed in fruit. There are three natural groups or families as follows: (a) Cycadacece. Practically confined to tropical and sub-tropical regions. Practically valueless for wood. To be here disregarded. (&) Gnetacece. Consists of undershrubs, shrubs, and small trees, most of which grow in the tropics. Practically valueless for wood. To be here disregarded. (c) Coniferce. This is by far the largest and most important of the three families, and the only one that yields merchantable lumber. The Pines, Spruces, Firs, and Cedars are among the members of this family. The seeds are borne on series of overlapping scales, arranged in what are known as cones. The leaves of ordinary species are narrow, rigid, needle-like, or scale-like. Resins are present. The trees are sometimes called Needle-leaf, Softwood, and Evergreen trees, as well as Coniferous and Cone-bearing trees. II. ANGIOSPERMS. The seeds are always enclosed in more or less obvi- ous seed-vessels or fruit. These plants greatly exceed those in the pre- ceding groups in the number of their species and in the variety of their habits. All ordinary flowering plants are Angiosperms. There are two classes, which, while they agree in having enclosed seeds, differ in other matters, and in none more than in the structure of their stems or trunks. The Angiosperms are sub-divided as follows: (a) Monocotyledons. These plants have one seed leaf or cotyledon, whence the name, Mono-cotyledon. The veins in the leaves are more or less parallel to one another. Some twenty-five thousand species are recognized, but very few of these species yield woods that are valued in construction. The few Monocotyledons that yield woods that are valued in construction are associated with the tropics. The Palms and Bamboos are Monocotyledons. (6) Dicotyledons. These plants have two seed-leaves or cotyledons, whence the name ZH-cotyledon . The veins in the leaves of the Dicotyle- dons are netted. The stems of these plants increase by layers of new material that form, each one upon the outside of others that were formed before. Coniferous trees increase in practically the same manner. Sev- eral hundreds of the over one hundred thousand Dicotyledons are trees, and these Dicotyledonous trees yield the so-called Broadleaf woods, Deciduous woods, or Hardwoods of commerce. The Oaks, Maples, and Hickories are among the Dicotyledons. NOMENCLA TURECLASSIF1 CA TIONS 5 The woods that are valued in construction are derived from the Conifers, the Dicotyledons, and the Monocotyledons, in the order named. The other divisions of plant life do not produce mer- chantable woods and may be disregarded in this connection. Practical Classification of Trees and Their Woods. Those who use woods are less concerned with the flowers, fruit, and leaves of the trees, than with the trunks, and the charac- teristics of the woods themselves. The present text has for its object a study of woods, as distinct from trees, and for this reason, the features of flowers, fruit, and leaves, which are so important to the botanist, will be regarded as secondary, and woods will be classified upon the basis of their own properties. From this viewpoint all trees, trunks, and woods will be divided primarily according to the way in which new material is added to their sections. Two great divisions will be distinguished: 1. Banded Trunks and Woods. In this case the wood is arranged in concentric bands or layers which, in cross-sections, appear as rings. The trees that yield banded woods are all FIG. 1. Section through a banded trunk (longleaf pine, Pinus paliLstris}. "outside-growers;" that is, new material is deposited in layers, each one of which is formed upon the outside of other layers that were formed before. Pines, oaks, and practically all other trees that yield woods that are valued in construction are included in this division. It is the group to which the name Exogen, or Outside-grower, has been applied by the engineer. 6 ORGANIC STRUCTURAL MATERIALS The names Exogen and Endogen are undesirable because engineers and botanists seldom employ them in the same way. Some botanists use the name Endogen in connection with Monocotyledonous trees and woods, but restrict the use of Exogen to Dicotyledonous trees and woods, while others do not employ these terms at all. This group is divided into Conifers and Dicotyledons. The first sub-series includes the so-called Softwoods. Coniferous, Softwood, Needleleaf and Evergreen woods are the same. It should be noted that in spite of the use of the word Softwood some of the individuals of this sub-series are actually very hard. The Dicotyledons are often referred to as Hardwoods although some of them are really quite soft. Dicotyledonous, Hardwood, Non-coniferous, and Deciduous woods are the same. 2. Non-banded Trunks and Woods. These woods are not arranged in concentric rings or layers. On the contrary, the FIG. 2. Section through a non-banded trunk (royal palm, Oreodoxa regid). NOMENCLA T URECLASSIFICA TIONS 7 wood is scattered irregularly in small fibrous groups throughout the tree which is, therefore, known as an " inside-grower." The Palms, Bamboos, and a few other plants of this group that yield useful woods are associated with the tropics. The woods are seldom used much in construction far from the places in which they grow. This group includes the Monocotyledons of the botanist and is the one to which the name Endogen, or Inside-grower, has been applied by engineers. 1 1 See first paragraph page 6. CHAPTER II TREES. PHYSIOLOGY OF TREES. VALUE OF FORESTS. FORESTRY A study of iron begins at the furnace; a knowledge of stone must include some facts with regard to the quarry from which the stone was taken; in the same way a study of wood must commence with a study of the tree within which the wood was formed. PHYSIOLOGY OF TREES. A tree has been defined (Century Dictionary) as "a perennial plant which grows from the ground with a single, perma- nent, woody, self-supporting trunk or stem, ordinarily attaining a height of at least twenty or thirty feet." A tree has three principal parts or sys- tems; they are the roots, the leaves or foliage, and the stem or trunk. The roots and the foliage are here regarded only as they are means by which the wood of the stem is manufactured. The Roots. This system of branches is as extensive as the one at the top of the tree. Roots serve in two ways: (1) they give stability and hold the tree firmly in its place; (2) they absorb moisture and various nutrient salts from the soil. With the exception of carbon and some oxygen used in respiration, all of the elements needed for the growth of trees are obtained from the soil through their roots. REFERENCES. " Cyclopedia of American Horticulture," Bailey; "Fores- try for Farmers," Fernow (United States Division of Forestry Bulletin No. 10); "First Book of Forestry," Roth; "Outlines of Botany," Leavitt (American Book Company); "Plant Anatomy," Stevens (Second Edition). 8 FIG. 3. Roots, a, Cross- section through root; 6, hairroots enlarged. PHYSIOLOGY OF TREES FORESTRY I One year J old The Leaves. Carbon, in the form of carbon dioxide, is ob- tained from the atmosphere by means of the green coloring matter which forms part of the leaf and which is known as chlorophyll. Leaves also serve as laboratories within which food materials are formed which may finally enter into the formation of wood. By some peculiar property of the chlorophyll, the living tissue of the leaf is able, in the presence of sunlight, to split apart the C0 2 and to recombine the constituents with H 2 so as to form a carbohydrate, probably some form of sugar. 1 The chemical formulas of grape sugar (C 6 H 12 O 6 ) and cellulose (C 6 H 10 O 5 ) are essentially alike, so it is clear that, with the development of carbohydrate compounds in the leaves, a fundamental step has been taken toward the formation of wood. The Trunk. The trunks of trees that yield banded woods must be distinguished from the trunks of trees that yield non- banded woods. In the first group, the wood-elements are arranged in concentric bands or layers, while in the second group they are distributed in separate bundles so that the cross sections, in this case, appear as though dotted (Figs. 1 and 2). All trunks increase in two ways : in length and in thickness. Increase in length is quite distinct from increase in thickness. The terms length-growth and thickness- growth will be employed to indicate these two methods of increase. Length-growth. All trees lengthen by means of material that forms upon the ends of the main axis and of the twigs and branches. A point of embryonic cells exists at the end of each ultimate twig. These apical cells grow, divide, and in the course of the year leave behind them a whole new section of twig with its leaves. The twig then thickens by a centrifugal growth to be described, and eventually the twig becomes a part of the bough. 1 "Light in Relation to Tree Growth," Zon and Graves (United States Forest Service, Bulletin No. 92.) .Hwo years old 10 ORGANIC STRUCTURAL MATERIALS Length-growth precedes thickness-growth and is quite distinct from it. A nail driven into a tree at a certain distance up from the ground may be finally covered by new wood material, but it will not move up higher from the ground. Thickness- growth. With several exceptions, the few trees that yield non-banded woods do not increase in diameter by the formation of new layers deposited upon the outside of older growth. On the contrary these trees increase largely by the expansion of cells already formed. The trunks of these trees, few of which are of structural importance, do not continue to increase in diameter throughout their lives, but normally attain maximum diameters comparatively early in their growth. The trees that yield banded woods thicken as follows: During the first year, the wood material is in separate bundles arranged in a circle, but later these bundles are fused together so as to form a more or less compact cylinder. The a 6 c FIG. 5. Cross-section of very young banded stem, a, Six fibro-vas- cular bundles are shown, b, The same stem later; the bundles are increased to twelve, c, At the end of the year the bundles are in the form of wedges separated by pith rays. Acknowledgments to "Outlines of Botany," Leavitt (American Book Company). tissue known as primary wood is included in this early growth. 1 The several stages during the first year are sufficiently indicated in the pictures. After the first year, the food materials, which are formed in the leaves, descend to the growing part where the new wood is formed. This part is known as the " cambium layer." Wood formed from the cambium layer is known as secondary wood. Practically all of the wood formed by the tree is of this kind. After the first year a new layer of secondary wood is formed every growing season, and these annual layers or bands are characteristic of all banded woods. 1 Tissue at the growing end of the twig forms primary wood. The thin- walled cells of which it is composed are essentially similar to one another. PHYSIOLOGY OF TREES FORESTRY 11 The Cambium Layer. This part, which is of fundamental importance to the life of the tree, occupies the region between the sapwood and the bark, and may be described as a thin-walled formative tissue within which, by cell-division, growth, and modification, all wood-elements originate. The cambium layer consists of essentially the same kind of embryonic cells as those at the tips of the twigs. The cambium layer, which suggests a thin layer of mucilage, is com- posed of very thin-walled cells, filled with protoplasm, and other organic and nutrient compounds. These cells multiply and develop. The inner cells eventually form a new layer of wood while those at the outside form bark. The wood cells, which are at first soft and delicate, become harder, as a material known as lignin begins to be deposited within their walls. The resulting change from the soft cell to the tough, woody cell is known as lignification. The cambium, in its centrifugal advance, may leave one hun- dred or more thin layers of wood-elements behind every year and these very thin deposits together make up what is commonly known as the " annual band" already mentioned. Sap Movement. In the trees that yield banded woods, the " crude sap," containing mineral nutrients drawn from the soil, leaves the roots and passes upward through the outer sapwood to the foliage where the sap is by complex chemical changes " elabor- ated." The elaborated or completed sap, containing the more complex organic preparations needed for the life of the tree, then descends through the inner bark to the growing parts. The fluids of a tree move continuously during the growing season. Up-currents and down-currents move simultaneously. In the main, fluids pass upward through the outer sapwood and downward through the inner bark, as has been noted. This continues through the larger part of the year and is not confined to the spring alone as some suppose. The means by which sap ascends to the top of the tree are not fully understood, but evidence exists that the force is not capillary to the extent that was formerly supposed. The passage upward is doubtless encouraged by the evaporation of water from the leaves, but how far this acts in raising the water through dis- tances as great as several hundred feet is not known. 1 iSee "Tracheids." 12 ORGANIC STRUCTURAL MATERIALS Influence of Sunlight. All trees require sunlight and are influenced by the way in which they receive it. A tree that stands by itself in the open will differ in form from a tree that stands with others in the forest. In the former environment, the growth of lower branches is encouraged, while in the latter environment, it may be discouraged. Sunlight does not have free access to the side branches of ordinary trees standing near together in a forest. The higher branches of such trees are there- fore better nourished. These extend upward toward the sun- light, and consequently longer, cleaner trunks are formed. FIG. 6. Sugar maple tree grown in the open. (By courtesy of American Museum of Natural History.) It is possible to modify the shapes of trees. Either full- branched trees, that are prized in landscape effects, or long, straight trunks that are valued by lumbermen can be obtained by proper exposure to sunlight. The lower branches of many forest trees are pruned away by nature, that is, these branches die naturally for want of sunlight. In other cases the same results are obtained by ordinary pruning. In any case where lower branches are removed, wood-making material which would otherwise pass into these branches is diverted to the trunk. The value and influence of sunlight are described in the follow- ing quotation: 1 1 " Light in Relation to Tree Growth," Zon and Graves (United States Forest Service Bulletin No. 92). PHYSIOLOGY OF TREES FORESTRY 13 "Light is indispensable for the life and growth of trees. In common with other green plants a tree, in order to live, must produce organic substance for the building of new tissues. Certain low forms of vege- table life, such as bacteria and fungi, do not require light. They exist by absorbing organic substance from other living bodies; but the higher forms of plants manufacture their own organic material by extracting carbon from the air. The leaves, through the agency of their chlorophyll, or green coloring-matter, absorb from the air carbon dioxide, and give off a nearly equal volume of oxygen. The carbon dioxide is then broken up into its elements and converted into organic substances which are used in building up new tissues. "Light is not only indispensable for photo- synthesis, but it is essential for the formation of chlorophyll. Only in exceptional cases, as in the embryo of fir, pine, and cedar seeds, does chlorophyll form in the dark, and, with the exception of some microbes, the green cell is the only place where organic material is built up from inorganic substances. "Light also influences transpiration, and consequently the metabolism of green plants. It influences largely the structure, the form, and the color of the leaf, and the form of the stem and the crown of the tree. In the forest it largely determines the height-growth of trees, the rate at which stands thin out with age, the progress of natural pruning, the character of the living ground cover, the vigor of young tree growth, the existence of several- storied forests, and many other phenomena upon which the management of forests depends. A thorough understanding, therefore, of the effect of light upon the life of individual trees, and especially on trees in the forest, and a knowledge of the methods by which the extent of this effect can be determined are essential for successful cultural operations in the forest." VALUE OF FORESTS. The top- soil of forests is porous and loose. The mixture of leaves and loose top-soil that forms under the trees is known as " humus." The humus receives and pro- tects young seeds and is also valuable because it assists in equal- izing the flow of streams. FIG. 7. Tulip tree grown in the forest. (Courtesy of the American Museum of Natural History.) 14 ORGANIC STRUCTURAL MATERIALS Rain-water rolls quickly from sun-baked or otherwise com- pacted soil, but humus permits the raindrops to pass through into the more or less broken and comparatively loose and porous soil below and then obstructs the free evaporation of moisture from this soil. It is not known that forests influence rainfall, but their value in regulating stream-flow is beyond estimate. 1 FIG. 8. Ability of Surface Materials to hold Water. A, Most of the water in this bottle, which contains gravel, has passed through into the beaker. B, C, and D, These bottles contain sand, barren soil and loam. E, This contains leaf mould, which retains the most water. F, This contains leaves. (From "Trees and Forestry," Dickerson. By permission American Museum of Natural History.) Forests Reduce or Prevent Erosion. The humus protects the surface, and the roots contribute to the resistance offered by the soil below. Water flows with erosive force over unprotected and hardened surfaces. Quantities of soil are carried from higher elevations and deposited on lands below. Such results may be far reaching. Districts such as parts of India, China, Palestine, and Spain, that have supported considerable popula- tions in the past, have been changed in this way and are now little else than deserts. x Leighton estimated that the flood damages to this country amounted to $237,800,000 in 1908; "Conservation of Natural Resources in the United States" (Van Hise, p. 182). See also Swain in "American Forestry," April, 1910, and Burr in "Engineering News," July 27, 1911, etc. PHYSIOLOGY OF TREES FORESTRY 15 The possibilities in this direction are described further as follows (Van Hise 1 ) : "Not only so, but after the rivers are partly filled with silt, at times of flood they overflow their banks and often cover with coarse debris large areas of arable land. When this process of erosion has continued for a sufficient length of time after the removal of the forests, the steep mountains are left with nearly bare rock and little soil. When this stage of the process has been reached the violence of the floods is then further greatly increased. The rain falling upon the bare rocks is car- ried down to the streams below as from the roof of a house, and unites in torrential floods. It is after this condition of affairs has come about as a result of a removal of the forests that the enormous flood losses occur to railroads, cities, and other structures of man." FORESTRY. Forestry is a phase of agriculture, rather than of lumbering. Under this system forests are not destroyed for immediate profit but are maintained so as to secure recurring crops of desirable, matured trees. Besides this, appropriate species are planted, top-soil or humus is preserved, fire risks are lowered, and young trees are introduced as older ones are cut down. Forestry yields smaller profits but these continue from year to year. The lumberman, who disregards the principles of forestry, receives larger profits once and for all. The results that may be obtained by the practice of forestry are expressed in the quotations that follow : 2 "Under right management our forests will yield over four times as much as now. We can reduce waste in the woods and in the mill at least one-third, with present as well as future profit. We can perpetuate the naval-stores industry. Preservative treatment will reduce by one- fifth the quantity of timber used in the water or in the ground. We can practically stop forest fires at a total yearly cost of one-fifth the value of the standing timber burned each year." .... "By reason- able thrift we can produce a constant timber supply beyond our present need and with it conserve the usefulness of our streams for irrigation, water-supply, navigation, and power." 1 "Conservation of Natural Resources in United States" (p. 246). See also "Washed Soils and How to Prevent Them" (United States Dept. Agriculture, Farmers' Bulletin No. 20); "Conservation of Water by Stor- age," Swain (Yale University Press, 1915). 2 United States Forest Service Circular No. 171, Price, Kellogg and Cox. 16 ORGANIC STRUCTURAL MATERIALS The size and character of the trunk, and the range, locality, and distribution of the species, have much to do with the utility of the wood. Large and perfect timbers cannot be derived from species characterized by small or crooked trees. A given kind of wood is always used more if it is widely distributed and easily available. CHAPTER III WOOD. CHARACTER AND ARRANGEMENT OF WOOD-ELEMENTS. INFLUENCE OF CELLULAR STRUCTURE UPON CHEMICAL COMPOSITION AND PHYSICAL PROPERTIES OF WOODS. IDENTIFICATIONS. STATEMENTS OF WEIGHTS AND MODULI EMPLOYED IN TABULAR DESCRIPTIONS OF SPECIES Wood is the solid part of trees the part which, when otherwise suitable, is used in construction. It consists of a ground-work of starch-like substance known as cellulose, permeated by materials collectively known as lignin. There are also secretions, such as resin, coloring-matter, and water. The small proportion of mineral in wood is evident as ash. Wood, timber, and lumber may not mean the same. Prop- erly speaking, all woody tissue is wood; but roots and branches contain much wood that is not suitable for construction. Wood that is suitable, although not necessarily ready, for construc- tion, is "timber;" and wood that is not only suitable, but also ready for construction, is "lumber." The word timber may thus include living trees in the forest, as well as logs and shaped pieces; whereas, lumber refers only to boards, planks, beams, and other sawn pieces of limited sizes, and then only in America. The term lumber, which is not sharply definable, is not used much outside of North America. Wood is composed of innumerable minute structural units, known as wood-cells, 1 or wood-elements, which differ from one 1 So named by Robert Hooke in 1667 because of resemblance to cells of honeycombs. REFERENCES. "Structure of Certain Timber Ties," Dudley (United States Forest Division, Bulletin No. 1, p. 31); "Timber," Roth (United States Forest Division, Bulletin No. 10); "The Decay of Timber," von Schrenk (United States Bureau of Plant Industry, Bulletin No. 14, p. 12); "Trans. American Railway Engineering Association," Tiemann (Bulletins No. 107 and No. 120); "Plant Anatomy," Stevens; "Identification of Economic Woods of United States," Record (John Wiley & Sons, 1912); "Wood," Boulger (London, Second Edition); "North American Gymno- sperms," Penhallow; "Outlines of Botany," Leavitt; "Pithray Flecks in Wood," Brown (United States Forest Service Circular No. 215); etc. 17 18 ORGANIC STRUCTURAL MATERIALS another in shapes and sizes, in the thickness and surfaces of their walls, and in the ways in which they are arranged. There are also compounds associated with, although actually foreign to, the wood-elements. Of these associated materials, water is the most important. The subject is fundamentally important. Physical properties, such as hardness, elasticity, and weight are influenced by (1) the FIG. 9. Pits. A, Longitudinal section through parts of two adjoining walls w.w. One pair of bordered pits 6. p., is shown. B, Longitudinal sec- tion through portions of two adjoining wood-fibers. Four pairs of simple pits in adjoining walls are shown; only one pair is marked s.p. The lumen of each fiber is marked 1. The walls are marked w. C, Cross-section through entire wood-element, with parts of walls of adjoining wood- elements. Bordered pits are shown on the right, and on the left b. p. The torus t is the thick part of the common, separating, or primary portion of the wall also known as the "middle lamella." D, A larger and more detailed section through bordered pits shown in figure C. Two adjoining pits with torus and pit-canal are shown. character of the wood-elements, (2) the arrangement of the wood- elements, and (3) by the characteristics and quantities of the compounds that are associated with the wood-elements. WOOD-ELEMENTS. These vary in details, but are similar in this regard that all partake of the nature of minute tubes. The cavities within the tubes are the "lumina." A cell-cavity, or lumen, may be empty, or it may contain water or other com- pounds. Wood-elements are of several kinds, as wood-fibers, PLATE I. ARRANGEMENT OF WOOD ELEMENTS CROSS SECTIONS (a) Cross-section of Longleaf Pine (Pinus palustris) . (6) Cross-section of White Oak (Quercus alba). Acknowledgments to Bureau of Plant Industry, United States Department of Agriculture. (Facing page 18.) WOODS WOOD ELEMENTS 19 tracheids, vessels, wood-paren- chyma fibers, and pith-ray cells. Each of these classes of wood-ele- ments includes several varieties. The walls of all wood-elements are thickened and appear under the microscope as double lines. The young primary wall, is a very thin, practically imperforate and continuous membrane, which constitutes the first outline of the cell. This membrane originally surrounded the protoplasm and other materials that were contained within the living cell. The secondary thickening is laid on later and gives strength to the wood- element. It is seldom, if ever, im- perforate, but contains pits of char- acteristic shapes. The layer is some- times disposed in ridges on the inside of the cell, much as a spiral stair- case is placed within a tower. This structure is never present within wood-fibers, but is occasionally found within tracheids and vessels. Holes or thin spots in the walls of wood-elements are known as "pits." Some pits are round, while others are elliptical or slit-shaped. They are further divided into what are known as "simple pits" and "bordered pits." Pits are "simple" when the walls that extend out from the middle lamella are nearly parallel, and they are "bordered" when the walls that extend out from the middle lamella diverge. The bordered pits that are present in the walls of tracheids, vessels, and some wood-fibers, are invaria- -c.w. (Nyssa sylvaticd). gu _ _ Wood-fibers of black walnut (Juglans nigra). indicates lumen; s.p. indicates simple pit. FIG. 10. Wood-fibers. A, Wood-fiber of white oak (Quercus alba.) B, Wood-fiber of black C, Wood-fiber of beech (Fagus americana). D, c.w. indicates cell-wall; I 20 ORGANIC STRUCTURAL MATERIALS FIG. 11. Tracheids. A, Tracheid of yew (Taxus bacata). B, Tracheid of pinon pine (Pinus edulis). C, Tracheid of red oak (Quercus rubra). D, Tra- cheids of western yellow pine (Pinus ponderosa) . b.p. indicates bordered pit; s.p. indicates spiral. bly paired exactly in position with similar pits in the walls of ad- joining elements. They do not open through, however, but are closed by partitions which exist in the primary walls or "middle lamellae." There is usually a thickened disc in the middle of the partition that is known as the "torus." Wood-Fibers. Ordinary wood-fibers are long, slender, com- paratively smooth-surfaced, and sharp-pointed wood-elements. The walls are thick and lignified, and the pits are usually simple; that is, they are without borders. Wood-fibers are not found in conif- erous woods, but are nearly always present in, and are regarded as char- acteristic of the so-called broadleafed woods to which they contribute much strength and hardness. The wood- fibers also give mechanical strength to the living tree and probably con- tribute in some way to the transporta- tion of water through the tree, from the roots to the foliage. Tracheids ( Tra-ke-ids). Tra- cheids are elongated, taper-pointed cells, with peculiar markings, which appear, either in the form of bordered pits, located, for the most part, on the radial surfaces of the tracheids, or else in the form of ridges, variously disposed upon the inner walls. Tra- cheids are the wood-elements upon which coniferous woods largely de- pend for strength. They are charac- teristic of coniferous woods and although they do exist in many of the broadleafed woods are then in- variably subordinate to wood-fibers and vessels. Tracheids serve in the living tree because they contribute to its me- chanical support, and also because the bordered pits are so designed as to assist very materially in the conduc- tion of water through the stem from the roots to the leaves. b.f>- b.p WOODS WOOD ELEMENTS 21 -b.p. p.w.- The means by which water is thus raised has been credited to root pressure, transpiration, and osmotic pressure. 1 Vessels. These compound structures are formed by the breaking down of partitions that exist between the abutting ends of simpler or shorter structures, known as "vessel-segments." Tubes of very considerable length are formed in this manner and, as is the case with oak, are often so large in diameter that they can be seen with .the unaided eye. These large cavities are commonly referred to as "pores," and the vessels themselves have been variously named by plant anatomists as pores, canals, ducts, tubes, vasa, tracheae, tracheal-tubes, and fistulae. Vessels Differ with Spe- cies. The central cavities of lumina of the vessels of some species are open, while those of other species are obstructed by parenchymatous growths known as "tyloses." Air can readily be blown through several feet of red oak, even before it has been seasoned, because tyloses are absent in the vessels of this species. On the contrary, a pressure of one hundred pounds per square inch is sometimes insufficient to force air through a single inch of unseasoned white oak, because the vessels of that species contain quantities of tyloses. A vessel increases in thickness by means of layers that are gradually deposited on its walls. Several layers of unequal thickness can often be distinguished with the aid of a powerful microscope. The thick- ened portions of the walls give strength, while the unthickened por- tions permit water and materials in solution to pass in and out. The differences in thickness are evidenced by markings such as are shown in the picture. C FIG. 12. Vessel-segments. A, Vessel- segment of cotton gum (Nyssa aquat- ica). B, Vessel-segment of black walnut (Juglans nigra). C, Vessel-segment of oak (Quercus). sc.p. indicates scalari- form (ladder-like) perforations; b.p. and p.w. indicate bordered pit and partition wall respectively. 1 "Plant Physiology," Jost (Gibson, Oxford, 1907, pp. 45-47.) 22 ORGANIC STRUCTURAL MATERIALS Wood-Parenchyma Fibers ( Pa-ren-kih-ma ) . These com- paratively short, compound structures are made up of shorter, oblong, thin-walled cells, in groups, from a few in number to as many as eight or ten, of which the upper and lower cells are taper-pointed. Wood-parenchyma fibers resemble fibers and tracheids in general form, but differ from them in that, as groups of living cells, they contain, besides proto- plasm, the various foods and products connected with the life-processes of the tree. They may contain crystals of calcium oxalate or crystals of calcium carbonate. The cells that contain these crystals are often cubical in outline and the cavities are sometimes completely filled with the crystalline mass. Such elements are known as "idioblasts." Wood-parenchyma fibers are usually, although not always, shorter than wood- fibers in the same species. They are pecu- liar, in that they retain their power of cell- division after they leave the cambium, and usually divide into a number of short parenchyma-cells, separated by horizontal or oblique partition- walls, as has been noted. There are simple pits that on the whole vary only slightly in different species of woods. Sanio, author of the term " wood- parenchyma fiber," describes them as tis- sues that originate through the division of cambium cells and that conduct and store up carbohydrates. He divides them into two classes, namely, septate and non-septate or intermediate wood-parenchyma fibers. The latter are sometimes difficult to dis- tinguish from wood-fibers, but usually have A B FIG. 13. Wood-par- enchyma fibers. A, Wood-parenchyma fiber of white oak (Quercus alba). Bj Wood-paren- chyma fiber of black walnut (Juglans nigra). w.p.c. indicates wood- parenchyma cell; s.p. in- dicates simple pit; c.w. indicates cell-wall; ex. indicates cell-cavity ; c. indicates crystal of cal- cium salts. thinner walls and larger cell-cavities. Solereder classifies wood-parenchyma fibers with wood-fibers, vessels, and tracheids, under the general term " wood-prosenchyma, " and not with pith-ray elements. 1 igee also "Wood," Boulger (Second Edition, pp. 28 and 29); "North American Gymnosperms," Penhallow (p. 109). PLATE II. ARRANGEMENT OF WOOD ELEMENTS TANGENTIAL SECTIONS (a) Tangential Section of Longleaf Pine (Pinus palustris). (b) Tangential Section of White Oak (Quercus alba) showing large Pith Ray. Acknowledgments to Bureau of Plant Industry, United States Department of Agriculture. WOODS WOOD ELEMENTS m.r.c. - rt t _ -re: ~r.t C D FIG. 14. Pith-rays. A and J5, rPith-rays in radial and tangential sec- tions of black walnut (Juglans nigra). C and D, Pith-rays in radial and tangential sections of western yellow pine (Pinus ponderosa). p.r. indi- cates pith-ray ; t indicates tracheid ; c.w. indicates cell wall; r.t. indicates ray tracheid; r.c. indicates ray cells; m.r.c. indicates marginal ray cell; s.p. indi- cates simple pit; r.d. indicates resin-duct; r.c. indicates resin-cell. 24 ORGANIC STRUCTURAL MATERIALS Pith-rays. These compound structures are made up of short, cubical or oblong cells, arranged in rows that pass radially from the center of a tree to its circumference. Pith-rays differ strikingly from other wood-elements in that they are arranged horizontally. They cross the tree, bind the vertical wood-ele- ments together, and also serve as a vital link between the living elements of the tree. The cells of which pith-rays are composed resemble those making up wood-parenchyma fibers in form and structure, and because of the fact that they, too, contain various foods and products connected with the life-processes of the tree. The terms pith-ray, medullary ray, and ray mean the same. Pith-rays are plainly visible in some woods, as oaks, but are not easily visible in other woods, as poplars, even when a hand magni- fying glass is employed. Pith-rays contribute to the appearance of "quartered oak," which with other " quartered woods," are obtained by cutting logs radially (see Fig. 25). When cut in this way the pith-rays are split and their larger surfaces are exposed. Otherwise, in the tangential cut, the pith-rays are cut through vertically and appear as short lines. Pith-rays are not visible in some woods except when very thin pieces are placed under a compound microscope. The small, cubical or oblong cells, of which pith-rays are composed, are indented with minute, simple pits. The pith-rays of some conifers also contain, in addition to the small parenchyma cells, one or more rows of peculiar flattened tracheids, known as "ray-tracheids." Resin- ducts are also present in some of the pith-rays that exist in the pines. Pith-rays may be divided into primary and secondary pith-rays. The first are those that extend completely through from the pith-cavity at the center of the tree to the bark, while the second are those that do not extend through thus completely. The function of the pith-ray has been described as follows: 1 "The medullary-rays have, for their primary function, the radial transmission and storage of food. Their intimate relation with the cells of the phloem at their outer and with the xylem parenchyma along the inner course, and the fact that we usually find them gorged with food, points to this conclusion. The short, vertical extent of the rays, and their isolation from each other renders them unsuited for the vertical or longitudinal transmission of foods. If they were of value in this respect girdling would not prevent the downward flow of foods." 1 "Plant Anatomy" Stevens (p. 162). WOODS WOOD ELEMENTS 25 Resin-canals. Resin-canals are not wood-elements like tra- cheids and wood-fibers. On the contrary, they are inter- cellular passages which appear scattered irregularly here and there throughout the woods of some coniferous trees. They are not numerous and do not form conspicuous structural features in the cross-sections in which they occur. The continuity of the passages through some of these canals, as those in Douglas P r w.p c.- FIG. 15. Resin-canal. Resin-canal in transverse section of western yellow pine (Pinus ponderosa). r.c. indicates resin-canal; e.p.c. epithe- lium cells; w.p.c. wood-parenchyma cells; p.r. pith-ray; t. tracheid; b.p. bordered pit; and c.w. cross-wall. fir, is interrupted by constrictions. In some woods resin-canals are simple cavities known as " cysts." Resin-canals and resin- ducts are the same. The resin-passages that exist in the trees that produce commercial resins have received most attention. Tschirch divides these passages, as they exist in the pines, into " primary resin-ducts " and "secondary resin-ducts." The former, scattered through the heartwood and the sapwood, produce comparatively small quantities of resins, while the latter, formed in the outer sapwood of trees that have been wounded, pour crude turpentine over the wounded surfaces in order to protect them. The turpentine of commerce is obtained from these "secondary 26 ORGANIC STRUCTURAL MATERIALS resin-canals." It will be seen that the resins produced by the " primary canals" are physiological products, whereas those produced by the " sec- ondary canals" are pathological products. Tschirch has demonstrated that the seat of resin-production is in a mucilaginous layer (epithelium cells, Fig. 15) that lines the inside of the resin canal. 1 Arrangement of Wood-elements. The character of wood depends not only upon its wood-elements but also upon the way in which these wood-elements are arranged. Most wood- elements are arranged up and down, a fact that explains the comparative ease with which most woods are split. But besides this, there is a horizontal arrangement. The pith-rays pass radially, that is horizontally, from the center of the tree to its circumference, and bind the vertical wood-elements together. The arrangement of wood-elements is much more regular in some woods, as pines, than in others, as eucalyptus and lignum vitae; and woods are easy or difficult to work, in proportion as their elements are thus arranged in a simple or a complicated manner. Associated Compounds. Certain materials are associated with, although they do not form part of, the wood-elements, and such compounds are notable because they exert a material influence upon the character of the wood-elements, and, therefore, upon the character of the wood. Of these associated materials, the most important is water, which acts by distending the wood- elements and thus making them weaker and more pliable. The influence of moisture is so great as to require further notice (see " Moisture in Wood"). 2 Influence of Cellular Structure upon Chemical Composition and Physical Properties of Wood. Chemical and physical prop- erties of woods are influenced by the character and arrangement of the wood-elements, and by the qualities and quantities of the materials associated with these wood-elements. Chemical com- position, strength, weight, appearance, and other properties re- garded by those who use woods depend much upon these details. 1 "Resin-Canals in White Fir," Mell (American Forestry, June, 1910); "Relation of Light Chipping to the Commercial Yield of Naval Stores," Herty (U. S. Forest Service, Bulletin No. 90). 2 "Sap in Relation to the Properties of Wood," Record (Proc. American Wood Preservers Association, Baltimore, Md., 1913, pp. 160-166); "Effect of Moisture upon the Strength and Stiffness of Wood," Tiemann (United States Forest Service Bulletin No. 70 and United States Forest Service Circular No. 108). WOODS WOOD ELEMENTS 27 Identification of Woods. External appearances differ and are hard to describe. Colors vary, even in pieces cut from the same tree ; moreover, colors are not permanent, but often change FIG. 16. Dissection showing waving cell arrangement in a specimen of curly redwood. with age and exposure. Artisans become familiar with the working qualities of a few woods, but are commonly uncertain with regard to the working qualities of other woods. On the whole, the character and arrangement of the wood-elements 28 ORGANIC STRUCTURAL MATERIALS afford the only reliable basis upon which many woods can be finally identified. Some of the cellular characteristics of woods are evident to the naked eye, but, in most cases, the microscope is required. The cellular characteristics of woods are most evident in their cross-sections. The cross-sections of different species differ from one another, but each one exhibits certain traits that remain FIG. 17. Photomicrograph of spruce (cross-section). Thought to be about 500,000 years old. 1 constant for that species, and in many cases these traits are suffi- cient to serve as a means of practical identification. For example, it will be noted that the section of white oak (Plate I) contains large vessels but is without resin-ducts, whereas the section of long- leafed pine (Plate I) contains resin-ducts but is without vessels. footnote, p. 29. PLATE III. ARRANGEMENT OF WOOD ELEMENTS RADIAL SECTIONS (a) Radial Section of Longleaf Pine (Pinus palustris). (6) Radial Section of White Oak (Quercus alba}. Acknowledgments to Bureau of Plant Industry, United States Department of Agriculture. (Facing page 28.) WOODS WOOD ELEMENTS 29 The identification of a log removed from an ancient forest bed is described by Koehler. 1 The extent and character of the soil and other material deposited upon the log caused geologists to believe that it was 500,000 years old. The wood was brittle, and much distorted, most of the cell-elements being flattened. But when under a microscope the characteristic structure of the wood was revealed. The wood was re- ported as Spruce. (See Figures 17 and 18.) FIG. 18. Photomicrograph of fresh spruce (cross-section). 1 Banded woods may be easily distinguished from non-banded woods by the presence or absence of yearly bands, layers, or rings (Figs. 1 and 2); while the- needleleaf and broadleaf woods, which together make up the banded woods, may be told from one an- other by noting the differences shown in the table that follows (Record 2 ) : 1 From " Wood Older than the Hills," Koehler, by Courtesy of The Ameri- can Forestry Magazine, Washington, D. C. (February, 1916). 2 " Identification of Economic Woods of the United State \ t " Record (p. 13). 30 ORGANIC STRUCTURAL MATERIALS BANDED WOODS Needleleaf Woods, Softwoods (Conifers). True vessels absent. Wood tracheids present and form- ing bulk of wood. Ray tracheids present or absent. Wood fibers absent. Wood parenchyma present (ex- cept in Taxacese), but usually subordinate. Ray parenchyma present. Broadleaf Woods, Hardwoods (Dicotyledons). True vessels present. Tracheids present or absent; al- ways subordinate. Ray tracheids absent. Wood fibers present. Wood parenchyma present, and very often conspicuous. Ray parenchyma present. The key prepared by Fernow and Roth 1 is based upon a divi- sion of banded woods into three classes, namely: non-porous woods, ring-porous woods, and diffuse-porous woods. The dis- tinctions are as follows: 1. Non-porous Woods. The pores (vessels) of these woods are not evident, even with magnifiers. The annual layers are distinguished by means of denser, dark-colored bands of summer-wood (see Fig. 19A). This group includes the pines and other so-called softwoods. 2. Ring-porous Woods. The numerous pores (vessels) are usually vis- ible even without magnifiers. The pores are collected in the spring deposits, which thus contrast with the denser summer- woods. This group includes oak, ash, catalpa, chestnut, black locust, hickory, per- simmon, and others (see Fig. 19B). 3. Diffuse-porous Woods. The numerous pores (vessels) are not col- lected in the spring-wood as in the case of the ring-porous woods, but are scattered throughout the entire annual layer. The pores are not usually visible without magnifiers. This group includes cherry, maple, beech, black walnut, holly, sycamore, cottonwood, and others. (See Fig. 19C.) The value of cross-sections, which are more serviceable than radial or tangential sections in making microscopic examinations of woods, is influenced by the tools that are used to prepare these sections. Smooth surfaces are desired and, therefore, very sharp 1 "Timber," Fernow and Roth (United States Forest Service Bulletin No. 10, pp. 59-83). See also "Identification of Economic Woods of the United States," Record (John Wiley & Sons); "Confusion of Technical Terms in Study of Wood Structure," Mell (Forest Quarterly, Vol. IX, 1911, No. 4, pp. 574-576) ; " Wood," Boulger (Second Edition, London) ; etc. The actual sections prepared by Hough are very helpful. "The Jesup Collection of Woods" at the American Museum of Natural History is, available for those living near New York City. WOODS WOOD ELEMENTS 31 tools should be employed. If the tools are not sharp, the surfaces will be rough and the characteristic features obscure. A shaving cut by a well-sharpened plane is sometimes sufficient, but, for more technical work, a microtome is necessary. Sections should be cut precisely at right angles to the vertical axis of the tree, since otherwise the rounded sections of the vessels appear as ovals. A B C FIG. 19. Original photomicrographs. A, Cross-section of non-porous wood (longleaf pine). B, Cross-section of ring-porous wood (white oak). C, Cross-section of diffuse-porous wood (sweet gum). For ordinary examinations, any microtomes, save those of the rotary type, are serviceable. The instrument shown in the picture gives excellent results. Compound microscopes manufactured by the Bausch & Lomb Optical Company of Rochester, and by the Spencer Lens Company of Buffalo, are very satisfactory. 32 ORGANIC STRUCTURAL MATERIALS Identification of Trees. Trees are not always easily iden- tified by laymen. Forms in the forest differ from those in the open. Bark varies with age, while leaves and fruit are often lacking in the winter. Most laymen find it easier to tell genus than species. They know that a tree is an oak, but do not know whether it is a red oak or a pin oak. Experience is required. Sargent's " Manual of the Trees of North America," and Hough's " Handbook of Trees of the Northern States and Canada" FIG. 20. Modification of Jung-Thoma microtome for cutting wood, as described by Thomson, University of Toronto, in Botanical Gazette, August, iy lu. are convenient reference books, while Hough's "Leaf Key to Trees" and Ernest Thompson Seton's "Foresters' Manual" are serviceable in the field in identifying trees that are in summer condition. l 1 See also Bibliography. WOODS WOOD ELEMENTS 33 WEIGHTS AND MODULI. It seems best thus early to introduce the two series of weights and moduli to be employed in the tabu- lar descriptions of species that form part of succeeding chapters. Further descriptions and the reasons for preferring these par- ticular series of figures will be given later. The figures referred to are as follows : First. Results of experiments conducted by the National Forest Service. These figures occupy the leading spaces in the descrip- tions of species (Chapters V, VI, VII, and VIII) under the titles of "Weight," "Modulus of Elasticity," and "Modulus of Rupture." Results have not yet been obtained for all of the species thus de- scribed so that some of the spaces set apart for the figures reported for the National Forest Service are vacant. Second. Results of experiments conducted by the Watertown Arsenal for the Tenth United States Census. These figures appear in the spaces immediately following those occupied by, or set apart for, the National Forest Service figures. Weights are given in pounds, and coefficients in pounds per square inch. Fractions of pounds and lower figures in coefficients have been omitted as superfluous. l J See also Chapter IX. CHAPTER IV BANDED TRUNKS AND WOODS (Conifers and Dicotyledons) The trunks from which banded woods are obtained grow in thickness from the outside. The new layers of wood are deposited upon the outside of others that were formed before. Practically all of the woods that are used in construction are of this type. The forest sources are widely distributed, and the numerous species present an almost infinite range of possibilities. PARTS OF A BANDED TRUNK. A section through a banded trunk is made up as follows: A point or pith-cavity exists at the center of the section : This pith-cavity is surrounded by con- centric rings made up of layers or bands of heartwood and sap-wood, which together constitute the wood, or xylem. The entire section is surrounded by bark, the succulent, fibrous inner part of which is the phloem. The line of separation between the bark and wood is the cambium. The wood-elements, the bands or layers in which they are arranged, and some character- istics of the bark, the sapwood, the heartwood, and the pith are im- portant. Wood-elements. The character- istics of fibers, tracheids, and other wood-elements have been described. So far as is known, there are no wood-elements that are particularly associated with the banded woods alone. Some wood-elements may be modified in certain cases, but the same kinds exist in both banded woods and non-banded woods. Annual Bands, Rings, or Layers. The wood-elements that stand vertically are arranged in concentric bands or layers one of which is formed every growing season between the bark and the wood that was formed during the preceding season. Each 34 FIG. 21. Section through young stem of box elder. Pith cavity surrounded by three an- nual deposits of wood. The whole enclosed by bark, b. The radiating lines p.r. are pith-rays. The cambium is at c. ANNUAL DEPOSITS DEFECTS 35 one of these bands or layers encloses all of the other bands or layers that were formed before, and each one will eventually be enclosed by others that are formed later. The bands cover the trunk and all of the living branches of the tree. A band or layer is made up of two, more or less, well-defined parts as follows: 1. Early Growth. This portion, sometimes referred to as " spring growth," is formed at a time of the year, when, because the leaves are unfolding, there is an increased demand for water. FIG. 22. Instrument for removing cores to determine ages of trees. 1 The more porous water conduction elements preponderate and as a result this part of the band is lighter, softer, and more porous than the other. (See Plate I, page 18). 2. Late Growth. This portion, often referred to as " summer growth," is formed after the leaves have been fully expanded and when the cambium can devote itself more exclusively to the production of the wood-elements that contribute more to strength. It is, therefore, denser and heavier than the other. 1 The instrument shown in the picture is manufactured by The Keuffe & Esser Company of New York. 36 ORGANIC STRUCTURAL MATERIALS The contrasts that exist between the porous early growth and the more compact later growth of the preceding year serve to define the limits of the yearly bands. Bands exist in all needleleaf or softwood trees (conifers), and in all broadleaf or hardwood trees (dicotyledons), which grow where there are alternating seasons of wet and dry, or heat and cold. They also exist, but are often correspondingly less pro- nounced in localities where the differences in seasons are less marked. Bands are valuable as means by which the ages of trees can be determined, and, since they vary in thickness from year to year as the seasons are wet or dry, they also serve as his- tory of the local conditions of growth. The history of a Redwood tree, dating from two hundred and seventy- one years before the Christian Era, was reported by Professor Dudley to the United States Senate through the late Senator Platt of Connecti- cut, on February 11, 1904. The record obtained by counting the con- centric layers of growth on the cross-section of the felled tree showed that forest fires had occurred during the years 245, 1441, 1580, and ' 1797 A.D. The last fire was locally severe, since it had charred a space thirty feet in height and eighteen feet in breadth. It is needless to state that this tree was exceptionally vigorous or it would not have re- covered from such a wound. The new tissue, as deposited upon the outside of this wound, was full, even, and continuous. The value of the band, layer, or ring as a means by which age can be determined is indicated in the quotation that follows (Fernow 1 ) : "In a young, sound, and thrifty timber, the rings are laid on with the utmost regularity, and a cross-section of a stem furnishes, therefore, not only information as to the age of the given section, but is a fair indicator of the life-history of the tree, periods of suppression and thrift being indicated, respectively by zones of correspondingly narrow or broad rings. In such timber, the countings along different radii always give the same results. . "If, on the other hand, the rings are very old, especially if slow-grown stems are counted, it happens not infrequently that counting along one radius gives one to five rings more than the counting along some other radius. The reason for this is not always apparent; in some cases, such a difference in results is due merely to the inability of the eye to detect 1 "Age of Trees and Time of Blazing Determined by Annual Rings," Fernow (United States Division of Forestry, Circular No. 16, pp. 2, 3, and 6). ANNUAL DEPOSITS DEFECTS 37 an extremely narrow, but otherwise well-defined ring, and the error may be corrected by microscopical examination. In other cases, however, the difference is based on the actual absence of one or more rings of only a given radius, extremely unfavorable circumstances having led to failure of the regular continuous development of these rings." Pith (Medulla). Central pith areas, around which wood is deposited, are more or less evident in the sections of young trees, saplings, and young branches. They do not grow in size after the first year, and in mature trees are usually so compressed as to be quite obscure. Pith itself is made up of thin- walled paren- chymatous cells within which food for the rapidly growing parts is stored, at least in the younger stems. The service which pith renders to the stem is apparently of a temporary nature. Heartwood (Duramen). Heartwood is modified sapwood. Heartwood gives stability to the tree but is not utilized in its physiological processes. A tree can survive, even although much of its heartwood has decayed or been otherwise removed. Heart- wood is heavier, tougher, stronger, and darker than sapwood. Its cell-structures are older and its walls appear thicker through the accumulation of deposited materials. The protoplasm has disappeared and inert minerals, tannin, gums, and pigments have appeared. The change from sapwood to heartwood goes for- ward rapidly in the trees of some species, such as redwood and locust, and the sections of these trees appear to be almost wholly heartwood. In trees of other species, the changes take longer. Von Schrenk believes that sapwood changes to heartwood suddenly; that the change does not take place in one ring every year, but that it frequently skips many years, so that eight, ten, or even more rings may change from sapwood to heartwood in one year. He also calls attention to the fact that one side of the tree may change before the other, and that part of a ring may be heartwood, while the rest remains sapwood. 1 Sapwood (Alburnum). This is the younger, lighter-colored, and more porous wood. It is the part that is directly beneath the bark, the part that later turns to heartwood. Sapwood is vitally essential to the life of the tree, but is less durable, and usually weaker, and less valued in construction than heartwood. The cell-elements are the same as those in heartwood, but the latter are usually modified, as was noted in the preceding para- graph. Sapwood is more pliable than heartwood, and the sap- 1 United States Bureau Plant Industry, Bulletin No. 14, p. 15. 38 ORGANIC STRUCTURAL MATERIALS woods of several trees, such as hickory and ash, are preferred and much valued for this reason. The sap currents travel upward in the sapwood, hence the name. The wood manufactured by a tree when it is old is usually softer and weaker than that made by the tree when it is younger. Because of the time in the life of the tree when it is grown, the sapwood of a large log may be inferior in strength to equally sound but older heartwood in the log. The United States Forest Service 1 reports upon the com- parative strength of sapwood and heartwood as follows: " Sap wood, except that from old, overmature trees, is as strong as heartwood, other things being equal, and so far as the mechanical properties go should not be regarded as a defect." Bark. This husk or outer cover resembles the wood, although many of its properties are quite unlike those of wood. Bark is characteristic of exogenous trees and assists these trees in two ways: First, it is an agent in the physiological processes of the tree; and second, it affords protection. The bark is made up of several parts. They are as follows : 1. The phloem, inner, or FIG. 23. Compound structure of fibrous bark, is composed partly of very long, thick- walled cell-structures, known as "bast fibers." These are the ele- ments that give character to the stringy bark of the basswood and the grapevine, and that form the " fiber" of flax from which linen fabric is woven. These constitute the "hard bast." Associated with the cell-structures noted above are specialized elongated parenchyma- cells with their living contents. These constitute the "soft bast"; they are the sieve tubes and companion cells which serve as channels through which the elaborated sap passes in its journey from the leaves. These parts together are known as the "phloem." 2. The living or green part in the middle, called "green bark" or cortex, is largely composed of rounded parenchyma-cells, which contain the green substance, chlorophyll, that also exists in the leaves. The green part of the bark of a twig resembles the substance of a leaf, in that it also is a tissue which manufactures elaborated food. This layer 1 "Tests of Structural Timber" (United States Forest Service, Bulletin No. 108, p. 35). ANNUAL DEPOSITS DEFECTS 39 loses its green color in older stems because the surrounding " corky layer" is thick enough to cut out all the light. In the outer portion of this layer of green bark there are developed regions of "cork-cambium," which, by their repeated division, give rise to the outermost or corky layer. 3. The outermost corky layer is made up of dead and empty cells derived from the outermost cortex cells, constituting the "cork cam- bium." The walls of these cells are suberized, that is, they have been altered and rendered impermeable to water by the addition of a sub- stance known as "suberin," or cork. This layer serves to prevent un- due losses of fluids from the tree by evaporation. Moreover, it is a non-conductor and protects from the cold; it also protects against the entrance of disease. Composed as it is of dead cells, this cork layer cannot expand, but is, usually, gradually split by the expansion of the wood cylinder into ridges or scales, in characteristic fashion for each species, and is, usually, eventually worn away or otherwise lost, in large part, from the surface of the tree. 4. The epidermis consists of a single layer of close-fitting, tabular cells with thick, outer walls. It is impervious to water but lasts in most trees only during the first year or two, and is best seen on the surfaces of young stems or twigs. In smooth-barked trees, it may live many years. - Cross Section Radial Cuf FIG. 24. C, Cross surface. R, Radial surface. T 7 , Tangential surface. Three Surfaces of Wood. The appearance or " grain " of wood is influenced by the way in which it is cut. There are three funda- mental surfaces or exposures. They are as follows: (1) Cross surfaces in which the markings appear as circles. This is shown on the surface C. (2) Radial surfaces in which the yearly rings are cut directly across and appear as lines, as on the surface R. (3) Tangential surfaces in which the surface is cut parallel to the annual rings. Characteristic tangential figures are shown on the surface T. Logs are sometimes quartered and then cut across the yearly rings. These "quarter-sawn" pieces are stronger and better 40 ORGANIC STRUCTURAL MATERIALS than other pieces, but are more costly because of the extra labor and the waste. Edge-grained, vertical-grained, straight-grained, and rift-grained pieces are the same as quartered pieces when these names are applied to manufactured woods. The pith-rays of some woods are exposed by quartering; " quarter-sawn " oak is attractive for this reason. The best effects in grain or figure are sometimes obtained when pieces are de- veloped by what is known as the " rotary cut." This is often the case with the wood of the birdseye maple. A revolving log of the wood that is to be cut is advanced against a tool that pares a broad, thin ribbon from its surface. The ribbons are later used as veneers. FIG. 25. One method of quarter-sawing. s It should be noted that grain and figure differ in different pieces of the same species. One Hard Maple tree (Acer saccharum) may yield char- acterless pieces that are suitable for little else than flooring, while another nearby tree of the same species may contain beautiful birdseye or curly maple, suitable for costly cabinet work. Ordinary planks and boards are cut parallel to the diameters of the logs. Grain is not regarded in these pieces, which are used in ordinary construc- tions. Such pieces are known as bastard, slash- cut, or slice-cut boards or planks. The segments of bark and sapwood that are removed from the out- side of a log are known as " slabs." The uneven ap- pearance of the edges of boards that have been cut through from one side of the log to the other is re- ferred to as "wain." "Edging" refers to the uneven pieces or edges that are removed when the boards are cut down to standard widths. Slabs and edging are worked into laths or are burned as fuel. DEFECTS. Defects are of many kinds. The cracks or separations that radiate from the centers of trees are known as FIG. 26. Ordinary method of sawing a log. S represents slabs; E represents edging. ANNUAL DEPOSITS DEFECTS 41 " heart-shakes " and " star-shakes." The separations between the yearly layers are known as " cup-shakes." It is assumed that "cup-shakes" are influenced by the winds, which roll the trees to and fro, and, for this reason, the pieces in which cup- shakes occur are referred to as "rolled lumber." Separations FIG. 27. Tree rolled by wind. caused by wind or frost are "wind-shakes" or "frost-shakes" and the short but comparatively deep cracks that appear in planks as a result of rapid drying are known as "checks." Knots are the Result of Branches. Buds connected with the pith-cavity at the center appear upon the surface of the trunk. They extend and eventually develop into branches. The adja- 42 ORGANIC STRUCTURAL MATERIALS cent wood-elements between the pith-cavity and the surface of the trunk are disturbed and the result is a knot. Knots may be prevented by removing the buds while they are small. Many Names Apply to Results of Diseases. Wet-rot, dry-rot, soft-rot, disease, decay, bluing, rust, mildew, canker, bot, dote, and other terms are all thus employed. The results indi- cated by aJl of these names are usually due to the presence of bacteria or fungi. Wood that is lifeless and brittle as the result of disease is known as "brashwood," a name that is also applied to wood that has become lifeless and brittle as a result of age. Defects have been described and stand- ardized by manufacturers and others, and lumber is now classified and sold upon the basis of accepted specifications. Such speci- fications have been prepared by the Hard- FIG. 28. Distortion wood Manufacturers' Association of the [by branch. United ^^ the padfic Co ^ Lumber Manufacturers' Association, the Yellow Pine Manufacturers' Association, and others. The principal series of specifications have been listed and published under one cover by the National Government. 1 Standards have also been prepared by the American Society for Testing Materials and by the American Railway Engineering Association. A Committee appointed by the American Society for Testing Mate- rials, has defined the several kinds of knots that appear in structural timber as follows (see Year Book, 1910) : 1. Sound Knot. A sound knot is one which is solid across its face and which is as hard as the wood surrounding it; it may be either red or black, and is so fixed by growth or position that it will retain its place in the piece. 2. Loose Knot. A loose knot is one not firmly held in place by growth or position. 3. Pith Knot. A pith knot is a sound knot with a pith hole not more than one-fourth inch in diameter in the center. 4. Encased Knot. An encased knot is one which is surrounded wholly or in part by bark or pitch. Where the encasement is less than one- 1 "Rules and Specifications for the Grading of Lumber Adopted by the Various Manufacturing Associations of the United States" (United States Forest Service Bulletin, No. 71). PLATE IV. INFLUENCE OF WIND UPON TREES AT TIMBER LINE ANNUAL DEPOSITS DEFECTS 43 eighth inch in width on both sides, not exceeding one-half the circum- ference of the knot, it shall be considered a sound knot. 5. Rotten Knot. A rotten knot is one not as hard as the wood it is in. 6. Pin Knot. A pin knot is a sound knot not over one-half inch in diameter. 7. Standard Knot. A standard knot is a sound knot not over one and one-half inches in diameter. 8. Large Knot. A large knot is a sound knot, more than one and one-half inches in diameter. 9. Round Knot. A round knot is one which is oval or circular in form. 10. Spike Knot. A spike knot is one sawn in a lengthwise direction; the mean or average width shall be considered in measuring spike knots. All banded woods, and the trees that yield them are divided as follows: 1. The Coniferous Series (Coniferce). The terms softwoods, needleleaf and evergreen woods, which are so often used in con- nection with the woods of this series, are convenient but some- times inaccurate. These names are unsatisfactory; first, because some of the woods are actually very hard; second, because the leaves of some are broader than the name " needleleaf" would indicate; and third, because the leaves of some drop away every year and are not evergreen as this term is understood. The name " conifer" which is best, includes, among others, the pines, spruces, firs, hemlocks and cedars. 2. The Broadleaf Series (Dicotyledons) . These woods are often incorrectly called hardwoods and deciduous woods. The first of these terms is incorrect, because some of the woods are very soft; the second fails because the leaves of some of the trees are persistent or evergreen, rather than deciduous. The leaves, with netted veins, are comparatively broad, and the name "broadleaf" is, on the whole, the best of the popular names. This series includes, among others, the oaks, elms, maples, hickorys and birches. CHAPTER V BANDED TRUNKS AND WOODS (CONTINUED) CONIFEROUS OR NEEDLELEAF SERIES Conifers Coniferous trees cover large areas in parts of Canada and the United States. The Pines, Spruces, Hemlocks, and other so- called softwoods are of this group. Coniferous woods are comparatively light in weight and the arrangements of the wood-element is, on the whole, simpler than in the woods of the broadleaf series. The vertical fabric is made up almost entirely of tracheids. The preponderance of tracheids and the absence of true vessels are characteristic of these woods which, because of the simpler arrangement of the wood-elements, are comparatively easy to work. Coniferous woods are pre- ferred where the demand is for bulk and strength rather than fine qualities, and the total requirement as to amount exceeds the requirement for woods of the broadleaf series. The trunks of many species yield very large, straight pieces. The leaves of the coniferous trees are resinous and usually needlelike and evergreen. The seeds are exposed on the inner surfaces of woody scales arranged, overlapping one another, in what are known as cones. As already stated, the names " softwood" and " evergreen" do not always apply so that the name " conifer" should be preferred. 44 PINE Pinus These woods, which were formerly plentiful in the districts where the demands of construction were the greatest, have been more used in carpentry and construction than any others. They are to the coniferous woods what oaks are to the broadleaf woods; and, in this country, they yet stand to all woods somewhat as iron does to all metals. The pines are prized because of qualities, such as strength, elasticity, light weight and working qualities, that fit them for the constructions that require the largest quan- tities of wood. 1 Pine trees have straight, solid trunks, which, when grown in forests, are usually free from branches for many feet up from the ground. They mature slowly and it is probable that, ultimately, some species will survive only as cultivated trees. The needle-shaped, evergreen leaves, which are from one inch to fifteen or more inches in length, occur singly or in clusters of two, three, and five. Thirty-six of the known species grow naturally in the United States. The Dantzic or Northern Pine (Pinus sylvestris) is an important European species. Pines are often divided into "soft pines" and "hard pines." Soft Pines. The woods that form this group are soft, light, rather weak, clean, uniform, easily worked, and compara- tively free from knots and resin. The yearly bands are less pronounced than in the hard pines. Many resin-ducts, that are often plainly visible without the microscope, are distributed over the sections. The Soft Pines may be divided according to their sources into White Pine (Pinus strobus) on the one hand, and Sugar Pine (Pinus lambertiana) with some minor species on the other hand. White Pine (Pinus strobus}. This tree, formerly the principal eco- nomic tree of North America, grows in the northern, central, and eastern portions of the United States. It formed the basis of the early forest resources of Maine and Michigan, and methods devised to cut and trans- 1 See also "Uses of Commercial Woods of United States: 2, Pines" (United States Forest Service, Bulletin No. 99, 1911). 45 46 ORGANIC STRUCTURAL MATERIALS fer the logs have influenced logging practices in all subsequently devel- oped fields. White Pine was once the only soft wood seriously consid- ered by lumbermen in the north, and, until as late as the beginning of the present century, it supplied about thirty per cent, of all the lumber that was used in this country. 1 No other wood known to man has been more valuable. There are no perfect substitutes, although sugar pine, spruce, fir, redwood, and even whitewood are used in its stead. Sugar Pine (Pinus lambertiana) . These trees grow at high elevations in parts of Oregon and California. The soft, coarse, clean wood can be used in place of true White Pine. Some of the trees are very large. Other minor American sources and localities are as follows: White Pine (P. flexilis), Rocky Mountain Region; White or Silver Pine (P. monti- cola), Pacific Coast Region; Whitebark Pine (P. albicaulis}, Pacific Coast Region; Mexican White Pine (P. strobiformis) , Arizona into Mexico; Parry's Pine (P. quadrifolia), Southern California; Nut Pine (P.cem- broides), Arizona into Mexico. Hard Pines. These differ from soft pines in that they are harder, stronger, heavier, more resinous, of a deeper color, and more difficult to work. The yearly bands are pronounced. Large-sized pieces of Hard Pine can be obtained. The principal supplies are obtained from the Longleaf Pine (Pinus palustris), the Shortleaf Pine (Pinus echinata), the Cuban Pine (Pinus heterophylla) , and the Loblolly Pine (Pinus tceda). Longleaf Pine (Pinus palustris). This is the principal tree of the Hard Pine group. The wood, which is the strongest native construc- tion wood obtainable in large-sized pieces in the United States, is used in docks, trestles, and other heavy constructions. The trees yield tur- pentine, tar, and resin. They are usually tapped a few times and are then felled and cut up into lumber. The woods of the Cuban, Shortleaf, and Loblolly Pines are so nearly like that of the Longleaf Pine, that it is often hard to tell them from that wood or from one another. Either, or all of these woods may thus be delivered in response to a demand for Southern Hard Pine. It should be noted, however, that pieces of Southern Hard Pine may now be graded without difficulty by means of the so-called Density Rule 2 ; and the results obtained by following this practical rule show that the strength of pieces of Longleaf, Shortleaf, Loblolly, and other kinds of Southern Hard Pine depend less upon distinctions due to species than upon relative densities of individual pieces. 1 Roth (United States Forestry Bulletin No. 22, p. 73); "White Pine Timber Supplies" (United States Senate Doc. 55-1, Vol. IV). 2 See Index "Density Rules." CONIFEROUS TRUNKS AND WOODS 47 Much of the "Hard Pine" used on the Pacific Coast is derived from the Douglas Spruce or "Oregon Pine" (Pseudotsuga taxifolia). The species of pine may be distinguished from one another by differences that exist between their leaves and cones. These are as follows: 1 Names Leaves Cones Number in cluster Length Diameter (open) Length Longleaf pine (P. palustris) . . Cuban Pine (P. heterophylla) Shortleaf Pine (P. echinata).. Loblolly Pine (P. taeda) 2 or 3 2 or 3 2 or 3 3 10 to 15 in. 8 to 12 in. 2 to 5 in. 5 to 10 in. 4 to 5 in. 3 to 5 in. 1 to 2 in. 2 to 3 in. 6 to 10 in. 4 to 7 in. 2 in. 3 to 4 in. Tar, turpentine, and resin, which are included in what are known as " naval stores," are derived principally from the Longleaf and Cuban Pine trees. The quantities of naval stores that are contained in these trees vary with individuals. From five to twenty per cent, of the dry weight of the heartwood may be due to resin. There is less resin in sap wood. The resin in pine is known as rosin. An exhaustive investigation 2 has proved that strength, weight, and shrinkage are not influenced by "bleeding," and that "bled" lumber is as good as lumber that has not been "bled." The Louisville & Nash- ville Railroad once specified "unbled" lumber. Some bled pieces were included by error. The mill offered to take them back again if they could be separated from the others. This proved to be impossible and the matter was dropped. Confusion exists in regard to the names of the pines. All Southern Pines are known commercially as Yellow Pines. Ameri- can White Pine is known as Yellow Pine in Europe, where all Hard Pines are often referred to as Pitch Pines. Spruce Pine, Bull Pine, and Bastard Pine are names frequently used to hide ignorance. The species palustris has thirty local names. Botan- ical names should be used to designate these as well as other trees. 1 See also "Timber Pines of the Southern United States" (United States Forest Service, Bulletin No. 13, 1897); "Properties and Uses of the Southern Pines" (United States Forest Service, Circular No. 164, 1909); "Relation of Light Chipping to the Commercial Yield of Naval Stores," Herty (United States Forest Service, Bulletin No. 90, 1911); "The Naval Stores Industry," Schorger and Betts (United States Department of Agriculture, Bulletin No. 229); etc. 2 United States Bureau of Forestry, Bulletins No. 8 and No. 10. 48 ORGANIC STRUCTURAL MATERIALS White Pine. Pinus strobus Linn NOMENCLATURE (Sudworth). Soft Pine (Pa.). White Pine (local and common Northern Pine (N. C.). name). Spruce Pine (Tenn.). Weymouth Pine (Mass., S. C.). Pumpkin Pine. Patternmaker's Pine. LOCALITIES. North-central and northeastern United States, northward into Canada; southward along the coast to New Jersey, and along the Alleghenies into Georgia; also Illinois. FEATURES OF TREE. Seventy-five to one hundred and fifty feet in height; three to six feet in diameter; sometimes larger; erect impressive form; tufts of five, slender, evergreen leaves in long sheaths; cones four to six inches long, one inch thick, slightly curved; the cone-scales are without prickles. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood cream white; sapwood nearly white; close, straight grain; compact structure; comparatively free from knots and resin. STRUCTURAL QUALITIES OF WOOD. Soft and uniform; seasons well, is easy to work, nails without splitting, and is quite durable in exposed positions ; one of the lightest and weakest of eastern United States pines; shrinks, swells and warps less than other pines; receives paints well. REPRESENTATIVE USES OF WOOD. Carpentry, construction, matches, spars, boxes, and numerous other uses WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 24 (United States Forestry Division). 1 24. MODULUS OF ELASTICITY. 1,390,000 (average of 130 tests by United States Forestry Division). 1 1,210,000. MODULUS OF RUPTURE. 7,900 (average of 120 tests by United States Forestry Division,) 1 8,900. REMARKS. Formerly the chief lumber tree of the United States. The stand "is rapidly diminishing. Besides its natural enemy the lumberman, the White Pine is seriously threatened by a disease known as the "White Pine Blister Rust." l See p. 33. See also "The White Pine," Spaulding (United States Forestry Bulletin No. 22); "White Pine a Study," Pinchot (Century Com- pany); "White Pine Timber Supplies" (United States Document No. 40, Senate, 551, Vol. IV); "White Pine," Pinchot (United States Forest Serv- ice, Circular No. 67, 1907), "The White Pine," Detwiler (American For- estry, July, 1916). CONIFEROUS TRUNKS AND WOODS 49 White Pine. Pinus flexilis James NOMENCLATURE (Sudworth). White Pine (Cal., Nev., Utah, Bull Pine (Col.). Col., N. M.). Western and Rocky Mountain White Pine (Utah, Mont.). Pine (Cal.). Limber Pine. Limber-twig Pine. Rocky Mountain Pine. Arizona Flexilis Pine. LOCALITIES. Rocky Mountains, Alberta to Texas and southwestern California. FEATURES OF TREE. Forty to fifty feet in height; one to three feet in diameter; tufts of five rather short, rigid leaves in sheaths; the leaves are not more than two and one-half inches in length; the oval or cylindrical cones are about four inches in length. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light, clear yellow, turning red upon exposure; sapwood nearly white; close-grained; compact structure; numerous and con- spicuous medullary rays. STRUCTURAL QUALITIES OF WOOD. Light and soft; saws, planes, nails, and receives paints well; fairly durable; similar to White Pine (Pinus strobus). REPRESENTATIVE USES OF WOOD. Construction. Similar to White Pine (Pinus strobus). WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 27. MODULUS OF ELASTICITY. 960,000. MODULUS OF RUPTURE. 8,800. REMARKS. This tree forms mountain forests of considerable extent. 1 See also "Limber Pine, Pinus flexilis" James (United States Forest Serv- ice, Silvical Leaflet No. 46, 1909). 50 ORGANIC STRUCTURAL MATERIALS Sugar Pine. Pinus lambertiana Dougl NOMENCLATURE (Sud worth). Sugar Pine (local and common Little or Great Sugar Pine. name). Gigantic Pine. Big Pine, Shade Pine (Cal.). White Pine. LOCALITIES. Oregon and California. Best at high altitudes (above four thousand feet). FEATURES OF TREE. One hundred to occasionally three hundred feet in height; fifteen to some- times twenty feet in diameter; the finely toothed leaves, in tufts of five, are about four inches long; the cones are from ten to eighteen inches in length and contain edible seeds; there are sugar-like exudations; a great tree; the tallest and largest of all the pines. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood pinkish-brown; sapwood cream-white; coarse, straight- grained; compact structure; satiny, conspicuous resin-passages. 1 STRUCTURAL QUALITIES OF WOOD. Light, soft and easily worked; resembles White Pine (Pinus strobus). In fact this is the "White Pine" of the Pacific Coast. REPRESENTATIVE USES OF WOOD. Carpentry, interior finish, doors, blinds, sashes, etc. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 22. MODULUS OF ELASTICITY. 1,120,000. MODULUS OF RUPTURE. 8,400. REMARKS. This is the most impressive tree form of the genus. Some of the Sugar Pines may be grouped as to size with some Redwoods and other giant trees. The Sugar Pines grow at high elevations and form extensive forests. The sugar-like exudations contain a principle known in medi- cine as "pinite." The Sugar Pine, as well as the White Pine, is subject to the disease known as "Blister Rust," which bids fair to injure seri- ously the stands of these trees. 1 "Sugar Pine and Western Yellow Pine in California," Cooper (United States Forest Service, Bulletin No. 69, p. 25, 1906); "Sugar Pine," Larsen and Woodbury (United States Argricultural Bulletin, 426, 1916); "The Sugar Pine," Detwiler (American Forestry, May 1, 1917). CONIFEROUS TRUNKS AND WOODS 51 White Pine. Pinus monticola Dougl NOMENCLATURE (Sudworth). White Pine (Cal., Nev., Ore.). Little Sugar Pine, Soft Pine (Cal.). Mountain Pine, Finger Gone Pine Western White Pine. (Cal.). Mountain Weymouth Pine. Silver Pine. LOCALITIES. Montana, Idaho, Pacific States, and British Columbia. FEATURES OF TREE. Eighty to one hundred and fifty feet in height; two to three feet in di- ameter; sometimes larger; foliage resembles, but is denser than that of White Pine (Pinus strobus)', the stiff, bluish-green needles are about four inches long; long, smooth cones. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood light brown or red; sapwood nearly white; straight-grained; compact structure; suggests White Pine (Pinus strobus). STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong. REPRESENTATIVE USES OF WOOD. Lumber. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 24. MODULUS OF ELASTICITY. 1,350,000. MODULUS OF RUPTURE. 8,600 REMARKS. Found at elevations of seven thousand to ten thousand feet. Common and locally used in northern Idaho. 52 ORGANIC STRUCTURAL MATERIALS Georgia Pine, Hard Pine, Yellow Pine, Longleaf Pine. Pinus palustris Mill NOMENCLATURE (Sudworth). Turpentine Pine. Florida Pine. Rosemary Pine. Florida Longleaved Pine. North Carolina Pitch Pine. Southern Pitch Pine. Southern Pine. Southern Hard Pine. Longleaved Yellow Pine. Southern Heart Pine. Longleaved Pitch Pine. Southern Yellow Pine. Long Straw Pine. Georgia Pitch Pine. Pitch Pine. Georgia Longleaved Pine. Fat Pine. Georgia Heart Pine. Heart Pine. Georgia Yellow Pine. Brown Pine. Texas Yellow Pine. Florida Yellow Pine. Texas Longleaved Pine. LOCALITIES. South Atlantic and Gulf States, Virginia to Florida, intermittently. FEATURES OF TREE. Fifty to one hundred and twenty feet in height; one to three feet in di- ameter; tufts of three leaves, ten to fifteen inches long, in long sheaths; the cones are usually at the ends of the small branches; the cone-scales have stout, recurved prickles. 1 COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood orange; sapwood lighter; compact structure; conspicuous medullary rays; fine and even appearance in cross-section; quite uni- form; narrow annual rings (twenty or twenty-five per inch); wide sap- wood in young trees. 1 STRUCTURAL QUALITIES OF WOOD. Hard, heavy, tough, elastic, durable, and resinous; the strongest and stiffest of Pines. 1 REPRESENTATIVE USES OF WOOD. Heavy constructions, ship-building, cars, docks, beams, ties, flooring, house-trim, and many other uses. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 38 (United States Division of Forestry). 2 43. MODULUS OF ELASTICITY. 2,070,000 (average of 1,230 tests by United States Forestry Division). 2 2,110,000. MODULUS OF RUPTURE. 12,600 (average of 1,160 tests by United States Forestry Division). 2 16,300. REMARKS. One of the best woods for car-building. One of the principal lumber trees of the Southeast. 1 American Forestry (September, 1915). 2 See p. 33. CONIFEROUS TRUNKS AND WOODS 53 Cuban Pine. Pinus caribcea Morelet; Pinus heterophylla (Ell.) Sudivorth NOMENCLATURE (Sudworth). Cuban Pine, Slash Pine (local Swamp Pine (Fla., Miss.). and common names). Bastard Pine, Meadow Pine, Spruce Pitch Pine, She Pine, She Pitch Pine. Pine (Ga. } Fla.). LOCALITIES. Coast region, North Carolina to Florida, westward to Louisiana; also Bahamas and Western Cuba. FEATURES OP TREE. Fifty to eighty feet in height; one to two feet in diameter; the leaves, which are ten to fifteen inches long, are gathered in tufts of two and three; the laterally attached cones are four or five inches long, and have short, recurved prickles. COLOR, APPEARANCE, OR GRAIN OF WOOD. Resembles Loblolly Pine wood; the color is dark straw, with tinge of flesh color; variable and coarse appearance in cross-section; annual rings are usually wide (ten or twenty per inch). STRUCTURAL QUALITIES OF WOOD. Similar to those of Longleaf Pine and of selected pieces of Loblolly Pine (Pinus tceda); sometimes more resinous than Longleaf Pine (Pinus palustris). REPRESENTATIVE USES OF WOOD. Similar to those of Longleaf Pine, from which it is seldom separated. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 39 (United States Forestry Division). 1 MODULUS OF ELASTICITY. 2,370,000 (average of 410 tests of United States Division of Forestry). 1 MODULUS OF RUPTURE. 13,600 (average of 410 tests by United States Division of Forestry). 1 REMARKS. This wood resembles and is marketed with Longleaf Pine (Pinus palustris), and also resembles Loblolly Pine (Pinus tceda). Cuban Pine trees repro- duce rapidly and are often large enough to yield pitch and turpentine when they are forty years of age. This is important, since the species from which most "naval stores" are obtained are being destroyed so rapidly. The Cuban Pine grows in Honduras and Cuba, as well as in the sub-tropical regions of the United States. This explains why it is called the Cuban Pine. 1 See p. 33. 54 ORGANIC STRUCTURAL MATERIALS Shortleaf Pine, Yellow Pine. Pinus echinata Mill; Pinus mitis Michx NOMENCLATURE (Sud worth). Common Yellow Pine, Hard Rosemary Pine (N. C.). Pine. Virginia Yellow Pine. Spruce Pine (Del., Miss., Ark.). North Carolina Yellow Pine. Bull Pine (Va.). North Carolina Pine. Shortshat Pine (Del.). Carolina Pine. Pitch Pine (Mo.). Slash Pine. Poor Pine (Fla.). Old Field Pine. Shortleaved Yellow Pine (N. C.). LOCALITIES. Staten Island to Florida; westward intermittently to Illinois, Kansas, and Texas. FEATURE OP TREE. Sixty to sometimes ninety feet in height; two to sometimes four feet in diameter; a large, erect tree; small, lateral cones have minute, weak prickles; the leaves are about four and one-half inches long; they are usually gathered in groups of two; the sheaths are long. COLOR, APPEARANCE, OR GRAIN OF WOOD. Resembles Longleaf and Loblolly Pines; variable appearance in cross- section; wide annual rings near heart. STRUCTURAL QUALITIES OF WOOD. Variable, usually hard, tough, strong, durable, and resinous; lighter than Longleaf and Loblolly Pines. REPRESENTATIVE USES OF WOOD. Lumber and construction; similar to Longleaf Pine (Pinus palustris). WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 32 (United States Forestry Division). 1 30. MODULUS OF ELASTICITY. 1,680,000 (average of 330 tests by United States Forestry Division). 1 1,950,000. MODULUS OF RUPTURE. 10,100 (average of 330 tests by United States Forestry Division). 1 14,700. REMARKS. The Shortleaf Pine yields considerable pitch and turpentine, and is the principal species of northern Arkansas, Kansas, and Missouri. 2 iSeep. 33. 2 "Southern Pine," Mohr (United States Forestry Circular No. 12); ''Timber Pines of Southern States," Mohr (United States Forestry Bulletin No. 13); "Shortleaf Pine," Mattoon (United States Department Agriculture Bulletin, 308, 1915) ; "The Shortleaf Pine," Detwiler (American Forestry, September, 1916). CONIFEROUS TRUNKS AND WOODS 55 Loblolly Pine. Pinus tceda Linn NOMENCLATURE (Sudworth). Old Field Pine. Sap Pine. Torch Pine. Meadow Pine. Rosemary Pine. Cornstalk Pine (Va.). Slash Pine. Black Pine. Longschat Pine. Foxtail Pine. Longshucks. Indian Pine. Black Slash Pine. Spruce Pine. Frankincense Pine. Bastard Pine. Shortleaf Pine. Yellow Pine. Bull Pine. Swamp Pine. Virginia Pine. Longstraw Pine. North Carolina Pine. LOCALITIES. Southern New Jersey to Florida; westward intermittently to Texas. FEATURES OF TREE. Fifty to one hundred or more feet in height; two to sometimes four feet in thickness; leaves in groups of threes are about six inches long; scales of lateral cones have short, straight spines; a large tree. COLOR, APPEARANCE, OR GRAIN OF WOOD. Resembles Longleaf Pine (Pinus palustris}, but is variable; coarse cross- sections; very wide annual rings (three to twelve per inch). STRUCTURAL QUALITIES OF WOOD. Resembles Shortleaf Pine (Pinus echinata)', selected pieces rank with Longleaf Pine (Pinus palustris). 1 REPRESENTATIVE USES OF WOOD. Used with other Southern pines; inferior in uniformity, strength, and durability. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 33 (United States Forestry Division). 2 33. MODULUS OF ELASTICITY. 2,050,000 (average of 660 tests by United States Forestry Division). 2 1,600,000. MODULUS OF RUPTURE. 11,300 (average of 650 tests by United States Forestry Division). 2 12,500. REMARKS. These trees grow naturally on deforested land, whence the name of Old Field Pine. A source of abundant and cheap material. A vigorous, prolific grower, probably one of the pines of the future. 1 "Loblolly Pine in eastern Texas," Zon (United States Forest Service, Bulletin No. 64, 1905). 2 See p. 33. 56 ORGANIC STRUCTURAL MATERIALS Bull Pine, Yellow Pine, Western Yellow Pine. Pinus ponderosa Laws NOMENCLATURE (Sudworth). Big Pine. Heavy-wooded Pine. Longleaved Pine. Western Pitch Pine. Red Pine. Heavy Pine (Cal.). Pitch Pine. Foothills Yellow Pine. Southern Yellow Pine. Montana Black Pine. LOCALITIES Rocky Mountains; westward intermittently to Pacific Ocean; always at elevations of eighteen hundred or more feet. FEATURES OF TREE. One hundred to sometimes three hundred feet in height; six to sometimes twelve feet in diameter; thick, deeply furrowed bark; the leaves, which are in tufts of twos and threes, are from five to nine inches long; the conical cones are at the ends of small branches; the scales are tipped with prickles. 1 COLOR, APPEARANCE, OR GRAIN OF WOOD. The thin heartwbod is light red; sapwood nearly white; rather coarse grain; compact structure. STRUCTURAL QUALITIES OF WOOD. Variable, heavy, hard, strong, and brittle; not durable. REPRESENTATIVE USES OF WOOD. Lumber, railway ties, mine-timbers, fuel, etc. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 29. MODULUS OF ELASTICITY. 1,260,000. MODULUS OP RUPTURE. 10,200. REMARKS. These trees are often killed by tree-boring beetles (Dendroctonus ponder- osa), and the wood of trees thus attacked eventually assumes a bright blue color (see also von Schrenk, United States Bureau of Plant In- dustry, Bulletin No. 36). The specific name ponderosa was given because of the great size of the trees. 1 "Western Yellow Pine in Arizona and New Mexico," Woolsey (United States Forest Service, Bulletin No. 101, 1911). "Western Yellow Pine in Oregon," Munger (United States Department of Agriculture, Bulletin No. 418, 1917). CONIFEROUS TRUNKS AND WOODS 57 Norway Pine, Red Pine. Pinus resinosa Ait NOMENCLATURE (Sudworth). Norway Pine, Red Pine (local and Hard Pine (Wis.). common names). Canadian Red Pine (Eng.). LOCALITIES. Southern Canada, northern United States from Maine to Minnesota; Pennsylvania. FEATURES OF TREE. Sixty to ninety feet in height; one to three feet in diameter; reddish bark on branchlets; leaves are in twos from long sheaths; the cones are at the ends of the branches; the scales are not prickle-tipped; a tall, straight tree. COLOR, APPEARANCE, OR GRAIN OF WOOD. The thin heartwood is light red; sapwood yellow to white; numerous pro- nounced medullary rays. STRUCTURAL QUALITIES OF WOOD. Light, hard, elastic, not durable, and resinous. REPRESENTATIVE USES OF WOOD. Piles, telegraph poles, masts, flooring, and wainscoting. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 31 (United States Forestry Division). 1 30. MODULUS OF ELASTICITY. 1,620,000 (average of 100 tests by United States Forestry Division). 1 1,600,000 MODULUS OF RUPTURE. 9,100 (average of 95 tests by United States Forestry Division). 1 12.500. REMARKS. In spite of the specific name resinosa, which signifies resinous, these trees yield unimportant quantities of turpentine and resin. 2 1 See p. 33. 2 "Red or Norway Pine, Pinus resinosa Ait," (United States Forest Service, Silvical Leaflet No. 43, 1909); "Norway Pine in the Lake States," Woolsey (United States Department of Agriculture, Bulletin No. 139, 1914). 58 ORGANIC STRUCTURAL MATERIALS Pitch Pine. Pinus rigida Mill NOMENCLATURE (Sud worth). PitchPine (local and common name) Yellow Pine (Pa.). Longleaved Pine, Longschat Pine Black Pine (N. C.). (Del.). Black Norway Pine. Hard Pine (Mass.). Rigid Pine, Sap Pine. LOCALITIES. New Brunswick to Ontario and Ohio, southward to northern Georgia and Alabama; the predominant tree of the New Jersey " pine-barrens." FEATURES OP TREE. Forty to sometimes eighty feet in height; one to sometimes three feet in diameter; the rigid, flattened leaves, which are three and one-half to five inches long, are in groups of threes; the sheaths are short; the cones are compact; the reddish scales have stout, recurved prickles. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light brown or red; thick sapwood yellow to nearly white; coarse, conspicuous grain; compact structure; very resinous. STRUCTURAL QUALITIES OP WOOD. Light, soft, not strong, and brittle. REPRESENTATIVE USES OP WOOD. Coarse lumber, fuel, and charcoal. WEIGHT OP SEASONED WOOD IN POUNDS PER CUBIC FOOT. 32. MODULUS OP ELASTICITY. 820,000. MODULUS OF RUPTURE. 10,500. REMARKS. In North America the name, "Pitch Pine" is sometimes misleadingly used to include all Hard Pines ; abroad, it is sometimes made to include White Pine. So much resin is present that Pitch Pine is not greatly valued in construction. In spite of this fact, the trees are not relied upon for naval stores. The trees are hardy. They sometimes grow on rocks or on sand near the ocean where they survive in spite of occasional inundations. CONIFEROUS TRUNKS AND WOODS 59 Northern Pine, Scotch Pine, D . , . T . _ . . _. Pinus sylvestns Linn Dantzic Pine. NOMENCLATUKE. Dantzic Fir (from place of ship- Swedish Fir. ment). Scots or Scottish Fir. Rigi Fir (from place of shipment). Northern Fir. Memel Fir (from place of shipment). Redwood, Yellow-wood. Stettin Fir (from place of ship- Deal (local). ment). LOCALITIES. Widespread in Europe, as Scotland, Germany, and Russia; also Asia. r . Cultivated in the United States. FEATURES OF TREE. Fifty to one hundred feet in height; two to five feet in diameter; sometimes larger; the leaves, which are about four inches in length, are slightly twisted, and are gathered in tufts of twos and threes; the cones are at the ends of the small branches; the scales are not prickle-tipped. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood reddish white to yellowish white; sapwood similar; even, straight grain (varies with locality). STRUCTURAL QUALITIES OF WOOD. Moderately light, hard, tough, and elastic; easily worked (varies with locality). REPRESENTATIVE USES OF WOOD. Carpentry, construction, planks, beams, masts, and heavy timber. 1 WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 34 (Laslett) (varies with locality). MODULUS OF ELASTICITY. 1,680,000 (Laslett) (varies with locality). 1,800,000 (Thurston). MODULUS OF RUPTURE. 7,000 (Thurston) (varies with locality). REMARKS. This is the principal softwood produced by the forests of Europe. The trees are widely distributed. The Dantzic and Rigi forests produce the best wood. Wood "equal to Dantzic Fir" is sometimes specified. The wood suggests true White Pine (Pinus strobus). 1 "Scotch Pine" (Pinus sylvestris), Pinchot (United States Forest Service, Circular No. 68, 1907). 60 ORGANIC STRUCTURAL MATERIALS The Stone Pine (Pinus cembra,) which is said to be best de- veloped in Switzerland, yields a smooth, fine-grained wood which suggests true White Pine. This wood is often seen in carvings. The Bhotan Pine (Pinus excelsa) of the Himalayas closely re- sembles the White Pine tree in size and habit, and yields a wood which is very similar to White Pine. The Lodgepole Pine (Pinus murrayana) also called the Tamarack, Tamarack Pine, Murray Pine, Prickly Spruce, Black Spruce, and White Spruce, grows from Alaska to California and New Mexico. Trees often grow at altitudes of six to eleven thousand feet. The remarkably tall, slender trunks can be made into ties, posts, and poles. The light, straight-grained woods are hard to season, but easy to work. Trees are sensitive to fires, but these fires do not normally kill the seeds (see also Erickson, "Forestry and Irrigation," p. 503, 1904; "The Lodgepole Pine," Ziegler, U. S. Forest Service Circular No. 126; "Utilization and Management of Lodgepole Pine in the Rocky Mountains," Mason. United States Department of Agriculture, Bulletin No. 234, 1915; etc.). The Spruce Pine (Pinus glabra) is the least common of the lower southern states pines. It seldom forms pure forests and is of relatively small commercial importance. The wood resembles that of the Lob- lolly Pine. The name Spruce Pine is popularly applied to trees of ten other American species (Sudworth). Two of these are not pines. The Pond Pine (Pinus serotina). This is the Marsh Pine of the woods- man. The wood is seldom distinguished at the mills where it furnishes much of the lumber known as North Carolina Pine. Pond pine trees grow along the Atlantic coast from Albermarle Sound south to Florida. The six-inch or eight-inch leaves are in tufts of three. The cones some- times remain on the trees for several years. The trees are now bled for turpentine. The Pond Pine is also known as the Meadow, Loblolly, Spruce, Bastard and Bull Pine (see also Roth, U. S. Forestry Bulletin No. 13). The Monterey Pine (Pinus radiata). This tree grows best near Monterey, California. It is often one hundred feet high and is sym- metrical or distorted, according to its exposure. Monterey pine trees are widely transplanted for landscape effects, and the trunks are occa- sionally cut into lumber. The Digger, Grayleaf, Gray or Sabine Pine (Pinus sabiniana) of western California affords a poor and seldom-used wood. The nuts were prized by Digger Indians, whence the name. The tree forms are unusual. The trunks are divided and the sparse, grayish foliage is more or less concentrated near the ends of the branches. The Digger Pine yields a turpentine (abietene) that is used in medicine. The Scrub Pine or Jack Pine (Pinus divaricata) of the north-central and Atlantic states, yields a wood that is sometimes classed among the CONIFEROUS TRUNKS AND WOODS 61 lighter Hard Pines and that is used for ties and fuel. The species is hardy in some semi-arid regions where other pines will not grow. The Scrub Pine or Jersey Pine (Pinus virginiana) grows from Staten Island, southward and westward into Alabama and Tennessee. The inferior wood is used for fuel, water-pipes, and coarse lumber. l l See also "Scrub Pine" (Pinus virginiana), (United States Forest Service, Bulletin No. 94, 19 ID. KAURI PINE Dammara The Kauri Pine grows in New Zealand and yields a strong light, durable, and elastic wood. The tough, leather-like leaves suggest those of the Box. The reputation of the species depends principally upon a resin which is much used in the manufacture of high-grade varnishes. This resin unites with linseed oil more perfectly and at lower temperatures, than most other varnish resins, and has sold for more than one thousand dollars a ton. The best Kauri, known as " fossil resin," is obtained by digging over areas from which the trees have disappeared. These deposits exist a few feet below the surface and yield pieces that commonly vary in size from small pebbles to lumps as large as eggs. One exceptional mass, weighing two hundred and twenty pounds, has been reported. 1 There are also "semi-fossil" and " fresh-product" resins. The fresh exudations from Kauri Pine trees resemble the product known as Venice turpentine. Varnish resins may be roughly divided according to the manner in which they unite with oil and with spirit. In the first case, oil becomes part of the whole, whereas, in the second case, spirits simply dissolve the ingredients and then evaporate from them. As noted, Kauri resin is one of the best of the oil-varnish resins, and, in a similar way, shellac is among the valuable spirit- varnish resins. Gums and resins should be distinguished from one another. A true gum usually dissolves in water, while a true resin usually yields to oil or spirit. A solution of gum and water forms a mucilage. The name gum is often applied for convenience to substances that are actually resins. 1 "Notes on Fossil Resins," R. Ingham Clark (published by C. Letts & Company, London). 62 CONIFEROUS TRUNKS AND WOODS 63 . Dammara australis Lambert Agathis australis Salisbury OMENCLATURE. Kauri Pine (local and general). Cowdie Pine (New Zealand and many localities). LOCALITIES. New Zealand. FEATURES OF TREE. Ninety to one hundred feet in height; three to four feet in diameter; occasional specimens much larger; a tall, handsome tree; the willow- like leaves are from two to three and one-half inches long, and from one-half to three-fourths of an inch in breadth; the cones are about two and one-half inches in diameter; the resin is characteristic. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood straw-colored ; fine, straight grain, with silky luster suggesting Satinwood; "mottled Kauri" is separated and used for cabinet work. STRUCTURAL QUALITIES OF WOOD. Moderately hard, light, elastic, and strong; it seasons well, works readily, and receives a high polish; it is quite free from knots; it stands well, wears evenly, and has an agreeable odor. REPRESENTATIVE USES OF WOOD. Carpentry and masts. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 33 (Laslett) varies with locality. MODULUS OF ELASTICITY. 1,810,000 (Laslett). MODULUS OF RUPTURE. REMARKS. The species is widely known by its resin. The most valuable forest tree of New Zealand. SPRUCE Picea Spruce trees form forests in North America and in Europe. The Norway Spruce, or " White Fir" (Picea excelsa), is the prin- cipal species in Europe, while the Black Spruce (Picea nigra), the White Spruce (Picea alba), and the Red Spruce (Picea rubens) are notable in some parts of the East in the United States. The White Spruce (Picea engelmanni) is an important species in the West. In North America spruce trees prefer northern localities where there are short summers and long winters. The eastern American species yield soft, clean, light, close- grained woods that are much valued in constructions. The Western Spruce yields a valuable wood, but this is less familiar because of its remoteness from the eastern markets. Spruce resembles and forms one of the best eastern substitutes for White Pine. It is also valued for paper pulp. The eastern product is divided according to appearance, and irrespective of species, into " White Spruce" and "Black Spruce." The pieces that have wide annual layers are usually classed as White Spruce, while those that have narrow layers are classed as Black Spruce. Spruce woods and Fir woods are often confused with one another, and there are so-called spruce trees, as "Doug- las Spruce" and "Kauri Spruce," that are not true spruces. European Spruce is sometimes known locally as "White Deal." The insect and fungus enemies of spruce trees have received much attention. 1 The largest and best trees seem most liable to attack. Hopkins states that the spruce-destroying beetle (Dendroctonus piceaperda) is accountable for much of the damage done in the eastern states. This beetle gains entrance to the tree through crevices in the bark, and then cuts grooves on the surface of the sensitive outer sap wood. The resins that collect in these grooves or tunnels are ejected and form what are known as "pitch tubes." The presence of pitch tubes and particles of wood on the ground at the base of a tree is evidence that the tree has been attacked. An intimate connection exists between the attacks of these and other insects, and those of fungi. The 64 CONIFEROUS TRUNKS AND TREES 65 latter may lodge in and infect wounds caused by the former. It should be noted that wood may remain sound for sometime after the physical death of the tree, and that such wood can be used for lumber and for paper pulp. " Windfalls" may result from insects, fungi, age, fire, and tornadoes, or from a combination of these agencies. In windfalls, trees are piled promiscuously upon one another like giant jackstraws. Trunks and limbs intermingle and later the mass is often penetrated by wiry, second- growth saplings. Passage through such a district is made by cautiously walking backward and forward, up and down over trunks and limbs. It is sometimes impossible to proceed for more than two or three miles daily in a straight line through a windfall, also sometimes used. 2 The term "blowdown" is Spruce trees have single, short, sharp-pointed leaves which are keeled above and below and which therefore appear four-sided. Spruce cones hang downward. Spruce trees may be distin- guished from Pines, Firs, and Hemlocks, by remembering that pine leaves are longer and grow in clusters, that hemlock leaves are flat, blunt, and two-ranked, and that the cones of the Fir tree point upward. Names Arrangement of leaves Shape of leaves Cones Pine (Pinus) . . . In tufts or clusters. Comparatively long. Spruce (Picea). Single, scattered, Short, sharp ends, Hang down, point in all direc- keeled above and be- 1 to 6 inches tions. low. Somewhat long. four-sided. Fir (Abies) Single, scattered, ap- Short, blunt ends, Stand erect, pear somewhat as in flat. 2 to 4 inches tiwo ranks. long. Hemlock Single, scattered, ap- Short, blunt ends, Hang down, (Tsuga). pear as in two ranks. flat. % to 1 inch long. 1 "Insect Enemies of Spruce in the Northeast" and "Insect Enemies of the Forest of the Northwest," Hopkins (United States Division Entomology, Bulletins No. 28 and No. 21); also "Diseases New England Conifers," von Schrenk (United States Division Vegetable Physiology and Pathology, Bulletin No. 25. 2 See "Transactions American Institute Mining Engineers," 1899; see also "Third Annual Report Pennsylvania Department Agriculture." 66 ORGANIC STRUCTURAL MATERIALS Picea nigra Link Black Spruce. D . y . ,,. Picea manana Mill NOMENCLATURE (Sudworth). Spruce (Vt.), Yew Pine, Spruce White Spruce (W. Va.). Pine (W. Va.). He Balsam (Del., N. C.). Double Spruce (Me., Vt., Minn.). Water Spruce (Me.). Blue Spruce (Wis.). LOCALITIES. Labrador and Alaska, southward to New York, Pennsylvania, Wisconsin, and Saskatchewan. FEATURES OF TREE. Forty to eighty feet in height; one to two feet in diameter; conical shape, with straight trunk; four-sided leaves are somewhat narrowed toward the tips; the leaves are from three-eighths of an inch to five-eighths of an inch in length; they are lighter on the upper surfaces than on the lower; cones remain for several years, being thus distinct from those of the White Spruce (Picea alba). COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood reddish, nearly white; sapwood lighter; straight grain; com- pact structure. STRUCTURAL QUALITIES OF WOOD. Light, soft, not strong, elastic, and resonant; not durable when exposed. REPRESENTATIVE USES OF WOOD. Lumber, flooring, carpentry, ship-building, piles, posts, railway ties, paddles, oars, "sounding-boards," and paper-pulp. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 28. MODULUS OF ELASTICITY. 1,560,000. MODULUS OF RUPTURE. 10,600. REMARKS. A substitute for Soft Pine. See also "Black Spruce, Picea mariana (Mill.)" (United States Forest Service, Silvical Leaflet No. 28, 1908). The Red Spruce (Picea rubens) is one of the principal lumber trees of northern New England. This tree, which is much like the Black Spruce, is from fifty to eighty feet in height, and from two to three feet in diameter. Large quantities of its light, close-grained, reddish, satiny wood are cut into lumber or used in the manufacture of paper-pulp. CONIFEROUS TRUNKS AND WOODS 67 White Spruce. Picea alba Link Picea canadensis Mill NOMENCLATURE (Sudworth). Single Spruce (Me., Vt., Minn.). Skunk Spruce (Wis., New Eng ) Bog Spruce, Cat Spruce (New Eng.). Spruce, Double Spruce (Vt.). Pine (Hudson Bay). LOCALITIES. Northern United States, Canada to Labrador and Alaska. FEATURES OF TREE. Fifty to one hundred feet in height; one to two feet in diameter; occa- sionally larger; compact, symmetrical, conical shape; foliage lighter than Black Spruce; cones fall sooner than those of Black Spruce; whitish resin. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light yellow; sapwood similar; straight-grained; numerous prominent medullary rays; compact structure. STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong (similar to those of Black Spruce (Picea nigra). REPRESENTATIVE USES OF WOOD. Lumber, flooring, carpentry, etc. (similar to those of Black Spruce (Picea nigra). WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 25. MODULUS OF ELASTICITY. 1,450,000. MODULUS OF RUPTURE. 10,600. REMARKS. Notable as resident of high latitudes. One of the chief trees of the Arctic forests. The wood, used similarly to Black Spruce, is substi- tuted for White Pine. It is often difficult to distinguish between Black Spruce trees and those of the White Spruce. On the whole, the foliage of the former is darker; there are also differences in the shapes and in the persistence of the cones. The names " Double Spruce" and "Single Spruce" are without botanical founda- tion. Woods obtained from these two trees exhibit similar qualities and are not separated by lumbermen. 68 ORGANIC STRUCTURAL MATERIALS White Spruce. Picea engelmanni Engelm NOMENCLATURE (Sudworth). White Spruce (Ore., Col., Utah, White Pine (Idaho), Mountain Idaho). Spruce (Mont.). Balsam, Engelmann's Spruce (Utah). LOCALITIES. British Columbia to Oregon, eastward to Alberta, and south through the Rocky Mountain region to northern New Mexico and Arizona. FEATURES OF TREE. Frequently seventy-five to one hundred feet in height; sometimes one hundred and fifty feet in height; two to three feet in diameter; sometimes a low shrub; the straight, slender leaves are from three-fourths of an inch to one and one-fourth inches in length; they are flexible, with sharp, thick tips, and they spread in all directions; the elliptical cones are from one and one-half inches to two and one-half inches long; the scales are toothed at the apex. 1 COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood pale reddish yellow; sapwood similar; close, straight grain; compact structure; conspicuous medullary rays. STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong. REPRESENTATIVE USES OF WOOD. Lumber, charcoal and fuel; bark rich in tannin is sometimes used for tanning. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 21. MODULUS OF ELASTICITY. 1,140,000. MODULUS OF RUPTURE. 8,100. REMARKS. Notable as a resident of high altitudes, extensive forests occurring at eight to ten thousand feet above sea-level. A valuable tree of the cen- tral and southern Rocky Mountain regions. ^'Engelmann Spruce in the Rocky Mountain," Hodson and Foster (United States Forest Service, Circular No. 170); "Engelmanns Spruce" Pinchot (United States Forest Service, Silvical Leaflet No. 3, 1907). CONIFEROUS TRUNKS AND WOODS 69 Sitka Spruce. Picea sitchensis Trautv. and Mayer NOMENCLATURE (Sudworth). Sitka Spruce (local and common Menzies Spruce, name). Western Spruce. Tideland Spruce (Cal., Oreg., Great Tideland Spruce. Wash.). LOCALITIES. Pacific Coast region, Alaska to central California; extends inland about fifty miles; prefers low elevations. FEATURES OP TREE. One hundred and fifty or more feet in height; three feet or more in di- ameter; the stiff, straight, flat leaves, which are from five-eighths of an inch to three-fourths of an inch in length, radiate in all directions; the oval or cylindrical cones are from three to four inches in length; the bark is scaly and of a reddish-brown color. 1 COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light reddish brown; sapwood nearly white; coarse-grained; satiny. STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong. REPRESENTATIVE USES OF WOOD. Construction, interior finish, fencing, boat-building, and cooperage. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 2,626. MODULUS OF ELASTICITY. MODULUS OF RUPTURE. 10,400. REMARKS. A giant among the spruces. Forms an extensive coast-belt forest. 1 "Sitka Spruce," Pinchot (United States Forest Service, Silvical Leaflet No. 6, 1907). DOUGLAS SPRUCE, DOUGLAS FIR, OREGON PINE Pseudotsuga. These trees form almost pure forests in Washington and Ore- gon. They grow sparingly in Mexico, Texas, and at high alti- tudes in Colorado. Transplanted specimens have survived in New York. It should be noted that the Douglas Spruce is neither Spruce, Fir, or Pine. The generic name is from pseudo or "false," and tsuga or " Hemlock," and the tree may be regarded as in the nature of a bastard Hemlock. The species has also been classed as Pinus taxifolia and Abies taxifolia. 1 The durable, strong, light red, or yellow wood, which resembles larch or true hard pine is used in place of hard pine on the Pacific Coast. It is one of the general utility woods of that coast. The trees are among the greatest known to man. Individuals have reached heights of three hundred and fifty feet, 2 and diame- ters of twelve and even fifteen feet. Logs that yield timbers two feet square and one hundred feet long are not uncommon. Single trees have been cut that scaled sixty thousand feet board measure. The Douglas Spruce grows rapidly. It is hardy, and, like the redwoods, is likely to resist commercial extinction. Red and Yellow varieties of Douglas Spruce wood are recog- nized by lumbermen. The former woods come from younger trees, and are coarser and less valuable than the latter kinds which come from the older trees. The wood is also marketed under the commercial names of Oregon Pine, Hard Pine, Pacific Pine, Red Spruce, Red Fir, Yellow Fir, etc. The genus includes one other species, the much less important Big Cone Spruce (Pseudotsuga macrocarpa) of California, which yields an inferior wood. 1 Some difficulties associated with the classification of this tree are enumerated on pages 23 and 24 of Sudworth's Check List. 2 The tallest specimen recorded was three hundred and eighty feet high. See also "Growth and Management of Douglas Fir in Pacific Northwest," Munger (United States Forest Service Circular No. 175, p. 23); "Properties and Uses of Douglas Fir," Cline and Knap (United States Forest Service Bulletin No. 88); "Douglas Fir," Frothingham (United States Forest Service, Circular No. 150, 1909); "Douglas Fir," Detwiler (American Forestry, February, 1916). 70 CONIFEROUS TRUNKS AND WOODS 71 Pseudotsuga mucronata Sudw. Douglas Spruce, Douglas Fir. Pseudotsuga taxi/olio, Lam Pseudotsuga Douglasii Can NOMENCLATURE (Sudworth). Oregon Pine (Cal., Wash., Ore.) Douglas-tree, Cork-barked Douglas Red Fir, Yellow Fir (Ore., Wash., Spruce. (Occasional) Idaho, Utah, Mont., Col.). Spruce, Fir (Mont.) Red Pine (Utah, Idaho, Col.). Puget Sound Pine (Wash.). LOCALITIES. Pacific Coast region, Mexico to British Columbia; best in Western Ore- gon and Washington. FEATURES OF TREE. One hundred and seventy-five to sometimes three hundred feet in height ; three to five and sometimes ten feet in diameter; older bark rough-gray, often looking as though braided. One of the world's greatest trees. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light red to yellow; scant sapwood nearly white; comparatively free from resins; pronounced variable rings (four to forty per inch). STRUCTURAL QUALITIES OF WOOD. Variable, usually hard, and strong; rather difficult to work, durable, splits easily, can be obtained in large pieces. l REPRESENTATIVE USES OF WOOD. Heavy constructions, dimension-timbers, lumber, railway ties, paving blocks, wood-stave pipes, posts, poles, piles, masts, and fuel. The wood is used much as hard pine is used. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 32 (United States Forestry Division). 2 36 (Average of 20 tests by Soule). 3 32. MODULUS OF ELASTICITY. 1,680,000 (average of 41 tests by United States Forestry Division). 2 1,862,000 (average of 21 tests by Soule). 3 1,824,000. MODULUS OF RUPTURE. 7,900 (average of 41 tests by United States Forestry Division). 2 9,334 (average of 21 tests by Soule). 3 12,500. REMARKS. 1 See also" Properties and Uses of Douglas Fir: Pt. 1, Mechanical Properties; Pt. 2, Commercial Uses" (United States Forest Service, Bulletin No. 88, 1911). 2 See p. 33. 3 Professor Frank Soule", University of California, Trans. Am. Inst. M. E., Vol. XXIX, p. 552. FIR A hies The Silver Fir (Abies grandis), the Red Fir (Abies magnified], and the Noble Fir (Abies nobilis), are valued west of the Rocky Mountains, while the Balsam Fir (Abies balsamea) is of some com- mercial importance in the East. Some of the Fir trees in the Western States are so large as to call for the special methods that are used to fell the giant .speci- mens of other species. In such cases platforms are erected, far enough up from the ground, so that axemen, standing upon them, can" cut through above the hollow or decayed parts that are common near the surface of the ground. It is also arranged so that the trees, as they fall, shall strike the ground more or less uniformly along their sides and thus diminish the danger from splintering or breaking, which is associated with the impact of such large trunks. 1 Fir and Spruce resemble one another in appearance and struc- tural qualit'es and are often used in place of one another in the United States. Fir, Spruce, and Pine are often confused with one another in Europe. Fir trees have flat, scattered, evergreen leaves and erect cones. The Balsam Fir may be distinguished by blisters, abundantly supplied in the bark of all but the oldest trunks, which contain a clear, liquid resin known as Canada Balsam. 1 Descriptions of special methods employed in harvesting Douglas Spruce, Redwoods, Giant Cedars, and other Western species are as follows: Engi- neering Magazine, Bishop (Vol. XIII, p. 70) ; National Geographic Magazine, Gannett (Vol. X, No. 5, May, 1899). 72 CONIFEROUS TRUNKS AND WOODS 73 Balsam Fir, Common Balsam Fir. Abies balsamea (L.) Mill. NOMENCLATURE (Sud worth). Balsam (Vt., N. H., N. Y.). Blister pine, Fir Pine (W. Va.). Fir Tree (Vt.). Single Spruce, Silver Pine (Hudson Balm of Gilead (Del.). Bay). Canada Balsam (N. C.). Balm of Gilead Fir.(N. Y., Pa.). LOCALITIES. Labrador, southward through the mountains, and westward to Minnesota. FEATURES OF TREE. Fifty to seventy feet in height; one to two feet in diameter; sometimes a low shrub; blisters in smooth bark contain thick balsam; erect cones. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood white to brownish; sap wood lighter; coarse-grained; compact structure; satiny. STRUCTURAL QUALITIES OF WOOD. Soft, light, not durable or strong, resinous, and easily split. REPRESENTATIVE USES OF WOOD. Occasionally used as inferior lumber. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 23. MODULUS OF ELASTICITY. 1,160,000. MODULUS OF RUPTURE. 7,300. REMARKS. These trees grow naturally over Northern pine lands, and yield wood which is commonly sold with Spruce and Pine. Of all the native coni- fers this is one of the most difficult trees to cultivate. The thick fluid-resin, or balsam, known as Canada Balsam, is used in medicine. It should be noted that the Poplar (Populus balsamifera) is also called Balm of Gilead. See also "Balsam Fir," Zon (United States Depart- ment of Agriculture Bulletin No. 55). 74 ORGANIC STRUCTURAL MATERIALS Great Silver Fir, White Fir. Abies grandis LindL NOMENCLATURE (Sudworth). Silver Fir (Mont., Idaho). Yellow Fir (Mont., Idaho) Oregon White Fir, Western White Lowland Fir. Fir (Cal.). LOCALITIES. Vancouver region, northwestern United States; best in western Washing- ton and Oregon. FEATURES OP TREE. Two hundred to sometimes three hundred feet in height; two to five feet in diameter; leaves deep green above, silvery below, usually curved; a handsome tree. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light brown; sapwood lighter; coarse-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong. REPRESENTATIVE USES OF WOOD. Lumber, interior finish, packing-cases, and cooperage. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 22. MODULUS OF ELASTICITY. 1,360,000. MODULUS OF RUPTURE. 7,000. REMARKS. These trees form an important part of local mountain forests and furnish much lumber locally. They grow best on rich bottom lands, but are also found at altitudes of five thousand and even six thousand feet. The balsam contained in blisters in the young bark is used in medicine. The specific name grandis was given because of the great size to which some trees of this species grow. See also " Lowland Fir," Pinchot (United States Forest Service, Silvical Leaflet No. 5, 1907). CONIFEROUS TRUNKS AND WOODS 75 Red Fir. Abies magnified Murr NOMENCLATURE (Sudworth). California Red Fir, California Magnificent Fir, Golden Fir (Cal.). Red-bark Fir (Cal.). LOCALITIES. Mountains of northern California, Oregon, and Nevada. FEATURES OF TREE. One hundred to two hundred and fifty feet in height; six to ten feet in diameter; large, erect cones; beautiful form. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood reddish; sapwood distinguishable; rather close-grained; com- pact structure. STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong, durable when exposed, liable to injury in seasoning. REPRESENTATIVE USES OF WOOD. Construction, sills, lumber, and fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 29. MODULUS OF ELASTICITY. 940,000. MODULUS OF RUPTURE. 9,900. REMARKS. The specific name refers to the appearance and size of the tree. 76 ORGANIC STRUCTURAL MATERIALS White Fir, Balsam Fir. Abies concolor Lindl. and Gord. NOMENCLATURE (Sudworth). White Balsam (Utah). Silver Fir, Balsam (Cal.). Balsam-tree (Idaho). California White Fir (Cal.). Colorado White Fir, Concolor White Black Gum, Bastard Pine (Utah). Fir. LOCALITIES. Rocky Mountains and coast ranges; high elevations. FEATURES OF TREE. Seventy to one hundred and fifty feet in height; three to five feet in diameter; the blisters in the bark are filled with clear pitch. 1 COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light brown to nearly white; sapwood same or darker; coarse- grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong; without odor. REPRESENTATIVE USES OF WOOD. Butter-tubs, packing-boxes, and lumber. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 22. MODULUS OF ELASTICITY. 1,290,000. MODULUS OF RUPTURE. 9,900. REMARKS. Not always distinguished from the species Abies lowiana. *" White Fir," Pinchot (United States Forest Service, Silvical Leaflet No. 4, 1907). CONIFEROUS TRUNKS AND WOODS 77 Red Fir, Noble Fir. Abies nobilis LindL NOMENCLATURE (Sudworth). Noble Silver Fir, Noble Red Fir. Bigtree, Feather-cone, Red Fir Larch (Oreg.). (Cal.). LOCALITIES. Northwestern United States; cultivated in the East. FEATURES OF TREE. One to two hundred feet in height; six to nine feet in diameter; the leaves are curved; a large, beautiful tree. 1 COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood reddish-brown; sap wood darker; rather close-grained; com- pact structure. STRUCTURAL QUALITIES OF WOOD. Light, hard, strong, and elastic. REPRESENTATIVE USES OF WOOD. Fitted for house-trimmings. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 28. MODULUS OF ELASTICITY. 1,800,000. MODULUS OF RUPTURE. 22,200. REMARKS. Red Fir trees grow at elevations of three thousand and four thousand feet. With other fir trees, they form extensive forests. The wood is often sold as Larch. 1 Peters (Forestry and Irrigation, Vol. VIII, No. 9, Sept., 1902, pp. 362, 366); "Noble Fir," Pinchot (United States Forest Service, Silvical Leaflet No. 7, 1907). HEMLOCK Tsuga Hemlock trees grow in some of the central and northern states east of the Rocky Mountains, and also on the Pacific Coast as far north as Alaska. They sometimes mingle with other trees, and sometimes form pure forests by themselves. The wood of the Eastern Hemlock (Tsuga canadensis) is coarse, brittle, often cross-grained, usually hard to work, liable to warp and splinter, and perishable when exposed. It cannot be relied upon to sustain shocks. It holds nails firmly and is used for coarse lumber, dimension pieces, paper pulp, and cheap finish. Some of the prejudice that exists against hemlock is due to the fact that it was formerly compared with white pine, spruce and fir. The supplies of these better woods have since diminished and the value of hemlock has increased correspondingly. The wood of the Western Hemlock (Tsuga heterophylla) , which is much better and stronger than Eastern Hemlock, has suffered because of the reputation of the Eastern Hemlock. Western Hemlock has a pronounced odor which makes it disliked by insects and rodents. For this reason it is sometimes used to line grain-bins. The wood is also used for flooring, mill frames, boxes, and paper pulp. It is seldom sold under its true name, but names such as Alaska Pine and Red Fir are preferred. Black streaks sometimes exist with the grain. These are more or less evident and the pieces in which the streaks exist are often sold as Black Hemlock. The True Black or Alpine Hemlock (Tsuga mertensiana) often grows at high altitudes or in the far North and is not yet widely available. 1 Hemlock trees have flat, blunt, evergreen leaves, the under- sides of which appear to be whitened. The leaves are arranged in two ranks. The inner bark is red. The Western Hemlock (Tsuga heterophylla} grows from Alaska to Cali- fornia and attains a height of one hundred and eighty feet and a diameter of nine feet. It is said to afford heavier and better wood than that obtained from the common Hemlock. The Western Hemlock is known by the fol- lowing names (Sudworth) : Western Hemlock, Hemlock Spruce (Cal.); Hem- 78 CONIFEROUS TRUNKS AND WOODS 79 lock (Oreg., Idaho, Wash.); Alaska Pine (Northwestern Lumberman); Prince Albert's Fir, Western Hemlock Fir, California Hemlock Spruce (England). 2 l " Black Hemlock (Tsuga mertensiana) (United States Forest Service, Silvical Leaflet No. 31, 1908). 2 "The Western Hemlock," Allen (United States Forestry Bureau, Bulletin No. 33); "Mechanical Properties of Western Hemlock," Goss (United States Forest Service, Bulletin No. 115). 80 ORGANIC STRUCTURAL MATERIALS Hemlock. Tsuga canadensis (L.) Carr NOMENCLATURE (Sudworth). Hemlock Spruce (Vt., R. I., N. Y., Hemlock (local and common Pa., N. J., W. Va., N. C., S.C.) name). Spruce (Pa., W. Va.). Spruce Pine (Pa., Del., Va., N. C., Ga.). LOCALITIES. Eastern and central Canada, southward to North Carolina and Tennessee. FEATURES OF TREE. Sixty to eighty or more feet in height; two or three feet in diameter; short leaves, green above and white beneath; straight trunk, beautiful appearance. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood reddish brown; sapwood distinguishable; coarse, pronounced, usually crooked grain. STRUCTURAL QUALITIES OF WOOD. Light, soft, not strong or durable, brittle, difficult to work; the wood splinters easily; it retains nails firmly. REPRESENTATIVE USES OF WOOD. Coarse lumber, joists, rafters, laths, plank walks, and railway ties. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 26. MODULUS OF ELASTICITY. 1,270,000. MODULUS OF RUPTURE. 10,400. REMARKS. The specific name canadensis refers to Canada, the locality where these trees excel. See also "The Eastern Hemlock," Frothingham (United States Department of Agriculture, Bulletin No. 152, 1915). The Southern or Carolina Hemlock (Tsuga caroliniana) yields wood that resembles that of Hemlock. LARCH OR TAMARACK Larix The Eastern Larch (Larix americand) grows in low, wet areas known as tamarack swamps. The Western species (Larix occidentalis) grows where it is dry and the European Larch (Larix europcea) also thrives upon dry soil. Many interesting records exist with regard to the wood, which was apparently known and prized centuries ago. It was men- tioned by Pliny, and Vitruvius wrote of a bridge, which having burned, was replaced by one of Larch, because it was thought that that wood would not burn as readily. Some of the piles upon which the city of Venice is founded are said to be of larch. 1 While seemingly authoritative, such statements should be re- ceived with caution, since the names of woods mentioned by ancient writers are not always those employed at the present time. Larch wood is hard and very durable. In structure it resem- bles spruce, and in weight and appearance it resembles hard pine. The tall, straight trunks are so slender that they are seldom cut up into lumber. The trunks are usually used for poles, posts, and railway ties. Although the Eastern species is usually found in deep swamps, it often grows better on drier ground. A swamp specimen required forty-eight years to reach a diameter of two inches, while another specimen, located where there was less water, was eleven inches thick at the end of thirty-eight years. The European Larch is often employed in American landscape effects. The foliage of the Larch is shed every autumn, and, for this reason, Larch trees are not truly " evergreen." The tufts of small needle-like leaves are of a fresh pea-green color when they first appear in the spring, and the trees are then very beautiful. The trees present a somewhat gloomy appearance in the winter. Larch trees are very hardy, and the species deserves more atten- tion than it receives. 81 82 ORGANIC STRUCTURAL MATERIALS The European Larch (Larix europcea) is a native of central Europe. The trees thrive upon dry soil and are used in American landscape work. They are good coniferous trees to plant near houses, because they lose their leaves during the winter. The wood is similar to that obtained from American species. The European Larch yields the Venice turpentine of commerce. This substance, once collected through Venetian markets, is now largely drawn from America. See also " European Larch," Pinchot (United States Forest Service, Circular No. 70). 1 Pliny, XVI, 43-49 and XVI, 30; also Vitruvius II, 9; also Encyclo- paedia Britannica, Vol. XIV, p. 310; and "Forestry in Minnesota," Green. CONIFEROUS TRUNKS AND WOODS 83 / Larix americana Michx. Tamarack, Larch. < T . 7 .. fr . D .,. ^ , \ Larix lancina (Du Roi) Koch NOMENCLATURE (Sudworth). Black Larch, Red Larch (Minn., Tamarack, Larch, American Mich.). Larch (local and common Juniper (Me., Canada). names). Hackmatack (Me., N. H., Mass., R. I., Del., 111., Mich.) LOCALITIES. From Newfoundland, Labrador, and Alaska, southward to New York, Pennsylvania, and Minnesota FEATURES OF TREE. Seventy to ninety feet high; one to three feet in diameter; short, pea-green, deciduous leaves in tufts ; a slender tree, winter aspect gloomy. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light brown; sapwood nearly white; coarse, conspicuous grain; compact structure; annual layers pronounced. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, very strong, and durable; resembles spruce. REPRESENTATIVE USES OF WOOD. Railway ties, fence-posts, sills, ship-timbers, telegraph poles, flagstaffs, etc. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 38. MODULUS OF ELASTICITY. 1,790,000 MODULUS OF RUPTURE. 12,800. REMARKS. Almost all of the comparatively slender logs are used for poles, masts, posts, and railway ties. Very few of them are cut up into lumber. Lumber- men sometimes divide tamarack logs as they are "Red" or " White." Red Tamarack is thought to be better and more durable than White Tama- rack. This distinction is probably due to differences in the ages of the trees. Tamarack trees grow in swamps, known as Tamarack Swamps, which are often very extensive. See also "Transactions American Institute of Mining Engineers" (Vol. XXIX, p. 157). ^ee also "Tamarack, Larix laricina (Du Roi)," Koch (United States Forest Service, Silvical Leaflet No. 32, 1908). 84 ORGANIC STRUCTURAL MATERIALS Tamarack, Larch. Larix occidentalis Nutt. NOMENCLATURE (Sud worth). Western Larch, Great Western Tamarack, Larch (local and Larch, Red American Larch. common names). Western Tamarack (Cal.). Hackmatack (Idaho, Wash.). LOCALITIES. Washington and Oregon, intermittently to Montana. FEATURES OF TREE. Ninety to one hundred and twenty-five feet high; two and one-half to four feet in diameter; a large tree. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light red; thin sap wood lighter; coarse-grained; compact structure; annual rings pronounced. STRUCTURAL QUALITIES OF WOOD. Hard, heavy, strong, and durable. REPRESENTATIVE USES OF WOOD. Posts, railway ties, and fuel; limited quantity of lumber; similar to Larch (Larix americana). WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 46. MODULUS OF ELASTICITY. 2,300,000. MODULUS OF RUPTURE. 17,400. REMARKS. These trees are much larger than those of the species Larix americana. They also differ, in that they grow on dry ground, often at compara- tively high elevations. 1 1 See also "Mechanical Properties of Western Larch," Goss (United States Forest Service, Bulletin No. 122); "Western Larch," Pinchot (United States Forest Service Silvical Leaflet No. 14). CEDAR Cedrus, Thuya, Chamcscyparis, Libocedrus, Juniperus The name Cedar was first applied to the true, foreign, or Lebanon Cedars (Cedrus), but was later applied to certain Arborvitaes (Thuya], Junipers (Juniperus), Cypresses (Chamce- cyparis), and other trees 1 that yield the durable, fine-grained characteristically scented woods that are commonly known as cedar woods. It is recorded that cedar was employed in such early constructions as the Temple of Solomon and the Temple of Diana at Ephesus, 2 and it is possible that the product referred to was the same as that to which this name applies at the present time. Cedar is divided as it is Red Cedar and White Cedar. Red Cedar. A large part of the supply is derived from the Eastern, Western, and Southern species (Juniperus virginiana) , (Juniperus scopu- lorum), and (Juniperus barbadensis) , The woods are soft, light, durable, fine-grained, fragrant, and of a reddish-brown color. They are some- times used in construction, but are more often employed in lead-pencils, chests, and closets. The demand for wood to be used in lead-pencils alone is very great. 3 Cedar chips and shavings are often used in place of camphor to protect woolens. The total demand is greater than the supply. Trees grow easily on almost any soil. They are normally hardy, but are sometimes subject to disease. 4 Some of these diseases cease after the trees have been felled and the wood cut from the diseased trees is as durable as wood cut from trees that are not diseased. The Western Red Cedar (Juniperus scopulorum) and the Southern Red Cedar (Juniperus barbadensis) yield woods that resemble those from the Cedar (Juniperus virginiana). White Cedar. Most " White Cedar" is obtained from several Arbor- vitses and Cypresses. The woods are soft, light, durable, fine-grained, and very inflammable. They are used for fence posts and shingles. Practically all cedar that is not red cedar, is white cedar. White cedar railway ties are defective because they crush and cut under the rails and because they do not hold spikes. The trees often grow in swamps. 5 85 86 ORGANIC STRUCTURAL MATERIALS Some important Red and White Cedars are as follows: Red Cedar White Cedar Red Cedar (Juniperus virginiand) . Arborvitse (Thuya occidentalis) . Red Cedar (Juniperus scopulorum). Canoe Cedar (Thuya gigantea). Red Cedar (Juniperus barbadensis) . White Cedar (Chamcecyparis thy- oides). Port Orford Cedar (Chamcecyparis lawsoniand) . Yellow Cedar (Chamoecyparis nut- katensis). Incense Cedar (Libocedrus decur- rens) . 1 See "Spanish Cedar" (Cedrela odorata}. 2 Pliny, 16, 213, and 16, 216. 3 "Notes on Red Cedar," Mohr (United States Division of Forestry, Bulletin No. 31). See also "Uses of Commercial Woods of United States: 1, Cedars, Cypresses, and Sequoias" (United States Forest Service, Bulletin No. 95, 1911). 4 Two diseases are recognized. They are white rot, caused by Polyporus Juniperus, and red rot, caused by Polyporus carneus, von Schrenk (United States Division Vegetable Physiology and Pathology, Bulletin No. 21); also von Schrenk, Shaw School of Botany, Contribution No. 14 (St. Louis, Mo.). 5 Timbered swamps are very formidable. For example, the " White Cedar swamp," of the Lake Superior region, is covered close down to the ground, by the vigorous branches of the trees. These branches meet and cross one another, and passage through such a district resembles passage through a cul- tivated hedge. The roots lie partly out of the water, and, while apparently sound, are slippery and sometimes decayed, so that the pedestrian, stepping or springing from one root to another, encumbered by burdens, and ob- structed by the wiry branches, is liable to slip and fall. The constant use of arms and legs, with the shock caused by packs shifting upon the shoulders when the pedestrian falls, and the annoying insects, require much strength and patience. Such Northern swamps can best be penetrated during the winter season, when the ground is frozen. The "Tamarack swamp" of the North differs from the " White Cedar swamp," in that the lower branches of the Tamarack are higher from the ground. The "Cypress" is the charac- teristic swamp tree of the South. CONIFEROUS TRUNKS AND WOODS 87 Red Cedar. Juniperus virginiana Linn. NOMENCLATURE (Sudworth). Savin (Mass., R. I., N. Y., Pa., Red Cedar (local and common Minn.). name). Juniper, Red Juniper, Juniper Bush Cedar (Conn., Pa., N. J., S. C., (local). Ky., 111., la., Ohio). Pencil Cedar, Cendre (La.). LOCALITIES. Atlantic Coast, Canada to Florida, westward intermittently to the Mississ- ippi River in the North and the Colorado River in the South. FEATURES OP TREE. Fifty to eighty feet in height; two to three feet in diameter; dark-green, scale-like foliage; loose, ragged, outer bark. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood dull-red; thin sapwood nearly white; close, even grain; com- pact structure; annual layers easily distinguishable. STRUCTURAL QUALITIES OF WOOD. Light, soft, weak, and brittle; easily worked; durable; fragrant; the fra- grance is such that the wood is used as an insecticide. REPRESENTATIVE USES OF WOOD. Ties, sills, posts, interior finish, pencil-cases, chests, and cigar-boxes. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 30. MODULUS OF ELASTICITY. 950,000. MODULUS OF RUPTURE. 10,500. REMARKS. The trunks of these trees are sometimes attacked by fungi similar to those that attack Cypress and Incense Cedar trees. The disease stops when the trees are felled, and boards cut from such trees have been known to last for over fifty years. See also Contribution No. 44, Shaw School of Botany, von Schrenk; "Two Diseases of Red Cedar" (United States Division of Vegetable Physiology and Pathology, Bulletin No. 21); Mohr (United States Forestry Bulletin No. 31); "Red Cedar," Pinchot (United States Forest Service, Circular No. 73). 88 ORGANIC STRUCTURAL MATERIALS Juniper. Juniperus occidentalis Hook NOMENCLATURE (Sud worth). Cedar, Yellow Cedar, Western Juniper (Oreg., Cal., Col., Utah, Cedar (Idaho, Col., Mont.). Nev., Mont., Idaho, N. M.). Western Red Cedar, Western Juni- per (local). LOCALITIES. California, Washington, Oregon, and Idaho. FEATURES OF TREE. Twenty-five to fifty feet in height; two to four feet in diameter; often smaller. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood reddish-brown; sapwood nearly white; very close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Ligfct, soft, and durable; receives a high polish. REPRESENTATIVE USES OF WOOD. Fencing, railway ties, posts, and fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 35. MODULUS OF ELASTICITY. MODULUS OF RUPTURE. REMARKS. Rarely found below an altitude of six thousand feet. Fruit said to be eaten by Indians. The California Juniper (Juniperus californica) grows intermittently in some districts in California, near the coast line. The trees are sometimes as much as thirty or forty feet in height, and one or two feet in diameter, but are often much smaller. The shaggy bark is of a grayish color. The soft, close-grained, fragrant, durable wood has been used to meet minor needs. CONIFEROUS TRUNKS AND WOODS 89 White Cedar, Arborvitae. Thuya occidentalis Linn. NOMENCLATURE (Sudworth). Atlantic Red Cedar (Cal.). White Cedar, Arborvitse (local Vitse (Del.). and common names). Cedar (Me., Vt., N. Y.). LOCALITIES. Northern States, eastward from Manitoba and Michigan; northward, also occasionally southward, as in the mountain region of North Carolina and eastern Tennessee. FEATURES OF TREE. Thirty to sixty feet high; one to three or more feet in diameter; often smaller; bruised leaves emit a characteristic pungent odor; the trunks taper rapidly. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light brown, darkening with exposure; the thin sapwood is nearly white; even, rather fine grain; compact structure. STRUCTURAL QUALITIES OF WOOD. Soft, light, weak, brittle, durable, and inflammable; does not hold spikes firmly. REPRESENTATIVE USES OF WOOD. Railway ties, telegraph poles, posts, fencing, shingles, and boats. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 19. MODULUS OF ELASTICITY. 750,000. MODULUS OF RUPTURE. 7,200. REMARKS. The comparatively slender trunks are seldom cut up into lumber, but are used for poles; or else, the thin, upper ends are used for posts, and the lower parts are flattened and used for ties. The wood is remarkably durable. Hough describes a prostrate cedar tree over the trunk of which a hemlock, which later exhibited one hundred and thirty yearly bands, had taken root. The cedar tree had evidently been in contact with the ground for at least one hundred and thirty years, yet much of its wood was sound enough to be cut up into shingles. 90 , ORGANIC STRUCTURAL MATERIALS Canoe Cedar, Arborvitae, Thuya plicata Don. Giant Arborvitae. Thuya gigantea Nutt. NOMENCLATURE (Sudworth). Cedar, Giant Cedar, Western Cedar Canoe Cedar, Giant Arborvitse (Oreg., Cal.). (local and common names). Shinglewood (Idaho). Red Cedar, Giant Red Cedar, Pacific Red Cedar (Wash., Oreg., Cal., Idaho). LOCALITIES. Coast region, California to Alaska, Idaho to Montana. FEATURES OF TREE. One hundred to two hundred feet in height; two to eleven feet in diameter; the trunks are often buttressed at the surface of the ground; the tiny, bright green leaves are scale-like. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood dull reddish brown; the thin sapwood is nearly white; coarse- grained; compact structure; annual layers distinct. STRUCTURAL QUALITIES OF WOOD. Soft, weak, light, brittle, easily worked, and very durable. REPRESENTATIVE USES OF WOOD. Shingles, fencing, cooperage, interior finish and canoes. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 23. MODULUS OF ELASTICITY. 1,460,000. MODULUS OF RUPTURE. 10,600. REMARKS. The large parts at the bottoms of the trees are usually hollow. See also "Giant Arborvitae Thuya plicata Don," (United States Forest Service Silvical Leaflet No. 11, 1907); " Western^Red Cedaiy^ Detwiler (American Forestry, March, 1916). CONIFEROUS TRUNKS AND WOODS 91 White Cedar. Chamcecyparis thyoides L. NOMENCLATURE (Sudworth). Post Cedar, Swamp Cedar (Del.). White Cedar (local and common Juniper (Ala., N. C., Va.). name). LOCALITIES. Maine to Florida, Gulf Coast to Mississippi; best in Virginia and North Carolina. FEATURES OF TREE. Sixty to eighty feet in height; three to four feet in diameter; shaggy, rugged bark; a graceful tree. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood pinkish brown to darker brown; sap wood lighter; close- grained; compact structure; conspicuous layers. STRUCTURAL QUALITIES OF WOOD. Very light and soft; not strong; extremely durable in exposed positions; fragrant; easily worked; White Cedar posts last for many years. REPRESENTATIVE USES OF WOOD. Boats, railway ties, fencing, poles, posts, and shingles. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 23 (United States Forestry Division). 1 20. MODULUS OF ELASTICITY. 910,000 (average of 87 tests by United States Forestry Division). 1 570,000. MODULUS OF RUPTURE. 6,310 (average of 87 tests by United States Forestry Division). 1 6,400. REMARKS. These trees often grow in swamps, as see footnote, page 86. p. 33. 92 ORGANIC STRUCTURAL MATERIALS Port Orford Cedar, Lawson Cypress. Chamcecyparis lawsoniana Murr. NOMENCLATURE (Sudworth). White Cedar, Oregon Cedar, Ginger Pine (Cal.). (Oreg., Cal.). LOCALITIES. Pacific Coast, California and Oregon. FEATURES OF TREE. One hundred to sometimes two hundred feet in height; four to ten feet in diameter; the leaves overlap in sprays; the very small cones are one- fourth of an inch in diameter. 1 COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood yellowish-white; sapwood similar; very close-grained. STRUCTURAL QUALITIES OF WOOD. Light and hard; strong, durable, and easily worked; fragrant; resinous. REPRESENTATIVE USES OF WOOD. Lumber, flooring, interior finish, ties, posts, matches, and shipbuilding. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 28. MODULUS OF ELASTICITY. 1,730,000. MODULUS OF RUPTURE. 12,600. REMARKS. The resin is employed as an insecticide. x See also "Port Orford Cedar," Pinchot (United States Silvical Leaflet No. 2). The Yew (Taxus) yields a close-grained wood that suggests Cedar, save that it is tough like Hickory. The early Celtic races associated Yew trees with funerals. The wood was one of the "fighting woods" of the Greeks. The best Yew bow-staves came from Italy, Turkey and Spain, and were dis- tributed through the Venetian markets. Spanish staves were once so impor- tant that they were controlled by the Spanish Government. More recently, European bows were backed with other and more plentiful woods. Yew is now occasionally employed for chairs, canes, and whips. Pacific Coast Indians prized the Western, Oregon, or California Yew (Taxus brevifolia) for bows, paddles, and fish hooks. The Florida Yew (Taxus floridana) is another United States species. Ernest Thompson Seton classes American woods suitable for bows in order of excellence as follows: "Oregon Yew, Osage Orange, White Hickory, Elm, Cedar, Apple, etc." CONIFEROUS TRUNKS AND WOODS^ 93 Yellow Cedar, Yellow Cypress, Sitka Cypress. f Chamcecyparis nootkatensis (Lamb) Spach \ Chamcecyparis nutkaensis Spach NOMENCLATURE (Sudworth). Nootka Cypress, Nootka Sound Alaska Cypress, Alaska Ground Cypress (local). Cypress (local). LOCALITIES. Oregon to Alaska. FEATURES OF TREE. One hundred or more feet in height; three to five or more feet in diameter; sharp-pointed, overlapping leaves; small, globular cones. COLOR, APPEARANCE. OR GRAIN OF WOOD. Heartwood clear light yellow; thin sapwood nearly white; close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Light, not strong, brittle, and hard; durable in contact with soil; easily worked; receives a high polish; fragrant. REPRESENTATIVE USES OF WOOD. Ship-building, furniture, and interior finish. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 29. MODULUS OF ELASTICITY. 1,460,000. MODULUS OF RUPTURE. 11,000. REMARKS. A valuable lumber tree. 94 ORGANIC STRUCTURAL MATERIALS Incense Cedar, White Cedar. ( Libocedrusdecurrens Torr. ( Heydena decurrens. NOMENCLATURE (Sudworth). Post Cedar, California Post Cedar California White Cedar (local), (local). Juniper (Nevada). Bastard Cedar, Red Cedar. LOCALITIES. California, Lower California, Oregon, and Nevada. FEATURES OF TREE. Ninety to one hundred and twenty-five feet in height, occasionally higher; three to six feet in diameter. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood brownish; sapwood lighter; close-grained; compact struc- ture; heartwood often pitted; fragrant. STRUCTURAL QUALITIES OF WOOD. Light, brittle, soft, and durable. REPRESENTATIVE USES OF WOOD. t Flumes, shingles, and interior finish. ^e^c^ jM&tjf +"*- ' * v * " WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 25. MODULUS OF ELASTICITY. 1,200,000. MODULUS OF RUPTURE. 960,000. REMARKS. The heartwood of these trees is often attacked by fungi that create large, oval pits. The wood between the decayed spaces is apparently sound, even in living trees. The disease stops when the trees are felled, and the wood that remains is so durable that it can be used for posts or for other purposes where appearance is not important. Some dealers charge as much for wood with pits as for that without pits. This disease is similar to the diseases that attack Cypress and Red Cedar. It is said that about one-half of the standing supply of In- cense Cedar has been affected by this disease, which is popularly known as "pin rot" (see also von Schrenk, Contribution No. 14, Shaw School of Botany). CYPRESS Cupressus and Taxodium The name Cypress has been applied to trees of the genera Chamcecyparis, Cupressus, and Taxodium. Most of the species of the genus Chamcecyparis are now classed as Cedars. The genus Cupressus includes true Cypresses, and is important in Europe, but the trees themselves, rather than their woods, are valued in the United States. The single species of the genus Taxodium is not a Cypress, but the trees of this species supply the " cypress wood" of American commerce. The name Cypress will be applied only to the true Cypresses (Cupressus), and to the commercial Cypress (Taxodium). True cypress wood is mentioned by Herodotus and other an- cient authors, and is construed by some to have been the " Gopher wood" of which the Ark was built. 1 Pliny mentions cypress doors that were good after four hundred years, and a cypress statue that was preserved for six hundred years. It is said that the cypress gates of the early Saint Peter's, removed after one thousand years of service, were found to be in excellent condi- tion. 2 Cypress wood has been prized for mummy cases, and cypress trees are yet planted as funeral emblems over graves in Turkey and in Italy. 3 The common or evergreen Cypress is the principal species in Europe. The eight or nine American species (Cupressus) do not produce valuable woods, but the trees are sometimes used for ornamentation, as in hedges. The Monterey Cypress (Cupressus macrocarpa) is evidenced by a group of trees that includes the only original specimens of this species that survive in the United States. The famous " seventeen mile drive" near Monterey, California, passes through the district in which these trees are located. Their weird forms, with gnarled, wind-beaten branches, are very unusual. The fact that transplanted specimens of the Monterey Cypress grow so readily in many places on the Pacific Coast is hard to reconcile with the further fact that so few of the original trees remain at the present time. 95 96 ORGANIC STRUCTURAL MATERIALS American Cypress wood is obtained from the Bald Cypress (Taxodium distichum) which grows on submerged lands and in deep swamps, making unusual logging methods necessary. The trees are subject to a peculiar fungus disease that causes cavities such as would be made by driving pegs into the wood and then withdrawing them, and wood thus affected is known as "peggy cypress." The disease ceases as soon as trees are felled, and wood then cut from them is as durable as wood cut from per- fectly healthy trees. About one-third of the standing supply is affected. American Cypress wood has many names. Pieces that float and pieces that sink in water have been classed as White Cypress and Black Cypress respectively. All dark pieces are now classed as Black Cypress, while the tinted woods are sometimes sold under the names of Red Cypress and Yellow Cypress. 4 The Bald Cypress bears needle-like leaves, which are about three-fourths of an inch in length, and separated from one another. They are not arranged in tufts as in the case of the larch, yet the foliage resembles that of the larch, in that it is shed at the end of the season. The name Bald Cypress is due to the appearance of the trees after the leaves have fallen. The roots that appear above the surface of the surrounding soil or water are known as " cypress knees." 1 Pliny, 16, 214 and 16, 215; Herodotus, 4, 16; Virgil, Georgics, 2, 443. Funk & Wagnalls' Standard Dictionary, quoting Horace Smith, "Gayeties and Gravities," Chapter VII, p. 57. 2 Encyclopaedia Britannica, B. 6, p. 745. 3 Brockhaus, Konversations-Lexikon, B. 4, p. 654. 4 See also von Schrenk, (Contribution No. 14, Shaw School of Botany); "Uses of Commercial Woods of the United States," Hall and Maxwell (United States Forest Service, Bulletin No. 95, 1911); "The Cypress and Juniper Trees of the Rocky Mountain Region," Sudworth (United States Department of Agriculture, Bulletin No. 207); "The Southern Cypress," Matoon (United States Department of Agriculture, Bulletin No. 272, 1915); "The Bald Cypress," Detwiler (American Forestry, October, 1916). CONIFEROUS TRUNKS AND WOODS 97 Cypress, Bald Cypress. Taxodium distichum Rich. NOMENCLATURE (Sudworth). White Cypress (N. C., S. C., Fla., Swamp Cypress (La.). Miss.). Deciduous Cypress (Del., 111., Tex.). Black Cypress (N. C., S. C., Ala., Southern Cypress (Ala.). Tex.). Red Cypress (Ga., Miss., La., Tex.). LOCALITIES. South Atlantic and Gulf States, Maryland, through Florida to Texas, Mississippi Valley from southern Illinois to the Gulf. Forms forests in swamps and barrens. 1 FEATURES OF TREE. Seventy to one hundred and fifty feet in height; four to ten feet in diame- ter; the knees on the roots often become hollow with old age; the leaves are flat and deciduous. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood brownish; sapwood nearly white; close, straight grain; the trunks are frequently pitted by disease. STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong; durable; green wood is often very heavy. REPRESENTATIVE USES OF WOOD. Carpentry, construction, cooperage, and railway ties. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 29 (United States Forestry Division). 1 28. MODULUS OF ELASTICITY. 1,290,000 (average of 655 tests by United States Forestry Division). 2 1,460,000. MODULUS OF RUPTURE. 7,900 (average of 655 tests by United States Forestry Division). 2 9,600. REMARKS. Cypress is of ten divided into "White Cypress" and "Black Cypress," the difference being probably due to differences in the ages and environ- ment of the trees from which these two grades were cut. Cypress trees are often attacked by fungi that create pits in the wood. The disease stops when the trees are felled, and the wood that remains is very durable. This disease is similar to others that attack Incense Cedar trees and Red Cedar trees. 1 See "Transactions American Institute of Mining Engineers" (Vol. XXIX, p. 157). 2 See p. 33. 7 REDWOOD Sequoia These trees grow in California. There are two species as follows : The Common Redwood (Sequoia sempervirens) grows near the coast line where it is said to " follow the fogs." The trees are large and very perfect. The soft, light, clean, reddish-brown wood works easily and can be obtained in large-sized pieces. Fio. 29. Assembling parts of redwood stave pipe. The wood resists fire more than many others and is extremely durable in exposed places. It repels some forms of terrestrial wood-borers, but has given way before the attacks of shipworms. It is used for fence posts, railway ties, water-pipes, house-trim, flumes, coffins, and shingles. Average pieces are often used in cheaper forms of indoor finish, while unusual and attractive pieces, in which grain is distorted, are classed as Curly Redwood and preferred in a better grade of work. CONIFEROUS TRUNKS AND WOODS 99 Some of the trees of this species are so large that they have been con- fused with the exceptional or "giant" specimens of the Mammoth Red- wood. The fire-resisting qualities of the wood were shown in the build- ings that existed in San Francisco before the earthquake. Redwood was largely employed in these buildings, yet comparatively few fires took place until the conflagration caused by the earthquake. Durability is shown by trunks that fell in the forests one hundred or more years ago. Some of these trunks not only have not rotted, but contain good wood that can be used in construction. Resistance to attacks by land wood-borers is shown by the stave-pipes used in irrigation work in the West. These pipes usually remain safe from attack as long as the wood remains wet and in use. It should be noted, however, that they are sometimes attacked by termites while dry. FIG, 30. Completed redwood stave pipe with gate. The Mammoth Redwood (Sequoia washingtoniana) is found inland where there is less moisture. Some of the trees are the most massive, although not the tallest, trees known to man. Individuals three hundred and twenty feet high and thirty-five feet in diameter have been measured. It is estimated that some specimens twenty-five feet in diameter were thirty-six hundred years old, and it is thought probable that under favorable condi- tions such trees could have survived for a total of five thousand years. The almost non-inflammable bark is sometimes nearly two feet in thickness. Even the oldest trees are sound through- out. The wood is brittle, but otherwise resembles and is seldom 100 ORGANIC STRUCTURAL MATERIALS distinguished commercially from the wood of the Common Red- wood. Many of the smaller trees of this species are cut down every year, but the largest trees are now protected or used for exhibition purposes. Most of these exceptional trees have names such as the " Pride of the Forest/' the ''Grizzly Giant," and the "U. S. Grant." These exceptional specimens, which do not exceed several hundred in number, are grouped in the Mari- posa, Calavaras, and other groves. The genus is notable, first, because of the present value of the wood, and second, because the quick-growing, healthy trees are likely to resist commercial extinction. The name Sequoia is that of an Indian Chief. Redwood trees may be known by their size and locality, and also by their fine, dull, evergreen leaves. 1 ^ee also "The Big Trees of California" (United States Forestry Division Bulletin No. 28); "The Bigtree," Sudworth (United States Forest Serv- ice Silvical Leaflet No. 19); "Redwood" (United States Forest Service Bulletin No. 38); "Mechanical Properties of Redwood," Heim (United States Forest Service, Circular No. 193, 1912); "The Secret of the Big Trees," Huntington (United States Department of Interior, Document); "Uses of Commercial Woods of the United States," Hall and Maxwell (United States Forest Service, Bulletin No. 95, 1911). CONIFEROUS TRUNKS AND WOODS 101 Redwood. Sequoia sempervirens (Lamb.} Endl. NOMENCLATURE (Sudworth). Redwood (local and common Sequoia, California Redwood, Coast name). Redwood (local). LOCALITIES. Central and North Pacific Coast region. FEATURES OF TREE. Two hundred to three hundred feet in height, sometimes higher; six to eight and sometimes twenty feet in diameter; straight, symmetrical trunk; low branches are rare. COLOR, APPEARANCE, OR GRAIN OF WOOD. Thick heart wood red, changing to reddish brown when seasoned; thin sapwood nearly white; coarse, normally straight grain; compact structure; very thick bark. STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong; very durable; easily worked, and receives a high polish; not resinous, and does not burn easily. REPRESENTATIVE USES OF WOOD. Timber, shingles, flumes, fence-posts, coffins, railway ties, water-pipes, and interior decoration; the bark is made into souvenirs. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 26 (Census figure, see p. 33). MODULUS OF ELASTICITY. 790,000 (average of 8 Humboldt specimens). 1 1,140,000 (average of 7 Humboldt -specimens). 1 960,000 (Census figure, see p. 33). MODULUS OF RUPTURE. 4,920 (average of 9 Humboldt specimens). 1 7,138 (average of 7 Mendocino specimens). 1 8,400 (Census figure, see p. 33). REMARKS. Redwood is the principal construction wood of California. Occasional pieces with curled or distorted grain are valued for minor cabinet work. The Bigtree, Mammoth Tree, or Giant Redwood (Sequoia washingtoniana) is the largest tree known to man. The wood, which resembles that of the Common Redwood, is used locally. See also " Bigtree, Sequoia washing- toniana (Winsl.) Sudw." (United States Forest Service, Silvical Leaflet No. 19, 1908); etc., etc. 1 Soule, Transactions American Institute of Mining Engineers (California Meeting, 1899). CHAPTER VI BANDED TRUNKS AND WOODS (CONTINUE. ) BROADLEAF SERIES. PART ONE Dicotyledons The trees of the Broadleaf Series grow in natural forests and under cultivation in many parts of the world. The Oaks, Elms, Maples, and other so-called hardwood trees are of this group. Broadleaf woods are comparatively heavy in weight and, in most cases, the arrangement of the wood-elements is more com- plicated than in the woods of the Coniferous series. Broadleaf woods are difficult to work in proportion as they are complicated in cellular structure. Tiemann has compared the cellular struc- ture of broadleaf woods with the cellular structure of coniferous woods as follows: 1 "The wood of the angiosperms (broadleaf woods), on the other hand, is much more complex, as the vertical cells are exceedingly variable both in size and character. The vertical cells, consisting of wood-fibers, vessels, tracheids, and others, in some species of the angiosperms, are often of four, or five distinct kinds, and vary in size and shape from the finest hair of a few millimeters in length, to the long vessels as large as the lead in a lead-pencil. There are also short, thin-walled cells inter* spersed. The Oak is one of the most complex woods in this respect? while the Red Gum and the Tulip are comparatively simple. In the Conifers, it is the tracheids which give the strength to the wood, but in the angiosperms it is the long, narrow, hair-shaped cells or wood-fibers which are the chief parts of the structure producing the strength. The latter are usually grouped in bunches and form the principal structural feature in the angiosperms. In the late wood of the annual rings, their walls, compared to their diameters, become exceed- ingly thick. These also have pits, but of a simpler kind, which are slit- like and known as "simple pits." Broadleaf woods are used in construction, although the greater need as to quantity in this field is met by the woods of the other series. Woods for cabinet purposes and implements are drawn 102 BROADLEAF TRUNKS AND WOODS 103 from the present group which, with a few exceptions, cannot be depended upon for the large, straight pieces so often obtained from coniferous trees. The comparatively broad leaves of the trees of this series are usually distinguished from the more or less needlelike, resinous leaves of the conifers. Most, but not all, broadleaf trees are deciduous, and many, but not all, of the woods are comparatively hard. The names " deciduous" and " hardwood" are less satis- factory than the name " Broadleaf," which should be preferred. 1 " Wood Preservation" (American Railway Engineering and Maintenance of Way Association, Bulletin No. 120, p. 361). OAK Quercus The Oaks grow in many parts of the northern hemisphere, and at high altitudes just south of the equator. The historical importance of the wood was founded upon the reputation of the English Oaks (Quercus robur var. pedunculata and Quercus robur var. sessili flora) , l which once formed large forests over parts of northern and central Europe. The woods were formerly relied upon to meet many needs in ships and houses, and did not give way to iron for vessels, and to the so-called softwoods for houses, until comparatively recent periods. Practically all ships were built of wood until the battle of the Merrimac and the Monitor; and oaken timbers were used in many English houses, even of the cottage type, until the sup- plies of softwoods from the Baltic forests and from those of North America became easily available. Oak is yet used for railway ties and high-grade construction timbers, but to a more limited extent than formerly; while the demands for oak to be used in cabinet work are constantly increasing. Oak wood is tough and durable in contact with the ground. It receives a high polish and is more or less easily obtained. On the other hand, it is liable to warp and check in seasoning, and hard to nail without splitting. It contains gallic acid, which attacks iron fastenings. Experiments indicate that the iron is eventually protected by the formation of a scale, and that the wood, although darkened, remains practically uninjured. Oak bark is so charged with gallic acid that it is used in the tanning of leather. An experiment made to determine the effect of gallic acid upon iron 2 was as follows: Five grams of clean iron wire were immersed in a 5 per cent, solution of gallic acid. In nine days the weight was 4.720 grams and the solution intensely black. Thirteen days later the same specimen weighed 4.7453 grams. The fact that the iron increased in weight during the last thirteen days, was thought to indicate the forma- tion of a crust, which probably protected it to some extent. 104 BROADLEAF TRUNKS AND WOODS 105 Oak trees commonly require many years to reach maturity but are then usually long lived. The leaves of some species are deciduous, while those of others are evergreen. Oak trees bear oblong thin-shelled kernels which protrude from hard scaly cups and are known as acorns. In the United States the woods are grouped under three heads as follows: The White Oaks. These woods, which are more or less easily obtained, are preferred for most purposes. The principal sources are White Oak (Quercus alba], Cow Oak (Quercus michauxii), Chestnut Oak (Quercus prinus), Post Oak (Quercus minor}, Bur Oak (Quercus macrocarpa), Pacific Post Oak (Quercus garryana). The Red or Black Oaks. These woods are inferior to the others, but are yet very valuable. The principal sources are Red Oak (Quercus rubra), Pin Oak (Quercus palustris), Spanish Oak (Quercus digitata), Yellow or Black Oak (Quercus velutina) . The Live Oaks. The Live Oaks, which are among the hardest and most durable of all construction woods, were formerly valued for ship building. The supply is now limited. The name is due to the " live" or evergreen leaves. The principal sources are Live Oak (Quercus vir- giniana}, California Live Oak (Quercus agrifolia), Live Oak (Quercus chrysolepis) . 1 Usually taken as sub-species or varieties of the species Quercus robur, but thought by some botanists to be distinct species, namely, Quercus pedunculata and Quercus sessiliflora. 2 Havemeyer Chemical Laboratory of New York University. 106 ORGANIC STRUCTURAL MATERIALS White Oak. Quercus alba Linn. NOMENCLATURE. White Oak (general). Stave Oak (Ark.). LOCALITIES. Widespread throughout north-central and eastern United States. FEATURES OP TREE. Seventy-five to one hundred and fifty feet in height; three to six feet in diameter; fine shape and appearance; grayish-white bark; compara- tively sweet, ovoid, oblong acorns in rough, shallow cups; the leaves are blunt, they are not bristle-tipped. COLOR, GRAIN, OR APPEARANCE OF WOOD. Heartwood brown with sapwood lighter; annual layers are well marked; medullary rays are broad and prominent. STRUCTURAL QUALITIES OF WOOD. Tough, strong, heavy and hard; liable to check unless seasoned with care; durable in contact with the soil; receives a high polish. REPRESENTATIVE USES OF WOOD. Ship-building, construction, cooperage, cabinet-making, railway ties, fuel, etc. The bark is rich in tannin. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 50 (United States Forestry Division). 1 46. MODULUS OF ELASTICITY. 2,090,000 (average of 218 tests by United States Forestry Division). 1 1,380,000. MODULUS OF RUPTURE. 13,100 (average of 218 tests by United States Forestry Division). 1 12,800. REMARKS. The best known of the American oaks. A tree of the first economic importance. The cellular arrangement of the wood is complicated, and, for this reason, the wood is hard to season. It stands well, how- ever, after it has once been seasoned. 2 1 See p. 33. 2 See also "White Oak," Pinchot (United States Forest Service, Circular No. 106, 1907); "The American White Oak," Detwiler (American Forestry, January, 1916); etc. BROADLEAF TRUNKS AND WOODS 107 Cow Oak. Quercus michauxii Nutt. NOMENCLATURE (Sud worth). Cow Oak (local and common name). Swamp White Oak (Del., Ala.). Basket Oak (Ala., Miss., La., Tex., Swamp Chestnut Oak (Fla.). Ark.). LOCALITIES. Southeastern United States, Delaware, and Florida, westward along the Gulf to Texas; also southern Indiana and Illinois to the Gulf; best on rich bottoms in Arkansas and Louisiana. FEATURES OF TREE. Seventy-five to one hundred feet in height; three to six feet in diameter; rough, light-gray bark with loose, scaly ridges; the leaves are only shallowly toothed; the blunt teeth are not bristle-tipped. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light-brown; sapwood light-buff; conspicuous medullary rays; close-grained. STRUCTURAL QUALITIES OF WOOD. Hard, heavy, very strong, tough, durable, and easily split. REPRESENTATIVE USES OF WOOD. Construction, agricultural implements, and wheel-stock. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 46 (United States Forestry Division). 1 50. MODULUS OF ELASTICITY. 1,610,000 (average of 256 tests by United States Forestry Division.) 1 1,370,000. MODULUS OF RUPTURE. 11,500 (average of 256 tests by United States Forestry Division). 1 15,800. REMARKS. The principal white oak of the Southern States; the acorns are devoured by cattle, whence its name. 1 See p. 33. 108 ORGANIC STRUCTURAL MATERIALS Chestnut Oak. Quercus prinus Linn. NOMENCLATURE (Sudworth). Chestnut Oak (local and com- Tanbark Oak (N. C.). mon name). Swamp Chestnut Oak (N. C.). Rock Oak (N. Y., Del., Pa.). Mountain Oak (Ala.). Rock Chestnut Oak (Mass., R. I., Pa., Del., Ala.). LOCALITIES. Maine to Georgia, westward intermittently to Kentucky, Tennessee, and Alabama; best development in southern Alleghany Mountain region. FEATURES OF TREE. Seventy-five to eighty feet in height; three to four feet in diameter; the leaves resemble those of the Chestnut (Castanea dentata) ; the shallow teeth are not bristle-tipped. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood dark-brown; sapwood lighter; close-grained; conspicuous medullary rays. STRUCTURAL QUALITIES OF WOOD. Heavy, tough, hard, strong, and durable in contact with the soil. REPRESENTATIVE USES OF WOOD. Largely used for railway ties, The bark is rich in tannin. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 46. MODULUS OF ELASTICITY. 1,780,000. MODULUS OF RUPTURE. 14,600. REMARKS. 1 1 See also "Chestnut Oak, Quercus prinus Linn." (United States Forest Service, |Silvical Leaflet, No. 41, 1908). BROADLEAF TRUNKS AND WOODS 109 {Quercus minor Sargent Quercus obtusiloba Michx. Quercus stellata Wang NOMENCLATURE (Sudworth). Post Oak (local and common Overcup Oak (Fla.). name). White Oak (Ky., Ind.). Iron Oak (Del., Miss., Neb.). Box Oak (Md.) Box White Oak (R. I.). Brash Oak (Md.). Chene Stone" (Quebec). LOCALITIES. East of Rocky Mountains Nebraska and the Gulf States, eastward intermittently to Massachusetts and northern Florida. FEATURES OF TREE. Fifty to seventy feet in height; two to three feet in diameter; a low shrub in Florida; there are blunt lobes or projections to the leaves; the deeply- cut lobes are not bristle-tipped; the leaves are clustered at the ends of the branches; a fine tree with a rounded top. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light or dark brown with lighter sapwood; close-grained; annual rings well marked; numerous and conspicuous medullary rays. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, and strong; checks badly in drying; durable in contact with the soil. REPRESENTATIVE USES OF WOOD. Largely used, particularly in the Southwest, for fencing, railway ties, and fuel; also for cooperage, construction, etc. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 50 (United States Forestry Division). 1 52. MODULUS OF ELASTICITY. 2,030,000 (average of 49 tests by United States Forestry Division). 1 1,180,000. MODULUS OF RUPTURE. 12,300 (average of 49 tests by United States Forestry Division). 1 12,900. REMARKS. A common tree in the Gulf States west of the Mississippi River. The wood of this species is seldom distinguished commercially from that of white oak. 1 See p. 33. 110 ORGANIC STRUCTURAL MATERIALS Bur Oak. Quercus macrocarpa Michx. NOMENCLATURE (Sudworth). Bur Oak (local and common Mossycup Oak (Mass., Pa., Del., name). Miss., La., Tex., Ark., 111., Iowa, Overcup Oak (R. I., Del., Pa., Neb., Kan.). Miss., La., 111., Minn.). Scrub Oak (Neb., Minn.). Mossycup White Oak (Minn.). Overcup White Oak (Vt.). LOCALITIES. Nova Scotia to Manitoba, Wyoming, Georgia, and Texas. FEATURES OF TREE. Seventy to one hundred and thirty feet in height; five to seven feet in diameter; deep, opposite depressions in leaves; the deeply-cleft lobes are not bristle-tipped; this is the only Oak yielding structural woods which bears acorns with mossy, fringed borders around their cups; there are corky ridges on the twigs and young branches. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood rich brown; sapwood lighter; close-grained; broad, conspicu- ous medullary rays. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, strong, tough, and very durable in contact with the ground. REPRESENTATIVE USES OF WOOD. Similar to those of the White Oak (Quercus alba). WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 46. MODULUS OF ELASTICITY. 1,320,000. MODULUS OF RUPTURE. 13,900. REMARKS. The range extends farther into the West and Northwest than that of other Eastern oaks. The Bur Oak has been recommended for planting on the prairies. 1 x See also "Bur Oak," Pinchot (United States Forest Service, Circular No. 56, 1907). BROADLEAF TRUNKS AND WOODS 111 White Oak. Quercus garryana Douglas NOMENCLATURE (Sudworth). White Oak (Cal., Oreg.)- Oregon White Oak (Cal.). Pacific Post Oak (Oreg.). California Post Oak. Western White Oak (Oreg.). LOCALITIES. Pacific Coast, British Columbia into California. FEATURES OF TREE. Sixty to ninety feet high; one and one-half to two and one-half feet in diameter; a small shrub at high elevations; the rounded lobes of the leaves are not bristle-tipped. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light-brown or yellow; sapwood lighter, often nearly white; compact structure; distinctly-marked annual rings; medullary rays often conspicuous. STRUCTURAL QUALITIES OF WOOD. Heavy, strong, hard, and tough. REPRESENTATIVE USES OF WOOD. Ship-building, carriages, furniture, indoor decoration, and fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 46. MODULUS OF ELASTICITY. 1,150,000. MODULUS OF RUPTURE. 12,400. REMARKS. Locally, this tree is important. The best substitute for Eastern White Oak produced on the Pacific Coast. 1 The Weeping, Valley, Swamp, White, or California White Oak (Quercus lobata), a native of central-western California, is one of the largest and most symmetrical of all oaks. It adds to landscapes where it grows as the elms add to landscapes in the East. The brittle wood is seldom used in construc- tion, but is an important local fuel. ^ee also "Oregon Oak," Graves (United States Forest Service, Silvical Leaflet No. 52, 1912). 112 ORGANIC STRUCTURAL MATERIALS Red Oak. Quercus rubra Linn. NOMENCLATURE (Sudworth). Red Oak (local and common name). Spanish Oak (Pa., N. C.). Black Oak (Vt., Conn., N. Y., Wis., la., Neb., So. Dak., Ont.). LOCALITIES. East of the Rocky Mountains, Nova Scotia to Florida, westward intermittently to Nebraska and Kansas; best in Massachusetts. FEATURES OF TREE. Ninety to one hundred feet in height; three to six feet and over in diameter; the brownish-gray bark is smooth on the branches; the leaves have sharp-pointed, bristle-tipped lobes; there are relatively small acorns in flat, shallow cups; a fine, complete tree. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light-brown or red; sapwood lighter; coarse-grained; well- marked annual rings; medullary rays few, but broad, STRUCTURAL QUALITIES OF WOOD. Heavy, hard, and strong; inclined to check in drying; acid; red oak is inferior to white oak. REPRESENTATIVE USES OF WOOD. Works of secondary importance, clapboards, cooperage, and fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 45 (United States Forestry Division). 1 40. MODULUS OF ELASTICITY. 1,970,000 (average of 57 tests by United States Forestry Division). 1 1,600,000. MODULUS OF RUPTURE. 11,400 (average of 57 tests by United States Forestry Division). 1 14,000. REMARKS. The Red Oak grows more rapidly than other oaks. The bark is used in tanning. 1 See p. 33. BROADLEAF TRUNKS AND WOODS 113 Pin Oak. Quercus palustris NOMNECLATURE (Sudworth). Water Oak (R. I., 111.). Pin Oak (local and common Swamp Oak (Pa., Ohio, Kans.), name). Swamp Spanish Oak (Ark., Water Spanish Oak (Ark.). Kan.). LOCALITIES. Massachusetts, Michigan, and Missouri, southward to Virginia, Ten- nessee, and Oklahoma. FEATURES OF TREE. Fifty to eighty feet in height; two to four feet in diameter; a full-rounded or pyramidal top; the bark is thin and smooth ; there are numerous small, pin-like branches; the leaves are deeply-cleft; their lobes are bristle- tipped. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood variegated light-brown; sap wood nearly white; coarse-grained; medullary rays numerous and conspicuous. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, and strong; checks badly in seasoning. REPRESENTATIVE USES OF WOOD. Shingles, clapboards, construction, interior finish, and cooperage. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 43. MODULUS OF ELASTICITY. 1,500,000. MODULUS OF RUPTURE. 15,400. REMARKS. The numerous slender, secondary branches suggest pins and cause the tree to be easily recognized, even in winter. 114 ORGANIC STRUCTURAL MATERIALS ( Quercus digitata Sudworth Spanish Oak. \ Quercus falcata Michx. ( Quercus triloba NOMENCLATURE (Sudworth). Spanish Oak (local and common name). Red Oak (N. C., Va., Ga., Fla., Ala., Miss., La., Ind.). LOCALITIES. New Jersey and Florida, westward intermittently to Illinois and Texas; most abundant in the Gulf States. FEATURES OF TREE. Thirty to seventy feet in height; two and one-half to four feet in diameter; variable foliage; the deeply-cleft, sharp-pointed leaves are bristle- tipped; the acorns are globular to oblong. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light-red; sap wood lighter; coarse-grained; the annual layers are strongly marked; the medullary rays are few, but conspicuous. STRUCTURAL QUALITIES OF WOOD. Hard, heavy, and strong; not durable; checks badly in drying. REPRESENTATIVE USES OF WOOD. Somewhat used for cooperage, construction, etc. The bark is very rich in tannin. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 43. MODULUS OF ELASTICITY. 1,900,000. MODULUS OF RUPTURE. 16,900. REMARKS. Grows rapidly, often on dry, barren soil. BROADLEAF TRUNKS AND WOODS 115 I Quercus velutina Lam. Black Oak, Yellow Oak. | NOMENCLATURE (Sudworth). Black Oak, Yellow Oak (local Tanbark Oak (111.). and common names). Spotted Oak (Mo.). Yellow Bark, Yellow-bark Oak Quercitron Oak (Del., S. C., La., (R.I., Minn.). Kans., Minn.). Dyer's Oak (Tex.). LOCALITIES. East of longitude 96 degrees; Maine and Florida, westward intermittently to Minnesota and Texas; best in North- Atlantic States. FEATURES OF TREE. Ninety to one hundred and thirty feet in height; three to five feet in diam- eter; dark-gray to black bark; yellow inner bark; the acorns have bitter, yellow kernels; the foliage turns handsomely in the autumn; the sharply- cleft leaves are bristle-tipped. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light reddish-brown; sapwood lighter; coarse-grained; the annual layers are strongly marked; the medullary rays are thin. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, and strong; liable to check in drying; not tough. REPRESENTATIVE USES OF WOOD. Cooperage, construction, furniture, and decoration. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 45 (United States Forestry Division). 1 44. MODULUS OF ELASTICITY. 1,740, 000 (average of 40 tests by United States Forestry Division). 1 1,470,000. MODULUS OF RUPTURE. 10,800 (average of 40 tests by United States Forestry Division). 1 14,800. REMARKS. The yellow inner bark affords a yellow dye See p. 33. 116 ORGANIC STRUCTURAL MATERIALS Liv Oak ^ Quercus virginiana Mill. \ Quercus virens Ait. NOMENCLATURE (Sudworth). Live Oak (Va., N. C., S. C., Ga., Chene Vert (La.). Fla., Miss., Ala., Tex., La., Gal.). LOCALITIES. Atlantic Coast from Virginia to Florida, westward to Texas and Lower California; southern Mexico, Central America, and Cuba; a Southern species; grows best in South- Atlantic States. FEATURES OF TREE. Fifty to sixty feet in height; three to six feet in diameter; general resem- blance to the Apple-tree; evergreen foliage; the oblong, blunt leaves are not bristle-tipped. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light-brown or yellow; sap wood nearly white; close-grained; compact structure; the medullary rays are pronounced; the annual layers are often hardly distinguishable. STRUCTURAL QUALITIES OF WOOD. Heavy, strong, tough, and hard; difficult to work; splits easily; receives a high polish; very durable. REPRESENTATIVE USES OF WOOD. Ship-building. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 59. MODULUS OF ELASTICITY. 1,600,000. MODULUS OF RUPTURE. 14,000. REMARKS. The trunks and branches furnish small, straight pieces, but the principal yield is in knees and crooked or compass timbers. The wood splits so easily that it is often fastened with bolts or trenails, rather than with spikes. The trees, which are now scarce, grow rapidly. BROADLEAF TRUNKS AND WOODS 117 California Live Oak. Quercus agrifolia Nee NOMENCLATURE (Sudworth). Coast Live Oak (Cal.). Encena (Gal.). California Live Oak (Cal.). Evergreen Oak (Cal.). LOCALITIES. California and Lower California. FEATURES OF TREE. Forty to seventy-five and occasionally more feet in height; three to six feet in diameter; evergreen foliage; the leaves are spiked like those of the Holly; the shape resembles that of the Apple-tree. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood creamy-white, darkens on exposure; compact structure; the annual layers are hardly distinguishable. STRUCTURAL QUALITIES OF WOOD. Heavy and hard, but brittle. REPRESENTATIVE USES OF WOOD. Fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 61. MODULUS OF ELASTICITY. 1,350,000. MODULUS OF RUPTURE. 13,200. REMARKS. 118 ORGANIC STRUCTURAL MATERIALS Live Oak. Quercus chrysolepis Liebm. NOMENCLATURE (Sudworth). Live Oak (Cal., Oreg.). Canyon Oak, Iron Oak, Maul Oak, Canyon Live Oak, Black Live Valparaiso Oak (Cal.). Oak, Golden-cup Oak (Cal.). LOCALITIES. West of the Rocky Mountains, in canyons and at high elevations. FEATURES OF TREE. Fifty to eighty feet in height; three to six feet in diameter; often a low shrub; impressive appearance; evergreen foliage; some leaves have smooth, thickened margins, but occasionally leaves have spiny-toothed margins. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light-brown; sap wood lighter; there are small pores in the wide bands that are parallel to the conspicuous medullary rays; close- grained. STRUCTURAL QUALITIES OF WOOD. Hard, heavy, strong, tough, and difficult to work. REPRESENTATIVE USES OF WOOD. Implements, wagons, and tool-handles. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 52. MODULUS OF ELASTICITY. 1,700,000. MODULUS OF RUPTURE. 18,000. REMARKS. Said to be the most valuable of the California oaks. Grows at eleva- tions of two thousand to five thousand feet. The Highland Live Oak (Quercus wislizeni) is an evergreen tree which also grows on the Pacific Coast. The Highland Live Oak differs from the Live Oak (Quercus chrysolepis) in the fact that the leaves of the former are always spiny- toothed. BROADLEAF TRUNKS AND WOODS 119 English Oak. Quercus robur var. pedunculata NOMENCLATURE. English Oak. Common Oak. British Oak. LOCALITIES. Widespread throughout northern and central Europe. FEATURES OF TREE. Seventy to one hundred feet in height; three to five feet in diameter; the branches are crooked, the leaves stalkless, and the acorns long-stalked. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light-brown, darker spots frequent; sap wood lighter; com- pact structure. STRUCTURAL QUALITIES OF WOOD. Hard, tough, strong, and durable; difficult to work; liable to warp in seasoning. REPRESENTATIVE USES OF WOOD. Ship-building, beams, and cabinet-work; used formerly in carpentry. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 51 (Laslett). MODULUS OF ELASTICITY. 1,170,000 (Thurston). MODULUS OF RUPTURE. 10,000 (Thurston). REMARKS. The English, Chestnut, Durmast, or Red Oak (Quercus robur var. ses- siliflora), which is distinguished from the English Oak (Quercus robur var. pedunculata) 1 by its long leafstalks and its short acorn stalks, yields a similar but lower-rated wood. These two trees supply the "British Oak" of commerce. Dantzic, Rigi, and some other European oaks are in all probability really English Oaks, which are named from the ports from which they are shipped. Durmast Oak (Quercus pubes- cens or Quercus robur intermedia) is not as common as the English Oak (Quercus robur var. pedunculata) with which it is often confused. Laslett states that it is often hard to distinguish one of these woods from another without tracing the logs back to their original sources. Early authorities advised that these woods, which contain much gallic acid, should not be fastened with iron; but the woods are now better seasoned, and, as stated before, oak woods are now safely fastened with iron, at least in the United States. 1 As stated, these two trees are usually assumed to be sub-species or varie- ties of the species Quercus robur. But by some they are believed to be dis- tinct species, that is, Quercus pedunculata and Quercus sessiliflora. ASH Fraxinus These trees grow in many places in the temperate regions of the northern hemisphere. The wood resembles oak in many particulars, but is coarser, lighter, easier to work, tougher, more elastic, and less attractive than oak. Ash seasons well, but does not last well when exposed to the weather. It is used for stairs, furniture, and some of the cheaper forms of cabinet work. Second-growth ash is tougher and more pliable than first-growth ash. 1 Ash woods are often grouped under two heads: White Ash includes the lighter colored and more desirable pieces, while Black Ash includes- the darker and inferior woods. This prac- tical division agrees with the botanical division in the North, since in the North the only notable species are White Ash (Fraxinus americana) and Black Ash (Fraxinus nigra). The wood of the Green Ash (Fraxinus lanceolata) of the south is usually classed as White Ash. One-half of the thirty-nine known species of the genus Fraxinus are natives of North America. 2 1 Trees that grow up after virgin forests are cut away afford what are known as " second-growth woods." Ordinarily, second-growth woods are inferior to first-growth woods, because second-growth woods, being younger, have more sapwood. In this case it is the sapwood that is often preferred. 2 See also "The Ashes: Their Characteristics and Management," Sterrett (United States Department of Agriculture, Bulletin No. 299). 120 BROADLEAF TRUNKS AND WOODS 121 White Ash. Fraxinus americana Linn. NOMENCLATURE (Sudworth). White Ash (local and common Cane Ash (Ala., Miss., La.). name). American Ash (la.). Ash (Ark., la., Wis., 111., Mo., Minn.). LOCALITIES. Nova Scotia to Florida, westward intermittently to Minnesota and Texas; greatest development in the Ohio River basin. FEATURES OF TREE. Forty-five to ninety feet in height, occasionally higher; three to four feet in diameter; the dark-brown or gray-tinged bark is deeply divided by narrow fissures into broad, flattened ridges; the seeds have long wings. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood reddish-brown, usually mottled; sapwood much lighter, some- times nearly white; coarse-grained; compact structure; the layers are clearly marked by large, open ducts; the medullary rays are often obscure. STRUCTURAL QUALITIES OP WOOD. Heavy, hard, strong, and elastic, becoming brittle with age; not durable in contact with the soil. REPRESENTATIVE USES OF WOOD. Agricultural implements, carriages, handles, oars, interior and cheap cabinet-work. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 39 (United States Forestry Division). 1 40. MODULUS OF ELASTICITY. 1,640,000 (average of 87 tests by United States Forestry Division). 1 1,440,000. MODULUS OP RUPTURE. 10,800 (average of 87 tests by United States Forestry Division). 1 12,200. REMARKS. These valuable trees grow rapidly, particularly when on low, rather moist soil. They are not apt to form forests, but are usually found in clumps or mingled with trees of other species. Large trees sometimes have large heart-cracks. The trees are also subject to a fungus disease which reduces the wood to a useless, soft, pulpy, yellowish mass. This dis- ease, which is known as white rot, progresses until the tree becomes so weak that it is blown over by the winds. The disease does not attack dead or seasoned woods. See also von Schrenk (United States Bureau of Plant Industry, Bulletin No. 32.) l See p. 33. 122 ORGANIC STRUCTURAL MATERIALS -; Red Ash < ^ nmrms pennsylvanica Marsh \ Fraxinus pubescens Lam. NOMENCLATURE (Sudworth). Red Ash (local and common Brown Ash (Mo.). name). Black Ash (N. J.). River Ash (R. I., Ont.). Ash (Neb.). LOCALITIES. New Brunswick to Florida, westward intermittently to the Dakotas and Alabama; best developed in the North- Atlantic States. FEATURES OF TREE. Rarely much over forty-five feet in height and about one foot in diameter. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood rich brown; sapwood light brown, streaked with yellow; coarse-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Heavy and hard; strong, but brittle. REPRESENTATIVE USES OF WOOD. Agricultural implements, handles, boats, oars, and paper-pulp. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 38. MODULUS OF ELASTICITY. 1,154,000. MODULUS OF RUPTURE. 12,300. REMARKS. Grows on borders of streams and swamps, in low, rich soil. BROADLEAF TRUNKS AND WOODS 123 Blue Ash. Fraxinus quadrangulata Michx. NOMENCLATURE (Sudworth). Blue Ash (Mich., 111., Ky., Mo., Ala.). LOCALITIES. Ontario and Minnesota, southward to Tennessee, Alabama, and Arkansas. FEATURES OF TREE. Fifty to seventy-five feet in height, occasionally higher; one to two feet in diameter; a slender tree; blue properties in inner bark; smooth, square twigs; leaves composed of seven to eleven pointed, rough- margined leaflets. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light yellow, streaked with brown; sapwood lighter; close- grained; compact structure; satin-like appearance. STRUCTURAL QUALITIES OF WOOD. Hard and heavy, but brittle; not strong; the most durable of the Ash woods. REPRESENTATIVE USES OF WOOD. Largely used in flooring, carriage-building, pitchfork and other tool- handles. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 44. MODULUS OF ELASTICITY. 1,100,000. MODULUS OF RUPTURE. 11,500. REMARKS. Blue Ash trees grow best on limestone formations. The inner bark con- tains properties which give water a bluish tint. Blue Ash has no supe- rior among the Ash woods. Blue Ash pitchfork-handles are highly prized. 124 ORGANIC STRUCTURAL MATERIALS \ Fraxinus niqra Marsh Black Ash. v * i- r ( Fraxinus samoucifoha Lam. NOMENCLATURE (Sudworth). Black Ash (local and common Swamp Ash (Vt., R. I., N. Y.). name). Brown Ash (N. H., Tenn.). Water Ash (W. Va., Tenn., Ind.). Hoop Ash (Vt., N. Y., Del., Ohio, 111., Ind.). LOCALITIES. Newfoundland, through Canada to Manitoba, southward to Illinois, Missouri, and Arkansas. FEATURES OF TREE. Seventy to eighty feet in height; one to one and one-half feet in diameter; a thin tree; excrescences or knobs are frequent on trunks; dark, almost black, winter buds. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood dark brown; sapwood light brown, often nearly white; coarse- grained; compact structure; the medullary rays are numerous and thin. STRUCTURAL QUALITIES OP WOOD. Separates easily in layers; rather soft and heavy, tough, and elastic; not strong or durable when exposed. REPRESENTATIVE USES OP WOOD. Largely used for interior finish, fencing, barrel-hoops, cabinet-making, splint baskets, an4 chair-bottoms. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 39. MODULUS OF ELASTICITY. 1,230,000. MODULUS OF RUPTURE. 11,400. REMARKS. The Black Ash is found farther north than other Ash trees. It is one of the most slender of trees. The distorted grain in the excrescences, knobs, or burls, causes the wood from such burls to be prized for veneers. BROADLEAF TRUNKS AND WOODS 125 f Fraxinus lanceolata Borkh. Green Ash. I Fraxinus viridis Michx. f. ( Fraxinus pennsylvanica var . lanceolata Sarg. NOMENCLATURE (Sud worth). Green Ash (local and common Ash (Ark., Iowa). name). Swamp Ash (Fla., Ala., Tex.). Blue Ash (Ark., Iowa). Water Ash (Iowa). White Ash (Kans., Neb.). LOCALITIES. East of the Rocky Mountains Vermont and northern Florida, inter- mittently to Utah and Arizona. FEATURES OF TREE. Forty to fifty feet in height; one to two feet in diameter; the upper and lower surfaces of the smooth leaves are bright green. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood brownish, sap wood lighter; rather coarse-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Hard, heavy, and strong, but brittle. REPRESENTATIVE USES OF WOOD. Similar to those of White Ash (Fraxinus americana). WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 39 (United States Forestry Division). 1 44. MODULUS OF ELASTICITY. 2,050,000 (average of 10 tests by United States Forestry Division). 1 1,280,000. MODULUS OF RUPTURE. 11,600 (average of 10 tests by United States Forestry Division.) 1 12,700. REMARKS. Sometimes considered a variety of Red Ash (Fraxinus pennsylvanica). 1 See p. 33. 126 ORGANIC STRUCTURAL MATERIALS Oregon Ash. Fraxinus oregona Nutt. NOMENCLATURE. Oregon Ash (Gal., Wash., Oregon). LOCALITIES. Pacific Coast, British Columbia to southern California. FEATURES OF TREE. Fifty to occasionally seventy-five feet in height; one to one and one-half feet in diameter; the dark grayish-brown bark exfoliates in thin scales. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood brown; sap wood lighter; coarse-grained; compact structure; there are numerous thin medullary rays. STRUCTURAL QUALITIES OF WOOD. Rather light and hard, but not strong. REPRESENTATIVE USES OF WOOD. Furniture, carriage-frames, cooperage, and fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 35. MODULUS OF ELASTICITY. 1,200,000. MODULUS OF RUPTURE. 9,400. REMARKS. One of the valuable deciduous trees of the Pacific Coast. Thrives only on moist soils and in moist climates. The Toothache Trees (Xanthoxylum americana and Xanthoxylum dava- herculis) are known as Ash and Prickly Ash. The Gopher Wood (Cladrastis tinctoria) is Yellow Ash. These woods are not important. The name "Mountain Ash" is applied to several species (Sorbus americana and Sorbus sambucifolia) that yield bright red berries and soft, light, close-grained, practically valueless woods. The trees are related to the apple. BROADLEAF TRUNKS AND WOODS 127 Most trees that yield edible fruits are valued for the fruits, and are not normally cut in large quantities for wood. The Apple (Pyrus mains) . These trees originated in Europe, but are now common in all temperate climates. They are seldom much over thirty feet in height, and normally afford hard, heavy, close-grained, brittle woods, that are liable to warp during seasoning. The woods are suitable for implements and tool handles. Many varieties of Apple have been perfected by cultivation. 1 The Sweet or American Crab Apple Trees (Pyrus coronaria) grow in many places from Massachusetts and Nebraska southward to Georgia and Texas. The trees are seldom more than twenty-five feet in height and one foot in diameter. The hard, close-grained wood is occasionally used in turnery. The trees are prized in landscape effects because of their sweet-scented blossoms. The Oregon Crab Apple (Pyrus rivularis) grows on the Pacific Coast from California to Alaska and sometimes attains a height of forty feet. The fine, hard, heavy, close-grained woods are used for mallets and tool handles. The Narrowleaf Crab Apple (Pyrus augustifolia) yields a similar wood. The Pear (Pyrus communis) is widely cultivated in many regions with temperate climates. The wood, which is rather hard and heavy, is so firm, fine, tough, and close-grained that it has been used for type, draw- ing squares, and triangles. It is used in turnery and occasionally in furniture. Many varieties have been obtained by cultivation. The Orange (several species, as Citrus aurantium and Citrus trifoliatd) was introduced into the West Indies, Florida, Louisiana, and California from Asia and the shores of the Mediterranean. The small trees bear oily, partially evergreen leaves, fragrant flowers, and edible fruit, which with oils and essences are highly prized. The strong, hard, heavy, close- grained, lemon-colored wood is cut into souvenirs and other small ob- jects. A piece of American Orange wood, exhibited at the St. Louis Exposition, was ten inches wide. Many varieties of Orange trees have been obtained by cultivation. The Olive (Olea europcea). Olive trees were introduced into southern California from Asia and the shores of the Mediterranean by the early Spanish missionaries. The irregularly formed trees, from thirty to forty feet in height, bear evergreen leaves and valuable oily fruit. The mottled, rich orange-brown, hard, heavy, close-grained heartwood of foreign trees is prized for inlaid work, small objects, and souvenirs. The heartwood of the older trees is the best. American Olive wood is not particularly attractive because the heartwood has not yet had time to mature sufficiently. Many varieties of Olive trees have been obtained by cultivation. 1 "The Apples of New York, " Beach, Booth and Taylor (New York State Department of Agriculture). ELM Ulmus The several species of Elm are distributed over the eastern and central portions of the United States. Elm trees are prized for their fine form and appearance. Because they have no lower branches, they are particularly good for planting along streets and near houses. Elm trees attain a high degree of perfection in some parts of New England. Elm wood is tough, fibrous, durable, strong, hard, heavy, and difficult to split and work. It stands well against shocks, and, for this reason, piles of Elm are useful in ferry slips. The grain arrangement is often attractive, and the wood is sometimes used in less important kinds of cabinet work. It is characteristically employed in piles, flumes, wagons, cars, agricultural implements, and machinery. The tall, straight trunks yield pieces of con- siderable size. The wood is used in naval construction from parts of the largest ships to canoes where it enters the lattice upon which occupants sit or place their feet. Elm is also used for carriages upon which heavy cannon are mounted. It is used in cooperage, floors, pump handles, and trunks. The bark of the elm tree was used by the Indians in canoes and for rope. The tree is easily recognized by its form. Fifteen or sixteen species are known to exist. 1 1 See also "The American Elm/' Detwiler (American Forestry, May, 1916). 128 BROADLEAF TRUNKS AND WOODS 129 White Elm. Ulmus americana Linn. NOMENCLATURE (Sudworth). White Elm (local and common Pa., N. C., S. C., la., Wis.). name). American Elm (Vt., Mass., R. I., Water Elm (Miss., Tex., Ark., Mo., N. Y., Del., Pa., N. C., Miss., 111., la., Mich., Minn., Neb.). Tex., III., Ohio, Kans., Neb., Elm (Mass., R. I., Conn., N. J., Mich., Minn.). LOCALITIES. East of the Rocky Mountains, Newfoundland to Florida, westward intermittently to the Dakotas, Nebraska, and Texas. FEATURES OF TREE. Ninety to one hundred feet in height; three to seven feet in diameter; a characteristic and beautiful form; smooth buds; the leaves, which are smaller than those of the Slippery Elm (Ulmus pubescens), are rough only when rubbed one way. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood light brown; sap wood yellowish white; rather coarse-grained; annual rings clearly marked. STRUCTURAL QUALITIES OF WOOD. Strong, tough, fibrous, and difficult to split. REPRESENTATIVE USES OF WOOD. Flooring, wheel-stock, barrel staves, ship-building, flumes, and piles. 1 WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 34 (United States Forestry Division). 2 40. MODULUS OF ELASTICITY. 1,540,000 (average of 18 tests by United States Forestry Division). 2 1,060,000. MODULUS OF RUPTURE. 10,300 (average of 18 tests by United States Forestry Division). 2 12,100. REMARKS. The concentration of the foliage at the top, together with their pleasing form, renders these trees valuable in landscape effects. Elm trees do not cause dense shade. Elm trees and Silver Maple trees are among the first to show life in the spring. At that time, discarded brown- ish scales cover the ground in the vicinity of the trees. 1 See also "White Elm," Pinchot (United States Forest Service, Circular No. 66, 1907); "The American Elm," Detwiler (American Forestry, May, 1916). 2 See page 33. 130 ORGANIC STRUCTURAL MATERIALS ~ . ! / Ulmus racemosa Thomas Cork Elm. s TT7 . _ I Ulmus thomasi Sarg. NOMENCLATURE (Sudworth). Cork Elm (local and common Rock Elm (R. I., W. Va., Ky., Mo. name). 111., Wis., la., Mich., Neb.). Hickory Elm (Mo., 111., Ind., la.). White Elm (Ont.). Cliff Elm (Wis.). LOCALITIES. Quebec, Ontario, Michigan, and Wisconsin, southward to Connecticut, northern New Jersey, Ohio, Missouri, and eastern Nebraska. FEATURES OF TREE. Seventy to ninety feet in height; two to three feet in diameter; thick, corky, irregular projections give the bark a characteristic, shaggy appearance. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light brown, often tinged with red; sapwood yellowish or greenish white; compact structure; the fibers interlace. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, very strong, tough, elastic, and difficult to split; receives a beautiful polish. REPRESENTATIVE USES OF WOOD. Heavy agricultural implements, wheel-stock, barrel staves, railway ties, sills, bridge-timbers, axe-helves, etc. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 45. MODULUS OF ELASTICITY. 2,550,000. MODULUS OF RUPTURE. 15,100. REMARKS. This is the best of the Elm woods. BROADLEAF TRUNKS AND WOODS 131 _ _ t f Ulmus pubescens Walt. Slippery Elm, Red Elm. < r , 7 ^ , ,,. , I Ulmus fulva Michx. NOMENCLATURE (Sudworth). Slippery Elm, Red Elm (local and Redwooded Elm (Term.), common names). Moose Elm (occasional). Rock Elm (Tenn.). LOCALITIES. Ontario and Florida, westward intermittently to Nebraska and Texas; best developed in the Western States. FEATURES OF TREE. Forty-five to sixty feet in height; one to two feet in diameter; characteristic form; mucilaginous inner bark; the buds are hairy; the leaves are rough when rubbed either way. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood dark brown or red; sapwood lighter; compact structure; the annual layers are marked by rows of large, open ducts; heartwood greatly preponderates. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, strong, and durable in contact with the soil. REPRESENTATIVE USES OF WOOD. Largely used for fence-posts, rails, barrel staves, railway ties, sills, sleigh- runners, and wheel-stock ; the mucilaginous bark is employed in medicine. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 43. MODULUS OF ELASTICITY. 1,300,000. MODULUS OF RUPTURE. 12,300. REMARKS. 132 ORGANIC STRUCTURAL MATERIALS Wing Elm, Winged Elm. Ulmus alata Michx. NOMENCLATURE. Mountain Elm, Red Elm (Fla., Wing Elm, Winged Elm (local Ark.). and common names). Elm, Witch Elm (W. Va.). Wahoo, Whahoo fW. Va., N. C., Water Elm (Ala.). S. C., La., Tex., Ky., Mo.). Small-leaved Elm (N. C.). Cork Elm, Corky Elm (Fla., Wahoo Elm (Mo.). S. C., Tex.). LOCALITIES. Southern United States, Virginia, and Florida, westward intermittently to southern Illinois and Texas. FEATURES OF TREE. Forty feet or more in height; one to two feet in diameter; there are corky "wings" on the branches; the smooth leaves are smaller than those of the White Elm (Ulmus americand). COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood brownish; sapwood lighter; close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Hard, heavy, tough, and fibrous. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 46. MODULUS OF ELASTICITY. 740,000. MODULUS OF RUPTURE. 10,200. REMARKS. Not a very common tree. MAPLE Acer Maple trees grow on all the northern continents. Nearly one- half of the known species are native to Asia. The principal European species (Acer pseudo-platanus) is known in Europe as a Sycamore. The Hard or Sugar Maple (Acer saccharum) is one of the principal deciduous trees of North America. 1 Maple wood is noted for its attractive appearance and its fine, compact structure. Its appearance is so attractive that selected pieces are classed with the most beautiful of the cabinet woods, and its structure is so fine and compact that it is sometimes used for carvings and even for type. Birdseye Maple and Curly Maple are not separate species, but are results of cellular distor- tions that may occur, in some form, on other trees as well as Maples. Birdseye and blister effects are most often seen in the wood of the Hard Maple (Acer saccharum), while curly effects are most often seen in the Soft Maples. It is usually impossible to tell definitely how the woods are figured until the bark is removed or the trees are cut. Maple wood is tough and strong. It shrinks moderately and stands well in protected places, but is not durable when exposed. It is used for flooring, panelling, furniture, school supplies, implements, machinery, and shoe- lasts. Sugar is separated from the sap of the Sugar Maple. The Boxelder (Acer negundo) is a true Maple. The trees are very beautiful, and, like other Maple trees, are valued for orna- mental purposes. The soft, light wood is occasionally used for woodenware, interior finish, and paper pulp. Small quantities of sugar are present in the sap of this tree. Maple trees bear two-seeded fruit or "keys;" the parts of these keys spread differently in different species. The leaves of some species change from green to red and other brilliant colors in the autumn. Sixty to seventy species have been distinguished. Nine of these are native to North America. 1 See also "Beech, Birches and Maples," Maxwell (United States Depart- ment of Agriculture Bulletin No. 12, 1913:) 133 134 ORGANIC STRUCTURAL MATERIALS ( Acer saccharum Marsh Sugar Maple. Hard Maple. T . TT . I Acer sacchannum Wang NOMENCLATURE (Sudworth). Sugar Maple, Hard Maple (local Rock Maple (Me., Vt., N. H., and common names). Conn., Mass., R. I., N. Y., Black Maple (Fla., Ky M N. C.). Tenn., 111., Mich., la., Kan., Sugar Tree (frequent). Wis., Minn.). LOCALITIES. Best development Newfoundland to Manitoba. Range extends south- ward to Florida and Texas. FEATURES OF TREE. Seventy to one hundred or more feet in height; one and one-half to four feet in diameter; the flowers appear with the leaves in the spring; the fruit or "maple-keys," with wings less than at right angles, ripen in the early autumn; one seed-cavity in each is usually empty; the leaves exhibit brilliant reds and other colors in the autumn ; a large, impressive tree. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood brownish; sap wood lighter; close-grained; compact structure; occasional curly, blister, or birdseye effects. STRUCTURAL QUALITIES OF WOOD. Tough, heavy, hard, strong, and receives a good polish; wears evenly; not durable when exposed. REPRESENTATIVE USES OF WOOD. Furniture, shoe-lasts, piano-actions, wooden type for showbills, pegs interior finish, flooring, ship-keels, vehicles, fuel, veneers, rails, etc. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 43. MODULUS OF ELASTICITY. 2,070,000. MODULUS OF RUPTURE. 16,300. REMARKS. 1 1 See also "Sugar Maple, Acer saccharum Marsh" (United States Forest Service, Silvical Leaflet No. 42, 1908). "The Sugar Maple," Detwiler (American Forestry, November, 1915). BROADLEAF TRUNKS AND WOODS 135 / Acer saccharinum Linn. Silver Maple, Soft Maple. , , I Acer dasycarpum E,hr. NOMENCLATURE (Sud worth). Silver Maple, Soft Maple (local White Maple (Me., Vt., R. I., N. Y., common names). N. J., Pa., W. Va., N. C., S. C., Swamp Maple (W. Va., Md.). Ga., Ma., Ala., Miss., La., Ky., Water Maple (Pa., W. Va.). Mo., 111., Ind., Kans., Neb., River Maple (Me.,.N. H., R. I., Minn.). W. Va., Minn.).' LOCALITIES. New Brunswick to Florida, westward intermittently to the Dakotas and Oklahama; best development in lower Ohio River basin. FEATURES OF TREE. Forty to ninety feet in height, occasionally higher; three to five feet in diameter; fine form, sometimes suggesting that of the Elm; the maple- keys, with long, stiff, more than right-angled wings, ripen in the early summer; the flowers appear before the leaves in the spring; the leaves exhibit yellows, but seldom reds, in the autumn. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood reddish brown; sapwood ivory white; fine-grained; compact structure; the fibers are sometimes twisted, waved, or " curly." STRUCTURAL QUALITIES OF WOOD. Light, brittle, easily worked, and moderately strong; receives a high polish; not durable when exposed to the weather. REPRESENTATIVE USES OF WOOD. Woodenware, turned work, interior decoration, flooring, and fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 32. MODULUS OF ELASTICITY. 1,570,000. MODULUS OF RUPTURE. 14,400. REMARKS. Waving, spiral, or curly figures are pronounced in the woods of this species. Resemblances to light and shadows are particularly real on planed surfaces. 136 ORGANIC STRUCTURAL MATERIALS Red Maple, Swamp Maple. Acer rubrum Linn- NOMENCLATURE (Sudworth). Red Maple, Swamp Maple (local Water Maple (Miss., La., Tex., Ky., and common names). Mo.). Soft Maple (Vt., Mass., N. Y., White Maple (Me., N. H.). Va., Miss., Mo., Kans., Neb., Red Flower (N. Y.). Minn.). LOCALITIES. New Brunswick and Florida, westward intermittently to the Dakotas and Texas. Wide range. FEATURES OF TREE. Sixty to eighty feet and more in height; two and one-half to four feet in diameter; red twigs and flowers appear before the leaves in the early spring. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood brown, tinged with red; sapwood lighter; close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, and elastic, but not strong; easily worked. REPRESENTATIVE USES OF WOOD. Largely used in cabinet-making, turnery, woodenware, and gun-stocks. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 38. MODULUS OF ELASTICITY. 1,340,000. MODULUS OF RUPTURE. 15,000. REMARKS. The wood occasionally shows a "curly figure." BROADLEAF TRUNKS AND WOODS 137 Oregon Maple. Acer macrophyllum Pursh. NOMENCLATURE (Sudworth). Oregon Maple (Oreg., Wash.). Broad-leaved Maple (Central Cal M White Maple (Oreg., Wash.). Willamette Valley, Ore.). Maple (Cal.). LOCALITIES. Alaska to California; best in rich bottom lands of southern Oregon. FEATURES OF TREE. Seventy to one hundred feet in height; three to five feet in diameter; beautiful appearance; pendant clusters of flowers appear after the leaves in the spring. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood reddish brown; sapwood whitish; close-grained; compact structure; occasionally figured. STRUCTURAL QUALITIES. Light, hard, and strong; receives a high polish. REPRESENTATIVE USES OF WOOD. Locally used for tool-handles, turned work, and furniture. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 30. MODULUS OF ELASTICITY. 1,100,000. MODULUS OF RUPTURE. 9,720. REMARKS. This ornamental tree has been introduced into Europe. 1 also "Manual Trees of North America," Sargent, p. 628. 138 ORGANIC STRUCTURAL MATERIALS Bozelder, Ash-leaved Maple. ^ I Negundo aceroides Moench. NOMENCLATURE (Sudworth). Boxelder, Ash-leaved Maple Stinking Ash (S. C.). (local and common names). Negundo Mapie (HI.). Red River Maple, Water Ash Three-leaved Maple (Fla.). (Dak.). Black Ash (Term.). Cut-leaved Maple (Colo.). Sugar Ash (Fla.). LOCALITIES. Atlantic Ocean, westward intermittently to Rocky Mountains and Mexico. FEATURES OP TREE. Forty to seventy feet in height; one and one-half to three feet in diameter; the wings to the keys are straight or incurved; the leaves exhibit yel- lows, but seldom reds, in the autumn; the flowers appear with or before the leaves in the spring. COLOR, APPEARANCE, OR GRAIN OF WOOD. Thin heartwood, cream white; sapwood similar; close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong. REPRESENTATIVE USES OF WOOD. Woodenware, cooperage, paper-pulp, and occasionally interior finish. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 26. MODULUS OF ELASTICITY. 82,000. MODULUS OF RUPTURE. 7,500. REMARKS. The Boxelders withstand severe climatic changes, grow rapidly and are good trees to plant in many otherwise treeless sections. Sugar is sometimes obtained from the sap of this species. See also "Boxelder" (United States Forest Service Circular No. 86). WALNUT Juglans The English or Royal Walnut (Juglans regia) is the principal species in Europe, while the Black Walnut (Juglans nigrd), and the Butternut or White Walnut (Juglans tinerea) grow in the United States. Botanically, Circassian Walnut is the same as English, Royal, or European Walnut. English Walnut is the name used almost exclusively by those who grow the tree for its nuts, while Circassian Walnut is the name usually applied to the wood. 1 The English Walnut was introduced from Asia into Greece and Italy, and, through these countries, into others. It is cultivated in the United States, but principally for its nuts. The appear- ance and desirability of the wood differ with localities. Pieces cut from English trees are said to be paler and coarser than those cut from Italian and French trees. Ordinary pieces exhibit large open figures, with waves and streaks of gray and yellowish- white, while exceptional excrescences known as burrs, which are sometimes two or three feet across, yield figured woods of great beauty. Circassian Walnut is very valuable, and is now used almost exclusively in costly decorations, piano cases, and high- grade furniture. No other wood is better for gun-stocks, and, until the battle of Waterlo, othe demand in Europe for this pur- pose was so great that as much as six hundred pounds sterling is said to have been paid for a single tree. At the present time (1917) the supply of Black Walnut for making stocks for military rifles is ample. A manufacturer writes as follows: "At the beginning of the great war (1914) we were under the im- pression that we might experience some difficulty in securing sufficient of this wood; but we have had no such trouble, in fact, we have had much more of it offered to us than we require." American or Black Walnut was once very popular, in the United States, as a cabinet wood. The trees are now scarce; lighter colored Woods are preferred, and, at present, walnut is seldom seen save in gun-stocks and old furniture. The figures that characterize pieces of Circassian Walnut are absent in the 139 140 ORGANIC STRUCTURAL MATERIALS darker, more uniformly tinted American woods. Black Walnut trees seldom form forests by themselves, but are usually found mixed with those of other species. They grow rapidly, but the valuable heartwood does not mature until a number of years after the trees have been planted. Small pieces of dark, rich brown wood are obtained from the Mexican or Arizona Walnut (Juglans rupestris), which grows in some of the sparsely settled regions of the Southwest, where it is also known as the Western, Dwarf, Little, and California Walnut. The true California Walnut (Juglan calif or nica) is found on the Pacific Coast from the Sacramento River to the San Bernardino Mountains, and sometimes attains diameters of fifteen inches. The blue-brown woods can be, but seldom are, used in cabinet making. The White Walnut or Butternut (Juglans cinerea) yields a rather soft, light, grayish-brown heartwood that is sometimes used in cabinet making. Walnut trees may be known by their nuts. The husks or pods are not quartered as in the case of the hickories. 1 "Circassian Walnut," Sudworth and Mell (United States Forest Service, Circular No. 212). BROADLEAF TRUNKS AND WOODS 141 Circassian Walnut, European Walnut. Juglans regia NOMENCLATURE (Sudworth and Mell). Circassian Walnut, European Walnut, Russian Walnut. English Walnut, Royal Walnut (local Turkish Walnut. and common names). Nogal (Spain, Cuba, and Persian Walnut. South America). French Walnut. Ancona Auvergne (Italy). Italian Walnut. Noyer (France). Austrian Walnut. LOCALITIES. Widely planted on all of the continents. FEATURES OF TREE. About 40 feet in height; attractive in appearance. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood dark chocolate brown, tints sometimes extending from light brown to black; sapwood lighter; beautiful veins and figures, particularly in the wood of older trees; fine, close grain. STRUCTURAL QUALITIES OF WOOD. Moderately hard, moderately heavy; splits but little in seasoning; the sapwood is liable to become worm-eaten. REPRESENTATIVE USES OF WOOD. Circassian Walnut was formerly used in turnery, toys, carved work, carpentry, wooden shoes, and gun-stocks. The wood is now scarce and is only employed in the most costly furniture and cabinet work. WEIGHTS OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. MODULUS OF ELASTICITY. MODULUS OF RUPTURE. REMARKS. For many years the demands for this wood have been greater than the supply. Among the related woods which have been used as substi- tutes are the Caucasian Walnut (Pterocarya caucasica) 1 , the West Indian Walnut (Juglans insularis), the Nogal (Juglans australis), and the Butternut (Juglans cinered). The Red Gum (Liquidambar styra- ciflua), which is sometimes called the Satin Walnut, is often handsomely veined, and is then very similar to true Circassian Walnut. 1 The similarity of names is such that Caucasian Walnut and Circassian Walnut are sometimes confused with one another. The wood of the former lacks the veining which characterizes the latter. 142 ORGANIC STRUCTURAL MATERIALS Black Walnut. Juglans nigra Linn. NOMENCLATURE (Sudworth). Black Walnut (local and common name). Walnut (N. Y., Del., W. Va., Fla., Ky., Mo., Ohio, Ind., la.). LOCALITIES. Ontario and Florida, westward intermittently to Nebraska and Texas. FEATURES OP TREE. Ninety to one hundred and twenty-five feet in height; three to eight feet in diameter; a tall, handsome tree with rough, brownish, almost black, bark ; the compound leaves are composed of from thirteen to twenty- three leaflets; the nuts are large and rough-shelled. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood rich, dark, chocolate brown; the thin sapwood is much lighter in color; rather coarse-grained. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, strong, easily worked, and durable; receives a high polish. REPRESENTATIVE USES OF WOOD. Cabinet-making and gun-stocks; also formerly furniture and decoration. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 38. MODULUS OF ELASTICITY. 1,550,000. MODULUS OF RUPTURE. 12,100. REMARKS. This tree is now somewhat rare in the Eastern parts of the United States. 1 See also "Handbook Trees of Northern States and Canada," Hough. BROADLEAF TRUNKS AND WOODS 143 Butternut, White Walnut. Juglans cinerea Linn. NOMENCLATURE. Butternut, White Walnut (local Walnut (Minn.). and common names). White Mahogany. Oil Nut (Me.,. N. H., S. C.). LOCALITIES. New Brunswick to Georgia, westward to Dakota and Arkansas; best in Ohio River basin. FEATURES OP TREE. Medium size, sometimes seventy-five feet or over in height; two to four feet in diameter; the branches are widespread; the compound leaves a re composed of from eleven to seventeen leaflets; there are large-sized, oblong, edible nuts. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light gray-brown, darkening with exposure; sapwood nearly white; coarse-grained; compact structure; an attractive wood. STRUCTURAL QUALITIES OP WOOD. Light, soft, and easily worked, but not strong; receives a high polish. REPRESENTATIVE USES OP WOOD. Interior finish and cabinet-work. The inner bark furnishes a yellow dye. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 25. MODULUS OF ELASTICITY. 1,150,000. MODULUS OP RUPTURE. 8,400. REMARKS. 1 also "Handbook Trees of Northern States and Canada," Hough. HICKORY Hicoria The Hickories grow in the temperate regions of eastern North America, and eastern Asia. The woods, which are noted for strength, toughness, flexibility, and resilience, are used for handles, implements, machinery and carriage parts. Axe handles and hammer handles of this wood have no superiors. The reputation of American axes and hammers owes much to the qualities of these handles. The properties that render Hickory valuable are most pronounced in the sapwood, which, in this species, is more desirable than the heartwood. Second growth Hickory is prized, since, being younger, it contains more of the pliable sapwood. Hickory does not last well in exposed positions. The genus includes about a dozen species. The Hickories may be distinguished from the Walnuts by the nuts. In most cases, the nuts of the Hickories are covered with husks that divide into four parts, while those' of the Walnuts remain un- broken. 1 1 See also "The Commercial Hickories," Boisen and Newlin (United States Forest Service, Bulletin No. 80, 1910); "Manufacture and Utiliza- tion of Hickory," Hatch (United States Forest Service, Circular No. 187, 1911). 144 BROADLEAF TRUNKS AND WOODS 145 f Hicoria ovata Mill. Shagbark ttckory, Shellbaik Hackory, ( Shagbark. NOMENCLATURE (Sudworth). Shagbark or Shellbark Hickory Hickory (Vt., Ohio). (local and common names). Upland Hickory (111.). Scalybark Hickory (W. Va., S. C., White Hickory (la., Ark.). Ala.). Walnut (Vt., N. Y.). Shellbark (R. I., N. Y., Pa., N. C.). Sweet Walnut (Vt.). Shagbark (R. I., Ohio). Shagbark Walnut (Vt.). LOCALITIES. Quebec to Florida, westward intermittently to Minnesota and Texas. Wide range, best in Ohio Valley. FEATURES OP TREE. Seventy-five to ninety feet in height, occasionally higher; two and one- half to three feet in diameter; shaggy bark; the compound leaves are composed of five and, rarely, seven leaflets; there are thin-shelled, edible nuts. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light brown; sapwood ivory white or cream colored; close- grained; compact structure; the annual rings are clearly marked; the medullary rays are numerous but thin. STRUCTURAL QUALITIES OF WOOD. Very heavy, very hard, strong, exceptionally tough and flexible; not durable when exposed. REPRESENTATIVE USES OF WOOD. Largely used for agricultural implements, wheels, runners, axe handles, baskets, and fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 51 (United States .Forestry Division). 1 52. MODULUS OF ELASTICITY. 2,390,000 (average of 137 tests by United States Forestry Division). 1 1,900,000. MODULUS OF RUPTURE. 16,000 (average of 137 tests by United States Forestry Division). 1 17,000. REMARKS. The nuts form an important article of commerce. "Shagbark" refers to the shaggy appearance of the bark. 2 1 See p. 33. 2 See also "Shagbark Hickory" (United States Forest Service, Circular No. 62, 1907). 146 ORGANIC STRUCTURAL MATERIALS Pignut. Hicoria glabra Mill. Gary a porcina Nutt. NOMENCLATURE (Sudworth). Pignut (local and common name). White Hickory (N. H., la.). Black Hickory (Miss., La., Ark., Broom Hickory (Mo.). Mo., Ind., la.). Hardshell (W. Va.). Brown Hickory (Del., Miss., Red Hickory (Del.). Tex., Tenn., Minn.). Switchbud Hickory (Ala.). Bitternut (Ark., 111., la., Wis.). LOCALITIES. Maine to Florida, westward intermittently to southern Nebraska and eastern Texas. FEATURES OF TREE. Seventy-five to one hundred feet in height, occasionally higher; two to four feet in diameter; rather smooth bark; the compound leaves are composed of from three to seven leaflets; the large, thick-shelled nuts contain kernels that are often astringent or bitter. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light and dark brown; the thick sapwood is lighter; close- grained. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, flexible, tough, and strong. REPRESENTATIVE USES OF WOOD. Similar to those of Shagbark Hickory (Hicoria ovata). WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 56 (United States Forestry Division). 1 51. MODULUS OF ELASTICITY. 2,730,000 (average of 30 tests by United States Forestry Division.) 1 1,460,000. MODULUS OF RUPTURE. 18,700 (average of 30 tests by United States Forestry Division.) 1 14,800. REMARKS. 2 1 See p. 33. 2 See also "Pignut Hickory, Hicoria glabra (Mill.)" Britton (United States Forest Service, Silvical Leaflet No. 48, 1909). BROADLEAF TRUNKS AND WOODS 147 f Hicoria alba Linn. Mocker Nut. j Carya tomentosa NuiL NOMENCLATURE (Sudworth). Mocker Nut, Whiteheart Hick- Big-bud, Red Hickory (Fla.). ory (local and common names). Common Hickory (N. C.). Bullnut (N. Y., Fla., Miss., White Hickory (Pa., S. C.). Tex., Mo., Ohio, 111., Minn.). Hickory Nut (Ky., W. Va.). Black Hickory (Tex., Miss., La., Hog Nut (Del.). Mo.). Hard bark Hickory (111.). Hickory (Ala., Tex., Pa., S. C., Neb.). LOCALITIES. Ontario to Florida, westward intermittently to Missouri and Texas. Wide range. FEATURES OF TREE. Seventy-five to one hundred feet in height; two and one-half to three and one-half feet in diameter; a tall, slender tree with rough, but not shaggy, bark; the compound leaves are composed of from five to nine leaflets; there are thick-shelled, edible nuts. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood rich, dark brown; the thick sapwood is nearly white; close- grained. STRUCTURAL QUALITIES OP WOOD. Very heavy, hard, tough, strong, and flexible. REPRESENTATIVE USES OP WOOD. Similar to those of Shagbark Hickory (Hicoria ovata). WEIGHT OP SEASONED WOOD IN POUNDS PER CUBIC FOOT. 53 (United States Forestry Division). 1 51. MODULUS OF ELASTICITY. 2,320,000 (average of 75 tests by United States Forestry Division). 1 1,630,000. MODULUS OP RUPTURE. 15,200 (average of 75 tests by United States Forestry Division). 1 16,000. REMARKS. The most generally distributed species of the genus in the South 1 See p. 33. 148 ORGANIC STRUCTURAL MATERIALS p / Hicoria pecan Marsh I Carya olivceformis Nutt. NOMENCLATURE (Sud worth). Pecan (local and common name). Pecan Nut, Pecan-tree, Pecanier (La.). LOCALITIES. Valley of Mississippi, southward to Louisiana and Texas. FEATURES OF TREE. Ninety to one hundred feet in height, sometimes higher; two and one-half to five feet in diameter; a tall tree; the compound leaves are composed of from nine to fifteen leaflets; there are smooth-shelled, oblong, edible nuts. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light-brown, tinged with red; sapwood lighter brown; close- grained and compact; the medullary rays are numerous, but thin. STRUCTURAL QUALITIES OF WOOD. Heavy and hard, but not strong and brittle. REPRESENTATIVE USES OF WOOD. Fuel; seldom used in construction. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 49 (United States Forestry Division). 1 44. MODULUS OF ELASTICITY. 2,530,000 (average of 37 tests by United States Forestry Division). 1 940,000. MODULUS OF RUPTURE. 15,300 (average of 37 tests by United States Forestry Division). 1 8,200. REMARKS. Grows on borders of streams in low, rich soil. It is the largest and most important tree of Western Texas. The sweet, edible nuts form an important article of commerce. 1 See p. 33. CHESTNUT, CHINQUAPIN Castanea These trees grow in many parts of eastern North America, southern Europe, northern Africa, western Asia, and parts of China and Japan. European Chestnut wood was once held in high regard. It should be noted, however, that some of the constructions, in which this wood was thought to exist, were actually built of oak. The wood of the North American Chestnut (Castanea vulgaris), which is weak, brittle, easily worked, and very durable, is one of the best of those used for fence posts, and mud sills, where dura- bility rather than great strength is required. Hough mentions a Chestnut fence-rail that was good after having been exposed for about one hundred years. The chestnut bark disease now tentatively named Diaporthe para- sitica Murrill 1 was first detected in New York City parks in 1904. Seventeen thousand trees soon succumbed in one park alone (Forest Park, Brooklyn). The disease, which was probably introduced from Japan, is conveyed by winds and insects, and no tree once attacked ever recovers. The value of the trees thus far destroyed is very great and the prospective losses are enormous. 2 The name Chinquapin applies to two North American species : the Common Chinquapin (Castanea pumila) grows in the Central and Southeastern States; while the Western, Goldenleaf, or California Chinquapin, or "Evergreen Chestnut," (Castanopsis chrysophylla) grows on the Pacific Coast. Both of these species afford woods that resemble ordinary chestnut. The American Chestnut (Castanea vulgaris) is known by its large, prickly burrs that contain from one to three thin-shelled, triangular, wedge-shaped, edible nuts. The Chinquapins bear prickly burrs that hold one, or occasionally two, sweet edible nuts. 1 Some botanists believe that this blight is Endothia gyrosa, while others characterize it as Endothia gyrosa var. parasitica. 2 See also Journal of New York Botanical Garden (Vol. II, p. 143) ; also, Marlatt (National Geographic Magazine, April, 1911); "Report of Chest- nut Tree Blight," Mickleborough (Pennsylvania State Department of Forestry); etc. 149 150 ORGANIC STRUCTURAL MATERIALS (Castanea dentata (Marsh) Borkh. Castanea vesca var. americana Michx. Castanea vulgaris var. americana A. de C. NOMENCLATURE. Chestnut (local and common name). LOCALITIES. New England, Ontario, and New York to Georgia, Alabama, and Missis- sippi; also Kentucky, Missouri, and Michigan ; best on the Western slope of the Alleghany Mountains. FEATURES OF TREE. Seventy-five to one hundred feet in height; five to twelve feet in diameter ; a fine, characteristic shape, not easily distinguished from that of the Red Oak (Quercus rubra) in winter; the trees blossom in midsummer; the prickly burrs contain three, exceptionally five, thin-shelled nuts. 1 COLOR, APPEARANCE OR GRAIN OF WOOD. Heart wood brown; sap wood lighter; coarse-grained. STRUCTURAL QUALITIES OF WOOD. Light and soft; not strong; liable to check and warp in drying; easily split; very durable in exposed positions. REPRESENTATIVE USES OF WOOD. Cabinet-making, railway ties, posts, fencing, and sills. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 28. MODULUS OF ELASTICITY. 1,200,000. MODULUS OF RUPTURE. 9,800. REMARKS. In the eastern part of the United States, chestnut trees have been attacked by a fungus (tentatively named Diaporthe parasitica), 2 which (1913) is apparently destroying all of the chestnut forests. 1 See also "Chestnut," Pinchot (United States Forest Service, Circular No. 71, 1907); "The American Chestnut Tree," Detwiler (American Forestry, October, 19 15); etc. 2 As stated elsewhere, some botanists believe that this blight should be characterized as Endothia gyrosa or Endothia gyrosa var. parasitica. BROADLEAF TRUNKS AND WOODS 151 Chinquapin. Castanea pumila (Linn.} Mill. NOMENCLATURE (Sudworth). Chinquapin (Del., N. J., Pa., Va., W. Va., N. C., S. C., Ga., Ala., Fla., Miss., La., Tex., Ark., Ohio, Ky., Mo., Mich.). LOCALITIES. Pennsylvania and New Jersey to Florida, Mississippi, Louisiana, Texas, Arkansas, Ohio, Kentucky, Missouri, and Michigan. FEATURES OF TREE. A small tree, sometimes forty-five feet in height; one to two feet or over in diameter; sometimes a low shrub; can be distinguished from the Chestnut (Castanea dentata} by the fact that the leaves are smooth on both sides; the small, prickly burrs contain single, small chestnut-col- ored nuts. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood dark brown; sapwood hardly distinguishable; coarse-grained; the annual layers are marked by rows of open ducts. STRUCTURAL QUALITIES OF WOOD. Rather heavy, hard, and strong; durable in exposed positions; liable to check in drying. REPRESENTATIVE USES OF WOOD. Posts, rails, railway ties, etc. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 36. MODULUS OF ELASTICITY. 1,620,000. MODULUS OF RUPTURE. 14,000. REMARKS. This tree is more suitable for planting in parks than as a source of lumber. The Chinquapin (Castanopsis chrysophylla} is a tree with characteristics which are between those of the Oak and Chestnut. Its wood, which is nearly similar to that of the Chinquapin (Castanea pumila}, is sometimes used for implements. It is native in Oregon and California. BEECH Fagus The Beeches are represented in the temperate regions of the northern hemisphere by a single species (Fagus americana). The European Beech (Fagus sylvatica) is an important tree abroad. 1 Beech wood is hard, heavy, strong, fine-grained, not durable when exposed, and somewhat subject to attack by insects. European Beech is employed to a considerable extent in construc- tion and turnery, and is used more than almost any other local wood for fuel. Beech possesses almost all of the properties that are valued in construction, save durability in exposed positions; in Europe, this deficiency is corrected by artificial means. Beech responds more completely than Oak to treatment with anti- septics, and the French secure longer service from many treated Beech ties, than Americans secure from many treated Oak ties. Beech trees are covered with smooth, light-colored bark. They produce small prickly burrs, each of which contains two triangular, sharp-edged nuts, which are sometimes referred to as beech-mast, and which yield an oil that is occasionally used in place of olive oil. The nuts are not gathered to any extent in the United States. The Coffee, Coffeenut, Coffeebean, Coffeebean-tree, or Mahogany (Gymnocladus dioicus). These trees grow best between the Alleghany Mountains and the Mississippi River. They are valued in landscape effects, and, in many places, are cultivated. The strong, durable, reddish-brown wood works easily, polishes well, and can be used in cabinet work. The Hackberry, Sugarberry, One-berry, Nettle-tree, or False Elm (Celtis occidentalis) . This tree is occasionally found between Canada and Florida and between the Atlantic Coast and the Rocky Mountains. Isolated specimens are sometimes locally famed as " Unknown Trees." The rather hard, strong wood is occasionally used in fencing andjn cheap furniture. 2 1 See also "Beech, Birches and Maples," Maxwell (United States Depart- ment of Agriculture, Bulletin No. 12, 1913). 2 See also "Hackberry," Pinchot (United States Forest Service, Circular No. 75, 1907). 152 BROADLEAF TRUNKS AND WOODS 153 Fagus americana Sweet Fagus grandifolia Fagus atropunicea (Marsh} Sudworth Fagus ferruginea Ait. NOMENCLATURE (Sudworth). White Beech (Me., Ohio, Mich.). Beech (local and common name). Ridge Beech (Ark.). Red Beech (Me., Vt., Ky., Ohio). LOCALITIES. Nova Scotia to Florida, westward intermittently to Wisconsin and Texas. FEATURES OF TREE. Sixty to eighty feet in height, occasionally higher; two to four feet in diame- ter; the small, rough burrs contain two thin-shelled nuts. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood reddish, variable shades; sapwood white; rather close-grained; conspicuous medullary rays. STRUCTURAL QUALITIES OF WOOD. Hard, strong, and tough; not durable when exposed; liable to check during seasoning; takes a fine polish. REPRESENTATIVE USES OF WOOD. Shoe-lasts, plane-stocks, ship-building, handles, and fuel; carpentry (abroad), wagon-making, etc. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 42. MODULUS OF ELASTICITY. 1,720,000. MODULUS OF RUPTURE. 16,300. REMARKS. There is but one species of Beech in North America. The wood is occasionally divided into "Red Beech" and "White Beech," according to its color. This division has no botanical basis, since both of these woods come from the same tree. 154 ORGANIC STRUCTURAL MATERIALS Ironwood, Blue Beech. Carpinus caroliniana Walt. NOMENCLATURE (Sudworth). Ironwood, Blue Beech (local and Hornbeam (Me., N. H., Mass., common names). R. I., Conn., N. Y., N. J., Pa., Water Beech (R. I., N. Y., Pa., Del., N. C., S. C., Ala., Tex., Del., W. Va., Ohio, 111., Ind., Ky., 111., Kans., Minn.). Mich., Minn., Neb., Kans.). LOCALITIES. Quebec to Florida, westward intermittently to Nebraska and Texas. FEATURES OF TREE. Thirty to fifty feet in height; six inches to occasionally two feet in di- ameter; a small tree. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light brown; thick sapwood nearly white; close-grained. STRUCTURAL QUALITIES OF WOOD. Very hard, tough, strong, and heavy; very stiff; inclined to check during seasoning; not durable when exposed. REPRESENTATIVE USES OF WOOD. Levers, tool-handles, etc. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 45. MODULUS OF ELASTICITY. 1,630,000. MODULUS OF RUPTURE. 16,300. REMARKS. The name Ironwood is also applied to the Hornbeam (Ostrya virginiana), and to some other North American species that afford unusually hard, heavy woods suitable for handles and implements. The trunks of the species known as Ironwoods are generally small. BROADLEAF TRUNKS AND WOODS 155 Ironwood, Hop Hornbeam. Ostrya virginiana Willd. NOMENCLATURE (Sudworth). Ironwood, Hop Hornbeam (local Hornbeam (R. I., N. Y., Fla., S. C., and common names). La.). Leverwood (Vt., Mass., R. I., Hardback (Vt.). N. Y., Pa., Kans.). LOCALITIES. Nova Scotia to Florida, westward intermittently to North Dakota, South Dakota, and Texas. FEATURES OF TREE. Thirty to forty feet in height; one foot or less in diameter; the bark ex- hibits long, vertical rows of small squares; small fruit suggest hops in appearance; the leaves resemble those of the Birch. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood reddish brown, sometimes white; sap wood lighter or white; close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Very strong, hard, heavy, and tough; durable when exposed. REPRESENTATIVE USES OF WOOD. Posts, levers, tool-handles, axe-helves, mill-cogs, and wedges. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 51. MODULUS OF ELASTICITY. 1,950,000. MODULUS OF RUPTURE. 16,000. REMARKS. Trees over twelve inches in diameter are often hollow. SYCAMORE Platanus The name Sycamore applies to a Maple (Acer pseudo-platanus) in Europe, to a Fig tree (Ficus sycomorus) in the Orient, and to the Buttonball or Plane trees (Platanus) in North America. Of the Sycamore or Plane trees, the Common or Oriental Plane (Platanus orientalis) is a native of Europe; the Plane, Buttonball, or Sycamore tree (Platanus occidentalis) is a native and common tree of eastern North America; and the California Sycamore (Platanus racemosa) is a native of western North America. 1 American sycamore wood is tough, strong, and difficult to split. The cellular structure is complicated, and a typical use of the wood is for butcher's blocks. Because of its beauty, quar- tered sycamore is used in cabinet work and indoor finish. American Plane, Buttonball, or Sycamore trees are distin- guished by rough heads or balls, which remain hanging on long stems throughout the winter. The bark is also characteristic. Large flakes of the outer bark drop away and expose inner sur- faces, so smooth and white that they appear to be painted. Six or seven species are included in this genus. Three of the species occur in North America. 1 The sycamore possesses an emblematic interest because of its biblical association with Zaccheus. Many European sycamores were planted by religious persons during the Middle Ages because of the belief that they were the trees referred to in the Bible. 156 BROADLEAF TRUNKS AND WOODS 157 Sycamore, Buttonwood, Buttonball-tree. Platanus occidentalis Linn. NOMENCLATURE (Sudworth). Sycamore, Buttonwood, Button- Plane Tree (R. I., Del., S. C., Kans., ball-tree (local and common Neb., la.). names). Water Beech (Del.). Buttonball (R. I., N. Y., Pa., Platane, cotonier, Bois puant (La.). Fla.). LOCALITIES. Maine and Ontario to Florida, westward intermittently to Nebraska and Texas; best in the bottom lands of the Ohio and Mississippi River basins. FEATURES OF TREE. Ninety to over one hundred feet in height; six to sometimes twelve feet in diameter; the inner bark is exposed in white patches; the rough balls or heads are about one inch in diameter. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood reddish-brown; sap wood lighter; close-grained; compact structure; satiny; conspicuous medullary rays; the wood is attractive when quartered. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, and difficult to work; not strong; stands well when not exposed. REPRESENTATIVE USES OF WOOD. Tobacco-boxes, ox-yokes, butcher-blocks, and cabinet-work. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 35. MODULUS OF ELASTICITY. 1,220,000. MODULUS OF RUPTURE. 9,000. REMARKS. Some specimens are among the largest of American deciduous trees, but the bottoms of such exceptionally large trees are usually hollow. The bark is thin and soft when the tree is young but becomes thicker and harder as the tree grows older, until a point is reached when it can no longer stretch to accommodate the growth of the tree. Large areas of the bark are then thrown off by the tree and the inner surfaces which are exposed appear so smooth and white as to suggest the possibility that they have been painted. 158 ORGANIC STRUCTURAL MATERIALS California Sycamore. Platanus racemosa Nutt. NOMENCLATURE. Sycamore, Button wood, Buttonball Tree, Buttonball (California). LOCALITIES. California and Lower California. FEATURES OP TREE. Seventy-five to one hundred feet in height, occasionally higher; three to four feet in diameter; differs from the Sycamore (Platanus occidentalis) in that the balls or heads are in clusters and not solitary; the bark exfo- liates in irregular patches. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light reddish brown; sapwood lighter; close-grained; compact structure; the medullary rays are numerous and conspicuous; the wood is quite attractive when quartered. STRUCTURAL QUALITIES OF WOOD. Brittle, very difficult to split and season; the qualities are similar to those of the Sycamore (Platanus occidentalis) . REPRESENTATIVE USES OF WOOD. Decoration and furniture; used as the wood of the Sycamore (Plalanus occidentalis) is used. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 30. MODULUS OF ELASTICITY. 800,000. MODULUS OF RUPTURE. 7,900 REMARKS. BIRCH Betula Birch trees grow in many places in North America, Europe, and Asia. The ranges of some species extend far into the North. Birch trees are noted for their bark, quite as much as for their wood. 1 The Paper Birch (Betula papyrifera) is the species that is most noted for its bark, which is smooth, pliable, inflammable, water-tight, of a cream or ivory-white color, and marked with long, horizontal, raised dashes or lenticels. The bark contains resinous oils and is so durable that it often remains intact on fallen trees, long after the wood inside has rotted and disappeared. The layers, of which it is composed, separate easily from one another and can be obtained in large-sized pieces. The North American Indians employed it for canoes, tents, troughs, and buckets. It has also been used to write upon and to cover houses. The Yellow Birch (Betula lutea) and the Sweet Birch (Betula lento) are prized for their hard, heavy, strong, fine-grained, and attractive woods, which, however, are not durable in exposed positions. These woods are used in spools, woodenware, in- terior finish, and furniture. They are often stained so as to imitate cherry and mahogany. One of the best of the "imita- tion mahoganies" is obtained by staining Birch. The European Birch (Betula alba) yields the cheapest native hardwood obtain- able in many parts of Europe. This wood, which is moderately hard and strong, but not durable, is used for furniture, plates, spoons, sabots, and similar objects. The Russians glue rotary- cut veneers of birch across one another and form thin, rigid planks that are used for tea-chests and chair-bottoms. Occa- sional burrs yield figured woods that are turned into cups, bowls and mallets. 1 See also " Beech, Birches and Maples," Maxwell (United States De- partment of Agriculture Bulletin No. 12, 1913); "The Birches," Detwiler (American Forestry, April, 1916). 159 160 ORGANIC STRUCTURAL MATERIALS White Birch. Betula populifolia Marsh NOMENCLATURE (Sudworth). Oldfield Birch, Poverty Birch (Me.). White Birch (local and common Poplar-leaved Birch, Small White name). Birch (Vt.). Gray Birch (Me., R. I., Mass.). LOCALITIES. Atlantic Coast, Canada to Delaware and Kentucky. FEATURES OF TREE. Twenty to forty feet in height; rarely one foot in diameter; durable, lam- inated, smooth white bark on the large branches and on the trunk, save near the ground; the bark is not very easily detached from the tree. COLOR, GRAIN, OR APPEARANCE OF WOOD. Heartwood light brown; sapwood lighter; close-grained. STRUCTURAL QUALITIES OF WOOD. Soft and light; not strong or durable. REPRESENTATIVE USES OF WOOD. Clothes-pins, shoe-pegs, toothpicks, and paper-pulp. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 35. MODULUS OF ELASTICITY. 1,036,000. MODULUS OF RUPTURE. 11,000. REMARKS. The white bark is distinct from that of the Paper Birch (Betula papyrifera) in that it does not cover the whole trunk. The layers split less easily from one another. BROADLEAF TRUNKS AND WOODS 161 Paper Birch, White Birch. Betula papyrifera Marsh NOMENCLATURE (Sud worth). Paper Birch, White Birch (local Boleau (Quebec). and common names). Canoe Birch (Me., Vt., N. H., R. I., Silver Birch (Minn.). Mass., N. Y., Pa., Wis., Mich., Large White Birch (Vt.). Minn.). LOCALITIES. Northern United States, northward into Canada and to the valley of the Yukon in Alaska. FEATURES OF TREE. Fifty to seventy feet in height; one and one-half to two and one-half feet in diameter; smooth white exterior bark on large limbs and on trunks at a distance from the ground; brown or orange-colored inner surfaces of bark; the bark splits freely into thin, paper-like layers. COLOR, GRAIN, OR APPEARANCE OF WOOD. Heartwood brown, tinged with red; sapwood nearly white; very close- grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Strong, hard, and tough; is not durable when exposed to the weather; the bark takes fire easily, even when it is wet. REPRESENTATIVE USES OF WOOD. Spools, shoe-lasts, pegs, pill-boxes, paper-pulp, and fuel; the bark was used in canoes. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 37. MODULUS OF ELASTICITY. 1,850,000. MODULUS OF RUPTURE. 15,000. REMARKS. These trees grow at higher latitudes than most other American deciduous trees. They form forests. 1 1 See also "Paper Birch, Betula papyrifera Marsh" (United States Forest Service, Silvical Leaflet No. 38, 1908). 11 162 ORGANIC STRUCTURAL MATERIALS Red Birch. Betula nigra Linn. NOMENCLATURE (Sudworth). Red Birch (local and common River Birch (Mass. R. I., N. J., name). Del., Pa., W. Va., Ala., Miss., Black Birch (Fla., Tenn., Tex.). Tex., Mo., 111., Wis., Ohio). Birch (N. C., S. C., Miss., La.). Water Birch (W. Va., Kans.). Blue Birch (Ark.). LOCALITIES. Massachusetts to Florida, westward intermittently to Nebraska and Texas; best development in South Atlantic and lower Mississippi valley regions. FEATURES OF TREE. Thirty to eighty feet in height; one to three feet in diameter, sometimes larger; dark red-brown scaly bark on trunk; red to silver-white bark on branches; the bark separates into thin, paper-like scales, which curl outward. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood light brown; sapwood yellowish white; close-grained, com- pact structure. STRUCTURAL QUALITIES OF WOOD. Light, rather hard, and strong. REPRESENTATIVE USES OF WOOD. Furniture, wooden ware, shoe-lasts, and ox-yokes; inferior cask -hoops are made from the branches; also used as a base upon which enamelled paints are applied. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 35. MODULUS OF ELASTICITY. 1,580,000. MODULUS OF RUPTURE. 13,100. REMARKS. Dark-brown bark, whence the name Red Birch. Prefers moist bottoms, whence the name River Birch. BROADLEAF TRUNKS AND WOODS 163 Yellow Birch. Betula lutea Michx. f. NOMENCLATURE (Sudworth). Yellow Birch (local and common Swamp Birch (Minn.). name). Silver Birch (N. H.). Gray Birch (Vt., R. I., Pa., Mich., Merisier, Merisier Rouge (Quebec). Minn.). American Mahogany. LOCALITIES. Newfoundland to North Carolina, westward intermittently to Manitoba and Texas; best developed north of the Great Lakes. FEATURES OP TREE. Sixty to eighty or more feet in height; two to four feet in diameter; a medium-sized tree; the bark on the trunk is silver-gray to silver-yellow, while the bark on the branches varies between green and lustrous or dull-brown; the bark exfoliates, causing a rough, ragged appearance. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light reddish brown; sapwood nearly white; close-grained; compact structure; satin-like appearance. STRUCTURAL QUALITIES OF WOOD. Heavy, strong, hard, and tough; is susceptible to a high polish; the quali- ties suggest those of Maple; is not durable when exposed to the weather. REPRESENTATIVE USES OF WOOD. Furniture, buttons, tassel-moulds, pill-boxes, spools, wheel-hubs, and chair seats; occasional burls are valued for making mallets; the wood is also used as a base upon which enamelled paints are applied. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 40. MODULUS OF ELASTICITY. 2,290,000. MODULUS OF RUPTURE. 17,700. REMARKS. The thin outer bark is sometimes ruptured in such a way as to show the almost metallic yellow of the inner bark. The name is due to the yellow appearance of the inner bark, which is also characterized by the fact that it possesses a pungent, pleasant flavor. 164 ORGANIC STRUCTURAL MATERIALS Sweet Birch, Cherry Birch. Betula lenla Linn. NOMENCLATURE (Sudworth). Black Birch (N. H., Vt., Mass., Sweet Birch, Cherry Birch. R. I., Conn., N. Y., N. J., Pa., (many localities). W. Va., Ga., 111., Ind., Mich., Mahogany Birch (N. C., S. C.). Ohio). River Birch (Minn.). Mountain Mahogany (S. C.). LOCALITIES. Newfoundland, intermittently to Illinois, southward intermittently along the Alleghanies to Kentucky, Tennessee, and Florida. FEATURES OF TREE. Fifty to eighty feet in height; three to four feet in diameter; the dark red- dish-brown bark resembles that of the Cherry; it does not separate into layers as in the case of the Paper Birch (Betula papyrifera) ; the leaves, bark, and twigs are sweet, spicy, and aromatic. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood dark brown, tinged with red; sapwood light brown or yellow; close-grained ; compact structure. STRUCTURAL QUALITIES OF WOOD. Heavy, very strong, and hard ; the wood is often stained so as to resemble cherry and mahogany; it is also used as a base upon which enamelled paints are applied. REPRESENTATIVE USES OF WOOD. Woodenware, furniture, ship-building (Canada), and fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 47. MODULUS OF ELASTICITY. 2,010,000. MODULUS OF RUPTURE. 17,000. REMARKS. A common tree in some of the Northern States. The name Cherry Birch is due to the bark, the appearance of which suggests that of the Cherry tree. The name Sweet Birch is due to the sweet, spicy essences in the bark. LOCUST, MESQUITE Robinia, Gleditsia, Prosopis The name Locust applies to species of three distinct genera of the family Leguminosse. The Black Locust (Robinia pseud- acacia), the Honey Locust (Gleditsia triacanthos) , and the Mesquite or Honey Locust (Prosopis juli flora) grow in the United States. 1 The wood of the Black Locust is noted for toughness, dura- bility, and great torsional strength. Black Locust trenails and wheel-spokes have few, if any, superiors. Black Locust trees may be known by their clusters of large peablossom-shaped flowers and by their bean-shaped pods, which are from three to six inches in length. The large thorns on the trunks are also characteristic. There are several species and varieties of the genus Robinia in the United States. The wood of the Honey Locust resembles that of the Black Locust, but is seldom used, save in rough constructions, as fence rails. The Honey Locust bears blossoms that are smaller than those of the Black Locust, but the pods of the Honey Locust are from ten to eighteen inches long. There are several species and varieties. The wood of the Mesquite is hard, heavy, and practically indestructible when exposed. Mesquite beams exist in some native houses in the Southwest, and Mesquite railway ties and fence posts are also occasionally seen. Mesquite trees are found where those of other species cannot grow. They can survive when almost entirely covered with sand. To the localities in which they grow, they are much as Bamboos are to China and Japan. The woods themselves are valued; the rich, pulpy pods are used as food ; a mucilage is made from the gum ; and a dye is made from the sap. One other species, the Screwpod Mesquite (Prosopis odorata) is found in the United States. 1 See also "An Economic Study of Acacias/' Shinn ("United States Depart- ment of Agriculture, Bulletin No. 9, 1913). "The Locusts/' Detwiler (American Forestry, February, 1917). 165 166 ORGANIC STRUCTURAL MATERIALS Locust, Black Locust, Yellow Locust. Robinia pseudacacia Linn. NOMENCLATURE (Sudworth). Red Locust, Green Locust (Term.). Locust, Black Locust, Yellow Honey Locust (Minn.). Locust (local and common White Locust (R. I., N. Y., Tenn.). names). Acacia (La.). False Acacia (S. C., Ala., Tex., Minn. Pea-flower Locust, Post Locust (Md.). LOCALITIES. Mountains, Pennsylvania to Georgia, westward to Iowa and Kansas; widely naturalized in the northeastern part of the United States. FEATURES OF TREE. Fifty to seventy feet in height; two to three feet or over in diameter; the seven to seventeen leaflets curl up or close at night ; there are long spines on young branches. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood brownish; the thin sap wood is of a light greenish-yellow color; close-grained and compact; the annual layers are clearly marked. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, and strong; durable when exposed to the weather. REPRESENTATIVE USES OF WOOD. Long wooden bolts or pins called trenails ; posts, ties, construction, turnery, ship-ribs, ornamentation, and fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 45. MODULUS OF ELASTICITY. 1,830,000. MODULUS OF RUPTURE. 18,100. REMARKS. Extensively planted, particularly in the West. Subject to attacks by insect-borers. One of the most valuable timber trees in the United States. Heartwood forms very early in the life of this tree. BROADLEAF TRUNKS AND WOODS 167 Honey Locust. Gleditsia triacanthos Linn. NOMENCLATURE (Sud worth). Honey or Honeyshucks (R. I., N. J., Honey Locust (local and common Va., Fla., La.). name). Honeyshucks Locust (Ky.). Thorn or Thorny Locust Tree or Sweet Locust (S. C., La., Kan., Acacia (N. Y., N. J., Ind., Neb.). Tenn., La.). Piquant Amourette (La.). Three-thorned Acacia (Mass., Confederate Pintree (Fla.). R. I., La., Tex., Neb., Mich.). Locust (Neb.). Black Locust (Miss., Tex., Ark., Kan., Neb.). LOCALITIES. Ontario and Pennsylvania to Florida, westward intermittently to Ne- braska and Texas; best in lower Ohio River basin. FEATURES OP TREE. Seventy to ninety feet or more in height; two to four feet in diameter; long spines are plentiful on some individuals, but are absent on others; the brown fruit pods, which are from ten to eighteen inches long, contain sweetish, succulent pulp. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood bright brown or red; sap wood yellowish; annual layers strongly marked; coarse-grained; the medullary rays are conspicuous. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, and strong; very durable in contact with the soil. REPRESENTATIVE USES OF WOOD. Fence-posts, rails, wagon-hubs, rough construction work, etc. 1 WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 42. MODULUS OF ELASTICITY. 1,540,000. MODULUS OF RUPTURE. 13,100. REMARKS. These trees are widely cultivated for landscape effects. They are also used in hedges. 1 See also "Honey Locust," Pinchot (United States Forest Service, Cir- cular No. 74, 1907). 168 ORGANIC STRUCTURAL MATERIALS Mesquite. Prosopis juliflora de C. NOMENCLATURE (Sudworth) Honey Pod or Honey Locust (Tex., Mesquite (Tex., N. M., Ariz., N. M.). Cal.). Ironwood (Tex.). Algaroba (Tex., N. M., Ariz., Cal.). LOCALITIES. Texas, west to the San Bernardino Mountains in California. Also Colorado, Utah, Nevada, and northern Mexico. Mesquite trees are cultivated in Hawaii. FEATURES OF TREE. Forty to fifty feet in heigth; one to two feet in diameter; sometimes a low shrub; the roots are often very large; the pods contain a sweet pulp; there are gums which resemble gum arabic. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood rich dark brown, often red; sapwood clear yellow; close- grained; compact structure; distinct medullary rays. STRUCTURAL QUALITIES OP WOOD. Weak, difficult to work, heavy, hard, and very durable receives a high polish. REPRESENTATIVE USES OF WOOD. Posts, fencing, ties, house-beams, fuel, and charcoal. WEIGHT OP SEASONED WOOD IN POUNDS PER CUBIC FOOT. 47. MODULUS OP ELASTICITY. 820,000. MODULUS OP RUPTURE. 6,800. REMARKS. The Mesquite tree can survive when almost entirely covered with sand. The roots develop greatly in their search for water, and are often dug up and used for fuel in localities where there is nothing better. The tree is important locally. CHAPTER VII BANDED TRUNKS AND WOODS (CONTINUED) BROADLEAF SERIES, PART Two Dicotyledons WHITEWOOD OR TULIP-TREE WOOD. POPLAR OR COTTON- WOOD. CUCUMBER-TREE WOOD. BASSWOOD. Liriodendron. Populus. Magnolia. Tilia. These unrelated trees are grouped together because they yield similar, soft, clean, fine-grained woods that are all valued for indoor work. The woods all last well when protected from the weather, but no one of them is durable when exposed. The Whitewood or Tulip-tree (Liriodendron tulipifera) is a native of North America. The wood, which is the best of its kind, is soft, rigid, fine-grained, clean, free from knots, straight- grained, capable of being nailed without splitting, and obtainable in large-sized pieces. It is used for boxes, shelves, the bottoms of drawers, and house-trim. In spite of its name, it is of a greenish-yellow color. The trees are often very large. Mat- thews 1 mentions a specimen that was thirty-nine feet in circum- ference. Whitewood trees may be known by their large tulip- shaped flowers. Poplar Trees Grow on Both Hemispheres. The tough, light woods will indent without breaking, and were formerly used for shields. The woods are now used much as whitewood is used, for trunks, boxes, woodenware, and indoor finish, but they are not as good as whitewood. The trees are sometimes called Cottonwoods because their seeds are covered with a cotton-like down. The foliage of some species, as the Aspen (Populus tremuloides) , is agitated by the slightest wind. This is due to the shape of the long leaf-stems 2 . The Balsam Poplar or Balm of Gilead (Populus balsamifera) , which thrives far into the North, must not be confused with the true Balsam or Balm of Gilead (Abies balsamea). Sudworth credits twelve species of the genus Populus to the United States. The Cucumber-tree (Magnolia acuminata) is a member of the Magnolia family, and yields a wood that is seldom distinguished commercially from Whitewood. 169 170 ORGANIC STRUCTURAL MATERIALS Basswood Trees are Known by Many Names. Limes, Lime- trees, Lind, Linden, Tiel, Tieltrees, Beetrees, Bass, and Basswood trees are the same. The woods are prized for their working qualities which resemble, but are inferior to those of white wood; and the trees are prized for their dense shade and fine appearance. The Basswood (Tilia americana) is the principal species in the United States. Basswood trees bear small, fragrant, cream- colored flowers that are often surrounded by bees. "Familiar Trees," F. Schuyler Matthews (p. 39, Appleton, 1901). 2 See also "The Aspens," Weigle and Frothingham (United States Forest Service, Bulletin No. 93, 1911); "Cottonwood in the Mississippi Valley," Williamson (United States Department of Agriculture, Bulletin No. 24, 1913.) BROADLEAF TRUNKS AND WOODS 171 Tulip Tree, Whitewood, Yellow Poplar. Liriodendron tulipifera Linn. NOMENCLATURE (Sudworth). Tulip Tree, Whitewood, Yellow Hickory Poplar (Va., W. Va., Poplar (local and common names). N. C.). Poplar (R. I., Del., N. C., S. C., Fla., Blue Poplar (Del., W. Va.). Ohio). Popple (R. I.). Tulip Poplar (Del., Pa., S. C., 111.). Cucumber Tree (N. Y.). Canoewood (Tenn.). LOCALITIES. New England to Florida, westward intermittently to Michigan and Arkansas. FEATURES OF TREE. Ninety to one hundred and fifty feet in height; six to twelve feet in di- ameter; tulip-shaped flowers appear in the spring; the greenish cone-like fruit dries and remains after the leaves have fallen. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light yellow or greenish brown; the thin sapwood is nearly white; close and straight-grained; compact structure; free from knots. STRUCTURAL QUALITIES OF WOOD. Light, soft, moderately strong, but brittle; easily worked; not dur- able in contact with the ground; hard to split; shrinks little; resembles White Pine (Pinus strobus); stands well in protected places. REPRESENTATIVE USES OF WOOD. Lumber, interior finish, woodenware, shelves, and bottoms of drawers; used as a base upon which enamelled paints are applied. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 26. MODULUS OF ELASTICITY. 1,300,000. MODULUS OF RUPTURE. 9,300. REMARKS. Very large trees were formerly common. Whitewood is sometimes divided by lumbermen into "White Poplar" and "Yellow Poplar." One of the largest and most useful of American deciduous trees. 172 ORGANIC STRUCTURAL MATERIALS Poplar, Largetooth Aspen. Populus grandidentata Michx. NOMENCLATURE (Sudworth). Poplar, Largetooth Aspen (local White Poplar (Mass.). and common names). Popple (Me.). Largetooth Poplar (N. C.). Large American Aspen (Ala.). Large Poplar (Tenn.). LOCALITIES. Nova Scotia and. Delaware, westward intermit tentty to Minnesota. Alleghany. Mountains, to Kentucky, and Tennessee. FEATURES OP TREE. Sixty to eighty feet in height; two feet or more in diameter; there are irregular points or teeth on the margins of the leaves; the flowers appear before the leaves in the spring; the gray bark is smooth. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood brownish; sapwood nearly white; close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Soft, light, and weak. REPRESENTATIVE USES OF WOOD. Paper-pulp and occasionally woodenware. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 28. MODULUS OF ELASTICITY. 1,360,000. MODULUS OF RUPTURE. 10,200. REMARKS. The Quaking Aspen (Populus tremuloides) has long leafstalks, flattened vertically to the leaf-surfaces, which cause the leaves to tremble in slight winds. This characteristic is more or less pronounced with other species of the genus Populus. Ailanthus (Ailanthus glandulosa). This sturdy, beautiful, very quick- growing, but short-lived tree was once popular in the United States, par- ticularly in city landscapes, but it was discarded because of the disagree- able, far-reaching odor of its flowers. The tree has many merits. In Europe, the wood is used for woodenware and charcoal; in China, certain silkworms feed upon the leaves of the trees. The Chinese call the Ailanthus the "Tree of Heaven." American specimens have grown in excess of ten feet in length during the first year. BROADLEAF TRUNKS AND WOODS 173 , IPopulus deltoides Marsh Cottonwood. 1 r> 7 -7 * A M (Populus monihfera Ait. NOMENCLATURE (Sudworth). Cottonwood (local and common Big Cottonwood (Miss., Neb.). name). Whitewood (la.). Carolina Poplar (Pa., Miss., La., Cotton Tree (N. Y.). N. M., Ind., Ohio). Necklace Poplar (Tex., Colo.). Yellow Cottonwood (Ark., la., Broadleaved Cottonwood (Colo.). Neb.). LOCALITIES. Canada to Florida, westward intermittently to Rocky Mountains. FEATURES OF TREE. Seventy-five to one hundred feet in height; four to five feet in diameter; occasionally much larger; long catkins distribute cotton-like fibers. COLOR, APPEARANCE, OR GRAIN OP WOOD. Thin heartwood dark brown; sapwood nearly white; close-grained; com- pact structure. STRUCTURAL QUALITIES OF WOOD. Light, soft, weak, liable to warp, and difficult to season. REPRESENTATIVE USES OF WOOD. Greatly valued in the manufacture of paper-pulp; also used for packing- boxes, fence-boards, and fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 24. MODULUS OF ELASTICITY. 1,400,000. MODULUS OF RUPTURE. 10,900. REMARKS. See also "Cottonwood" (United States Forest Service, Circular No. 77). 174 ORGANIC STRUCTURAL MATERIALS Black Cottonwood. Populus trichocarpa Ton. and Gr. NOMENCLATURE (Sud worth). Cottonwood (Oreg., Cal.). Black Cottonwood (Oreg., Cal.). Balm Cottonwood (Cal.). Balsam Cottonwood, Balm (Oreg.). LOCALITIES. Pacific Coast region, Alaska to California. FEATURES OF TREE. A large tree, sometimes one hundred and fifty feet in height and four to six feet in diameter; the broadly ovate leaves have blunt, marginal teeth. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light dull brown; sapwood nearly white; compact structure. STRUCTURAL QUALITIES OF WOOD. Light, soft, and weak. REPRESENTATIVE USES OF WOOD. Staves, and sometimes woodenware. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 23. MODULUS OF ELASTICITY. 1,580,000. MODULUS OF RUPTURE. 8,400. REMARKS. The largest deciduous tree of the Puget Sound district. The Cottonwood, Tacmahac, Balsam, Balsampoplar, or Balm of Gilead (Populus balsamifera) which grows from Hudson Bay and Alaska, southward to Oregon and New England is a distinctly northern species. The large upright trunk yields a light, soft, light-colored wood which has been used in making paper. The exudations are sometimes used in medicine. BROADLEAF TRUNKS AND WOODS 175 Cucumber-tree. Magnolia acuminata Linn. NOMENCLATURE (Sudworth). Mountain Magnolia (Miss., Ky.). Cucumber-tree (R. I., Mass., N. Y., Black Lin, Cucumber (W. Va.). Pa., N. C., S. C., Ala., Miss., La., Magnolia (Ark.). Ark., Ky., W. Va., Ohio, Ind., 111.). LOCALITIES. New York to Illinois, southward intermittently through Kentucky and Tennessee to the Gulf. FEATURES OF TREE. Fifty to occasionally one hundred feet in height; two to four feet in diame- ter; a large, handsome, symmetrical tree, with fruit suggesting cucum- bers; large greenish-yellow or cream-colored flowers. COLOR, APPEARANCE OR GRAIN OF WOOD. Heartwood brownish yellow ; sap wood nearly white; close-grained; com- pact structure; thin medullary rays. STRUCTURAL QUALITIES OF WOOD. Light, soft, not strong, but durable. REPRESENTATIVE USES OF WOOD. Cabinet-making, cheap furniture, flooring, pump-logs, troughs, crates, and packing-boxes. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 29. MODULUS OF ELASTICITY. 1,310,000. MODULUS OF RUPTURE. 9,500. REMARKS. The wood resembles and is often sold for that obtained from the Tulip Tree (Liriodendron lulipifera). 176 ORGANIC STRUCTURAL MATERIALS Basswood, Linn, Linden. Tilia americana Linn. NOMENCLATURE (Sudworth). Whitewood (Vt., W. Va., Ark., Basswood, Linn, Linden, Ameri- Minn.). can Linden (local and common Yellow Basswood, Lein (Ind.). names). Beetree (Vt., W. Va., Wis.). Limetree (R. I., N. C., S. C., Ala., White Lind (W. Va.). Minn., La., 111.). Wickup (Mass.). Black or Smooth-leaved Lime- tree (Tenn.). LOCALITIES. New Brunswick to Georgia, westward intermittently to Manitoba and Texas. A wide range. FEATURES OP TREE. Sixty to ninety feet in height; two to four feet in diameter; occasionally larger; large smooth leaves; fragrant flowers, borne on slender, leaf -like structures. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light or reddish brown ; thick sap wood nearly similar; very straight and close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Light, soft, easily worked, and tough; not strong or durable. REPRESENTATIVE USES OF WOOD. Sides and backs of drawers, bodies of carriages, woodenware, and paper- pulp. 1 WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 28. MODULUS OF ELASTICITY. 1,190,000. MODULUS OF RUPTURE. 8,300. REMARKS. Parts of the inner bark have occasionally been utilized for cordage. The fragrant flowers attract bees. The wood of the White Basswood (Tilia heterophylld] is not distinguished from that of the Common Basswood by dealers. !See also "Basswood," Pinchot (United States Forest Service, Circular No. 63, 1907). BROADLEAF TRUNKS AND WOODS 177 WILLOW Salix The willows grow in many places on both hemispheres. North Americans value the fast-growing, characteristically shaped trees; while Europeans value the woods. The principal experience with the wood of the Willow has been gained in Europe. The wood is light, tough, easily worked, and elastic. It resists splintering, stands well against abrasion, and in Europe is used for friction-brake linings, lapboards, cricket bats, keels and paddles, Willow charcoal ignites readily and for this reason is used in gunpowder. Willow rods are used in basket-making. 1 In the United States Willow trees are used to protect and some- times, by creating eddies, to recover land from water encroach- ment. Saplings up to three or four inches in diameter are used in river improvements. These saplings are made into mattresses which are placed along the banks of streams to prevent scour. Some of the mattresses thus constructed for Mississippi River improvement work are three hundred feet wide and one thousand feet long. 2 Saplings are known as " Osiers" and are regularly cultivated in Europe. The term Osier Willow is sometimes applied to trees that yield strong, slender shoots. The true Osier, Sandbar, or Longleaf Willow (Salix fluviatilis) grows in many places from the Arctic Ocean southward to Mexico. The White, Crack, Bedford, and Goat Willows (Salix alba, Salix fragilis, Salix russeliana, and Salix caprea) are said to afford good woods. 1 See also "The Basket Willow" (United States Forest Service, Bulletin No. 46); "Production and Consumption of Basket Willows in the United States, etc.," Mell (United States Forest Service, Circular No. 155, 1909); "Basket Willow Culture," Lamb (United States Department of Agriculture, Farmers" Bulletin No. 622, 1914); "Willows: Their Growth, Use, and Im- portance," Lamb (United States Forest Service, Bulletin No. 316, 1915). "The Willows: Identification and Characteristics," Detwiler, (American Forestry, January, 1917). 2 "Bank Revetment on the Lower Mississippi," Coppee (Transactions American Society of Civil Engineers, Vol. 35, p. 198); "Erosion of River Banks on the Mississippi and Missouri Rivers," Ockerson (Transactions American Society of Civil Engineers, Vol. 38, p. 396). 178 ORGANIC STRUCTURAL MATERIALS Black Willow. Salix nigra Marsh NOMENCLATURE (Sudworth). Willow (N. Y., Pa., N. C., S. C., Black Willow (local and common Miss., Tex., Cal., Ky., Mo., name). Neb.). Swamp Willow (N. C., S. C.). LOCALITIES. New Brunswick to Florida, westward intermittently to the Dakotas, Arizona, California, and Mexico ; grows best on bottom lands and along the borders of rivers. FEATURES OP TREE. Forty to fifty feet in height; two to four feet in diameter; long, narrow leaves; a characteristic appearance. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood brown ; sap wood nearly white ; close-grained. STRUCTURAL QUALITIES OF WOOD. Soft, light, and weak; checks badly in drying; readily worked; dents with- out splitting. REPRESENTATIVE USES OF WOOD. Lap-boards, basket-making, fuel, and charcoal. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 27. MODULUS OF ELASTICITY. 550,000. MODULUS OF RUPTURE. 6,000. REMARKS. Many species and varieties of Willow trees grow in the United States, but none of them yield wood that is used to any extent in construction. Willow rods, either whole or split, are used by basket makers. It is said that sap-peeled rods retain their light color, and that steamed rods turn yellow. The European uses of Willow wood have been referred to. The White Willow (Salix alba}, which has been naturalized in North Amer- ica, is hardy, even when located in dry places. On the prairies, this tree is sometimes used as a wind-break. Trees planted several feet apart serve as fence-posts to support barbed wire. BROADLEAF TRUNKS AND WOODS 179 CATALPA Catalpa Catalpa trees grow in the eastern part of the United States, in the West Indies, and in some parts of China. The Common Catalpa (Catalpa catalpa) and the Hardy Catalpa (Catalpa speciosa) are natives of North America. The name of the genus is that which was given to one of these species by the Cherokee Indians. Until recently the Catalpas have attracted but little attention. But they are now regarded with interest, because, when the right conditions prevail, the trees grow rapidly and yield woods that can be used in construction. Catalpa trees have reached a thickness of as much as sixteen inches in seventeen years. The wood is soft, weak, brittle, clean, smooth-grained, and very durable. Von Schrenk believes that the final disintegration of this wood will not be due to attacks from fungi, since no fungus has yet been found that will grow in dead Catalpa lumber. The wood is attractive in appearance and is suitable for some forms of interior finish as well as for carpentry. Catalpa posts and poles are highly valued, but railway ties of this wood do not stand well under heavy traffic. The supply of Catalpa wood thus far is limited. Catalpa trees may be known by their flowers and by their long beans, which are sometimes known as smoking-beans. 1 1 The Forester, October, 1900, and November, 1902. Forestry Quarterly, vol. iii, N. Y. "An Experiment in Western Catalpa." (Report of the Penn- sylvania Dept. of Forestry for 1910-11.) "Hardy Catalpa," Hall and von Schrenk (United States Forestry Bureau, Bulletin No. 37). 180 ORGANIC STRUCTURAL MATERIALS Catalpa, Hardy Catalpa. Catalpa speciosa Warder NOMENCLATURE (Sudworth). Catalpa (R. I., N. Y., La., 111., Western Catalpa (Pa., Ohio, la., Ind., Mo., Wis., la., Neb., Neb., 111.). Minn.). Cigar Tree (Mo., la.). Hardy Catalpa (111., la., Kan., Indian Bean, Shawneewood (Ind.). Mich.). Bois Puant (La.). LOCALITIES. Central Mississippi Valley, naturalized in many localities. FEATURES OP TREE. Forty to sixty feet or more in height; three to six feet in diameter; well- formed trunk; large, white, faintly mottled flowers; long pods or beans. COLOR, APPEARANCE, OR GRAIN OF WOOD. Thick heartwood brown; thin sapwood lighter, nearly white; coarse- grained; compact structure; annual layers clearly marked ; an attract- ive wood. STRUCTURAL QUALITIES OF WOOD. Light, soft, not strong, but durable in contact with the soil. REPRESENTATIVE USES OF WOOD. Railway ties, fence-posts, and rails; can be used in cabinet-work and interior finish. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 25. MODULUS OF ELASTICITY. 1,160,000. MODULUS OF RUPTURE. 9,000. REMARKS. Catalpa trees are not seriously injured by occasional inundations, and, for this reason, are sometimes planted along streams. Under the right conditions, they grow rapidly, and are sometimes used in landscape effects. As a rule, the trunks of the Hardy Catalpa are better formed than those of the Catalpa. Paulownia (Paulownia tomentosa). This tree is a native of Asia, but is now cultivated in some of the Central-Atlantic and Southern States. It has catalpa-like leaves, which are preceded by large pale blue or violet flowers and followed by woody, capsule-like fruit that in form suggests hickory nuts. The species, which is of small importance, is not related to the Catalpa, but is sometimes confused with it. BROADLEAF TRUNKS AND WOODS 181 P , . | Catalpa catalpa (Linn.) Karst \ Catalpa bignonioides Walt. NOMENCLATURE (Sudworth). Catalpa (local and common name). Indian Bean (Mass., R. I., N. Y., Indian Cigar Tree (Pa.). N. J., Pa., N. C., 111.). Smoking Bean (R. I.). Catawba, Catawba Tree (Del., Cigar Tree (R. I., N. J., Pa., W. Va. W. Va., Ala., Fla., Kan.). Mo., 111., Wis., la.). Beantree (N. J., Del., Pa., Va., La., Neb.). LOCALITIES. Native only in the Gulf States, but naturalized in many localities east of the Rocky Mountains. FEATURES OF TREE. Thirty to fifty feet in height; one to two or more feet in diameter; often the trunks are not well formed; low, wide trees, with large heart- shaped leaves and characteristic flowers; long slender pods or beans; distinguished from the Hardy Catalpa by the fact that the flowers are smaller and in denser clusters. COLOR, APPEARANCE, OR GRAIN OF WOOD. Thick heartwood is light pink brown; the thin sapwood is nearly white; coarse-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Light, soft, not strong, but durable in contact with the soil. REPRESENTATIVE USES OF WOOD. Fence-posts, railway ties, etc. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 27. MODULUS OF ELASTICITY. 960,000. MODULUS OF RUPTURE. 8,300. REMARKS. These trees grow rapidly, but the wood is less desirable than that obtained from the Hardy Catalpa (Catalpa speciosa). The long pods which remain on the trees after the leaves have disappeared, are sometimes used locally as cigars. 182 ORGANIC STRUCTURAL MATERIALS MULBERRY Morus Two species of Mulberry grow in North America, and a few others grow abroad. Of these, the most valuable is the White Mulberry (Morus alba), a native of northern China and Japan, which is now also cultivated in many other countries for its leaves which form the best food for silkworms. The Red Mul- berry (Morus rubra) and the Mexican Mulberry (Morus celtidi- folia) are the species that are native to the United States. The American species yield fairly hard, rather heavy, and quite durable woods that are sometimes used in cooperage, flumes, boats, and fences. White, Red, and Black Mulberry trees may be distinguished from one another by the color of their sweet berries. Red Mulberry, Mulberry. Morus rubra Linn. NOMENCLATURE (Sudworth). Red Mulberry, Mulberry (local Virginia Mulberry Tree (Term.). and common names). Murier Sauvage (La.). Black Mulberry (N. J., Pa., W.Va.). LOCALITIES. Massachusetts to Florida, westward intermittently to Nebraska and Texas; best in lower Ohio and Mississippi River basins. FEATURES OF TREE. Fifty to sixty feet in height; two and one-half to three feet in diameter; sweet, edible fruit; the leaves are very variable, sometimes entire, but often three-lobed; dark brown broken bark; smooth gray branches.- COLOR, APPEARANCE, OR GRAIN OF WOOD. Thick heartwood, light orange yellow; thin sapwood whitish; coarse- grained; compact structure; the annual layers are clearly marked. STRUCTURAL QUALITIES OF WOOD. Light, soft, not strong, but very durable in contact with the soil; it re- ceives a good polish. REPRESENTATIVE USES OF WOOD. Fencing, cooperage, etc. WEIGHT OF SEASONED WOODS IN POUNDS PER CUBIC FOOT. 36. MODULUS OF ELASTICITY. MODULUS OF RUPTURE. 11,700,000. 11,000. REMARKS. An ornamental tree. BROADLEAF TRUNKS AND WOODS 183 HORSE CHESTNUT. BUCKEYE Aesculus Horse Chestnut trees (Aesculus hippocastanum) , supposed to be natives of Asia, have long been among the most popular shade trees of Europe and North America. The Buckeyes (Aesculus glabra, Aesculus octandra, and Aesculus californica) grow from Ohio and southern Iowa, southward to northern Georgia and northern Louisiana, and in California. The name " Horse Chest- nut" is probably due to an ironical reference to the coarse nuts, while the name " Buckeye" refers to the appearance of the nut of that tree which, under certain conditions, suggests the eye of the deer. Horse Chestnut and Buckeye woods resemble one another, in that both are soft, straight-grained, and easily worked. They decay rapidly when exposed to the weather. The woods are sometimes employed in artificial limbs, splints, woodenware, and paper pulp. Both trees may be known by their nuts, which are enclosed in prickly husks. 1 also "Trees of Northern States and Canada," Hough, page 338. 184 ORGANIC STRUCTURAL MATERIALS Ohio Buckeye, Fetid Buckeye. Aesculus glabra Willd. NOMENCLATURE (Sudworth). Buckeye, Ohio Buckeye (local Stinking Buckeye (Ala., Ark.). and common names). American Horse Chestnut (Pa.). Fetid Buckeye (W. Va.). LOCALITIES. Ohio River basin to Alabama, portions of Iowa, Kansas, and Oklahoma. FEATURES OP TREE. Twenty-five to forty-five feet in height; one to one and one-half feet in diameter; the yellowish-white flowers are succeeded by round prickly pods which contain nuts. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heart wood white; sap wood a little darker; close-grained; frequent dark lines of decay. STRUCTURAL QUALITIES OF WOOD. Weak, light, and soft, but hard to split. REPRESENTATIVE USES OP WOOD. Artificial limbs, wooden ware, and paper-pulp; rarely lumber. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 28. MODULUS OF ELASTICITY. 910,000. MODULUS OF RUPTURE. 7,000. REMARKS. The nearly similar Horse Chestnut (Aesculus hippocastanum) is not native, but is largely planted in North America. It is from forty to fifty or more feet in height, and is from two to sometimes four feet in di- ameter. The Horse Chestnut tree is one of the most popular of all shade trees. The light, weak wood is seldom used. BROADLEAF TRUNKS AND WOODS 185 f Aesculus octandra Marsh Buckeye, Sweet Buckeye. 7/7 * . { Aesculus flava Ait. NOMENCLATURE (Sudworth). Buckeye (N. C., S. C., Ala., Miss., Yellow Buckeye (S. C., Ala.). La., Tex., Ky.). Large Buckeye, Big Buckeye (Tex. Sweet Buckeye (W. Va., Miss., Tenn.). Tex., Mo., Ind.). LOCALITIES. Alleghany Mountains, Pennsylvania to Georgia, westward intermittently to Iowa and Texas. FEATURES OF TREE. Forty to seventy feet in height; one to three feet in diameter; sometimes a low shrub ; the pods are distinguished from those of the Ohio Buckeye (Aesculus glabra) by the fact that they are smooth. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood creamy white; sapwood similar; compact structure; close- grained; difficult to split. REPRESENTATIVE USES OF WOOD. Similar to those of the Ohio Buckeye (Aesculus glabra). WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 26.64. MODULUS OF ELASTICITY. MODULUS OF RUPTURE. REMARKS. The California Buckeye or California Horse Chestnut (Aesculus calif or- nica), grows along the Pacific Coast from Mount Shasta, southward to Los Angeles. It is often quite small, but in some localities is from thirty to forty feet in height. The soft, light, compact, close-grained, ivory-white wood could probably be employed in turnery. 186 ORGANIC STRUCTURAL MATERIALS GUM Liquidambar, Nyssa This name applies to a number of trees that lie within at least two genera. One genus (Liquidambar) contributes about four species, which grow in many places in the eastern part of the United States and parts of Mexico, Central America, and Asia; while the other genus (Nyssd) includes five species which grow only in the eastern part of the United States and in the southern part of Asia. 1 The wood of the Red or Sweet Gum (Liquidambar styraciflua) is about as strong and stiff as that of the chestnut. It is brittle, straight-grained, rather fine and dense, absorbent, liable to warp and twist in seasoning, fairly heavy, and moderately soft. Its natural color is attractive, but this is often changed by staining, so as to resemble the colors of other woods. Some pieces of Red Gum resemble walnut and these are usually cut into veneers which are sometimes misleadingly sold under such names as " California Red Gum," "Hazel," " Satin Walnut," and even " Circassian Walnut." Ordinary pieces are sparingly used for many purposes, as railway ties, carpentry, flooring, furniture, paving blocks, packing boxes, barrel staves, pulley-facing, coffin boards, and woodenware. The trees, which are very attractive and which are prized in landscape effects, bear rough fruiting heads or balls about as large as the fruiting heads of the syca- more. Their pointed, star-shaped leaves exhibit bright scarlet and purple tints during the autumn. The wood of the Water Gum or Tupelo Gum (Nyssa aquatica) is often marketed with that of the Red Gum. This wood is light, strong, tough, fine-grained, easily glued, and comparatively cheap. Its cellular arrangement is complicated and the wood is correspondingly hard to split and work. The heartwood varies in color from dull gray to dull brown, while the color of the sap- wood resembles that of ordinary poplar. After seasoning, it is often hard to distinguish between the sapwood of the better grades of Tupelo Gum and ordinary poplar. This wood is also sold under other names, as "Bay Poplar," and "Circassian Wal- nut," and is used for packing boxes, furniture, the backs of drawers, and house-trim. The trees, which often grow in deep swamps and along the margins of water courses, bear leaves BROADLEAF TRUNKS AND WOODS 187 which exhibit beautiful purple and reddish tints in the autumn. The Sour Gum or Black Gum (Nyssa sylvatica) yields a rather soft, light, tough, fine, but irregularly grained wood, which is hard to split and work, and which is used for wheel-hubs, rollers, woodenware, thin lumber, and fruit crates. The Sour Gum tree grows in swamps and hardwood bottoms. Its range is greater than that of the others, but the Sour Gum forms a much less important part of the forest. 1 See also "The Red Gum" Chittenden and Hatt (United States Forest Service, Bulletin No. 58, 1906), "The Utilization of Tupelo," Holroyd (United States Forest Service, Circular No. 40, 1906), "Distinguishing Characteristics of North American Gumwoods," Sudworth and Mell (United States Forest Service, Bulletin No. 103, 1911), ''The Red Gum" Detwiler (American Forestry, November, 1916). 188 ORGANIC STRUCTURAL MATERIALS Gum, Sweet Gum, Red Gum. Liquidambar styraciflua Linn. NOMENCLATURE (Sudworth). Gum, Sweet Gum, Red Gum Gum Tree (Va., S. C., La.). (local and common names). Alligatorwood, Blisted, (N. J.). Liquidambar (R. I., N. Y., Del., N. J., Pa., La., Tex., Ohio, 111.). LOCALITIES. Connecticut to Florida, westward intermittently to Illinois, Texas, and . . Mexico; best development in basin of Mississippi River. FEATURES OF TREE. Eighty to one hundred or more feet in height; three to five feet in diameter; a tall, straight trunk; corky ridges are frequent on the branches; the star-shaped leaves turn to brilliant scarlet in the autumn; there are round balls on long stems. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood rich brown, suggests Black Walnut; sapwood nearly white; close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. About as strong and stiff as Chestnut ; l heartwood is durable when exposed ; wood shrinks and warps badly if seasoned by ordinary methods, but responds to special methods; glues and paints well; holds spikes well; receives a high polish; tasteless. REPRESENTATIVE USES OF WOOD. Veneers, cabinet-work, packing boxes, carpentry, shingles, clapboards, paving-blocks, wooden plates, and barrel staves. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 37 (United States Forestry Division). 36. MODULUS OF ELASTICITY. 1,700,000 (average of 118 tests by United States Forestry Division). 2 1,220,000. MODULUS OF RUPTURE. 9,500 (average of 118 tests by United States Forestry Division). 2 9,200. REMARKS. The wood has other commercial names as "Hazel," "Satin Walnut," "Star-leaved Gum." Clear wood can be obtained in boards of large size. The larger trees often have hollow butts. 1 Woodward, reported Gum ties as good after five years of service on the Texas & Pacific Railroad. 2 See p. 33. BROADLEAF TRUNKS AND WOODS 189 Tupelo Gum, Cotton Gum, Large Tupelo. Nyssa aquatica Linn. NOMENCLATURE (Sudworth). Tupelo Gum, Cotton Gum, Large Tupelo, Swamp Tupelo (N. C. Tupelo (local and common S. C., La.). names). Olivetree, Wild Olivetree (Miss. Sour Gum (Ark., Mo.). La.). LOCALITIES. Virginia and Kentucky, southward and westward to Missouri and Texas. FEATURES OF TREE. Sixty to eighty feet in height; two to three feet in diameter. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light brown, often nearly white; sapwood nearh r the same. STRUCTURAL QUALITIES OF WOOD. Soft, light, not strong; close, compact grain; difficult to work. REPRESENTATIVE USES OF WOOD. Turnery, woodenware, boxes, and fruit-crates; pieces of the root are some- times used to float nets. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 32. MODULUS OF ELASTICITY. 730,000. MODULUS OF RUPTURE. 9,300. REMARKS. These trees grow on rich bottom lands and in deep swamps. They are often associated with cypress trees. The specific name is due to the fact that the trees tolerate quantities of water. The butts of large trees are usually hollow, while the parts above are usually sound. The Sour Gum (Nyssa ogeche) grows along the Atlantic Coast from South Carolina to Northern and Western Florida. The trees, which are usually found on wet lands, attain heights of from thirty to fifty feet. The soft, compact, weak, brownish heartwood is hardly distinguishable from the brownish sapwood. The tree is also known as.Ogeechee Lime, Wild Lime- tree, Limetree, Tupelo, Sour Tupelo, and Gopher Plum. 190 ORGANIC STRUCTURAL MATERIALS Sour Gum, Black Gum, Tupelo. ( " yssa sylv ^ a " { Nyssa multiflora Wang. NOMENCLATURE (Sud worth). Sour Gum, Black Gum, Tupelo Wild Pear Tree, Yellow Gum Tree (local and common names). (Tenn.). Pepperidge (Vt., Mass., R. I., Gum (Md.). N. Y., N. J., S. C., Tenn., Mich., Stinkwood (W. Va.). Ohio, Ontario). Tupelo Gum (Fla.). LOCALITIES. Ontario and Maine to Florida, westward intermittently to Michigan and Texas. FEATURES OF TREE. Forty-five to one hundred feet in height; several inches to occasionally four feet in diameter; ovoid, bluish black, sour fruit, with ribbed seed; horizontal branches; short, spur-like lateral branchlets. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light brown or yellow, often nearly white; the sapwood is hardly distinguishable; fine-grained; interwoyen cell-structures. STRUCTURAL QUALITIES OF WOOD. Strong, tough, not hard; the cell-structures are interlaced, and for this reason the wood checks unless it is carefully seasoned; it is hard to work. REPRESENTATIVE USES OF WOOD. Wagon-hubs, rollers, and ox-yokes; wooden ware, such as bowls and shoes; thin lumber is used for boxes and crates; selected pieces used in cabinet work. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 39. MODULUS OF ELASTICITY. 1,160,000. MODULUS OF RUPTURE. 11,800. REMARKS. These trees grow on hillsides and along the borders of swamps and water- ways. Large trees are often hollow near the ground. The wood has a limited field of usefulness because it is so hard to work. BROADLEAF TRUNKS AND WOODS 191 HOLLY BOXWOOD LIGNUMVIT^ Ilex Buxus, Cornus, etc. . Guajacum These trees yield small but very perfect pieces of wood that fill needs for which no other woods seem equally fitted. Holly trees (Ilex opaca) grow along the coast in the United States from Quincy, Massachusetts, to Louisiana, and in the interior, in parts of Missouri, Illinois, Kentucky, Tennessee, and Arkansas. The wood, which is noted for its fine even grain and its smooth, ivory-white color, is used for carvings, decorations, and inlaid work, where fine qualities and white effects are re- quired. The European source is the Holly (Ilex aquifolium). Holly trees are noted for their brilliant evergreen foliage and bright red berries, that have long been associated with the Christ- mas season. The true Boxwood (Buxus sempervirens) becomes a tree in some parts of Europe, Asia, and northern Africa, but, in the United States, is generally a small shrub that is useless, save in landscape effects. The wood is noted for its fine, firm, even texture and is used for carvings and mathematical instruments. No other wood is better for wood engravings. Boxwood is often hard to season. It is said that French engravers place pieces designed for their finest work in dark cellars as soon as they are cut, and that they keep them in such surroundings for several years before they are used. American Boxwood is derived from the Flowering Dogwood (Cornus florida) and from several other species. The Lignum vitaes (Guajacum sanctum and Guajacum officinale) grow in Florida, the West Indies, Colombia, and Venezuela, and yield wood that is noted for great weight, strength, complicated cellular structure, and durability. Under the axe, it may be said to crumble rather than to split. It contains a resin (Guajac) that is sometimes used in medicine and as a lubricant. The wood is used for rollers, pulley sheaves, tool handles, and sometimes in place of bearing metals in parts of marine engines. Some lignum vitse ties, removed from the Panama Railway after more than thirty years of service, because they were too small to afford proper bearings for the rails, were still in good condition. 192 ORGANIC STRUCTURAL MATERIALS Holly, American Holly. Ilex opaca Ait. NOMENCLATURE (Sudworth). Holly, American Holly (local White Holly (Va.). and common names). LOCALITIES. Maine to Florida, westward intermittently to Indiana and Texas. FEATURES OF TREE. Occasionally fifty feet in height and three feet in diameter, but frequently much, smaller, particularly in the North ; the spiny-margined evergreen , leaves are of a bright green color; the bright red berries remain until the spring. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood cream white, darkening or spotting on exposure; sapwood similar or lighter; very close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Tough, moderately hard and heavy, easily worked. REPRESENTATIVE USES OF WOOD. Inlaid work, carvings, scrollwork, and turnery; moderately used for furni- ture and decoration. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 36. MODULUS OF ELASTICITY. 910,000. MODULUS OF RUPTURE. 9,700. REMARKS. The wood suggests ivory, and is characteristically employed for the white of inlaid work. The more elaborate specimens of inlaid work are manufactured in Italy, but are not always durable when brought into highly heated houses in the United States. Inlaid work manufactured in the United States may be less elaborate than the foreign product, but it is often more durable. BROADLEAF TRUNKS AND WOODS 193 ( Cornus florida Linn. Dogwood, Flowering Dogwood. | Cynoxylon NOMENCLATURE (Sudworth). False Box-dogwood (Ky.). Dogwood, Flowering Dogwood New England Boxwood (Tenn.). (local and common names). Cornel, Flowering Cornel (Tex., Boxwood (Conn., R. I., N. Y., R. I.). Mich., Ky., Ind., Ont.). LOCALITIES. Ontario and New England to Florida, westward intermittently to Minne- sota and Texas; also found in the Sierra Madre Mountains and in Mexico. FEATURES OF TREE. Twenty-five to thirty-five feet in height; one foot or more in diameter; often a low shrub; large, white flower-like bracts precede the develop- ment of the true, but less conspicuous, greenish flowers which precede the leaves; in the fall, red berries are exhibited; the bark is rough and dark. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood rich brown, changing to green and red; sap wood lighter; close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Heavy, strong, tough, and hard; it receives a high polish. REPRESENTATIVE USES OF WOOD. Wood-carving, wood-engraving, bearings of machinery, and turnery. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 50. MODULUS OF ELASTICITY. 1,160,000. MODULUS OF RUPTURE. 12,800. REMARKS. The Mexican or Black Persimmon, and the Great Laurel (Rhododendron maximum) yield woods that are used in place of Dogwood. The Yellow- wood (Schcefferia frutescens}, which is found in Florida, also yields wood that is known as Boxwood. The names Dogwood and Poison Dogwood are sometimes applied to the Sumach. 194 ORGANIC STRUCTURAL MATERIALS Lignumvitae. Guajacum sanctum NOMENCLATURE (Sudworth). Lignumvitae (Fla.). Ironwood (Fla.). LOCALITIES. Semitropical Florida, the Bahamas, San Domingo, Cuba, Puerto Rico, Jamaica and Yucatan. FEATURES OF TREE. Twenty-five feet in height; one foot in diameter; a low, gnarled tree. COLOR, APPEARANCE, OR GRAIN OF WOOD.. Heartwood rich yellow brown in younger specimens and almost black in older ones; sapwood light yellow; close-grained; compact structure. STRUCTURAL QUALITIES OF WOOD. Very heavy and exceedingly hard; strong, hard to work, and brittle; very durable; the wood contains a resin which acts as a lubricant when in water. REPRESENTATIVE USES OF WOOD. Rollers, pulley-sheaves, and tool-handles; bearings for parts under water. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 71. MODULUS OF ELASTICITY. 1,220,000. MODULUS OF RUPTURE. 11,100. REMARKS. Two other species (Guajacum officinale and Guajacum arboreum) afford similar woods which are not distinguished commercially from the above. BROADLEAF TRUNKS AND WOODS 195 LAUREL Magnolia, Rhododendron, Arbutus, etc. The name Laurel applies locally or botanically to a number of American plants, several of which attain to the dignity of trees. The Big Laurel or Magnolia (Magnolia fcetida) grows naturally along the Atlantic Coast from North Carolina to Florida, and thence through the Gulf region westward to Texas. The tree, which is also cultivated in other localities with temperate climates, is very beautiful and valued in landscape effects, while the hard, heavy, whitish wood is occasionally used in cabinet work. The California Laurel (Umbellularia calif ornica) and the Laurel or Madrona (Arbutus menziesii) are Pacific Coast species, which yield strong, hard, heavy, and attractive woods that are sometimes used in furniture. Sargent 1 regards the wood of the former species as the most valuable of those produced in the forests of the Pacific region for interior finish and furniture. The wood of the Great Laurel or Rose Bay (Rhododendron maximum) is hard, rather brittle, close-grained, and heavy, and is sometimes used as a substitute for Boxwood in wood engraving. The gnarled roots of the Mountain Laurel or Calico Bush (Kalmia latifolia) are occasionally used for rustic hanging-baskets, rustic seats, and the like. ltl Manual of the Trees of North America," Sargent (Houghton, Mifflin & Company, 1905, p. 335). 196 ORGANIC STRUCTURAL MATERIALS California Laurel, Mountain Laurel. Umbellularia calif ornica Nutt NOMENCLATURE (Sudworth). California Laurel, Mountain Myrtle-tree, Cajeput, California Laurel (Cal., Nev.). Olive (Oreg.). California Bay-tree, Spice-tree Californian Sassafras. (Cal., Nev., Oreg.). Laurel, Bay-tree, Oreodaphne (Cal.). LOCALITIES. California and Oregon. FEATURES OF TREE. Seventy-five to one hundred feet in height; three to five feet in diameter; evergreen foliage; beautiful appearance. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood light rich brown; sapwood lighter brown; close-grained; com- pact structure. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, and strong; receives a beautiful polish. REPRESENTATIVE USES OF WOOD. Ship-building, cabinet-work, cleats, and crosstrees. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 40. MODULUS OF ELASTICITY. 1,510,000. MODULUS OF RUPTURE. 11,400. REMARKS. A valuable local cabinet wood. BROADLEAF TRUNKS AND WOODS 197 Madron a, Madrona Laurel. Arbutus menziesii Pursh. NOMENCLATURE (Sudworth). Madrofia, Madrona Laurel (Cal., Madrone-tree, Manzanita (Oreg., Oreg.). Cal.). Laurel, Laurelwood, Madrone. Madrove (Cal.). LOCALITIES. Pacific Coast from British Columbia to southern California. FEATURES OF TREE. Fifty to seventy-five feet in height, occasionally higher; two to four feet in diameter; a straight, well-formed trunk; evergreen foliage; a shrub in the South. COLOR, APPEARANCE, OR GRAIN OF WOOD. Thick heartwood reddish; thin sapwood slightly pink; close-grained; numerous and conspicuous medullary rays. STRUCTURAL QUALITIES OF WOOD. Heavy, hard, and strong; checks badly in seasoning. REPRESENTATIVE USES OF WOOD. The charcoal is used in gunpowder; the wood is sometimes used for furniture. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 43. MODULUS OF ELASTICITY. 1,190,000. MODULUS OF RUPTURE. 12,000. REMARKS. A beautiful ornamental tree yielding attractive wood which is seldom used save locally. The Madrona tree has been confused with the Laurel, Madrona, or Mexican Madrona (Arbutus xalapensis or Arbutus texana), also called the Manzanita, and with the California species of the genus Arctostaphylos from which Manzanita wood is derived. The name Manzanita is somewhat loosely used to designate hard, heavy, close-grained, rich, reddish-brown woods, that in California are sometimes used for trinkets, such as cuff buttons, checkers, and rulers. Large-sized pieces of Manzanita wood are rare, and long pieces are practically un- known. Probably most of this wood is derived from the Manzanitas (Arc- tostaphylos pungens, Arctostaphylos tomentosa, and Arctostaphylos glauca). 198 ORGANIC STRUCTURAL MATERIALS SASSAFRAS CAMPHOR TREE Sassafras Cinnamomum The Sassafras grows in many parts of the eastern half of the United States. It was one of the first of the North American trees to be described in Europe, where at that early date, many fictitious properties were credited to the aromatic essences by which it is characterized. The soft, light, brittle, slightly aro- matic, and rather durable wood is occasionally used for buckets and fences. The trees may be known by their fragrant, mucilagi- nous leaves, some of which are without lobes, while others have lobes on one side, and still others have lobes on both sides. The characteristic sassafras odor and flavor are more or less evident in the wood, twigs, and leaves, but are much more pronounced in the bark of the roots. The Camphor tree (Cinnamomum camphora) , which is related to the Sassafras, has been acclimated in California, and, on the Atlantic Coast, from Charleston to Florida. The trees, with their shining, evergreen leaves, are very attractive, and, in the United States, are valued in landscape work. The close-grained, aromatic, yellowish woods are sparingly used in cabinet work and insect-proof chests. In Asia, where this tree is native, it is the chief source of commercial camphor; but, in this country, the trees, although thrifty, do not appear to secrete the same quanti- ties of this resin. Camphor is found also in the roots of the Cinnamon tree (Cinnamomum zeylam'cum) of India and Ceylon. The Cassia Bark (Cinnamomum cassia), of Burmah and China, yields cassia but no camphor. Transplanted specimens of the two last-named trees have been made to grow in some parts of California and Florida. 1 1 See also Dewey (United States Division of Botany, Circular No. 12, Revised). BROADLEAF TRUNKS AND WOODS 199 J Sassafras officinale Nees and Eberm. Sassafras. ^ Sassafras sassafras (Linn.) Karst. NOMENCLATURE (Sudworth). Sassafras (local and common Sassafac, Sassafrac (W. Va., Del.). name). Gumbo file (La., negro). Saxifrax, Sasifrax Tree (Fla., Tenn.). LOCALITIES. Vermont to Florida, westward intermittently to Michigan and Texas. FEATURES OF TREE. Thirty to fifty feet in height; one to three feet in diameter, sometimes larger; often a low shrub; characteristic odor; the greenish-yellow flowers precede the leaves in early spring. COLOR, APPEARANCE, OR GRAIN OF WOOD. Thick heartwood delicate brown; thin sapwood yellowish-white; coarse- grained; the annual rings are clearly marked. STRUCTURAL QUALITIES OF WOOD. Light, soft, not strong, and brittle; checks in drying; very durable in con- tact with the soil; the wood is slightly aromatic. REPRESENTATIVE USES OF WOOD. Pails, buckets, ox-yokes, fence-posts, and rails. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 31. MODULUS OF ELASTICITY. 730,000. MODULUS OF RUPTURE. 8,500. REMARKS. The leaves and young shoots are mucilaginous. The bark, leaves, and wood emit a characteristic odor. The bark of the root is particularly aromatic. Small Sassafras bushes often form thickets. 200 ORGANIC STRUCTURAL MATERIALS GREENHEART Nectandra The Greenheart tree (Nectandra rodioei), which is a member of the Laurel family, grows in British Guiana and some adjacent parts of South America, as well as in the West Indies. The wood is hard, strong, tough, and very heavy. The colors of the heartwood vary from dark green to chestnut brown, selected pieces presenting an exceptionally rich appearance when finished. The quality of durability, which is partly due to the presence of an alkaloid, known as "biberine," is so remarkable that the wood has earned a world-wide reputation. Greenheart is one of the best of all construction timbers and, although seldom seen in the United States, is used abroad for docks, bridges, keels, rollers, flooring, wagons, carriage-shafts, furniture, and belaying- pins. All of the gates, piers, and jetties of the Liverpool Docks, and the lock gates of the Bridge water and Manchester Canals, were built of this wood. Pieces used in the construction of the Canada Dock, which was built in 1856, were used again in the reconstruction of that work in 1894. Greenheart was specified for the sills and fenders of the lock gates of the Panama Canal. The Antarctic ship, Discovery, and Nansen's ship, The Fram, were built of it. 1 ^ee also "Greenheart," Mell and Brush (United States Forest Service, Circular, No. 211); "Greenheart Used in Panama Canal, etc." Armstrong (Engineering Record, Vol. 73, Nos. 5 and 6, pp. 149 and 180); "The Green- heart of Commerce," Mell (American Forestry, May, 1916). BROADLEAF TRUNKS AND WOODS 201 Greenheart. Nectandra rodioei NOMENCLATUKE (Mell and Brush). 1 Greenheart (local and common name). Sipiri, Bebeeru, Bibiru, Supeira (native Indian names). Torchwood. LOCALITIES. British, Dutch, and French Guiana, some adjacent parts of South Amer- ica, and the West Indies. It is seldom found more than fifty miles, and never found more than one hundred miles, from the coast. FEATURES OF TREE. Twenty-five to sometimes seventy feet in height; two to four feet in di- ameter. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood dark green to chestnut brown, sometimes nearly black; clean; straight-grained; free from knots; some pieces possess great beauty. STRUCTURAL QUALITIES OF WOOD. Hard, heavy, tough, elastic, strong, and durable; repels termites and tere- does; liable to split and splinter, and so requires care in seasoning and working; receives a high polish; withstands wear. REPRESENTATIVE USES OF WOOD. Abroad, the wood is used in docks, ships, machine parts, piles, trestles, bridges, floors, wagons, carriage-shafts, furniture, and belaying-pins. In the United States, it is occasionally used in veneers, automobile spokes, turnery, and in the tips of fishing rods. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 72 (Laslett). MODULUS OF ELASTICITY. 1,090,000 (Laslett). MODULUS OF RUPTURE. 10,000 (Thurston). REMARKS. The Yellow, Gray, and Black varieties recognized by dealers come from the same species, the distinctions being due to differences in the ages and environment of the trees from which the several kinds were cut. Black Greenheart resembles Lignumvitse and is valued more highly than the others. 1 ^ee also "Greenheart," Mell and Brush (United States Forest Service, Circular No. 211). 202 ORGANIC STRUCTURAL MATERIALS PERSIMMON EBONY OSAGE ORANGE CHERRY Diospyros Toxylon Prunus The Persimmon (Diospyros virginiana) grows in the eastern and southern parts of the United States and is a member of the Ebony family (Ebenacece). The trees may be known by their fruit, which is remarkably astringent when green, but sweet and palatable when ripe. The wood is tough and hard. The sap- wood, which resembles fine-grained hickory, is of a light brown color, while the thin heartwood is almost black. Persim- mon wood is sometimes used for plane-stocks, shuttles, and shoe-lasts. The true Ebony (Diospyros ebenwri) grows in Ceylon, India, and Siam. The Mexican Ebony (Diospyros ebenaster), which is a native of India, has been cultivated in the tropics of the western hemisphere, and in the Philippine Islands. The Madagascar Ebony (Diospyros mespiliformis) is a native of tropical Africa, and the Green Ebony (Diospyros chloroxylori) is a native of southern India. There are other sources in this and other genera. The Ebony of commerce, which is fine-grained, very hard and heavy, more or less durable, and of a deep black color, is used for veneers, cabinet work, and piano keys. The Osage Orange or Bois d'Arc (Toxylon pomiferwri) grows naturally in parts of Oklahoma, Arkansas, Texas, and Louisiana, while transplanted trees have succeeded as far north as New England. The more or less slender trees yield useless fruit which, in size and general appearance, suggests the common orange. The thin sapwood is of a light yellow color, while the thick heart- wood is bright orange. The wood is very hard and strong. It takes a beautiful polish and is worthy of much more attention than it receives. The aborigines made bows and arrows of it, whence the name Bois d'Arc. The Wild Black Cherry (Prunus serotina) grows in many localities in the eastern half of the United States, and bears small, purplish-black cherries, that are sweetly bitter when ripe. The Cherry wood of commerce is obtained from this species. The strong, clean, straight-grained, hard, durable, fine, reddish colored wood is easily worked; it receives a high polish, and is used in cabinet wood and indoor finish. It is often stained so as to imitate mahogany, while it itself is often imitated by staining the wood of the Sweet Birch (Betula lento). Wild Cherry bark contains a bitter principal that is used in medicine. BROADLEAF TRUNKS AND WOODS 203 Persimmon. Diospyros virginiana Linn. NOMENCLATURE (Sudworth). Persimmon (local and common Simmon, Possumwood (Fla.). name). Plaqueminier (La.)- Date Plum (N. J., Tenn.). LOCALITIES. Rhode Island to Florida, westward intermittently to Missouri and Texas. FEATURES OF TREE. Occasionally seventy feet in height; one to two feet in diameter; the soft, plum-like fruit is astringent when green and sweet when ripe. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood dark brown or black; sapwood light brown, often with darker spots; very thin heartwood; very close-grained; compact structure; the medullary rays are conspicuous; resembles Hickory. STRUCTURAL QUALITIES OF WOOD. Hard, heavy, and strong. REPRESENTATIVE USES OF WOOD. Plane-stocks, shoe-lasts, etc.; prized for shuttles. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT 49. MODULUS OF ELASTICITY. 1,110,000. MODULUS OF RUPTURE. 12,400. REMARKS. The astringent properties of the unripe fruit are due to tannic acid. The dark heartwood is not greatly developed in trees that are under one hundred years old. 204 ORGANIC STRUCTURAL MATERIALS I Madura aurantiaca Nutt Osage Orange. { m i v D f [ Toxylon pomiferum Raj. NOMENCLATURE (Sud worth). Osage Orange (local and common Hedge, Hedge-plant, Osage (111. name). la., Neb.)- Bois D' Arc (La., Tex., Mo.). Mock Orange (La.). Bodark, Bodock (Kans.). Bow-wood (Ala.). Yellow-wood, Osage Apple Tree (Tenn.). LOCALITIES. Southern Arkansas, Oklahoma, and Texas; cultivated elsewhere, as in Massachusetts, Pennsylvania, and Michigan. FEATURES OF TREE. Twenty to fifty feet in height; rarely beyond one and one-half feet in diameter; the form of the useless fruit suggests that of the orange. The trees survive when planted close together and the living trunks of trees thus planted are often used as fence posts. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood bright orange, which turns brown on exposure; the sap wood is light yellow; close-grained; the annual rings are clearly marked. STRUCTURAL QUALITIES OF WOOD. Hard, heavy, very strong, flexible, and durable in contact with the soil; receives a beautiful polish; shrinks in seasoning. REPRESENTATIVE USES OF WOOD. Fence-posts, piles, telegraph poles, railway ties, paving-blocks, occasion- ally indoor decoration, wagon felloes, and machinery. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 48. MODULUS OF ELASTICITY. 1,300,000. MODULUS OF RUPTURE. 16,000. REMARKS. The Indians used this wood for bows. The early name, Bois D'Arc, has been corrupted to Bow Dark or Bodark. Bodark wagon felloes are much prized in arid regions where the rains are confined to a short season of the year, and where the balance of the year is hot and dry. Under such circumstances, wheels made of some other woods shed their tires and are otherwise less satisfactory. BROADLEAF TRUNKS AND WOODS 205 f Prunus serotina Ehrh. Wild Black Cherry, Wild Cherry. < -n -, \ Padus serotina NOMENCLATURE (Sudworth). Wild Black Cherry, Wild Cherry Rum Cherry (N. H., Mass., R. I., (local and common names). Miss., Neb.). Black Cherry (Me., N. H., Vt., Whiskey Cherry (Minn.). R. I., N. Y., Miss., Ky., Mich., Choke Cherry (Mo., Wis., la.). Wis., Ind., Neb.). LOCALITIES. Eastern to central United States. FEATURES OF TREE. Forty to eighty feet in height; two to three or more feet in diameter; the bark and pea-sized fruit contain a bitter principal. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood reddish brown; sapwood yellow; fine, straight grain; compact structure. STRUCTURAL QUALITIES OF WOOD. Light, hard, strong, and easily worked. REPRESENTATIVE USES OF WOOD. Cabinet work and interior finish; preferred beyond many other woods as a base upon which enamelled paints are to be applied. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 36. MODULUS OF ELASTICITY 1,200,000. MODULUS OF RUPTURE. 11,700. REMARKS. 206 ORGANIC STRUCTURAL MATERIALS MAHOGANY Swietenia, Khaya, Soymida, Cedrela, etc. The many botanical sources of the woods known as Mahogany, may be grouped upon a geographical basis as they grow in Central America, the East Indies and Africa. Central American Mahogany was originally obtained from the Mahogany (Swietenia mahagoni), but is now derived from other trees as well, such as some of those of the genus Cedrela. Central Ameri- can Mahogany was once divided as it came from the then Spanish American possessions and from Honduras. The first was called "Spanish Mahogany" and the last "Honduras Mahogany." Most of the wood that comes from Mexico is named from the ports from which it is shipped. There are thus, Frontera, and other kinds of Mahogany. East Indian Mahogany is obtained, largely, from the Mahogany (Soymida febrifuga). The African sources are very numerous, a fact that explains the differences that exist in the quali- ties of these woods. The most 'important source is the Mahogany (Khaya senegalensis) , while other sources are the species Khaya grandifolia and Entandrophrdgma candollei. Some Mahogany is brought from the Philippine Islands. Mahogany has been used to a limited extent in construction, but is now so greatly valued as a decorative wood that it is used for little else, save, occasionally, the hulls of small pleasure craft. The decorative value of this wood is due to a combination of appearance, working qualities, and durability. The appearance of mahogany is influenced by its cellular structure and its warm reddish color. The latter is often comparatively light at first; but, usually, darkens eventually to characteristic tints, which, however, are usually induced at once by means of stains. The cellular structure of mahogany is not only beautiful of itself, but is such as to respond to the stains and finishing processes commonly applied. Mahogany works and glues well. It is very durable; few woods shrink or distort less than Mahogany after it is in place. It should be noted that woods produced in different localities differ in grain and color from one another, and that pieces cut from different trees in the same locality often differ also. Beautiful grain effects are often seen where trunks and branches join, and such pieces, known as "crotches," usually bring very high prices. BROADLEAF TRUNKS AND WOODS 207 The Spanish Cedar (Cedrela odorata) is not a true Cedar. In spite of its name it is not even remotely related to the trees from which the Cedar woods of commerce are ordinarily obtained. The true Cedars are all Conifers, whereas this tree is a Dicotyle- don, and belongs to the family which includes the mahoganies. 2 Aside from this the wood suggests fine Cedar in appearance, and possesses the odor that is associated with that wood. It is used for cigar boxes and cabinet work. The Prima vera or White Mahogany (Tabebuia donnell- smithii) is related to the Catalpas, and grows in Mexico and Central America, where it is often associated with the true Mahogany (Swietenia mahagoni). The wood resembles true Mahogany, save in color, which is a light yellow that darkens with age. The characteristic color of the finished wood is golden- yellow. It is hard to find large pieces of Prima vera free from worm holes. The wood is used in car finish, cabinet work, and fine furniture, where ordinary Mahogany might be used, save for its darker color. 1 The name Mountain Mahogany is applied to several trees that grow in the Rocky Mountain region and yield woods that are sometimes employed for fuel. Some of these species are Mountain Mahogany (Cercocarpus ledifolius), Mountain Mahogany; Valley Mahogany (Cercocarpus parvi- folius), Mountain Mahogany; Birchleaf Mahogany (Cercocarpus parvifolius betuloides). 2 Meliacese has been divided into Swietenice, which includes some of the true Mahoganies, and Cedreloe, which includes about nine genera and twenty- five species, distributed over tropical Asia and America. See also "True Mahogany," Mell (United States Department of Agriculture Bulletin No. 474, 1917). 208 ORGANIC STRUCTURAL MATERIALS Mahogany. Swietenia mahagoni Jacq. NOMENCLATURE. Mahogany (local and common Mexican Mahogany (Frontera, and name). other Mexican ports). Spanish Mahogany (Cuba, San Honduras Mahogany (Honduras). Domingo, West Indies). Bay wood, Madeira, Redwood. LOCALITIES. Florida Keys, the Bahamas, the West Indies, Mexico, Central America, and Peru. FEATURES OF TREE. Florida specimens are forty-five feet in height and two or more feet in diameter; foreign trees are larger. COLOR, APPEARANCE, OR GRAIN OP WOOD. Heartwood light, rich reddish brown; the thin sapwood is yellow; smooth, fine, uniform texture; inconspicuous rings; the conspicuous pores are sometimes filled with white substance. STRUCTURAL QUALITIES OF WOOD. Strong and durable, but brittle; it holds glue, takes stains, and receives a high polish; it changes but little in seasoning and stands well. REPRESENTATIVE USES OF WOOD. Veneers and cabinet-work; was formerly used in ship-building. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 45. MODULUS OF ELASTICITY. 1,510,000. MODULUS OF RUPTURE. 14,000. REMARKS. The desirability of Mahogany from this and other species varies with locality. Mahogany is usually stained, BROADLEAF TRUNKS AND WOODS 209 Spanish Cedar, Mexican Cedar. Cedrela odorata Linn. NOMENCLATURE. Spanish Cedar, Mexican Cedar, Cuban Cedar (local and common names). LOCALITIES. Mexico, Cuba, and the West Indies. FEATURES OF TREE. Fifty to eighty feet in height; two to five feet in diameter; pale yellow flowers ; there are pods that suggest pecan nuts as to form ; the form of the tree suggests that of the English Walnut (Juglans regia). COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood brownish red; straight, even, compact grain. STRUCTURAL QUALITIES OF WOOD. Soft, fragrant, porous, and durable; resembles Cedar woods which are derived from coniferous trees, and also resembles Mahogany. REPRESENTATIVE USES OF WOOD. Cigar-boxes, boats, and sometimes cabinet-work; may be used in place of Mahogany. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. MODULUS OF ELASTICITY. MODULUS OF RUPTURE. REMARKS. The trees grow rapidly. The related Australian Red Cedar (Cedrela aus- tralis) is locally used for furniture, joinery, carriages, ceilings, and door frames. These woods must not be confused with true cedars, which are derived from non-related trees of the coniferous series. The Toon Cedar (Cedrela toona Roxburgh} of the Orient is the same as the Red Cedar (Cedrela australis F. v. M.}. of Australia. The Cedar (Cedrela odorata Blanco} is thought to be a distinct Philippine species. 210 ORGANIC STRUCTURAL MATERIALS White Mahogany. Tabebuia donnett-smithii Rose Prima vera. NOMENCLATURE. White Mahogany, Prima vera Jenicero, (local and common names) Genesero, Roble. LOCALITIES. Southern States of Mexico to Peru. FEATURES OF TREE. Fifty to ninety feet in height; two to four feet in diameter; trunks are often clear for thirty or forty feet from the ground; numerous golden-yellow flowers precede the leaves; a beautiful tree. COLOR, APPEARANCE, OR GRAIN OF WOOD. The heartwood is of a cream white color which often darkens with expo- sure; the thin sapwood is almost white; beautiful mottled or clouded effects usually seen best when pieces are quarter sawn; fine grained; the wood resembles mahogany save in color. STRUCTURAL QUALITIES OF WOOD. Moderately heavy, tough, rather soft and not strong; dries without check- ing, works well and stands well; receives stains and retains high polish; durable in contact with the soil. RFPRESENTATIVE USES OF WOOD. Local constructions and railway ties; widely used for cabinet-work and fine furniture; veneers. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 28. (reported). MODULUS OF ELASTICITY. MODULUS OF RUPTURE. REMARKS. The wood can be used where fine, light colored, cheerful effects are required; or it can be stained so as to imitate ordinary mahogany. The wood of the butternut or white walnut is sometimes sold as white mahogany but is seldom if ever seriously confused with the true wood. 1 a See also Botanical Gazette (Vol. XVII, 1892, p. 418) ; Contribution, United States National Herbarium (Vol. I, No. 9, p. 346). BROADLEAF TRUNKS AND WOODS 211 TEAK Tectona, Oldfieldia The Indian Teak (Tectona grandis) grows in India, Burmah, the Malay Peninsula, Sumatra, Java, and Ceylon, and is a very important tree that is sometimes referred to as the "Oak of the East Indian forests." The less plentiful African Teak (Old- fieldia africana) is a native of western tropical Africa. These two trees are not related to one another, yet they yield woods that possess the same anatomical characteristics. Teak wood is fairly hard and heavy. The colors of freshly cut pieces vary from light yellow to brownish red. Older pieces are much darker. Teak contains a peculiar resin which probably contributes to durability for which this wood is noted. This resin also serves because it is obnoxious to insects and because it preserves iron fastenings. Teak was long regarded as one of the best of all woods for ship-building. It is now used in many local constructions, such as railway ties, bridge-timbers, and artillery wagons. It is extensively exported to Great Britain. The grain is such that the wood is often carved, and Teak wood is now known in North America chiefly through such carvings. 1 1 See also "Wood, " Boulger (London, 2d Ed., p. 285.) 212 ORGANIC STRUCTURAL MATERIALS Teak. Tectona grandis NOMENCLATURE. Teak. Teek. Indian Oak. Sagwan. LOCALITIES. India, Burma, Siam, and Ceylon. FEATURES OF TREE Eighty to one hundred feet in height; three to four feet in diameter; some- times larger; a straight trunk; large, drooping, deciduous leaves. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood is of a variable, brownish-yellow color; a straight, even-grained wood. STRUCTURAL QUALITIES OF WOOD. Moderately hard, strong, and easily worked; stands well; oily, fragrant, resists termites, and preserves iron. REPRESENTATIVE USES OF WOOD. Furniture, ship-building, timbers, and backing for armor-plates. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 50 (Laslett). MODULUS OF ELASTICITY. 1,338,000 (Laslett). 2,100,000 (Thurston). MODULUS OF RUPTURE. 15,000 (Thurston). REMARKS. It is thought that the properties by which iron fastenings are preserved, and by which termites are repelled, are due to oil contained in the wood. Burma Teak, Malabar Teak, and other kinds take their names from the districts in which they were produced, or from which they were shipped. Transplanted specimens have not succeeded well in California. The distinct African Teak (Oldfieldia africana) yields a wood that is some- times marketed as African Mahogany and African Oak. BROADLEAF TRUNKS AND WOODS 213 Some other tropical species that yield widely known woods, or other products, or that are valued in landscape work, are as follows: Sabicu (Lysiloma sabicu). This West Indian wood is hard, heavy, strong, and durable. It seasons and works well and has been used for ships and furniture. The wood is of a dark chestnut-brown color. Some pieces are highly figured. The appearance and the working quali- ties of the wood are such that it may be used in place of rosewood. Sissoo (Dalbergia sissoo) . These trees grow in northern India. Some transplanted specimens have succeeded in other places as California. The wood, which is highly valued in India, is hard, heavy, strong, and elastic. The sapwood rots quickly, but the heartwood remains sound and hardens as the wood grows older. Sissoo seasons well and stands well. It is used in wheels, boat-building, agricultural implements, and furniture. Gun-carriage wheels made of Sissoo wood are highly prized. Some pieces of Sissoo are almost as beautiful as pieces of rosewood. An important source of commercial rosewood is related to the Sissoo. The Rubber Tree. The substance known as India rubber is like sugar in that its constituents exist in a number of unrelated plants. These constituents form part of a milky juice which is secreted by most of the plants in question, and which is known as latex. Latex, which is quite distinct from sap, is a thin, watery emulsion made up of cream- like globules suspended in a thinner liquid of different composition; the appearance of latex is similar to that of cows' milk. The latex of the common milkweed is a familiar example. An exception to the rule that rubber is obtained from latex is furnished by the Guayule plant. The rubber obtained from this plant is distinct from most others in that it is not obtained from latex but exists as such in the cells of the plants. The trees, vines, and shrubs from which India rubber may be obtained are numbered by the hundred, but the sources from which it is actually obtained in commercial quantities are comparatively few. The prin- cipal trees from which it is obtained are the Para or Hevea Rubber Tree (Hevea braziliensis) the Central American Rubber Trees (Castilla elastica and others) and the Assam Rubber Tree (Ficus elastica). The wood of the rubber tree is seldom employed save locally. It should be noted that the latex from which India rubber is obtained is secreted only under favorable conditions. (See also Chapter XVII). The Pepper, California Pepper or Peruvian Mastic (Schinus molle) was introduced into California from Peru by the early Spanish mission- aries, and is now one of the most popular shade trees on the Pacific Coast, south of San Francisco. The Pepper tree grows to heights of thirty to fifty feet. The outline suggests that of the Apple tree, while the drooping foliage suggests the foliage of the Willow. There are long sprays of rose-tinted berries, masses of slender, drooping branchlets, and delicate, bright evergreen leaves that emit a pleasant, pungent 214 ORGANIC STRUCTURAL MATERIALS odor. The berries are the size of currants or pepper corns, whence the name Pepper tree. The soft, smooth, whitish-colored woods are seldom employed, save for fuel. The California Pepper tree is the host of the "black scale," and is now being replaced by the better, faster-growing, Longleaved Pepper tree (Schinus terebinthifolius) from Brazil. The Tung Oil Tree. The Tung Oil tree (Aleurites fordii) , also known as the Chinese Wood Oil tree, belongs to the family Euphorbiaceae. It is associated with China, but is grown in other parts of the world, and has succeeded, in the United States, in southern California, and in the region that extends southward from Cairo, Georgia. It grows to a height of thirty or more feet and has an ornamental value about equal to that of the Cat&lpa. The flowers precede the leaves and cause the tree to be very beautiful when in bloom. The soft wood is not valuable; but the fruit, which suggests an apple two or three inches in diameter, contains from two to eight large seeds from which the Tung oil of com- merce is obtained. The tree begins to bear fruit when four or five years old. It is said that, in China, a tree yields from thirty to seventy-five pounds of seed every year. 1 The Balsa (Ochroma lagopus). This native of Central America and the West Indies attains a diameter of about one foot. The large, broad leaves resemble those of the Catalpa. The weak, uniform, spongy, par- enchymatous wood is free from knots and checks and is so soft that it can be indented with the finger nail. It is one of the lightest of all woods, its weight of seven pounds per cubic foot being half that of ordinary cork. It does not last well; and it absorbs water so readily that it soon becomes water logged unless impregnated with paraffin or some similar compound. It is extremely porous, and for this reason is an excellent insulator against heat and cold. Balsa wood is used in refrigerator linings, and, after treatment with paraffin, is used in life preservers in place of cork. It is used locally for canoes. 2 The China or China-berry (Melia azedarach) is a native of India, China, and some other parts of the eastern hemisphere, but is now grown successfully in many parts of the world, including districts in the south- ern part of the United States. The China tree is also referred to as the Pride of India, the Bead tree, and the Umbrella tree. The short, straight trunk merges abruptly into numerous branches that radiate outward like the ribs of an umbrella. The peculiar form, rapid develop- ment, and thick, handsome foliage cause the true to be valued in land- scape effects, wherever it will grow. The wood, which is sometimes improperly referred to as "White Cedar" and "Bastard Cedar," is oc- casionally made into furniture. The berries contain pits that are some- times used as beads. The Rosewood. There are many "Rosewood trees." The African Rosewood (Pterocarpus erinaceus) grows in tropical western Africa. The Brazilian Rosewood (probably Dalbergia nigra) is a native of Brazil. The Canary Rosewood (Convolvulus scoparius) grows in the Canary BROADLEAF TRUNKS AND WOODS 215 Islands. In California, rosewood is derived from the stems of very large rose bushes. Commercial rosewood is hard, tough, fine grained, and compact. The colors vary from rich reds to chestnut browns; there are often black streaks and sometimes purplish effects. The name Rosewood is due to the more or less pronounced scent of roses which the woods emit. The wood is also known by other names, as Blackwood and Bloodwood. Rosewood is sometimes used in local constructions, but is normally seen in costly furniture, piano cases, burial caskets, and panel work. It is sometimes associated with Circassian Walnut and Satinwood in the decorative work in compartment cars. An oil, dis- tilled from one of the species from which commercial rosewood is ob- tained, has been used to adulterate attar of roses. The Sandalwood. The Sandalwood of commerce is obtained from many botanical sources. The genus Santalum alone includes about twenty species. Until the eighteenth century, Sandalwood was ob- tained from China. The discovery of sources on the Islands of the Pacific led to lawless traffic and much bloodshed. The adventures associated with the collection of this wood were equal to those encoun- tered in whaling and the search for ivory. The Sandalwood tree (San- talum album) yields a reddish-brown, close-grained, very fragrant wood that weighs about fifty-five pounds a cubic foot. Red Sandalwood or Sanderswood (Pterocarpus santalinus) yields a red dye that is known as "santalin." Sandalwood was prized by the French nobility for medal- lions that were mounted on otherwise decorated surfaces. It was also sometimes made into rich furniture, and is now occasionally seen in finely carved small objects, as jewel boxes and fan handles. The powdered wood is burned as incense. A fragrant oil is separated by distillation. Satinwood. The East Indian Satinwood (Chloroxylon swietenia), grows in India and Ceylon, while the Yellow-wood or Satinwood (Xanthoxylum cribrosum) is a native of Florida and the West Indies. There are other botanical sources. The yellow or orange-colored woods are hard, heavy, close-grained, durable, and beautifully figured. Pieces from San Domingo and Jamaica are particularly beautiful and bring the highest prices. Satinwood is very valuable and is seldom used, save in the finest cabinet work and furniture. A valuable list has been prepared by Mell under the title " Cabinet Woods of the Future." 3 1 "The China Wood Oil Tree," Fairchild (United States Bureau of Plant Industry, Circular No. 108); Files of "Oil, Paint and DrugReporter;" etc. 2 Missouri Botanical Garden Bulletin (August, 1915, p. 107); The Prop- erties of Balsa wood," Carpenter (Proceedings, American Society Civil Engineers, May, 1916). 3 "Cabinet Woods of the Future," Mell (American Forestry, Vol. XVI, No. 12. 216 ORGANIC STRUCTURAL MATERIALS EUCALYPTUS Eucalyptus The Eucalypts, locally known as Stringybarks, Ironbarks, Mahoganies, Box and Gum trees, are natives of Australia and the neighboring islands. 1 The genus is now represented by culti- vated specimens on each of the continents, where, in some places, it has influenced topographical and other conditions to a remark- able degree 2 . The Riviera, the Campania, the Nilgheri Hills in southern India and parts of Algeria, Brazil, and California have been practically transformed by Eucalyptus trees. Eucalyptus trees are noted for their rapid growth, fine appear- ance, great size, tough and durable woods, and their influence upon sanitation. Rapid Growth. This is shown by specimens of the Blue Gum (Euca- lyptus globulus) that have lengthened more than two feet in a single month. In three years, a tree of this species attained a diameter of about nine inches. A Pasadena tree was five feet thick at the end of twenty-five years, while some specimens in Santa Barbara that were twenty-five years old compared in general development with oaks that were over two hundred years old. Appearance. The trees of some species are very attractive in form. Some of the trees blossom during droughts when other flowers are scarce; others blossom twice a year; and still others blossom all the time. Size. The enormous size is seen in specimens of the Peppermint tree (Eucalyptus amygdalina} that have grown to heights of over four hun- dred feet and are the tallest, although not the largest, trees known to man. Character of Woods. Eucalyptus woods are tough and hard to season but some of them are very valuable. The working qualities of Aus- tralian grown Jarrah, Karri, Tuart, and Red Gum woods (Eucalyptus marginata, Eucalyptus diversicolor, Eucalyptus gomphocephala, and Euca- lyptus rostrata) are such that these woods are highly prized in many localities. In London and in Paris, blocks of Jarrah and Karri woods have been used to pave streets subjected to heavy traffic. REFERENCES. Works of von Mueller; Report J. Ednie Brown, Forest Commissioner of Western Australia; Works of Abbot Kinney (Press Baum- gardt, Los Angeles); Ingham (California State Agricultural Experiment Station, Bulletin No. 196); "Eucalypts Cultivated in the United States," McClatchie (United States Bureau of Forestry, Bulletin No. 35, 1902); ' 'Utilization of California Eucalypts, "Betts and Smith (United States Forest Service, Circular No. 179); "Eucalypts in Florida," Zon and Briscoe (United States Forest Service, Bulletin No. 87, 1911); "Yield and Returns of Blue Gum in California," Woodbury (United States Forest Service, Circular No. 210); "Eucalypts," Pinchot (United States Forest Service, Circular No. 59 Revised, 1907). BROADLEAF TRUNKS AND WOODS 217 Influence upon Health. Improvement in the health of residents has followed the introduction of the Blue Gum (Eucalyptus globulus} in malarial districts such as some in the vicinity of Rome. It is possible that these fortunate results may have been influenced to a slight extent by medicinal compounds in the foliage, but it is much more probable that they were due to the fact that the leaves of this species evaporate large quantities of water, and thus reduce the moisture conditions neces- sary for the growth of mosquitoes. The genus may be summarized from the viewpoint of the living tree and from the viewpoint of the woods as follows : Eucalyptus Trees Grow Rapidly. Some of them grow where those of other species will not; some form windbreaks and forest cover; some serve in landscape effects; some afford honey and many yield oils. The hard, tough woods present an unusual range of possibilities. Mc- Clatchie enumerates twenty-five ways in which these woods have been used in Australia : six species are valued for bridge timbers, five for piles, nine for paving, eight for posts, three for railway ties, four for car build- ing, five for lumber and shingles, seven for carriage parts, two for cooper- age, and two for handles. Thus far, comparatively little eucalyptus lumber has been produced in this country, but experience is sufficient to show that some kinds of eucalyptus can be used in place of other woods that are now used in the United States for piles, posts, poles, crossties, mine timbers, paving blocks, insulator pins, furniture, finish, veneers, cooperage, vehicle stock, and tool handles. Eucalyptus woods are hard to season. The structure is complicated and the woods are full of water. This is particularly true of woods produced in the United States where the trees are yet comparatively young. No really sat- isfactory method of seasoning the woods of the species thus far intro- duced into North America has yet been worked out on .a commercial basis. The colors of the woods vary; shades of yellow, brown and red predominate. The evergreen leaves exhibit many tints, normally of the colors gray, blue, and green. The characteristic odor is the only point in common between the leaves of young and old trees of some species. The genus includes nearly two hundred and fifty species. 1 The nomenclature is confusing. There are eleven Stringybarks, eight Ironbarks, nine Red Gums, and twelve Blue Gums. The Blue Gum (Eucalyptus globulus) is the species commonly referred to when the Eucalyp- tus is mentioned in North America. 2 Eucalyptus trees do not grow well in the United States outside of Cali- fornia, Arizona, New Mexico, Texas, and Florida and their success in New Mexico, Texas, and Florida has not been remarkable. The Florida climate is favorable most but not all of the time. The climate of Southern Cali- fornia is more equable and this district must still be regarded as the only real North American locality. 218 ORGANIC STRUCTURAL MATERIALS Blue Gum, Fever Tree. Eucalyptus globulus NOMENCLATURE. Blue Gum (local and common name). Fever Tree, Balluck (Australia). LOCALITIES. Native of Australia; acclimated in southern California and elsewhere in frostless regions throughout the world. FEATURES OF TREE. Sometimes three hundred or more feet in height; three to six feet in di- ameter; bark varies with age and environment; the form and color of the leaves which are sometimes twelve inches in length, vary with age; characteristic odor/ COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood straw color; sap wood lighter; complicated cellular arrange- ment; indistinct annual rings. STRUCTURAL QUALITIES OF WOOD. Hard and heavy; the cellular structure is such that the wood is hard to split and work after it has been seasoned ; the American product is hard to season, possibly because the trees are comparatively young and full of water. Not durable in contact with the soil. REPRESENTATIVE USES OF WOOD. Principal experience is abroad, where foreign-grown pieces are used for rollers, paving-blocks, ship-building, carriage parts, and fuel. In the United States, pieces boiled in water, and then in linseed oil, are used for insulator pins on telegraph poles; in California, the wood is used for piles and mine-timbers; an important fuel in southern California. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 43 to 69 (Mueller). 57 to 69 (Laslett). 47.9 (Betts & Smith). 1 MODULUS OF ELASTICITY. 1,712,000 (Average of 17 tests of California-grown specimens). 1 MODULUS OF RUPTURE. 12,400 (Average of 17 tests of California-grown specimens). 1 REMARKS. It should be noted that the name Blue Gum is applied to at least eleven other species. This Blue Gum is the Eucalyptus of California. 1 United States Forest Service, Circular No. 179, p. 12. BROADLEAF TRUNKS AND WOODS 219 Red Gum. Eucalyptus rostrata NOMENCLATURE. Red Gum (local and common name). LOCALITIES. Australia. Acclimated in California and elsewhere. FEATURES OF TREE. One hundred or more feet in height; the tress are often crooked; the bark, when young, is red. COLOR, APPEARANCE, OR GRAIN OP WOOD. The color of the heartwood varies from light red to dark blood-red; the color darkens with age; close-grained; the cellular arrangement is complicated. STRUCTURAL QUALITIES OF WOOD. Strong, hard, and heavy; said to resist attacks of shipworms and termites; pieces cut from American trees are hard to season ; capable of receiving a high polish. REPRESENTATIVE USES OF WOOD. Principal experience is abroad, where foreign-grown pieces are Used for posts, bridge-timbers, short beams, ship-timbers, ties, and paving- blocks. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 55.6. 1 MODULUS OF ELASTICITY. 1,201,000 (Average of 9 tests on California-grown specimens). 2 MODULUS OF RUPTURE. 12,369 (Average of 9 tests on California-grown specimens). 2 REMARKS. A Commission on State Forests and Timber Reserves in Melbourne gave as its opinion that Red Gum is the "most important tree in the State, on account of its durability and the many uses to which it (the wood) is put." Von Mueller wrote of Red Gum as "perhaps the most im- portant of the entire genus." The best grade of lumber is obtained from trees over one hundred years of age. It is believed that Red Gum trees will succeed well in California, but the wood thus far pro- duced in that region is hard to season, possibly because the trees are comparatively young and full of water. 1 United States Forest Service, Circular No. 179, p. 28. 2 United States Forest Service, Circular No. 179, p. 16 and 28. 220 ORGANIC STRUCTURAL MATERIALS Jarrah. Eucalyptus marginata NOMENCLATURE. Jarrah (local and common name). Mahogany Gum (Australia). LOCALITIES. Western coast of Australia; some specimens acclimated in California. FEATURES OF TREE. Ninety to one hundred or more feet in height; two to five feet in diameter; branches concentrated at tops of trees. COLOR, APPEARANCE, OR GRAIN OF WOOD. The reddish-brown wood resembles Mahogany; it also resembles Kauri wood. STRUCTURAL QUALITIES OF WOOD. Heavy, somewhat oily, -non-absorbent, does not take fire easily, durable in contact with the soil; it may be polished; it wears thin evenly, and is said to repel marine and land wood-borers. REPRESENTATIVE USES OF WOOD. Ship-building, dock and bridge-timbers, paving-blocks. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 65 (Ednie-Brown). 1 MODULUS OF ELASTICITY. 2,080,000 (Ednie-Brown). 1 MODULUS OF RUPTURE. 8,900 (Ednie-Brown). 1 REMARKS. The principal timber tree of southwestern Australia. The wood is often confused with that of the Karri, von Mueller calls it the least inflam- mable of woods. 1 Report on Forests of Western Australia, Presented to Parliament, 1896. BROADLEAF TRUNKS AND WOODS 221 Karri. Eucalyptus diversicolor NOMENCLATURE. Karri (many localities). White Gum (Australia). LOCALITIES. Australia and New Zealand; some specimens acclimated in California. FEATURES OF TREE. Sometimes three hundred and fifty feet in height; from four to eighteen feet in diameter; a straight, graceful tree, the lower branches of which are often one hundred and fifty feet from the ground; smooth, yellow- white bark. COLOR, APPEARANCE, OR GRAIN OF WOOD. Heartwood is reddish-brown; complicated cellular arrangement. STRUCTURAL QUALITIES OF WOOD. Hard, heavy, tough, elastic, non-absorbent, and durable; difficult to work; wears evenly; possesses a characteristic odor. REPRESENTATIVE USES OF WOOD. Heavy timbers, railway ties, piles, marine work, paving-blocks, masts, and lumber. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 63 (Ednie-Brown). 1 MODULUS OF ELASTICITY. 2,890,000 (Ednie-Brown). 1 MODULUS OF RUPTURE. 8,000 (Ednie-Brown). 1 REMARKS. The name diversicolor is due to the fact that the upper and lower sides of the leaves differ in color from one another. It should be noted, how- ever, that this characteristic is not confined to this particular species of this one genus. The Karri was once named Eucalyptus colossea because of its great size. This Karri is quite distinct from the Kauri (Dammara australis). Report on Forests of Western Australia, Presented to Parliament, 1896. 222 ORGANIC STRUCTURAL MATERIALS Tuart. Eucalyptus gomphocephala NOMENCLATURE. Tuart (local and common name). Tooart (Australia). Tewart (Australia). White Gum (Australia). LOCALITIES. Australia; acclimated elsewhere. FEATURES OF TREE. Sometimes one hundred and fifty feet in height; four to six feet in di- ameter; a straight trunk, with grayish-white bark; bright, cheerful appearance. COLOR, APPEARANCE, OR GRAIN OF WOOD. The heartwood is of a light-yellow color; close-grained; the cellular arrangement is complicated. STRUCTURAL QUALITIES OF WOOD. Strong, tough, rigid, hard, heavy, and durable; seasons well; is hard to split and work. REPRESENTATIVE USES OF WOOD. Keele, buffers, stern-posts, frames, wheel-hubs, and shafts. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 67 (Ednie-Brown). 1 MODULUS OF ELASTICITY. 2,300,000 (Ednie-Brown). 1 MODULUS OF RUPTURE. 9,300 (Ednie-Brown). 1 REMARKS. In California, trees have reached heights of eighty feet within twenty-four years. The wood is one of the strongest of all those used in construc- tion. Report on Forests of Western Australia, Presented to Parliament, 1896. BROADLEAF TRUNKS AND WOODS 223 Other important Eucalypts are as follows: Sugar Gum (Eucalyptus corynocalyx) . This is one of the Eucalypts that has succeeded in California. The tall, erect trees resist drought, but are less able than Red Gum trees to withstand frost. The trees blossom profusely for several months. The hard wood is of a yellowish- white color. Giant Eucalypt or Peppermint Tree (Eucalyptus amygdalind) . This is the tallest, although not the largest, of trees known to man. The leaves possess an odor that resembles that of peppermint. The woods are less desirable than those obtained from other Eucalypts. Manna Gum (Eucalyptus viminalis). The usually erect trees resist comparatively low temperatures almost as well as Red Gum trees. They grow rapidly, are thrifty, and yield woods that vary in color from light brown to yellowish- white. Ironbark or Stringybark (Eucalyptus macrorrhyncha) . The durable, dark gray, fibrous bark is used locally for roofing, while fibers drawn from the bark are used in making string. The hard, durable wood is employed for lumber, shingles, and fuel. Red Mahogany or Red Gum (Eucalyptus resinifera) . This tree yields a hard, heavy, durable, rich red wood, the appearance of which suggests Mahogany. The wood is used for shingles, posts, piles, and paving- blocks, and is suitable for use in furniture. CHAPTER VIII NON-BANDED TRUNKS AND WOODS Monocotyledons The trunks from which non-banded woods are obtained grow in thickness from the inside. With several exceptions these trunks increase principally by the expansion of cells already formed. 1 There are no layers or concentric bands, such as characterize the woods of the other group. On the contrary, the wood-elements are distributed in such a way as to appear as dots over the cross-sections. The trunks normally attain maximum diameters quite early, and, unlike Banded trunks, do not continue to increase throughout their lives. The trunks are enclosed by integuments that bear but slight resemblance to bark. The few forms that yield structural woods are asso- ciated with the tropics. Of these, the Palms and Bamboos are examples. The classes of wood-elements that exist in Non-banded woods are the same as those that exist in Banded woods. Some classes of cells may be modified as they exist in certain groups of Mono- cotyledons, just as they are also modified in some groups of Dicotyledons and Conifers; but, as far as known, there are no cell forms that are peculiar to Non-banded woods alone. The hardest parts of Non-banded stems are at their surfaces, while the softest parts are at their centers. In many cases, as with Bamboos, the tissues at the center are quite lacking. The quantity of structural material obtained from the Mono- cotyledons is comparatively small. Yet the group as a whole, with some forty families, including numerous genera and about twenty thousand species, is highly important. The grasses, including corn, wheat, rye, sugar-cane and bamboo; and the Palms, including many valuable trees, are of this group. 1 The Yucca and the Dragon-tree are Monocots which grow by a cambium region just within the cortical region. 224 NON-BANDED TRUNKS AND WOODS 225 PALM Palmacece More than one thousand species of Palms, grouped in the family Palmacese, are distributed over the tropical and semi- tropical regions of the eastern and western hemispheres. The Washington Palm (Washingtonia filif era), and several Palmettoes (Sabal palmetto, Thrinax parviflora, etc.), yield woods that are used in the United States; but the rule is, that the trees, rather than the woods, are valued in this country. 1 The wood is soft, light, weak, non-coherent, and more or less porous. Large fiber-bundles contrast sharply with the surround- ing tissue, and cause sections to present a spotted appearance (see preceding figure 2). Palm wood is comparatively safe from the attacks of shipworms, which are not " worms" but mollusks. These mollusks line the surfaces of their tunnels with shell, for which the weak and porous wood is, apparently, an insufficient foundation. The long leaf-stalks of the Washington Palm are worthy of attention. The material of which these stalks are composed resembles that of which Bamboo is composed. The stalks are seldom used, although they present what is, weight for weight, one of the strongest of all materials. Two roughly cured stalks were tested. The central portions of each specimen broke, leaving the edges, which stripped, without signs of fracture. In one case the Modulus of Rupture was 11,370 and in the other case it was 10,150. The figures were averaged for the entire sec- tions, including the parts that stripped without breaking. The strength, which would doubtless be increased by selection and appropriate season- ing, is even more significant when the very light weight of the material is remembered. Sudworth 2 enumerates the following palms as attaining to the dignity of trees in the United States: Sargent Palm (Pseudophcenix sar- Cabbage Palmetto (Sabal pal- gentii) . metto) . Fanleaf Palm (Washingtonia fill- Silvertop Palmetto (Thrinax mi- fera) . crocarpa) . Royal Palm (Oreodoxa regid). Silktop Palmetto (Thrinax parvi- flora}. Mexican Palmetto (Sabal mexi- cand) . 1 Many Palms seen at pleasure resorts in the South have been transplanted and are not native in those localities. 2 "Check List" (U. S. Forestry Bulletin No. 17). 226 ORGANIC STRUCTURAL MATERIALS Washington Palm. Washingtonia fill/era Wendl. Fan leaf Palm. Neowashingtonia filamentosa Wendl. NOMENCLATURE (Sud worth). Fanleaf Palm, Washington Palm, California Fan Palm, Arizona Palm, Desert Palm (Cal.). Wild Date (CaL). LOCALITIES. California. FEATURES OP TREE. Thirty to sixty feet in height; one and one-half to three feet in diameter; the fan-shaped leaves rise in a tuft from the summit of the trunk; the largest of the United States palms. COLOR, APPEARANCE, OR GRAIN OF WOOD. Light greenish-yellow to dark red; unstable, fibrous, and coarse. STRUCTURAL QUALITIES OF WOOD. Soft, light, shrinks in seasoning, unstable, hard to work. REPRESENTATIVE USES OF WOOD. Fuel. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 32. MODULUS OF ELASTICITY. MODULUS OF RUPTURE. REMARKS. This is the most popular of the palms used in California for landscape effects. The wood has but little value, but the light, tough, flexible, and stringy leaf -stalks possess characteristics that are worthy of notice. The results of experiments upon seasoned stalks are noted in the pre- ceding introduction. The name "Wild Date" should not cause these trees to be confused with true Date Palms (Phwnix dactylifera). Date Palm (Phcenix dactylifera). These trees, which grow in semi- tropical regions in the East, have been naturalized in Arizona, California, and Florida. In the East, the Date Palm is valued not only because it yields fruit, syrup, and vinegar, but because its wood is employed in car- pentry and simple furniture; the leaves are used in making fans, baskets, cord, and paper. 1 1 "Arabia," Zwemer; Swingle (Year Book, United States Department of Agriculture, 1900, pp. 453, 490); Tourney (Arizona Experiment Station, Bulletin No. 29). NON-BANDED TRUNKS AND WOODS 227 Cabbage Palmetto. Sahal palmetto Walt. NOMENCLATURE (Sudworth). Cabbage Palmetto, Palmetto Cabbage Tree (Miss., Fla.). (N. C., S. C.). Tree Palmetto (La.). LOCALITIES. Central- Atlantic, South Atlantic, and Gulf Coasts of the United States; the West Indies. FEATURES OF TREE. Thirty to forty feet in height; one to two and one-half feet in diameter. COLOR, APPEARANCE, OR GRAIN OF WOOD. Light brown; fibrous and coarse. STRUCTURAL QUALITIES OF WOOD. Soft and light; repels marine wood-borers. REPRESENTATIVE USES OF WOOD. Used locally for piles and docks. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 27. MODULUS OF ELASTICITY. MODULUS OF RUPTURE. REMARKS. Other Palmettoes grow in the United States. Among them are the Silver Thatch or Silktop Palmetto (Thrinax parvi flora), the Prickly Thatch or Silvertop Palmetto (Thrinax microcarpa), and the Mexican Palmetto (Sabal mexicana). 228 ORGANIC STRUCTURAL MATERIALS YUCCA Yucca This genus includes about thirty species and many varieties. Of the species which grow in the United States, the Tree Yucca or Joshua tree and eight others assume the habit and attain the size of small trees. The Yuccas are among the exceptional Mono- cotyledons that increase in diameter through the instrumentality of a cambium layer. 1 Several of the Yuccas are cultivated because of their beautiful lily-like flowers. Yucca wood is coarse and fibrous. Direct vertical cleavage is lacking. The fibers interlace so that thin sheets of rotary cut wood can be selected which bend almost as readily as thick felt. Yucca wood is used in special objects such as souvenirs, splints and artificial limbs. Eight species noted by Sudworth are as follows : Joshua tree (Yucca arborescens) . Aloe-leaf Yucca (Yucca aloifolid). Spanish Bayonet (Yucca trecu- Broadfruit Yucca (Yucca macro- leana) . car pa} . Spanish Dagger (Yucca gloriosa). Schott Yucca (Yucca brevifolia). Mohave Yucca (Yucca mohaven- Yucca (Yucca constricta}. sis) . See also "Textbook of Botany," Strasburger (p. 145). NON-BANDED TRUNKS AND WOODS 229 Yucca arbor escens Ton. Joshua-tree, Yucca. NOMENCLATURE (Sudworth). Joshua-tree, The Joshua, Yucca, Yucca Cactus (Cal.). Yucca Tree (Utah, Ariz., N. M., Cal.). LOCALITIES. Central and Lower Rocky Mountain region. FEATURES OE TREE. Twenty-five to forty feet in height; six inches to two feet in diameter; a thick, outer cover or bark. COLOR, APPEARANCE, OR GRAIN OF WOOD. Light brown to yellowish white; fibrous and coarse; interlaced cellular arrangement. STRUCTURAL QUALITIES OF WOOD. Light, soft, and spongy; flexible in thin sheets. REPRESENTATIVE USES OF WOOD. Small objects, as souvenirs; paper-pulp, splints and artificial limbs. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. 23. MODULUS OF ELASTICITY. MODULUS OF RUPTURE. REMARKS. Artificial limbs are made by bending veneers of Yucca wood over moulds; strong cements are employed, and the forms that result are strong, tough, and very light. The sheets of flexible Yucca which are sold in souvenir stores are rotary cut. 230 ORGANIC STRUCTURAL MATERIALS BAMBOO Bambusa These giant grasses grow in China, Japan, and other tropical and semi-tropical regions, and, in some places, even extend over into the temperate zone. In the United States they have suc- ceeded as far north as the Carolinas. 1 - 2 Bamboo stems often attain heights of seventy feet and diame- ters of five or six inches. They grow with surprising rapidity; a Philippine specimen grew two feet in three days, 3 while some Florida specimens reached heights of seventy-two feet in a single season. The stems of Bamboo may be compared with those of asparagus, in that both are more or less tender when young, and much more hard and fibrous when old. Stems that grow in a few weeks may require three or four years to season or harden. Those who use bamboo value it highly. The pieces are often employed without splitting. Sometimes, while yet green, they are split and flattened into rough boards, which, although they split everywhere nevertheless hold together. Johnson notes that " Bamboo is just twice as strong as the strongest wood in cross-bending, weight for weight, when the wood is taken in specimens with square and solid cross-sections." 4 The manipu- lation of this valuable material is not yet understood in the United States, but some of the many ways in which it is used abroad are summarized as follows: 5 "The Chinese make masts of it for their small junks, and twist into cables for their larger ones. They weave it into matting for floors, and make it into rafters for roofs. They sit at tables on bamboo chairs, eat shutes of bamboo with bamboo chop-sticks. The musician blows a bamboo flute, and the watchman beats a bamboo rattle. Criminals are confined in a bamboo cage, and beaten with bamboo rods. Paper is made of bamboo fiber, and pencils of a joint of bamboo, in which is inserted a tuft of goat's hair." 1 "Grasses. This is one of the largest and probably one of the most use- ful groups of plants, as well as one of the most peculiar. It is worldwide in its distribution, and is remarkable in its display of individuals, often growing so densely over large areas as to form a close turf. If the grass-like sedges be associated with them there are about six thousand species, representing nearly one-third of the Monocotyledons. Here belong the various cereals, sugar canes, bamboos, and pasture grasses, all of them immensely useful plants" ("Plants," Coulter, pp. 240-241). NON-BANDED TRUNKS AND WOODS 231 2 Fernow notes that "In addition to the genus Bambusa, the genera Arundinaria, Arundo, Dendrocalamus, and Guadua are the most important" (United States Forestry Bulletin No. 11, p. 29). 3 "Inhabitants of the Philippines," Sawyer (Scribner, 1900, p. 5). 4 "Materials of Construction" Johnson (John Wiley & Sons, 1897, p. 689). 5 "Cycle of Cathay," Martin (Fleming H. Revell Company, 1899, p. 172). See also "New Granada," Holton (Harper Bros., 1857, p. 109); "Bamboo and its Uses," Kurz (Calcutta, 1876); "The Bamboo Garden," Mitford (Macmillan, 1896); "Japanese Bamboos," Fairchild (United States Bureau Plant Industry, Bulletins Nos. 42-43) ; etc., etc. 232 ORGANIC STRUCTURAL MATERIALS Bamboo. Bambusa vulgaris NOMENCLATUEE. Bamboo (local and common name). LOCALITIES. Widespread throughout the tropics and semi-tropics; acclimated in Florida. FEATURES OF TREE. Seventy-five feet in height; four to six inches in diameter; glazed, greenish, jointed stems, delicate branches and leaves; extensive roots. COLOR, APPEARANCE, OR GRAIN OF WOOD. Yellowish brown; fibrous and coarse; moderately thin walls surround cen- tral canals which are broken by joints. STRUCTURAL QUALITIES OF WOOD. Light and elastic; works easily. REPRESENTATIVE USES OF WOOD. Posts, poles, troughs, pies, utensils, roofing, frames of aeroplanes, and paper. WEIGHT OF SEASONED WOOD IN POUNDS PER CUBIC FOOT. Variable. MODULUS OF ELASTICITY. 2,380,000 (Johnson's "Materials of Construction," p. 689). MODULUS OF RUPTURE. 27,400 (Johnson's " Materials of Construction," p. 689). REMARKS. Bamboos are not trees, although they are as tall as trees, but may be described as wood-producing grasses. Bamboos grow rapidly. A stem may reach its full height in a single year, but must then stand for three or four years in order to season and harden. Rattan. Rattan is obtained from several sources. One species (Calamus rudentum) is a climber, the stalks of which although not over one inch in thickness, are sometimes three hundred or more feet in length as they fall and ascend in festoons from tall trees. Another species (Rhapis flabelliformis) yields erect canes which grow in thick tufts. Pieces obtained from both climbing and ground rattans are tough, light, long, strong, and pliable. Locally, rattan is used for making houses, bridges, matting, hats, baskets, and cordage. In most civilized countries, split rattan is superseding willow for furniture, fancy carriage bodies, chair bottoms, and the like. The best rattan comes from Borneo. CHAPTER IX SPECIAL PROPERTIES OF WOODS DUE TO THEIR ORGANIC ORIGIN. CHEMICAL COMPOSITION OF WOODS. PHYSICAL PROPER- TIES OF WOODS: DESCRIPTIONS OF WEIGHTS AND MODULI EMPLOYED. MOISTURE IN WOODS; INFLUENCE OF MOIS- TURE, ANTISEPTICS, AND HEAT UPON THE PHYSICAL PROP- ERTIES OF WOODS All materials are studied from the viewpoints of chemical composition and of physical properties, but organic materials are also studied from the viewpoint of special or additional properties due to their organic origin. It is because of these additional traits or properties that wood and other organic materials are more complex and variable than inorganic materials. SPECIAL PROPERTIES OF WOODS DUE TO THEIR ORGANIC ORIGIN Cellular structure, inflammability at ordinary temperatures, and the qualities that attract and nourish micro-organisms have no counterparts among the inorganic materials. For example, wood and other organic materials as a class take fire readily under ordinary conditions and often liberate volumes of inflam- mable gases by means of which fires are spread, whereas stones and metal do not. Also the rotting of wood is due to the activi- ties of bacteria which do not attack inorganic materials. Besides these there are other characteristics, less definite but of at least equal importance. It is the result of "life" or physiological processes upon the chemical composition and physical properties of .woods and other organic materials, that causes these materials to be so variable. Not only do chemical and physical properties of woods vary with species, but they also vary with the age and health of individual trees from which the pieces are cut. CHEMICAL COMPOSITION OF WOODS From the standpoint of chemistry also, woods are complex and variable. Outer or living portions of a tree trunk contain 233 234 ORGANIC STRUCTURAL MATERIALS nitrogeneous food-materials and others, such as starches and sugars; while the inner parts, in which life-processes have ceased, contain other substances. The chemical composition of wood cut from young trees differs to some extent from the chemical composition of wood cut from older trees. Variations are also due to species. Chemical Elements, Organic Com- pounds, and Inorganic Compounds must all be noted. Chemical Elements. Wood is composed principally of carbon, oxygen, hydrogen, nitrogen, potassium, calcium, magnesium, phosphorous, and sulphur. The relative qualities are much in the order named. The greater part of all wood is made up of carbon and oxygen. These elements with hydrogen constitute about ninety-seven per cent, of dry wood. 1 Ordinary woods contain about 25 per cent, by weight of water. The remainder of 100 pounds of such wood, that is 75 pounds, contains about 37 pounds of carbon, 32 pounds of oxygen, 4 pounds of hydrogen, and 2 pounds of the other elements together. None of the elements noted above are taken up by the tree in the form or combination in which .they are eventually assimilated. Carbon, hydrogen, and oxygen are obtained jointly from carbon dioxide and water. Nitrogen is absorbed in the form of nitrate and to a limited extent as ammonia; while potash, calcium, magnesium, phosphorus, and sulphur are taken up in the mineral form. 2 Organic Compounds. Wood-substances must be distinguished from the secretions that permeate them. The cells, of which all woods are composed, are made up as follows: (1) The walls of the cells include bundles of a definite substance known as cellu- lose. (2) The bundles of cellulose are embedded in materials known collectively as lignin. (3) The cells normally contain such substances as water, protoplasm, gums, resins, tannin, etc., etc. Cellulose. This is the substance of which the walls of all plant-cells are commonly composed. Flax fiber and cotton wool are almost pure cellulose. The chemical formula for cellulose, which is C 6 HioO 5 or, better still (C 6 Hi O5) n , is the same as that of starch, but cellulose differs from starch in that it resists alcoholic fermentation. Plants themselves, however, and the 1 Wood dried at about 300F. contains about 49 per cent, of carbon, about 44 per cent, of oxygen, about 4 per cent, of hydrogen and about 3 per cent, of the other elements noted. See also "Timber," Roth (United States Division of Forestry, Bulletin No. 10, p. 51), etc. 2 See also "Outlines of Botany," Leavitt, pp. 229-239. CHEMICAL COMPOSITION OF WOODS 235 fungi that cause decay are both able to convert cellulose into starch and then change the starch into the various forms of sugar. 1 Lignin. At first the cells are soft and delicate, but eventually the cell-walls become tough and woody and the protoplasm disappears. These changes are due to the appearance of the lignin and the process is known as lignification. Lignin is harder and more elastic than cellulose. It forms the characteristic part of the woody-cell and a large part by weight of ordinary wood. 2 The chemical composition has not been satisfactorily established, but is variously given as Ci 8 H 2 oO8 and CigHigOs. Lignin differs from cellulose principally in its proportion of carbon. It is not known whether the composition of lignin is the same in all woods. The difference between hardwoods and softwoods seems to bear some relation to differences in proportions of cellulose and lignin rather than to differences in the composition of these compounds. As a general rule the harder the wood the larger is the proportion of lignin. Associated Materials. Chemical differences due to species are influenced less by the differences that exist in the walls of the cell-structures than by the differences that exist in the composi- tion of the materials that are contained in, or are associated with, the cell-structures. The composition of the walls is fairly con- stant for all species, but the composition of the numerous gums, resins, tannin, and other associated materials is not constant. 3 Sap. This is as necessary to plant life as blood is to animal life. The ascending, or " crude" sap, contains various minerals and nitroge- nous nutriment derived principally from the soil, while the descending, or- " elaborated " sap, contains the more complex organic preparations that have been completed in the foliage through the instrumentality of the chlorophyll. The influence of sap on decay is considerable. In the sap are sugary and other substances that attract and foster the microorganisms that cause decay. It is the presence of watery sap that makes necessary the curative processes included under the term " seasoning." l " Timber," Roth (United States Forestry Division, Bulletin No. 10, p. 51). 2 Lignin is contained in and forms the characteristic part of bast-cells. 3 See also " Microchemistry of Plant Products" Stevens ("Plant Anat- omy," pp. 330-367); United States Dispensatory; etc. 236 ORGANIC STRUCTURAL MATERIALS Protoplasm. The viscid semi-fluid substance that exists within young cells contains carbon, hydrogen, oxygen, and nitrogen, with traces of sulphur, phosphorus, etc. This is the substance in which all plant- structures originate. The name is from the Greek protos (first) and plasma (formed matter). 1 "The albuminous substances which compose protoplasm differ from the carbohydrates produced by assimilation, in containing a consider- able proportion of nitrogen often with some sulphur and phosphorus. It is in the formation of these nitrogenous, or albuminous, matters that the nutrient mineral salts are put to use. Where this final step in the production of proteid matter is taken is not definitely known. It may be that it is in the green tissue of the leaf, or it may be at all growing points." 2 Inorganic Compounds. The mineral constituents of wood are the parts that have been absorbed from the soil and then pre- pared for assimilation in the foliage. Much of this mineral matter remains in the foliage and is returned again to the soil when the leaves fall in the autumn, so that the net loss to the soil, caused by the tree, is inconsiderable. The quantity of mineral matter retained in the tree is very small when compared with the quantity of carbon that is gathered by the tree from the atmosphere. The principal inorganic compounds present in wood are sul- phates, phosphates, chlorides, and silicates of potash, calcium, and magnesium, and frequently nitrates of these latter elements. In addition, the basic elements, particularly potash and calcium, may be found combined with organic acids, such as citric, malic, tartaric, and oxalic. The larger number of chemical elements are within this group, but their total quantity is insignificant. The quantity varies between one-half of one per cent, and five per cent., according to soil, climate, and other factors. The average is about three per cent. When wood is heated, about one-fourth of its weight is given off as water. The volatile, inflammable gases then separate from the carbon which burns and releases the mineral matter as ash. The principal inorganic compounds found in ash, as dis- tinct from wood, are sulphates, carbonates, silicates, and chlo- rides of potash, calcium and magnesium, and usually, considerable 1 "Wood," Boulger (London, Second Edition, pp. 5 and 6.). 2 Outlines of Botany," Leavitb (p. 236). PHYSICAL PROPERTIES OF WOODS 237 quantities of free lime also. The sulphates and carbonates of potash and calcium usually predominate. 1 PHYSICAL PROPERTIES OF WOODS It is necessary to distinguish between the physical properties of woods and the physical properties of stones and metals. The variations due to life processes, age, and other physiological causes noticeable in the properties of woods, are without equiva- lents among the properties of the inorganic materials. The cellular structure of wood, and its influence upon physical properties, must be constantly remembered. This influence is due to (a) the character of the cell-elements of which wood is composed, (6) the arrangement of the cell-elements, and (c) the characteristics and quantities of compounds, such as water, that are often associated with the cell-structures without being actually part of them. The subject will be divided as follows: (1) The physical properties themselves will be enumerated or described. (2) The attempts that have been made to measure these properties as they exist in woods will be considered. (3) The changes produced by certain agents will be noted. DESCRIPTIONS OF PHYSICAL PROPERTIES. The first or qualitative part of the subject is not difficult. Some important properties are Strength, Rigidity, Elasticity, Resilience, Hard- ness, Ability to Hold Fastenings, Weight, Specific Gravity, Density and Porosity, Conductivity and Resonance. Strength. Strength has two meanings. There is the general meaning and the meaning as the word is used in mechanics. In the latter case, strength refers to properties by which resistance is offered to the application of outside forces. An outside force is opposed by an inside resistance, and any change that may take place in the shape of the body to which the force is applied is referred to as a "deformation." The five kinds of deformation commonly recognized are extension, compression, bending, twisting, and shearing. Extension and compres- sion are results of direct forces acting parallel to the axis of the specimen, while bending and twisting are due to forces that are perpendicular to the axis of the specimen. Shearing may occur under the application of forces longitudinally or transversely. A deformation is said to be " elas- See chapter entitled " Destruction of Wood by Burning." 238 ORGANIC STRUCTURAL MATERIALS tic" when the body in which the deformation takes place tends to recover its original form after the force that caused the deformation has ceased to act. The resistance offered to the forces that cause any or all of the forms of deformation is known as Strength. A material is said to be strong, or it is said to possess a certain amount of tensile strength, or a certain amount of compressive strength as the, case may be. The term elastic strength is used to denote the resistance that is offered to forces that produce the greatest amount of elastic deformation. The ultimate strength of any material is the greatest resistance that the material can offer to any kind of deformation. Modulus of Elasticity. Within certain limits, a definite relation exists between the resistance that develops in a body and the deformation FIG. 31. Machine for testing light wooden beams. 1 that accompanies it. It happens that within these limits, the ratio between the unit-resistance and the unit-deformation in tension, is usu- ally the same as the similar ratio in compression. This important ratio is known as the " Modulus of Elasticity." The Modulus of Elasticity expresses a law, first announced by Robert Hooke in 1675, that every solid is perfectly elastic up to a certain limit known as the elastic limit. The proportion is expressed as follows: The elongation or compression of a specimen one inch in sectional area: the original length of that specimen:: the weight necessary to produce the elongation or compression: the weight that would, theoretically, produce an elongation equal to the original length of the specimen; or The Modulus of Elasticity = Load per unit of cross-section E Elongation or compression per unit of length 1 Tinius Olsen, Philadelphia, Pa. PHYSICAL PROPERTIES OF WOODS 239 PI or E = - in which E = The Modulus of Elasticity in pounds per square Ae inch, P = the total load in pounds, I = the length in inches, A = the area of cross-section in square inches, and e = the elongation in inches. The meaning of The Modulus of Elasticity may also be expressed by the statement that it is the weight or force that would elongate a speci- men of unit-area to twice its original length, if the specimen remained perfectly elastic. The Modulus of Elasticity of any material is determined experimen- tally with the aid of machines prepared for that purpose. Typical speci- mens are selected, measured and then subjected to loads sufficient to cause deformations. The loads and deformations are measured and the moduli are found by proportion as above. FIG. 32. Machine for testing heavy wooden beams. 1 Modulus of Rupture. This is another measure of primary importance. This modulus for tension, compression, or shear, is the load that will rupture a bar of unit-section of the material in question. In other words, it is the maximum unit-stress sustained by the material just before rupture, or Modulus of Rupture = Maximum load in pounds l\i = Cross-sectional area of specimen in square inches Rigidity. There is the general meaning, and the definition as the word is sometimes used in mechanics and engineering. General Meaning. Rigidity is here the opposite of flexibility. A rigid body is one that is tense or stiff. Such a body is not easily de- formed. From this point of view, rigidity and stiffness are the same. 1 Tinius Olsen, Philadelphia, Pa. 240 ORGANIC STRUCTURAL MATERIALS Engineering Definition. Rigidity is the property by which a body resists change of form when acted upon by an external force; the amount of force and the nature of the deformation are not regarded. The form of a perfectly rigid body could not be changed by the application of an external force, but a perfectly rigid body does not exist. The distinction between rigidity and stiffness as these terms are used in mechanics, should be noted. From this point of view, rigidity is the property by which a body resists deformation, regardless of the nature of the de- formation; while stiffness is the property by which a body resists elastic deformation. FIG. 33. Olsen machine for making tortion tests. Elasticity. Elasticity has a popular meaning, a general mean- ing, and a meaning as the word is used in physics, engineering, and mechanics. Popular Meaning. The term elasticity is often used to denote the property by which a body sustains a large amount of deformation and regains its original form after the force that caused the deformation has been removed. Indiarubber is a very elastic material from this point of view. "General Meaning. Elasticity is the property by which a material tends to resume its original form after the forces that caused it to leave the original form have ceased to act. The difference between this defi- nition and the one that precedes it lies in the fact that in the present case the amount of the deformation is not material. Meaning in Physics. A body is said to be perfectly elastic when the work done in producing a deformation in the body equals the work done PHYSICAL PROPERTIES OF WOODS 241 when the body recovers its original form. A perfectly elastic body does not exist. There is always some motion between adjacent particles whenever a material suffers deformation and this causes friction and loss of work. Ivory is more elastic than Indiarubber from this point of view. Meaning in Engineering. The material of which a body is composed is said to be perfectly elastic for all forces equal to or less than a certain applied force, when the body having been deformed by that force suc- ceeds in recovering its original form after the force has ceased to act. Resilience. This property is intimately connected with elasticity. The name resilience has several meanings, as springi- ness, the power of springing back, and the power of resuming a former shape. Resilience also stands for the amount of work accomplished by a body when recovering from a deformation. Johnson 1 defines resilience as "the springing back of a deformed body after the deforming force has been removed. As used in mechanics, however, it is the work done by the body in this springing back, which is the same as the work done on the body in deforming it, so long as this is inside the elastic limits. Beyond the elastic limit, the work of deformation always exceeds the work given back by the body. The body then does not fully recover its initial position, shape or dimensions. Sometimes the work of deformation, whether inside or beyond the elastic limit, is spoken of as the resilience, but this is improper. The resilience proper is the amount of work or energy in foot-pounds, which can be stored in an elastic body up to a given stress per square inch, and which can be given out again by the body as useful work, if desired." Hardness. This is the property by which a material resists indentation and abrasion. Hardness is influenced by density and weight. Lignumvitse, greenheart, osage orange, and some of the eucalypts are very hard woods. Poplar and white cedar are soft woods. Resistance to abrasion has been determined by pressing blocks of wood against revolving discs covered with sandpaper. The amounts worn from the ends of the blocks have been taken as measures of the hardness of the specimens. The proper abrasive, the speed of the disc, the pressure and other details are important. Indentation testing ma- chines are also used. Tests to determine the hardness of commercial woods have been begun by the United States Department of Agriculture. 1 "Materials of Construction," p. 75, 1908 edition. 242 ORGANIC STRUCTURAL MATERIALS Ability to Hold Fastenings. This characteristic property con- tributes very largely to the usefulness of wood as a material of construction and may also be a measure of durability, as is shown in the case of railway ties which often fail because they cannot hold spikes. The spikes are driven so many times that the ends of otherwise good ties become cut and useless. 1 FIG. 34. Displacement caused FIG. 35. Displacement caused by common spike. Photograph, by screw spike. Photograph, Spencer Otis Company. Spencer Otis Company. The ability to hold fastenings is due principally to friction; in some cases, although to a less extent, it may also be due to adhesion. Nails cut, break, bend, and compress the fibers of the pieces into which they are driven. The mutilated fiber-extremities react and pre- sent roughened surfaces that press upon the surfaces of the nails. Pres- sure is also exerted by the fibers that have been bent and forced aside. The forces required to withdraw nails bear some resemblance to those required to drive them and vary with the character of the nails, the character of the wood, and the direction of penetration. (1) It is 1 European engineers sometimes use wooden dowels that are screwed into spaces cut for them in the ties. The spikes are driven into the dowels and the dowels are replaced when they become cut so that they cannot longer hold the spikes. (See United States Forest Division, Bulletin No. 50, p. 64). PHYSICAL PROPERTIES OF WOODS 243 harder to drive and withdraw rough, blunt nails than to drive and withdraw nails that are smooth and sharp. (2) Hard woods like oak offer greater resistance to penetration and withdrawal than softer woods like poplar. (3) It is easier to drive nails with the grain than across it, and it is easier to draw nails that have been driven with the grain than to draw those that have been driven across the grain. A series of experiments upon The Holding Power of Railroad Spikes, conducted at the University of Illinois, 1 indicates as follows: 1. The maximum resistance to direct pull varies from 6,000 pounds to 14,000 pounds for screw spikes, from 3,000 pounds to 8,000 pounds for ordinary spikes when driven into untreated timbers, and from 4,000 pounds to 9,000 pounds for ordinary spikes when driven into treated timbers. 2. The direct pull required to withdraw ordinary spikes ^ inch varies from 2,000 to 3,000 pounds for untreated timbers, and from 2,500 to 3,500 pounds for treated timbers. 3. The direct pull required to withdraw ordinary spikes Y inch varies from 3,000 to 5,400 pounds for untreated timbers and from 3,800 to 5,900 pounds for treated timbers. 4. Timbers having loose fiber-structures have lower resistances to direct pull than timbers having compact fiber-structures. 5. The amount of withdrawal which must occur for ordinary spikes to develop the maximum resistance is less for soft woods than for hard woods. 6. Spikes driven into treated timbers offer a greater resistance to direct pull than spikes in untreated timbers, and the difference between this resistance for treated and untreated timbers is greater for soft woods than for hard woods. 7. The difference in the resistance to direct pull for the different sized spikes in use (% 6 inch, i% 2 inch, and % inch) is very small. 8. The resistance of ordinary spikes to direct pull varies directly as the depth of penetration, neglecting the tapering point. 9. Blunt-pointed and bevel-pointed spikes have a slightly greater re- sistance to direct pull than chisel-pointed spikes. 10. For withdrawals less than y inch, ordinary spikes which are driven into bored holes have a little greater resistance to direct pull than spikes driven in the ordinary way. 1 University of Illinois Bulletin, Vol. Ill, No. 18, Webber. See also "Substitution of Metal for Wood in Railroad Ties," Tratman (United States Forestry Division, Bulletin No. 4, 1890); "Crosstie Forms and Rail Fastenings with Special Reference to Treated Timbers," von Schrenk (United States Forestry Bureau, Bulletin No. 50, 1904); "Holding Force of Railroad Spikes in Wooden Ties," Hatt (United States Forest Service, Circular No. 46, 1906). 244 ORGANIC STRUCTURAL MATERIALS 11. The resistance to direct pull for re-driven spikes is from 60 to 80 per cent, of the resistance of newly driven spikes. 12. The efficiency of screw spikes to resist withdrawal is nearly twice as great as that of common spikes. 13. The resistance of %-inch spikes to lateral displacement is slightly greater than that of % 6 -inch spikes. 14. The resistance to lateral displacement increases with the depth of penetration, but the increase is negligible for depths of penetration greater than 4 inches. 15. Screw spikes are more efficient than ordinary spikes in resisting lateral displacement. !f~ -> - ,;fj FIG. 36. Metal tie plate. Photograph, Spencer Otis Company. FIG. 37. Rail resting on tie plate. Pho- tograph, Spencer Otis Company. Weight, Specific Gravity, Density. The weight of a body is the downward or specific force of that body. The specific gravity of a piece of wood is the ratio of the weight of a given bulk of that wood to the weight of an equal bulk of water. Density and weight may be interchangeable. The wood tissues in the cell-walls of all species weigh about the same ; but the woods themselves vary considerably. Similar volumes of woods of different species contain more or less cell- wall tissue as the case may be. The greater the proportion of cell walls and the smaller the proportion of air spaces, the greater the density, and therefore the weight of the wood. Den- PHYSICAL PROPERTIES OF WOODS 245 sity and weight may thus be indications of hardness and strength. On the other hand, the smaller the proportion of cell-wall mate- rial and the larger the proportion of air spaces, the smaller the density, the weight, and the strength of the wood. Light woods are porous and buoyant. 1 FIG. 38. Turner impact testing machine. Not only does the weight of wood depend upon the character and quantity of the woody tissue, but it also depends upon the water, gums, resins, and other substances that may be associated with the woody tissues. The principal weight variations observed in woods are due to 1 See index, "Density Test." 246 ORGANIC STRUCTURAL MATERIALS the presence of water. Half of the weight of live sapwood may be made up in this way. There is less water in heartwood, and more in young and vigorous trees than in those that are older and less healthy. All trees contain more sap at some seasons of the year than at others. Woods that are apparently dry contain some water. The influence of water is so important as to warrant further attention. 1 As indicated, the weight of dry and clean wood is normally a sign of strength. A heavy piece of oak is usually stronger than a lighter piece; and, unless the extra weight is due to abnormal quantities of resin, a heavy piece of yellow pine is stronger than a piece that weighs less. It will be remembered that the quantity of water contained in a piece of wood will vary with the proportions of sapwood and heartwood, and with the state of the weather. The proportion of water in wood is usu- ally greater than in the surrounding air. The quantity is not constant, but, varying with humidity, amounts to about twelve per cent, of the weight of the dry wood. The weight of wood is usually calculated from small, sound specimens, which have been dried in a kiln at a tempera- ture of 100 degrees C. until they reach a weight that does not vary. The comparative weights in pounds per cubic foot of some broadleaf woods are as follows : Balsa Ochroma lagopus 7 Cork (from cork oak) Quercus cuber 14 Missouri corkwood Leitneria floridana 18 White Pine Pinus strobus 24 Catalpa Calalpa speciosa 25 Cypress Taxodium distichum 29 Douglas Fir. . Pseudotsuga mucronata 32 Sycamore Platanus occidentalis 35 Longleaf pine Pinus palustris 38 Maple Acer saccharum 43 . Locust Robinia pseudacacia 45 Mahogany Swietenia mahagoni 45 Red Oak Quercus rubra 45 White Oak Quercus alba 50 Hickory Carya alba 51 Live oak Quercus virginiana 59 Ironbark Eucalyptus leucoxylon 70 Lignumvitae Guajacum sanctum 71 Greenheart Nectandra rodioei 72 Ebony Diospyros ebenum 73 ^ee index, under "Moisture." See also Roth, United States Forestry Division, Bulletin No. 10. PHYSICAL PROPERTIES OF WOODS 247 Porosity, Penetrability. A porous substance is one that can be penetrated by another substance. It is one that is pervious or full of pores. Weight and density are both influenced by porosity. The porosity of wood depends upon the character and arrange- ment of the cell-elements of which it is composed, and also upon the characteristics and quantities of foreign materials that may be present, such as water and resin; and, since the content of water may vary, permeability may vary also. Heavy, dense woods are much less permeable than are light, loose-structured woods; while clean and seasoned woods are more permeable than woods that are resinous or green. Sapwood is more permeable than heartwood. A study of the porosity of woods is closely associated with a microscopic study of their cellular structure. 1 The permeability of wood has an important bearing upon its response when treated with solutions designed to prevent decay. A series of experiments conducted to determine facts with regard to the permeability of woods resulted in the statements that follow: 2 1. "All woods in the fresh, green state are impenetrable to gases even under high pressures, except through the open vessels in the angiosperms 3 and the resin-ducts in the conifers where these are not clogged by tyloses or resin. The same is true as regards liquids, except that water solu- tions may gradually seep through the membranes. Since it is the wood- fibers and the tracheids which form the main part of the structure of wood, impregnation of the vessels or resin-ducts would be of little or no value of itself in preservative treatment. The above is due to the fact that every cell is a closed vessel completely surrounded by its primary wall. 2. Whenever wood seasons (beyond its fiber saturation point), whether naturally or by artificial means, narrow microscopical slits occur in the walls of the fibers and tracheids which render them pene- trable to gases and liquids. These slits do not re-unite when the wood is re-soaked although they may close up somewhat. The greater the de- gree of dryness, the more penetrable the wood becomes. 3. Steaming green wood produces a somewhat similar effect but to a 1 American Railway Engineering Association, Bulletin No. 107, January, 1909. 2 American Railway Engineering Association, Bulletin No. 120, February, 1910. 3 Woods from Broadleaf trees. 248 ORGANIC STRUCTURAL MATERIALS less degree unless the wood be subsequently dried also. The reason then, that absolutely green wood cannot be successfully treated with preservatives is due, not so much to the fact that the wood contains water, but because the cell-walls are unbroken and therefore impene- trable. Just what pressure these walls would resist it is impossible to state, but it seems probable that it would run into the thousands of pounds per square inch." The influence exerted by tyloses upon porosity is very marked. These obstructions, which exist in the large vessels of a number of the broadleaf woods and in the resin-ducts of some of the needle- leaf conifers, and, which are often visible to the unaided eye, tend to block up the passages through which foreign fluids, such as antiseptics, are otherwise largely introduced. Weiss separates some of the broadleaf woods into three groups, depending upon the presence or absence of tyloses, as follows: 1 Tyloses Absent. The maples, birches, blue beech, flowering dogwood, holly, silverbell, black and water gums, black and red cherry, basswood, persimmon, honey locust. Tyloses Few. Yellow buckeye, beech, red gum (sap), yellow poplar, magnolias, sycamore, black cottonwood, eucalyptus (blue gum), white and Oregon ashes, and the elms. Tyloses Abundant. Large tooth aspen, hardy catalpa, desert willow, green, pumpkin and blue ash, mocker nut, water pignut, shellbark, bitternut, nutmeg and shagbark hickories, butternut, black walnut, red mulberry, blackjack, white, Garry, overcup, valley, bur, cow, post and swamp white oaks, black locust, and osage orange. Cleavability. When applied to wood this term denotes the ease with which the longitudinal fabric of the wood can be separated. The cleavability of wood is opposed by cohesion and by some phases of the cellular structure of the wood. Cleava- bility is influenced by temperature. It is less when it is extremely cold. Conductivity. This is the property by which heat, electricity, and sound are transmitted or conveyed. It is well known that wood is a poor conductor of heat and a good conductor of sound, particularly in the direction of the length of the pieces. Dry wood is an almost perfect non-conductor of electricity, but green or wet wood presents a comparatively low resistance to the passage of electricity. The results of experiments con- examinations by Eloise Gerry, United States Forest Products Laboratory. PHYSICAL PROPERTIES OF WOODS 249 ducted to determine the electrical resistance of woods treated with zinc and other preservatives are as follows: 1 1. The resistance of timber varies directly with the length and in- versely with the cross-section. 2. The resistance varies almost inversely with the amount of moisture present, between the limits of 15 and 50 per cent. 3. The resistance is lowest when measured along the grain, and highest when measured tangentially to the growth-rings. 4. When treated with a soluble salt such as zinc-chloride, the resist- ance varies approximately inversely as the amount of the salt present. 5. Treatment with such a soluble salt does not change the behavior of the resistance with respect to the percentage of moisture present. Only the amount of the resistance is changed. 6. The resistance of timber varies almost inversely with the tempera- tare between the limits of zero and 50 degrees C. 7. The resistance of non-porous woods, such as the pines, is higher than that of porous woods, such as the oaks and red gum. 8. Treatment of timber by different creosote processes does not greatly change the natural resistance of the timber. 9. The conductivity of wood is due primarily to the presence in the pores of an electrolyte formed by an aqueous solution of the salts found in the natural timber, or of these salts and others artificially introduced. Conductivity is diminished by porosity and increased by density and by water. It is less when the wood is diseased. Resonance. Strictly speaking, resonance is the property by which sound is repeated or sustained. Occurrences in other branches of physics, as electricity, are similar to those in acous- tics and have warranted an extension of the term to include cases in which sound plays no part. Hering expresses the wider mean- ing of the term resonance as follows: "If any rhythmic action in one body excites rhythmic action of like periodicity in another, whether in connection with the first body or apparently separated from it, the second body is said to be in resonance with the first." The meaning of "resonance" is limited to the acoustic property when the word is used in connection with wood. Pores, pith-rays, and other irregularities that occur in broad- leaf woods, interfere with the resonance of such woods and for this reason broadleaf woods are commonly less resonant than are 1 "The Electrical Resistance of Timber," Butterfield, Engineering News, April 6, 1911. 250 ORGANIC STRUCTURAL MATERIALS some of those of the coniferous series. All woods are more reso- nant when they are dry. Spruce is one of the most resonant of woods and is used for sounding boards in pianos and violins. "If a log or scantling is struck with the axe or hammer, a sound is emitted which varies in pitch and character with the shape and size of the stick, and also with the kind and condition of wood. Not only can sound be produced by a direct blow, but a thin board may be set vibra- ting and be made to give a tone by merely producing a suitable tone in its vicinity. The vibrations of the air, caused by the motion of the strings of the piano, communicate themselves to the board, which vi- brates in the same intervals as the string and re -enforces the note. The note which a given piece of wood may emit varies in pitch directly with the elasticity, and indirectly with the weight, of the wood. The ability of a properly shaped sounding board to respond freely to all the notes within the range of an instrument, as well as to reflect the character of the notes thus emitted (i.e., whether melodious or not), depends, first, on the structure of the wood and next on the uniformity of the same throughout the board. In the manufacture of musical instruments all wood containing defects, knots, cross grain, resinous tracts, alternations of wide and narrow rings, and all wood in which summer and spring wood are strongly contrasted in structure and variable in their propor- tions, is rejected, and only radial sections (quarter-sawed, or split) of wood of uniform structure and growth are used. "The irregularity in structure, due to the presence of relatively large pores and pith-rays, excludes almost all our broadleaved woods from such use, while the number of eligible woods among conifers is limited by the necessity of combining sufficient strength with uniformity in structure, absence of too pronounced bands of summer wood, and rela- tive freedom from resin. < "Spruce is the favored resonance wood; it is used for sounding boards both in pianos and violins, while for the resistant back and sides of the latter, the highly elastic hard maple is used. Preferably resonance wood is not bent to assume the final form; the belly of the violin is shaped from a thicker piece, so that every fiber is in the original as nearly unstrained condition as possible, and therefore free to vibrate. All wood for musical instruments is, of course, well seasoned, the final drying in kiln or warm room being preceded by careful seasoning at ordinary temperatures often for as many as seven years or more. The improvement of violins, not by age but by long usage, is probably due, not only to the adjust- ment of the numerous component parts to each other, but also to a change in the wood itself, years of vibrating enabling any given part to vibrate much more readily." 1 *" Timber," Roth (United States Division Forestry, Bulletin No. 10, pp. 24, 25). PHYSICAL PROPERTIES OF WOODS 251 Hygroscopicity. This is the property by which dry wood absorbs water from the air, loses it when dried again, and then gathers new supplies when the wood is re-exposed. Hygro- scopicity diminishes the value of wood, since variations in mois- ture are accompanied by changes in volume. A door will stick during the summer when outdoor air has free access to the house, but will loosen during the winter when the windows are closed and the house is heated. Contraction and expansion may be repeated so many times as to interfere with strength. A piece of wood affected in this manner has not decayed but rather may be said to have aged. The tendency is greatly reduced when wood- work is protected with oils, paints, and varnishes. Color. Color is a physical property. This is so regardless of the chemical means by which it is brought about. The color of wood, which is due to the presence of pigments manufactured by the tree during its lifetime, differs with species, and is more or less characteristic of them, so that it may be of considerable assist- ance in identifying woods. In practically every species the wood first formed is almost colorless. But later, as the wood changes from sapwood to heartwood, the char- acteristic pigments appear in the heartwood. Tints frequently vary as woods are cut from younger or older trees. When woods are exposed to the weather, chemical changes take place in the pigments, which then become darker. Prolonged immersion in water also causes woods to become darker. Some pigments are of such a character that they can be removed when the woods in which they were formed are soaked in water, and many pigments removed in this manner are used as dyes. Disease, such as " bluing," may cause colors in woods. 1 Color may or may not be desirable. One of the factors that causes many woods to be preferred in indoor finish is color; and, where natural color is lacking, it is often obtained artificially by means of stains. Color is not desirable in spokes, handles, and wood used for paper pulp. MEASUREMENTS OF PHYSICAL PROPERTIES. This second part of the subject is more difficult than the first. It is easy to describe qualities as such, but it is not as easy to measure such qualities serviceably where the material is as variable as the one in question. Not only do wood-specimens cut from trees of the same species 1 See also "The 'Bluing' and the 'Red Rot' of the Western Yellow Pine," von Schrenk (United States Bureau of Plant Industry, Bulletin No. 36, 1903). 252 ORGANIC STRUCTURAL MATERIALS vary with age, soil, and environment, but pieces cut from the same tree vary with water, imperfections, and proportions of sapwood and heartwood. Moreover, the properties of the same piece of wood may vary from day to day as the result of ordinary change? in the amount of moisture in the atmosphere. It is obviously easy to measure the strength of a specimen that has once been selected, but very difficult to secure the specimen if it is to stand for the species as a whole. A test designed to measure strength or any other property, includes three parts or operations : (1) A specimen that will repre- sent the material must be selected; (2) the specimen must be prepared for the test, that is, it must be reduced to exact dimen- sions; (3) the prepared specimen must be tested in a machine designed for that purpose. The difficulty is encountered under the first heading. The physical properties of woods are often measured, but comparatively few of the results obtained agree closely with one another; variations of as much as one hundred per cent, are not uncommon. All specimens are tested in practically the same manner so that the discrepancies must be due to the fact that the specimens are seldom selected and prepared upon a common basis. Differences which existed in the properties of several specimens of Eucalyptus wood are shown by the tables on pages 253 and 254. The principal points upon which engineers have not agreed when selecting and preparing test-specimens of wood relate to standards for moisture and sizes of test-specimens. (1) STANDARDS FOR MOISTURE. Wood-elements become soft, swollen and pliable where they are wet. Seasoning expels some of the moisture and brings a larger number of wood- elements within a given space. The wood is then stronger and more rigid. These matters may cause the strength of wood to vary as much as four hundred per cent. A standard is there- fore necessary. In tests conducted for the National Forest Service, Professors Fernow and Johnson adopted twelve per cent, by weight of dry wood as their standard. 1 (2) SIZES OF TEST-SPECIMENS. It is easier to select representative samples of stones and metals than to select samples of woods in which conditions with regard to age, grain, moisture, imperfections and proportions of heartwood are all approximately similar. 1 See index for "Moisture in Wood" and "Seasoning in Wood." PHYSICAL PROPERTIES OF WOODS 253 "^ w O S -2 2 * w 13 fc ) H g t* tills O iO O 00 O O IN ^ CO co c oo r- i-i ^ CN C^ OS CO O ^ t^ >C C^l O 1C Tj< Tt* CO IN 1C O OS I CO (N CM * 1C IBS fl M Sl32 02 Is H> 1-1 " _' _ _" 1-1 CM H C >O C 00 OS CO j < T}< CO CO ES 51 6 s 6*0-2 eji ^H OS HJ - i N i JELE8, CO * si&d alal S|/ 10 00 b- -! * OS O M M OS X t^ I-H IN' r-i oi ERKELEY, C. C CO O t^ 00 >O 1C **! 00 1C r-t *< .-H O 1-1 O 00 O OS t>^ IN I-H rH (N rH IN --H ffl h < 1 I 05 O (N t^ O CO OO (N 'S* 00 C CO r>-_ ic o I-H t> c N CO* of C._ OS a o fe d 3^ 3 5.2 OO O5 ^O ^ 1C ^ s l> O O O O O OO O t^ CO CO (N 00 1C IN 1C .-i b- 8 O o o * * 00 t> C 00 1-1 t^ 05 1C 00 O CO OS H C 00 * 2*0 III S : : J: : 8HIPME 2 i : S j ai B ^ (N |H g'o* . CO 1C C * 1C 0. ? 00 --H O Tfl CO T}H li ,1x O CO 00 OS O * 00 ^ 00 00 CO *H (N CO O p fp co oo 1-1 t*! ,-H ,-< CO CO CO * C * 1-1 r^ co os os o co co c c r^ 10 00 * (N CO t U5 u t- -IJ 00 i-l 00 (N O ^ 00 >O rj< Tt* ^f CO O if O * 2^8 8 28S CO CO CO CO ^ 00 * 1C CO (N (N 1-1 1 03 1C t^ O * Condition fl O Is 1-9 "8 Hi! o-^ 5^-8 >> ' ' i 1: S\l o^- 5^- a' : : o- : S S : S 8 U> 3 3 o> 3 3 ^.s III S ' 3 S ' s S S : S -< s JN Jii ^.a ill I s : | s : <^s ^^^ Average Maximum.. . . Minimum. . . . 254 ORGANIC STRUCTURAL MATERIALS M g 111 S.2 Ills* r-5" O * i-* M" rH C CNI O 0 10 * CO 00 * * 00 C 00 * (M CO k o co os co 1C >O CO 00 05 t~ 00 00 O 1C 1C (N (N r-l l> B* iH O IM r-( (M 0_ OO C3 o M H < H >0 * >C T ( Oi ^ T-H 1-H CC 00 t>-_ 1C O5 O3 t- rH t-T CO rH Cq rH -a c ID IJ1.S 111 O O 1C O O 00 05 O H OO CO O'O O 1C 00 CO b- O5 1C I-l i-H TjH PQ ns N 00 H H Tt t^ 1-H t3 A 4 rH t~ CO * 00 O s!-33-2 X! 03 OQ +3 O 1 EMI I C s'- ,lji CO * CM CO 00 CO O5 CO O CO CO TjH P ^|- IV 1-4 10 CO t^ CO O i-H CO co t^ co CO Tt< CSI Tj< O5 rH to l> 1C 1C t^ Tjt |1 - H -fj IN CO O IO 00 CO OS CO * CO O * s* 3 S3 >A*| t> "3 * 00 1-1 t^ Sol^ OS 1C CO rH O5 rH CO rH CO (N CN rH a 1 ; | . ... 1 II a ; i ! o^-i >> j : :-.-*.: j o-^ 3^^ : I ; Average.. . . Maximum. . Minimum. . Average. . . . Maximum. . Minimum . . ; a a i i s CD ^3 rJ CD ^ rJ bo 5 rf uc S 03 5 B 03 g B S 'g '3 3 g '3 533 4 a 3 M .. r ftr? ill J .2 P ** fl .3 2 5 PHYSICAL PROPERTIES OF WOODS 255 Large Test-specimens. It is hard to select large pieces of wood upon a common basis. Most large pieces are individual rather than representative and tests of such pieces yield results for the pieces thus broken rather than results that represent the species at large. On the other hand, tests of large pieces are useful because they show the results of imperfections. Small Test-specimens. The fact that small pieces are abnor- mally perfect causes them to yield results that are larger than those observed in actual practice. But such pieces possess the advantage that it is easier to select them upon a common basis. The results of tests upon small specimens agree more nearly with one another and are practical in that they make comparisons possible. Large and Small Test-specimens. The purpose for which the test is to be made should be considered. If the examination is to be exhaustive, large and small pieces should both be tested. The differences that, exist between the physical properties of woods and the physical properties of ordinary inorganic struc- tural materials, may be epitomized as follows : 1. Stones and metals possess physical and chemical properties, while woods possess physical and chemical properties and also other properties that result from physiological processes. 2. The properties that result from physiological processes cause woods to vary. Pieces cut from the same tree differ from one another, while the same piece may vary from day to day as water is absorbed and dis- pelled. Changes in woods are caused by seasoning and the application of preservatives. Stones and metals are much more homogeneous and constant. 3. It is comparatively easy to select representative samples of stones and metals, but it is not easy for the average experimenter to select samples of woods upon a common basis as to moisture and imperfections. 4. Engineers have agreed to a greater extent upon specifications for testing stones and metals, and to a less extent upon specifications for testing woods. 5. Stones and metals are often tested by those who use them. Woods are less often tested by those who use them. In the case of woods, the results of tests conducted in Government or other laboratories are often preferred when such figures are employed at all. 6. Tests of stones and metals when conducted upon a scientific basis, give helpfully practical results. The coefficients of safety are here com- paratively low and constant. 256 ORGANIC STRUCTURAL MATERIALS 7. Tests of woods when conducted upon a scientific basis do not give equally practical results. The coefficients of safety are high and vari- able. Results obtained in this way are not satisfactory criteria of the actual working strength of the pieces. 1 Two facts are emphasized: One is that the basis upon which the sample is selected and prepared is of unusual importance in the case of a substance as variable as wood; and the other is FIG. 39. Dorry machine for making abrasion tests. that all figures obtained for woods should be used with the very greatest caution. Such figures should never, under any con- sideration, be used with the confidence that is warranted in con- nection with figures obtained similarly for the more homogeneous stones and metals. The tests made to obtain values for the physical properties of woods can be arranged in several groups, each one depending 1 For discussion of factors of safety and safe working stresses for structural timbers, see Report of Committee on Wooden Bridges and Trestles, American Railway Engineering Association, Bulletin No. 107. PHYSICAL PROPERTIES OF WOODS 257 primarily upon the way in which the test-specimens were selected. These groups are as follows: 1. Many experiments have been performed from time to time that have not been characterized by any particular method or principle such as underlie the investigations that will be described in the succeeding paragraphs. Details as to the selection of specimens are incompletely given or are entirely lacking. The botanical accuracy of the specimens is open to doubt in many cases. Major attention was given to the manipulation of the specimens in the testing machines. Properties other than strength and weight were seldom noticed. All of the experiments that are not alluded to in the descriptions that follow are included in this group. The results of the experiments included under this head differ widely from one another, but some of them are helpful for special reasons; for example, Laslett and Rankin's experiments were performed principally upon foreign woods. 2. Experiments were conducted for the Tenth United States Census, by Sharpless, at the Watertown Massachusetts Arsenal. Botanical accuracy was assured, but in other respects the selection of specimens was not guided by factors that would now be considered. So far as is known, most of the specimens were from the butts of trees. Nothing is known of moisture conditions save that specimens were carefully seasoned. About twelve hundred specimens, representing over four hundred species, were tested. This allowed only two or three tests for each species. The series is valuable because it includes almost all American species, and the results arrived at are often quoted. It is well to note that part of the results of these experiments were originally reported in the metric system. Coefficients were originally com- puted in kilograms and millimeters, whereas weights were given in pounds. This has led to some confusion. These experiments are characterized as follows: Botanical accuracy was assured. Methods of selection were not definitely described. Moisture conditions were not standardized as far as known. Small specimens alone were tested. Few tests were performed. A large number of species was covered. 258 ORGANIC STRUCTURAL MATERIALS These experiments were described originally in Vol. IX, Tenth United States Census; Executive Document No. 5, Forty- eighth Congress, First Session; Sargent's "Silva of North America" and "Catalogue of the Jesup Collection of Woods." 3. Some experimenters, while admitting the difficulties that have been noted, prefer to test large specimens because they are the ones employed in practice. One important result obtained by such experiments is the determination of the extent to which imperfections lower strength. Experiments conducted under this head are described in Professor Lanza's " Applied Mechanics " and in publications noted in the succeeding sections. 4. In a series of experiments conducted for the National Forest Service, then called the United States Division of Forestry, Professors Fernow and Johnson acknowledged the difficulties of selection that have been noted. Test-specimens were selected upon a common basis as to age, moisture, proportions of heart- wood, imperfections, and other matters, and about forty thousand tests were made, distributed over thirty-one American species. Both large and small test-specimens were employed. The details considered and the methods evolved during this study were of such a nature as to influence all subsequent efforts. The study is disappointing, in that results were obtained for so few species. The series is characterized as follows : Botanical accuracy was assured. Soil and forest conditions were noticed. Test-specimens were from representative portions of trees. Representative trees were selected. Moisture conditions were standardized at 12 per cent, of the dry weight of the wood. Small test-specimens and large test-specimens were used. Studies of strength and weight were emphasized. Many tests were made. A small number of species was covered. The records are complete and reliable. These experiments were originally described in Circular No. 15 and other publications of the National Division of Forestry, in PHYSICAL PROPERTIES OF WOODS 259 Professor J. B. Johnson's "Materials of Construction" and in Professor Fernow's " Timber Physics," Parts 1 and 2. 1 5. A series of experiments begun more recently (1902) by the National Forest Service, is distinct from the one referred to in the preceding articles as follows: The earlier study was character- ized by emphasis laid upon strength and weight, while the later study is characterized by attention paid to other properties as well. Physical properties are studied, but, in addition to these, there are investigations of technological processes such as kiln- drying and the application of preservatives. The influences of some of these processes and materials upon physical properties have been investigated. These tests may be grouped as follows: (1) Tests of life-sized pieces or market products, such as bridge stringers, railway ties, wheel spokes, and axe handles, intended to yield results upon which grading rules, specifications, and coefficients for design can be based. (2) Tests of smaller pieces selected upon the same basis as to silvi-cultural conditions, age, grain, imperfections, and moisture. The details of the tests are varied. The influence of speed of application of load, temperature, etc., is noted. All the conditions alluded to in the earlier part of this chapter have been provided for in these experiments, which are second to none in both scientific and practical importance. These investigations, organized by Professor William Ken- drick Hatt, have been described in the " Transactions of the American Society of Civil Engineers," Vol. LI, 1903; in the " Progress Report on the Strength of Structural Timber" (United States Bureau of Forestry, Circular No. 32, 1904); in " Instruc- tions to Engineers of Timber Tests," Hatt (United States Forest Service, Circular No. 38, 1906); in the "Second Progress Report on the Strength of Structural Timber," Hatt (United States Forest Service, Circular No. 115, 1907); in "Strength Values for Structural Timbers," Cline (United States Forest Service, Cir- cular No. 189); and elsewhere. 2 1 Publications of the National Forest Service. 2 See also report of the Committee on Wooden Bridges and Trestles of The American Railway Engineering Association, reprinted in Engineering News, March 25, 1909, and referred to in Engineering News, February 22, 1912, as probably the best compilation of safe values to be used for unit stresses in structural timbers. 260 ORGANIC STRUCTURAL MATERIALS Density Test for Grading Southern Hard Pine. This test, which is employed to grade the various kinds of Southern Hard Pine timbers, is the result of a long investigation conducted by the United States Forest Service and the American Society for Testing Materials. The experiments showed that the strength of Southern Hard Pine timbers depends less upon peculiarities due to species than upon the cellular structure of individual pieces. Until the Density Test was suggested no standard existed by which the quality of individual timbers could be determined accurately. The rule, which is characterized by brevity and simplicity, is as follows: 1 DENSITY RULE FOR GRADING SOUTHERN HARD PINE "Dense Southern yellow pine shall show on either end an average of at least six annual rings per inch and at least one-third summer wood, or else the greater number of the rings shall show at least one-third summer wood, all as measured over the third, fourth and fifth inches on a radial line from the pith. Wide-ringed material excluded by this rule will be acceptable provided that the amount of summer wood as above measured shall be at least one-half. "The contrast in color between summer wood and spring wood shall be sharp, and the summer wood shall be dark in color, except in pieces having considerably above the minimum requirement for summer wood. "In cases where timbers do not contain the pith and it is impossible to locate it with any degree of accuracy, the same inspection shall be made over 3 inches on an approximate radial line beginning at the edge nearest the pith in timbers over 3 inches in thickness, and on the second inch (on the piece) nearest to the pith in timbers 3 inches or less in thickness. "In dimension material containing the pith, but not a 5-inch radial line, which is less than 2 by 8 inches in section or less than 8 inches in width, that does not show over 16 square inches on the cross-section, the inspection shall apply to the second inch from the pith. In larger mate- rial that does not show a 5-inch radial line the inspection shall apply to the 3 inches farthest from the pith. "Sound Southern yellow pine shall include pieces of Southern pine without any ring or summer-wood requirement." Von Schrenk comments upon these rules as follows: "While the new rule may at first sight appear to be a somewhat radical departure from past standards, a careful study will show that ^'Yellow-Pine Timber Graded Without Guesswork," von Schrenk (Engineering News, February 24, 1916). PHYSICAL PROPERTIES OF WOODS 261 such is not really the case. The Density Rule, when applied to a mixed lot of the various Southern pine timbers of the several botanical species, will include most of the pieces of the true botanical longleaf pine in the grade hereafter to be known as " Dense Pine;" a smaller percentage of the denser pieces of loblolly, Cuban and shortleaf pine also will fall within the dense grade; and on the other hand, a small percentage of the more rapid-growing pieces of longleaf will be excluded, as will also a great majority of pieces of loblolly, Cuban and shortleaf. "It should be clearly understood that the classes "Dense Pine" and the less desirable "Sound Pine" refer specifically to quality of density when considered from the structural or strength standpoint and that they replace the botanical terms hitherto used longleaf, shortleaf, lob- lolly, etc. "It should also be clearly understood that the usual specifications as to the percentage of heart and sap are in no way changed. In other words, where timber for long service is demanded, together with high strength qualities, Dense Pine should be specified with a minimum amount of sapwood, or what is known as heart timber. "A feature of the new rule that particularly recommends it is that it is easy of application. For the first time there is available for classifying structural timbers a rule which is based on actual measurement and which has nothing to do with catch- judgment or feeling. Numerous diagrams and illustrations in the Southern Pine Association's density rule book show how simple is the method and how effectually disagree- ments are eliminated." THE WEIGHTS AND MODULI THAT APPEAR IN THIS BOOK ARE: First. Those derived from experiments conducted by the National Forest Service and placed in the "fourth group" explained above. These figures, as far as they exist, occupy the leading spaces in the tabulated descriptions of species under the titles "Weight," "Modulus of Elasticity," and "Modulus of Rupture." The spaces set apart for these figures are left vacant for other insertions where results under this group have not been reported. Second. Those derived from experiments conducted at the Watertown Arsenal by the Tenth United States Census and placed in the "second group" explained above. These figures appear in the spaces that follow those set apart for the Forest Service figures or their equivalents. 1 All coefficients are in pounds per square inch; fractions of pounds in weight and the lower figures in coefficients have been omitted as superfluous. 1 Authorities responsible for figures other than those mentioned above are given in connection with the figures employed. 262 ORGANIC STRUCTURAL MATERIALS INFLUENCE OF MOISTURE, ANTISEPTICS, AND HEAT UPON THE PHYSICAL PROPERTIES OF WOODS MOISTURE IN WOOD. Moisture exerts a very real effect upon the physical properties of wood. Many of the variations so noticeable in these properties are due to this cause. Moisture also acts upon woods in other ways; for example, woods suffer from micro-organisms that are assisted in their life and growth by the presence of moisture. It is convenient to distinguish between the kinds of moisture that may be present within woods. The moisture may be sap, introduced while the tree was alive. Or, the moisture may have been introduced later after the tree was cut down, as when finished timbers are exposed to the weather. - Other moisture may be impure; but sap, a vital fluid necessary to the life of trees, contains preparations that are of an organic putrefactive nature; and these, more than other impurities, seem to attract micro- organisms, or else assist their progress after they have once entered the wood. The quantity of the moisture and its distribution are both important. Quantity of Moisture. One-half of the weight of live sapwood may be water. There is less water in heartwood than in sap- wood, and more in young and vigorous trees than in those that are older and less healthy. All trees contain more sap at some seasons of the year than at others; and all woods, even when well seasoned and apparently dry, contain some water. The porous structure of clean wood permits water to pass in and out, so that in the same piece, the quantity of water may vary from day to day. Influence of Season of Cutting. The influence which the season of cutting exerts upon wood may be noted in this connection. The usual preference exhibited for winter felled timber has several causes. (1) It is thought by many that the quantity of moisture in a tree is so much less during the winter that the quality of the wood is affected. (2) Others prefer the winter for felling because fungi are then less active and there is less danger of infection before the log can be cut up in the mill. (3) Yet others regard the quality of the wood itself as better during the winter season. (4) In the North, lumbermen prefer the INFLUENCE OF MOISTURE ON WOODS 263 winter season for cutting because transportation problems in the forest are then more easily met. These points will be considered separately : First, there is fully as much sap in a tree during the winter as during summer. Its composition may vary, but its total amount is, if anything, greater during the winter. 1 Second, it is true that fungi are less active during the winter season and that there is less danger of freshly cut wood becoming infected and consequently weakened at that time. Third, with the exception of the outer sapwood, no real difference exists in the quality of the trunk during the winter and the summer. Fourth, this point is one of convenience and has nothing to do with the quality of the wood. Of the above points the second only need be considered as a factor influencing the quality of wood. As a matter of fact if summer felled logs and winter felled logs could both be immediately cut up into lumber as soon as they were felled, and if the wood in each case could then ^be promptly and equally seasoned by the same process the two kinds could not be distinguished from one another. FIG. 40. Defects due to unequal shrinkage. 2 Distribution of Moisture. The practical importance of this subject will be appreciated when it is remembered that the prin- cipal difficulty encountered by those who season woods arises from attempts to expel moisture evenly from all parts of a piece in which it does not exist evenly. Distribution may be studied from the standpoint of the entire piece, and it may be studied locally as it relates to the wood- elements. The distribution throughout the entire piece is such that there is more water in the sapwood than in the heart. Mois- ture is distributed throughout the wood-elements, so that some of it occupies the cavities in the wood-elements and some satur- ates the walls of the wood-elements. 1 "Sap in Relation to the Properties of Wood," Record (Proc. American Wood Preservers' Association, Baltimore, Md., 1913, pp. 160-166). 2 Acknowledgments to United States Forestry Division, Roth, Bulletin No. 10, pp. 33 and 35. 264 ORGANIC STRUCTURAL MATERIALS Influence of Moisture. There are three ways in which mois- ture influences woods: (1) moisture causes weakness and other- wise affects the physical properties of woods; (2) moisture influ- ences distortion; and (3) moisture is a factor in decay. INFLUENCE OF MOISTURE ON PHYSICAL PROPERTIES OF WOODS. Wood-elements are swollen and pliable when they are wet. Seasoning expels moisture and brings more of them within a given space. The woods are then drier and stronger. Seasoning may increase strength as much as four hundred per cent.; and comparatively weak wood, such as pines, may be thus rendered stronger than better woods, such as oaks, that have not been seasoned. The influence of moisture upon the strength of wood has been summarized by Tiemann: 1 "As the moisture of a piece of wood is reduced by drying, the strength of the wood increases, and as moisture is re-absorbed, the strength, up to a certain limit, is again reduced. So great, indeed, is the effect of moisture, that under ordinary conditions it outweighs all other causes that affect strength, with the exception, perhaps, of decided imperfec- tions in the wood." An .exception must be noted. It is hard to dry a large timber that is full of knots and other irregularities without some injury to the piece as a whole; and this injury may offset much of the improvement that takes place otherwise through seasoning. To prevent decay, all wood should be dry, and all wood-elements and most timbers are stronger when they are dry; but the net strength of a very imperfect piece may not be always greatly increased by drying. The Influence of Moisture upon Distortion. The changes that take place in the form of a piece of wood are due to the discharge of water from the wood-elements. The fact that moisture is not distributed evenly throughout the wood, and the further fact that wood-elements vary in their character and arrangement are important in this connection. When a wood-element shrinks the principal change takes place in its thickness, and the least change takes place in the direction of its length; the length shrinkage of a plank can usually be prac- tically disregarded. Wood-elements near the surface of a log 1 "Effect of Moisture Upon the Strength and Stiffness of Wood," Tiemann (United States Forest Service, Bulletin No. 70). PHYSICAL PROPERTIES OF WOODS 265 contain more moisture than those within; and the sides of planks exposed to the weather may shrink differently than those pro- tected. Horizontal wood-elements usually shrink differently from the vertical wood-elements that are bound together by them. Severe strains at right angles to one another are then developed and the separations that take place are known as checks. Most needle-leaf woods shrink evenly, but it is often harder to expel moisture from broadleaf woods, such as oaks, that are characterized by complex fiber arrangements without some injury. Influence of Moisture upon Decay. Decay is due to the action of certain micro-organisms that require moisture for their development, and that cannot live when it is absent. Decay is not inherent in woods ; dry woods do not decay. Decay m a y p r o c e e d Fw 4i ;_ Result of when the moisture is unequal shrinkage. rmrA Hnt ear* a Hie The formation of pure, out sap, as ais- checks i tinct from pure water, contains compounds that attract or that add to the activity of the forms that cause decay. 2 Influence of Antiseptics and Preservative Treatment Upon the Physical Properties of Woods. The phj^sical properties of woods may be influenced by (1) the anti- septic, and by (2) the process employed to introduce the antiseptic. The effect of creosote upon the physical properties of woods is negligible or bene- ficial. But zinc chloride and some other preservatives designed to benefit woods in some ways may injure them in others. Not only can a concentrated solution of zinc chloride injure tissues with which it comes into contact, but the timber as a whole may 1 Acknowledgments to Roth (United States Division Forestry Bulletin No. 10, p. 34). 1 See index, " Fungi," "Fungus Diseases of Woods," etc., etc. FIG. 42. The rela- tion of horizontal wood-elements to verti- cal wood-elements. 6, a are vertical wood-ele- ments, while c, d are cells of a pith-ray. 1 266 ORGANIC STRUCTURAL MATERIALS be weakened by the addition of water. Otherwise, experiments indicate that the presence of zinc chloride will not weaken woods subjected to static loading, although the indications are that pieces that have been subjected to zinc chloride treatment become brittle under impact. 1 As distinct from the preservative, a process may be harmful whenever excessively high temperatures are employed. If an appropriate process is selected, and if proper care is observed while it is being applied, the wood will not suffer. Influence of Heat upon Physical Properties. 2 Dry heat must be distinguished from wet heat. Dry heat much in excess of 212 degrees expels some of the volatile products of the wood and the wood then becomes correspondingly weak and brittle. The equivalent of moist heat is not known. Up to a certain point high heat, either in steam or in dry air, produced the following results upon wood: "(1) It permanently reduces the moisture content below that of ordinary air-dried wood when again exposed to the air, at the same time rendering it less hygroscopic, so that it is less susceptible to changes in the humidity of the air; (2) the moisture condition of the fiber-saturation point is changed, being reduced by high temperatures with dry air or superheated steam; (3) the strength of the wood is increased, except in the resoaked condition." Woods deteriorate, or fail, from use, exposure, age, decay, fire, marine life, and land life; and they are defended more or less successfully by seasoning, internal treatment, and external treat- ment. These subjects will be treated separately in the chapters that follow. 1 "Experiments on the Strength of Treated Timber," Hatt (United States Forest Service, Circular No. 39, p. 21); "Crosstie Forms and Rail Fastenings with Special Reference to Treated Timbers," von Schrenk (United States Bureau of Forestry, Bulletin No. 50); "A Primer of Wood Preservation," Sherfesee (United States Forest Service, Circular No. 139, p. 9); see also chapter entitled "Preservatives Applied within Woods," etc. 2 See index, "Failure of Wood Because of Fire." CHAPTER X FAILURE OF WOOD BECAUSE OF USE, EXPOSURE, AGE, AND DECAY The changes that take place as a result of use, exposure, and age, are distinct from those that take place as a result of disease. Changes due to the former causes are of a mechanical nature; the wood-elements remain healthy but they separate more easily from one another. The changes due to decay are of a chemical nature; disease causes wood to break up into other compounds. FAILURE DUE TO USE. The mechanical deterioration of wood is influenced by the way in which it is used. Flooring is worn by abrasion. The life of a railway tie may be measured, by the speed, weight, and volume of traffic that passes on the rails above. Ability to hold fastenings is a factor in the life of wood when in some positions. Thus wood may wear out before it rots. Deterioration due to use is opposed by physical proper- ties such as strength, hardness, rigidity, and weight. FAILURE DUE TO EXPOSURE. Woods may deteriorate as the result of simple exposure to the weather. Expansion and contraction due to extremes of temperature and the presence or absence of water cause wood-elements to loosen from one another. Deterioration takes place more gradually when woods are pro- tected from the weather. Wooden roof-trusses in European churches have remained good during many centuries. FAILURE DUE TO AGE. Woods " age" much more rapidly when out of doors. Old wood becomes brittle and is then known as "brashwood." In a living tree age seldom acts alone, but, by lowering the vitality of the tree, makes it possible for disease to enter where resistance has been overcome. There is probably no such thing as the natural death of a tree in the forest and it is equally true that woods seldom fail in construction, simply because they are old. The vitality, soundness or resistance of a piece of wood may be roughly estimated by twisting a shaving of it between the fingers. 267 268 ORGANIC STRUCTURAL MATERIALS FAILURE DUE TO DECAY. FUNGOUS DISEASES. Trees in the forests, and woods waiting to be used, or already in con- structions, are susceptible to diseases that cause losses so serious as to constitute one of the greatest drains upon the timber resources of the world. All wood, whether employed in railroad ties, telegraph poles, bridge, mine or house timbers, are susceptible to the same or similar diseases. Wooden warships once suffered more from them than from the guns of the enemy. It is said that wooden ships have failed after seven or eight years of service. Selection, seas- oning, and the attention paid to protection makes it possible for woods to last longer at the present time; yet even now woods exposed to the weather endure for a comparatively short time, while the premature failure of beams in protected places is not uncommon. Many names refer to practically the same causes of deteriora- tion in wood. Wet-rot, dry-rot, disease, decay, mildew, soft-rot, canker, bluing, rust, bot, dote, mould, and other terms are thus employed. The results indicated by all of these names are due to the presence of bacteria or fungi. Fungi. These non-seedbearing plants differ from ferns and mosses, which are also non-seedbearing plants, in that the latter require light and contain the green substance chlorophyll which serves in the preparation of plant food; whereas the former, that is fungi, are without chlorophyll and do not require light. Fungi cannot draw their food from air and soil like ordinary plants and must therefore attach themselves to appropriate substances from which they can draw their food. Fungi are destructive rather than constructive and in this respect resemble animals rather than plants. REFERENCES. "Outlines of Botany," Leavitt; "Fungous Diseases of Plants," Duggar; "Diseases of Economic Plants," Stevens and Hall; "Flowerless Plants," Bennett (Gurney & Jackson, London); "Fungous Diseases of our Forest Trees," Halstead (3rd Annual Report Penn. Dept. of Agriculture) ; " Diseases of Trees," Hartig; "Diseases of Plants Induced by Cryptogamic Parasites," Tubeuf and Smith; "Studies of Some Shade Tree and Timber Destroying Fungi," Atkinson (Cornell Exper. Sta. Bulletin No. 193); Bulletins American Railway Engineering Association; "The Dis- covery of Cancer in Plants" (The National Geographic Magazine, Vol. XXIV, No. 1, 1913); etc. PLATE V. FUNGOUS DISEASES OF WOOD FIG. A. FIG. B. FIG. A. Fruiting Bodies of Fungus (Fomes fomentarius) (a). FIG. B. Fruiting Bodies of Fungus (Daedalea quercina) (6). FIG. C. FIG. C. Fruiting Body of Fungus (Lentinus lepidus) on Red Fir Railway Tie (c). (a) and (6) From "Diseases of Deciduous Forest Trees," von Schrenk and Spauldirig (United States Bureau of Plant Industry, Bulletin 149). (c) From " Seasoning of Timber," von Schrenk (United States Bureau of Forestry, Bulletin 41). (Facing page 268.) USE AGE AND DECAY OF WOODS 269 Plant Life Has Been Divided in Many Ways. The Linnsean classi- fication separates all plants into Phanerogams, or seed-bearing plants, and Cryptogams, or non-seedbearing plants. The Cryptogams are again divided into one part, sometimes called the higher, which includes the ferns and mosses; and another part, sometimes called the lower, which includes the algae, lichens, and fungi. The fungi are divided into saprophytes and parasites according as they derive food from dead or living tissues. Some species are capable of existing as both saprophytes and parasites and for this reason some authorities (see Tubeuf and Smith, p. 3) separate fungi into true and hemi-saprophytes and true and hemi -parasites. There are sub-divisions in each case. A piece of mouldy bread may be studied in this connection with profit. Such bread first emits a characteristic odor, then becomes discolored, and is eventually de- stroyed. Minute threads of the " mould" penetrate throughout the mass and their extremities eventually appear upon the sur- face of the bread as a delicate felt or fur. These extremities finally swell, burst, and liberate countless spores, some of which find a con- genial substratum, germinate, and produce similar results. The swollen ends of the ex- tremities are the "fruiting bodies" of the fungi within the bread. In the same way the toadstool-like FIG. 43. Mycelial threads of growths seen on rotting; trees or wood-destroying fungus (Nectria . , , ((f ... , ,. ,, cinnabarina) in maple wood. 1 timbers are the fruiting bodies of fungi that have entered such trees or timbers. Fruiting bodies are not always easily evident, and those of some fungi are quite obscure. An individual fungous thread or filament is called a "hypha," while masses of the threads or "hyphse" form what is known as "mycelium." Bread, wood, or other sub- 1 Acknowledgments to Roth (United States Division of Forestry, Bulletin No. 10). 270 ORGANIC STRUCTURAL MATERIALS stances that have become infected are the "hosts" 1 of the fungi that have gained entrance to them. Fungi attack woods through the action of solvents called "enzymes," some of which dissolve cellulose, while others dis- solve lignin, starches, sugars, and other compounds. The re- moval of any one of these constituents from the wood results, ultimately, in the total destruction of the usefulness of the wood. The general form of the diseased piece may be retained but its properties have been affected. Some of these wood residues are comparatively dry and brittle while others are moist, soft, and sponge-like. Some fungi attack live trees. Others attack dead trees, and yet others attack woods employed in construction. Some kinds of fungi prefer conifers and others broadleaf trees. Bark, heartwood, and sapwood all have their enemies. Some fungi attack many species of trees or woods, while others attack only one or two species. Fungi are very numerous. Many thousands of species are in existence. The subject is not a simple one; and the majority, who are not experts in this subject, find it more helpful to con- sider the Jew conditions under which all fungi act than to acquaint themselves, with the idea of identifying all of the many forms that cause the failures so constantly observed. 2 Conditions Under Which All Fungi Act. All fungi require moderate quantities of heat, air, and moisture for their develop- ment. They do not do well when excessive quantities of these agencies are present; nor do they do well when the said agencies are completely absent. 1. Influence of Heat upon Fungi. Growth is retarded and fungi are sometimes completely killed by high heat, that is by temperatures much beyond one hundred and seventy degrees. Many fungi are killed by the process of kiln-drying, but some are rendered inert by this process for the time being only. The growth of fungi is also retarded by cold, that is by temperatures much below thirty-five degrees. 3 Fungi are not killed by any 1 This term is usually restricted to the living organism upon which a parasite grows. Saprophytes grow upon a "substratum." 2 Fungi do not confine themselves to plants. " Ringworm" as seen in man is due to a fungus parasite (Trichophyton tonsurans). 3 These temperatures are approximate. It is not necessary to go below the freezing point to retard the growth of fungi. USE AGE AND DECAY OF WOODS 271 degree of natural cold, no matter how extreme, but their activities cease, or are restricted, while such low temperatures continue. 2. Influence of Air upon Fungi. The activity of fungi is more or less opposed by an abundance of pure air on the one hand, and by vacuum on the other. A moderate amount of air is necessary for their growth. 3. Influence of Moisture upon Fungi. Wood will not decay while it is quite dry; neither will it decay as long as it remains saturated with water. These facts explain why woods last better in cold climates and on well-drained hills, and why decay goes forward more rapidly in warm, moist climates, and in mines. A railway tie fails sooner than a beam that is raised up from the ground because the " med- ium" conditions of heat, air, and moisture are more nearly se- cured in positions where ties are employed. Fungous diseases may be considered as they attack trees in the forest, and as they attack woods ready for, or already in, construction. Fungous Diseases of Trees. These diseases are here described for the sake of completeness, and because some of them produce results that are evident in merchantable lumber. Some of the fungous diseases that attack living trees are similar to the fungous diseases that attack woods in constructions. Trees become infected through wounds such as the borings of insects and injuries caused by falling limbs and by pruning. There is sometimes an intimate connection between the attacks of insects and those, of fungi. Some insects transfer the micro- organisms to trees mechanically. Sap as distinct from pure water is an important agent in the growth of disease that has once entered the tree. The health of a tree is important. Good health increases resistance to disease, which resistance is less where health is low- ered, as it may be by poor soil, by lack of light, and by the attacks of insects. Old trees succumb more easily than younger ones, but there is probably no such thing as the natural death of a See also " Diseases of Trees," Hartig; "Diseases of Plants Induced by Cryptogamic Parasites," Tubeuf and Smith; "Disease of Taxodium known as Peckiness," von Schrenk (Contribution 14, Shaw School of Botany); "Fungus Diseases of Forest Trees," von Schrenk (United States Depart- ment of Agriculture Year Book 1900); "Diseases of Deciduous Forest Trees," von Schrenk (United States Bureau of Plant Industry, Bulletin No. 149 which also contains extensive bibliography); etc. 272 ORGANIC STRUCTURAL MATERIALS tree. To preserve health, some trees protect the raw surfaces of wounds with their own gums or resins. Intentional wounds, such as those caused by pruning, should be coated with tar or paint. The fungi that attack trees may be divided as they attack the foliage, the roots, or the trunks of the trees. Diseases of Foliage. Leaves that have been attacked by spot, mildew, or rust, cannot adequately perform their duties and the preparation of wood is correspondingly interrupted. The foliage of the Soft Maple (Acer saccharinum) is thus subject to attack by a fungus called Phyllosticta acericola. Chestnut foliage is similarly victimized by the fungus Marsonia ochroleuca, and other fungi are associated with other trees. FIG. 44. Section of wood cut from cypress after attack by wood-destroying fungus (Dcedalea vorax) . Diseases of Roots. Certain fungi attack the roots of trees. For example, the fungus known as the southern root rot (Ozonium omnivorum) attacks the roots of oaks and elms, and also those of some smaller plants as cotton. When the roots of trees are diseased, the wood making in the trunk is correspondingly re- tarded. Hartig states that barren places in forests are often caused by root fungi. Diseases of Trunks The trunks of live trees have many enemies. Cypress and Incense Cedar are sometimes attacked by the fungus Dcedalea vorax that causes peculiar cavities in the wood. The Bull Pine (Pinus ponderosa) is subject to attack by the fungus Ceratostomella pilifera that causes the wood to become blue. The bark of the chestnut is subject to the bark disease (Disporthe parasitica or Endothia gyrosa var parasitica), which USE AGE AND DECAY OF WOODS 273 eventually kills the tree. Hardy Catalpa, White Ash, and other trees have special enemies. 1 "The chestnut blight appears to confine itself to attacks upon species of the genus Castanea. It was first recognized in 1905 in trees near New York City but has now spread into many States and has prac- tically killed all of the trees that have been attacked. If the trunk is the part affected, the tree is killed perhaps in one season, but if the small branches are attacked, the tree may survive for several years. The spores produce running sores and the trunks or branches that have been girdled by these sores assume a characteristic appearance. One of the most easily detected symptoms is the growth of sprouts or " suckers" below the girdling lesions of the trunk and branches as well as at the base of the tree." Fungous Diseases of Structural Wood. The term "structural woods" here includes woods that are ready for construction and those that are finally in place. Life-processes have ceased in the woods that are now referred to, which may be either seasoned or green. The fungous enemies of such material are very numerous, and, just as conditions were noted under which all fungi thrive regardless of their species, so here it is more practical to note all of the ways in which timbers are exposed and to then study the influence that each one of these exposures exerts upon the life of fungi. Structural woods may be exposed in four ways. They are as follows : First. Woods may be coated by paint, metal, plaster, or simi- lar materials. Second. Woods may be coated, that is enclosed, by earth or water. Third. Woods that have not been coated may be exposed to the weather. Fourth. Woods that have not been coated may be protected from the weather. The "medium conditions" of heat, air, and moisture mentioned as necessary for the development of fungi are secured in the first ^'Disease of Taxodium known as Peckiness," von Schrenk (Contribu- tion 14, Shaw School of Botany); "Two Diseases of Red Cedar," von Schrenk (United States Division Vegetable Physiology and Pathology, Bulletin No. 21); "Diseases of Bull Pine," von Schrenk (United States Bureau of Plant Industry, Bulletin No. 36); "Diseases of the Hardy Catalpa" (United States Bureau of Forestry, Bulletin No. 37) ;" Diseases of White Ash," von Schrenk (United States Bureau of Plant Industry, Bulletin No. 32) ; etc., etc. 274 ORGANIC STRUCTURAL MATERIALS and third exposures. Woods are comparatively safe when in the second and fourth exposures. First Exposure. Paints and other impervious coatings protect from outside conditions but are detrimental if moisture and im- purities are within the wood when it is coated. Coatings sea) up the moisture and impurities, and a condition known as " dry- rot" is likely to occur. It should be noted that the name dry- rot refers to the results of the disease. The wreckage is dry and chalky but the fungi that caused this wreckage could not have lived without some moisture. The application of paint to an organic substance such as wood must be distinguished from the application of paint to an inorganic substance such as iron. The principles that here apply with woods resemble those that apply when fruits or meats are placed in cans. Air-tight coatings should not be placed around any of these organic materials unless they have first been sterilized, cured, or otherwise prepared. Second Exposure. This exposure is distinct from the one that precedes it in one vitally important particular. Paints and metals are practically inert, while mud and water are not. Mud and water protect from outside influences but at the same time dilute or cleanse away such impurities as have remained within the wood. Even green woods are safe while under water, and not only this, but changes take place that render them more durable after they have been removed from the water. 1 Woods do not no mally decay while submerged in mud or water. Records show that woodwork has lasted in this manner for over a thousand years, and there is no reason why it should ever decay while thus protected. The softening or physical disintegration that takes place under some conditions is not decay. Third Exposure. The third exposure is associated with what is commonly known as " wet-rot." The fungi that act when uncoated woods are exposed to the weather seem to require or to tolerate larger quantities of moisture than those accountable for the changes known as dry-rot. The medium moisture conditions necessary for the growth of fungi in this position are supplied in two ways: (1) Excessive quantities of water may be applied intermittently as with marine constructions that are exposed between the tides, or (2) 1 See index for "Water Seasoning." PLATE VI. PORTION OF FLOOR BEAM AFTER ATTACK BY DRY ROT FUNGUS 111 i . Lifeless Condition of Wood is Shown by Detached Material at Bottom of Picture. (Facing page 274.) USE AGE AND DECAY OF WOODS 275 smaller quantities of water may be present constantly as when timbers rest upon damp soil, and when they are exposed to the moist atmosphere of mines. The Influence of Top Soil. -This is so great that the expression, " durable in contact with the soil" is often used as a measure of the durability of wood. Surface soil is dangerous for several reasons. It is damp, and comparatively warm, and it restricts the air but does not cut it off entirely. Micro-organisms are present in the soil near the surface. The effect of contact with top-soil is shown in the case of posts and other timbers placed upright in the ground. Decay usually begins in the parts of these timbers that are nearest to the surface of the ground and later extends upward and downward from the surface as conditions permit. The tops of posts and similar timbers resist because they are drained and well ventilated, and the bottoms resist if they are driven down deep enough to escape the conditions that prevail at the surface. A beam raised a short distance from the ground lasts longer than one lying on its surface, because, although the space between the timber and the soil may not be more than a few inches, it is enough to secure some drainage and ventilation. Some woods noted for extreme durability, average durability, and perishability when in contact with the soil, are noted below. Weiss estimates 1 that most of the woods in the first column will Very durable woods Durable woods Perishable woods Black Locust Catalpa Cypress Greenheart Lignumvitse Mesquite Mulberry Red Northern White Cedar Osage Orange Redwood Western Red Cedar Chestnut Douglas Fir Longleaf Pine Southern White Cedar White Oak Ash Balsam Basswood Beech Birch Cottonwood Hemlock Loblolly Pine Lodgepole Pine Red Oak Sitka Spruce Sycamore Tupelo Western Yellow Pine White Spruce Preservation of Structural Timber," Weiss (p. 275). 276 ORGANIC STRUCTURAL MATERIALS probably last more than twenty-five years when in contact with the soil; that most of those in the second column will last between ten and twenty-five years, and that most of those in the third column will fail in less than ten years. Fourth Exposure. Uncoated woods do not normally decay as long as they remain protected from the weather in dry, venti- lated places. On the contrary, the quality of wood is likely to improve under such conditions, for reasons that are given in the section devoted to " Natural Seasoning." Many of the timbers seen in the covered wooden highway bridges that were erected in this country, in some cases more than one hundred years ago, are yet sound. Unpainted wooden roof-trusses have lasted for many centuries in European churches. Evidence of Disease in Wood. Disease becomes apparent in many ways. Some woods discolor, others swell and soften, while yet others become dry and brittle. Clots of hyphae sometimes fill cracks or appear beneath the bark of logs. Thick masses of orange, pink, or gray material often extend like giant cobwebs between rotting timbers in mines. Piles, ties, and mudsills may be sound without but soft and spongy within. Sometimes this order is reversed. Methods of Treatment. Preventative methods are much more valuable than curative methods. It is usually impracticable to attempt to control disease that has once started. It is said that acid solutions will counteract some kinds of fungi. Disease caused by lack of ventilation can sometimes be prevented from spreading rapidly by providing for ventilation. Methods of Protection. Fungous diseases are contagious and for this reason diseased woods should usually be destroyed. The means by which woodwork may be more or less successfully defended against fungus diseases are as follows: (1) Selection: Woods that have the fewest fungus enemies should be selected. (2) Seasoning: Resistance is greatly increased by seasoning. (3) External treatment: Paints and other coatings may be used to shut out the micro-organisms that cause disease. (4) Inter- nal treatment: Woods may be saturated with antiseptics. These subjects are treated elsewhere under appropriate titles. CHAPTER XI FAILURE OF WOOD BECAUSE OF FIRE. WOOD AS AN AGENT IN CONFLAGRATIONS. FIRE PROTECTION The fact that wood is inflammable is of far-reaching impor- tance. The direct losses caused by the burning of finished pro- ducts and of live woods in the forests, and the indirect losses caused by the communication of fires from burning wood to other property cannot be estimated. A large part of the world's incre- ment of wealth is burned up every year, and an undue proportion of this loss occurs in the United States, where large quantities of wood are used in construction. Wood is a principal agent in conflagrations for the reason that it is the only one of the primary structural materials that takes fire at ordinary temperatures. Stones and metals may fail because of fire, but they do not contribute directly to flames. Many attempts have been made to use other materials in place of wood in naval and house architecture and even the earliest of these attempts were due to the fact that wood will burn. REFERENCES. "Fire Protection of Mills, " Woodbury (John Wiley & Sons, 1895); "Contributions of Chemistry to the Methods of Preventing and Extinguishing Conflagrations," Norton (Journal of American Chemical Society, Vol. XVII, 1895) ; Publications of National Board of F\re Under- writers; Publications National Fire Protection Association; Files of Insurance Engineering; "Process of Fireproofing Wood for the Wood- work of Warships," Hexamer (Engineering News, March 23, 1899); "A New Investigation of the Fireproofing of Fabrics," Whipple and Fay (Part of "The Safeguarding of Life in Theatres," Freeman, Transactions of the American Society of Mechanical Engineers, Vol. 27, 1906); "Waste of Our National Resources by Fire," Baker (Proceedings of Meeting called jointly by the American Society of Civil Engineers, the American Institute of Min- ing Engineers, the American Society of Mechanical Engineers, and the American Institute of Electrical Engineers, published in pamphlet, 1909); "The Enormous Fire Waste of the United States," Cochrane (Scientific American, June 15, 1912); "Fire Prevention and Fire Protection," Freitag (John Wiley & Sons, 1912); "The Modern Factory," Price (John Wiley & Sons, 1914); "Tests on Inflammability of Untreated Wood and of Wood Treated with Fire-retarding Compounds," Prince (Report on Uses of Wood, National Fire Protection Association, 1915). 277 278 ORGANIC STRUCTURAL MATERIALS Fire losses are greater in the United States than in any other country. The direct losses now exceed two hundred million dollars every year. In its relation to the building operations of the country this is equivalent to the destruction of one house out of about every four built. 1 This loss, which is about equal to the total value of all gold, silver, copper, and petroleum produced in the United States in a year, and which is many times greater than the interest on the National debt, is one of the factors in the present high cost of living. The sum mentioned does not include indirect losses, or losses by forest fires. The direct fire losses in the United States for thirty-six years (1875-1910 inclusive), as estimated by the National Board of Fire Underwriters, were as follows : 1875 1876 1877 1878 . .. $78,102,285 . . . 64,630,600 . . . 68,265,800 64 315 900 1889. . 1890. . 1891.. 1892 . $123,046,833 . 108,993,792 . 143,764,967 151 516 098 1903. . . . 1904. . . . 1905.... 1906 $145,302,155 229,198,050 165,221,650 518 611 800 1879 1880 1881 1882 1883 ... 77,703,700 ... 74,643,400 . . . 81,280,900 . . . 84,505,024 100 149 228 1893.. 1894.. 1895.. 1896.. 1897 . 167,544,370 . 140,006,484 . 142,110,233 . 118,737,420 116 354 575 1907.... 1908.... 1909.... 1910.... 215,084,709 217,885,850 188,705,150 214,003,300 1884 110 008 611 1898 130 593 905 1885 1886 1887 . . . 102,818,796 . . . 104,924,750 120 283 055 1899.. 1900. . 1901 . 153,597,830 . 160,929,805 165 817 810 Over five direct lo six year billion dollars sses in thirty- 5 1888 . . . 110,885,665 1902 161 078 040 Fire losses are increasing faster than the population of the country is increasing, that is, the number of fires per capita is increasing. The indirect losses that take place as a result of fire must be considered also. Such losses include the costs of maintaining fire departments and water supplies for purposes of fire fighting, excessive insurance and losses in rents and business. It is estimated that in 1907 the total direct and indirect losses from fire amounted to $456,485,900, a sum almost half as great as the value of the new building constructions for that year. That is to 1 "Proceedings of the Forty-ninth Annual Meeting of the National Board of Fire Underwriters," p. 19. Report "National Conservation Commission, Section of Minerals," Washington, December, 1908. WOOD AN AGENT IN CONFLAGRATIONS 279 say, during that year about one billion dollars was expended upon new buildings and construction work, and approximately half of this increment was destroyed by fire. Such a sum is greater than the true value of the real property and improvements in any one of the States of Maine, West Virginia, North Carolina, North Dakota, Alabama, Louisiana, and Montana. 1 There is also the loss of human life. According toft-he United States Census, 6,000 persons died of burns and 10,000 persons were badly injured by the same cause during 1906. All comparisons in connection with this subject are startling, yet all of them are conservative. Baker estimates that the buildings destroyed every year in the United States if placed upon lots with an average frontage of 65 feet, would line both sides of a street long enough to extend from New York to Chicago. 2 "Picture yourself driving along this terribly desolated street. At every thousand feet you pass the ruins of a building from which an injured person was rescued. Every three-quarters of a mile there is the blackened wreck of a house in which some one was burned to death." ' 'Imagine this street before the fire touched it, lined with houses, stores, factories, barns, schools, churches. Suppose the fire starts at one end of the street on the first day of January and is steadily driven forward by a high wind, just as actually happens in a conflagration. Building after building takes fire; and while the fire fighters save some in a more or less injured condition, the fire steadily eats its way forward at the rate of nearly three miles a day, for a whole week, for a whole month, for all twelve months of the year. And at the end of 1907 did the conflagra- tion end? No; it began on a new street, a thousand miles long, which was likewise destroyed when 1908 was ended. And this same destruc- tion is going on today." The gravity of the situation is also expressed by Merrill as follows : "Fifteen years is a brief space of time in the history of an organiza- tion; it is briefer in the history of a nation. Yet for our country, this period includes the San Francisco, Baltimore, Chelsea and Bangor con- flagrations, the Windsor, Iroquois, Collingswood, Boyertown, Slocum, 1 "The Enormous Fire Waste of the United States," Cochrane (Scientific American, June 15, 1912). 2 Proceedings of meeting called jointly by The American Society of Civil Engineers, The American Institute of Mining Engineers, The American Society of Mechanical Engineers, and The American Institute of Electrical Engineers, March 24, 1909. 280 ORGANIC STRUCTURAL MATERIALS Lenox, Cherry, Newark, Chicago. Stock Yards and Asch disasters; not a day without its long list of properties destroyed and not a month without record of the sacrifice of human life. It marks a burnt offering of more than two thousand million dollars worth of our created sources, and the lives of more than twenty thousand of our people." 1 A comparison between per capita losses in some European countries and those in the United States is as follows (National Board of Fire Underwriters) : Austria (1898-1902) $0.29 Italy (1901-1904) $0.12 Denmark (1901) 0.26 Switzerland (1901-1903) . . . 0.30 France (1900-1904) 0.30 United States 2.50 Germany (1902) 0.49 In other words, the average per capita loss in six leading Euro- pean countries is thirty cents, while the average per capita loss in the United States is two dollars and fifty cents. No country, however rich, can afford to suffer such losses indefinitely; yet no great decrease can be expected until the average building in the United States is as good, from the fire- resisting viewpoint, as the average building in European coun- tries. Most of the structures erected to meet first needs in the United States were built of wood; and this, with the indiscrimi- nate use of wood in construction at the present time, is the prin- cipal explanation of why losses in this country have been and are so heavy. The policy in Europe is to prevent fires; but in this country, until recently, chief attention was given to perfecting apparatus and organizations by which fires might be extinguished. The present subject is part of the general field of Fire Protec- tion. The behavior of wood while burning and its influence upon the situation as a whole must be comprehended, but some knowl- edge of the wider field of which the present subject forms a part will also be of service. The notes that follow will relate to (1) Wood as an Agent in Conflagrations and (2) Some Principles of Fire Protection. WOOD AS AN AGENT IN CONFLAGRATIONS This part of the subject divides itself as it relates to the burning of wood, the attempts to prevent wood from burning, and the methods used to extinguish burning wood. 1 The great conflagrations that have taken place in the last and present centuries are listed on p. 272 of World's Almanac, 1911. WOOD AN AGENT IN CONFLAGRATIONS 281 THE BURNING OF WOOD. Wood consists of a definite chemical compound known as cellulose, permeated by materials collectively known as lignin, and secretions such as resins, color- ing matter, and water. Or, in terms of inorganic chemistry, it consists of carbon, oxygen, hydrogen, nitrogen, and small amounts of mineral salts that exist in the ash. Upon burning, wood first gives off some water, after which inflammable gases separate from a solid base of carbon; the carbon is next largely consumed and leaves a residue of ash, which is composed of metallic salts that were originally present, together with carbonates formed during the burning. Wood deteriorates and may then take fire spontaneously 1 when subjected to com- paratively slight elevations of temperature for long periods. In most cases, however, wood takes fire from flame communicated directly. Complex changes take place in wood as the result of heating without access of air. They are described as follows: 2 "When wood is heated in retorts, the moisture is driven out, but no decomposition occurs until the temperature approaches 160 degrees C. Between 160 degrees and 275 degrees C. a thin watery distillate is chiefly formed; above 275 degrees the yield of gaseous products becomes marked, and between 350 degrees and 450 degrees liquid and solid hydro- carbons are extensively formed. Above this last temperature little change occurs, and charcoal, containing the mineral ash, remains in the retort. "The fraction between 160 degrees and 275 degrees is called pyrolig- neous acid, and contains the important liquid distillates, methyl (wood alcohol), acetic acid, together with acetone, methyl acetate, allyl alcohol, phenols, and a great many other substances. "The fraction between 275 degrees and 450 degrees contains both aromatics (i.e., benzene derivatives) and parafnne hydrocarbons. Its most important constituent, from a commercial point of view, is the creosote oil, containing guaiacol, creosol, and other phenols of high molecular weight. "The variety of wood used affects the amount of distillate. Decidu- ous trees, especially birch, oak, and beech, are preferred. Coniferous woods afford less acid (watery) distillate, but more of the higher frac- tions containing turpentine and resin." 1 Wood should not come into contact with steam or hot water pipes and should not be placed too near registers; otherwise deterioration and spon- taneous combustion may result. See also "Spontaneous Ignition of Wood," Fairweather (Insurance Engineering, September, 1908.) 2 Quotation from Thorp's "Outlines of Industrial Chemistry." 282 ORGANIC STRUCTURAL MATERIALS ATTEMPTS TO PREVENT WOODS FROM BURNING Many attempts have been made to prevent woods from burning. The ancient Greeks used alum for this purpose; and later at- tempts were associated with methods designed to protect woods from decay. At the present time the most intelligent efforts are those that have followed great theater fires, and much of the literature upon this subject relates to efforts that have been made to protect the woods and fabrics used in theaters. The tendency now is to eliminate woods and other combustible materials for theater buildings. Woods treated with certain chemicals are referred to as "fire- proofed woods," but this is inaccurate. All woods burn under the right conditions, and, at best, it is possible only to retard oxidation, and to obstruct for a little the escape of volatile gases that are active agents in spreading fires. Correctly speaking fireproof ed woods do not exist; it is, however, correct to speak of methods that retard burning. Protective methods are of two kinds: fire-retarding chemicals are applied internally and externally. INTERNAL PROTECTION. The attempts made to protect woods from fire by injecting fire-retarding chemicals into them have not yielded satisfactory results; yet the fact exists that such at- tempts have been made and a statement with regard to this form of protection is, therefore, necessary. 1 The subject will be divided as follows: the materials known as fire retardants, the processes used to introduce these materials within the woods, and the selection and preparation of woods that are to receive the fire- retardant chemicals. Fire Retarding Materials. Alum^ boric acid, borax, sodium tungstate, water glass, magnesium phosphate, aluminum sulphate, ammonium chloride, ammonium sulphate, ammonium phosphate, " Paris theatre solution," " Chicago solution," and many other mixtures and compounds have been considered or used to retard the burning of fabrics and the burning of woods. Some of these substances serve because they decompose and liberate gases that smother flame. Borax owes its efficiency to other properties; it melts easily and then flows in thin films that cut off the supply of oxygen from burning wood. 1 Fireproof ed woods were used in ships, notably after the war with Spain. A small quantity of fireproofed wood has been used in the finish of special buildings. At the present time the demand for such material is limited. WOOD AN AGENT IN CONFLAGRATIONS 283 The value of ammonium phosphate as a fire retardant has been recognized for many years. In his report upon the burning of the Iroquois Theatre, Freeman states that no one of the many salts or mixtures tested was found to be so good. The properties and behavior of this salt are described in the following quotation. " First, it has a little tendency to gather dampness, and to dry this out absorbs a little heat. Next, as the heat rises, ammonia is given off, and the thin film of this repels the oxygen of the air. When the am- monia is gone we have left the ortho-phosphoric acid, which in liquid form covers the surface and preserves it from oxidation under increasing heat. At 300 to 400 degrees Fahrenheit this decomposes, giving off water; at higher temperatures it gives off its remaining water. In all of this disassociation it absorbs some heat until we have left, at full red heat, fused metaphosphoric acid as a liquid film surrounding the fixed carbon remaining from the destructive distillation. "On the other hand, the phosphate of ammonia has its disadvantages. A manufacturing chemist, perhaps of the widest experience of any in this country in the practical chemistry of the phosphates, warns me that for its best efficiency it must be applied in a strong or saturated solution, but, if very strong, it may in time disastrously affect the strength of the fiber, that it is somewhat deliquescent, has a tendency to develop fungous growth, that in time it may part with a portion of its ammonia, becoming the acid ammonium-phosphate which has a tendency in presence of moisture to attack metals, while in a warm atmosphere the free phosphoric acid attacks some colors." The result of a series of experiments upon the comparative worth of the several chemical substances and mixtures used as fire retardants, conducted by Whipple and Fay, is summarized as follows: 1 (a) That inert chemical substances can exert but very slight fire- retarding action. (6) The fire-retarding action of salts which depend for fire-retardant quality only upon their water of crystallization, like potash, alum, sodium phosphate and borax, is slight and unimportant, although some- what superior to that of inert substances. (c) Fire retardants of the class which suffer chemical decomposition under heating are decidedly more efficient than those which depend on the driving off of water of crystallization, but still far less efficient than the class that follows. (d) The most efficient salts are those which on decomposing leave ia A New Investigation of the Fireproofing of Fabrics" contained in "The Safeguarding of Life in Theatres," Freeman (pp. 57-65). 284 ORGANIC STRUCTURAL MATERIALS behind a non-volatile residue which is fluid at the temperature of the burning canvas, and covers the charring fabric with a thin glaze which prevents further access of air; and, of this type, phosphate of ammonium was found to be the best. It is necessary to distinguish between chemicals injected into woods as fire retardants and those that are applied within woods for other purposes. The latter are antiseptics, and woods are the better for their presence; but as distinct from these the salts which are applied as fire retardants attract water and in this way injure woods. Processes Used to Apply Fire Retardants Within Woods. The methods used to introduce fire retardants within woods are the same as those employed to introduce antiseptics within woods. There should be deep impregnation and the wood must not be injured. Processes are of two kinds: there are some that do not include pressure, and others that do include pressure. Solu- tions may be applied by dipping, brush-applications, and the open tank process; or they may be forced in by pressure applied within cylinders. Preparation of Woods to Receive Fire Retardants. Woods should be dry and receptive if fire retardants, or any other chemical substances, are to be introduced within them. Some attention should be paid to selection; it should be remembered that woods differ in receptivity and that some woods, such as California redwood, take fire less easily than others. EXTERNAL PROTECTION. Many attempts have been made to prevent or retard the burning of wood by means of coatings, and at least one of these attempts has succeeded sufficiently to serve practically in construction. 1 The properties of the materials employed, the methods by which they are applied, and the prepa- ration of woods to receive them, must be considered. Materials. Fire-retardant coatings are of many kinds. An ideal fire-coating is one that resists the disintegration and dis- tortion due to high heat and sudden cooling, and one that will not conduct heat. The materials available for this purpose do not meet these requirements satisfactorily, but they do resist the action of fire longer than other materials. Asbestos, the so-called fireproof paints, and certain metals, are used in fire-coatings. Asbestos. The name asbestos is applied to several products, as Canadian asbestos or chrysotile, which contains about fifteen 1 See description of fire doors and fire shutters. WOOD AN AGENT IN CONFLAGRATIONS 285 per cent, of water, and tremolite, a fibrous calcium silicate, which contains no water. Canadian asbestos, so largely used in the United States, loses strength and is otherwise altered by tem- peratures, just below red heat, that are sufficient to expel the water of crystallization. 1 The fact that common asbestos becomes brittle and loses strength when subjected to comparatively low temperatures has discouraged its use in making curtains to isolate the woodwork and other inflammable materials used in theaters, and such cur- tains although still used, are no longer regarded as the best form of protection. 2 Tenacity is less important if asbestos is to be used as a pigment in paint. Fireproof Paints. Fireproof paints differ from ordinary paints chiefly in that they are not themselves inflammable. These paints offer momentary but sometimes sufficient resist- ance to very small fires, such as flames from burning matches. But they do not resist fires that have gained headway or created appreciable draughts. It is obvious that crusts less than one one-hundredth of an inch in thickness cannot aid effectively any attempts to prevent conflagrations. Lime and asbestos are common pigments, while glue and water- glass are common vehicles. Oil should not be used. A number of mixtures purchased in open market were found upon analysis 3 to consist chiefly of slaked lime, powdered asbestos, alum, gyp- sum, and glue. A cold water paint containing a lime, asbestos, or magnesium base, and casein or glue as a binder, is doubtless as good as any. Although the National Fire Protection Asso- ciation considers well-made whitewash a good fireproof coating, 1 About 600 degrees C. 2 Steel now enters into the construction of the best curtains for proscenium openings. 3 Whipple and Fay Report. FIG. 45. Corner of tin-clad door. 286 ORGANIC STRUCTURAL MATERIALS the use of whitewash for this purpose is not general. Some fire-retardant paints are said to be composed of easily fusible glass mixed with ordinary paint. Metals. Wood is sometimes enclosed by metal. Combina- tions of wood and tin, such as are used for fire doors and fire shutters, have resisted where solid metal has buckled and failed. 1 Tin is superior to paint in that it resists for some time even when exposed to severe heat, whereas paints offer but momentary resistance even to very small fires. Paints soon blister and chalk under the influence of heat. Methods Used to Apply Fire Coatings. Fire-retardant paints are applied to surfaces of wood in the same way as other paints. That is, it is important that the wood should be clean, dry, and receptive; that the brush should be held at right angles to the surface., and that the paint should be laid on with strokes parallel to the grain of the wood. 2 Tin can be applied to wood in such a way that the two together offer a very real resistance to fire. Tin will warp, and wood will burn, but the two, when used together in standard fire doors, have lasted long enough to save buildings. They have retained the shapes of the openings, even after the wood within has charred and failed. Standard fire doors are made of not less than three layers of seven-eighths-inch wood. The tin covers overlap at all points so as to protect fastenings and resist strains. 3 The principles that apply when woods are to be coated with ordinary paints and varnishes apply equally when they are to receive fire coatings. All woods should be well seasoned, dry, and clean, if they are to receive coatings of any kind, and no wood that is moist, knotty, or resinous should ever be used in any fire door or fire shutter. Moisture if present would cause decay, while, if a fire should take place, moisture and resins would form hot gases that would burst through the tin. Clean, dry, white pine is used in the best fire doors. Methods of Testing " Fireproof ed" Woods. Small specimens are usually burned in laboratories 4 and the intervals that elapse before they are charred or consumed are taken as measures of their resistance. Although encouraging results are obtained in 1 See descriptions of fire doors. 2 See "Paints and Varnishes Applied to Surfaces of Woods." 3 See Rules and Requirements National Board of Fire Underwriters. 4 Bunsen burners are commonly employed. PLATE VII. APPEARANCE OF FIRE DOORS AFTER FIRE (Facing page 286.) WOOD AN AGENT IN CONFLAGRATIONS 287 this way, such tests have very little practical value save as they enable comparisons, because all wood whether protected or not will burn if the draught is sufficient. The way in which results are influenced by methods is shown in the case of some experiments upon so-called fireproofed canvas prepared for use in the scenery of theatres. These experiments are described as follows: 1 "In the effort to more nearly follow practical conditions, one set of tests was developed on the line of my earlier stovepipe experiment by burning fireproofed canvas within a piece of five-inch stovepipe two feet long lined with asbestos." "Six strips of the canvas, thoroughly treated with the different solutions, were placed three-fourths of an inch apart and ignited by burning one ounce of excelsior. In every case the canvas burned completely to ash in from three-fourths of a minute to one and one- half minutes, with flames which often extended two feet above the top of the stovepipe. Tests in the stovepipe apparatus on the efficiency of different flameproofing chemicals were made comparable by taking the same quantity of canvas in each and by lighting the fire with the same quan- tity of combustible." METHODS USED TO EXTINGUISH BURNING WOODS. Although the methods used to extinguish all fires are the same, yet there is good reason for associating such methods with the burning of wood. As already stated, in Europe the policy with regard to fires is to endeavor to prevent them. Less wood is used in Europe and the losses there are smaller than in the United States, where larger quantities of wood are used and the losses that take place by fire are larger. In the United States, until recently, more attention has been given to perfecting apparatus and organiza- tions designed to extinguish fires, than to means by which the fires might be prevented. Fire departments in Europe are inferior to those in the United States, because less need exists for fire departments in Europe. Those who visit European cities for any length of time are impressed by the fact that fire engines are so seldom seen. Dur- ing ten years passed in French and German cities Norton saw fire engines called out five times. 2 American efficiency in the 1 "A New Investigation of the Pireproofmg of Fabrics" contained in "The Safeguarding of Life in Theaters," Freeman (pp. 57-65). 2 Journal of the American Chemistry Society (Vol. XVII, No. 2). 288 ORGANIC STRUCTURAL MATERIALS field of extinguishing fires is unquestioned; but this is because the demands upon firemen are so great in the United States. Materials. The materials used to extinguish fires act by excluding air from the substances that are burning. It is need- less to say that water is the cheapest, most effective, and most widely available material for this purpose; it should not be for- gotten, however, that other materials are sometimes used. Some of these are as follows: Carbon Dioxide. It is generally conceded that much of the value of this gas, when mixed with water as in the discharge from chemical extinguishers, is due to the power generated, which propels the stream. Carbon dioxide is usually used mixed with water. It is very rarely used by itself. Sulphur Dioxide and Ammonia. These gases extinguish fires but are seldom used because it is often inconvenient to obtain and apply them and because they endanger life. They serve because they displace oxy- gen but they cannot be used easily save in enclosed spaces of limited extent. Carbon Tetrachloride. The properties of this compound were known in the past but until recently its usefulness has been limited by its high cost. The development of electrolytic cells for the production of chlo- rine and caustic soda, with the consequent cheapening of chlorine gas, has recently opened the way for the cheaper manufacture of carbon tetrachloride. 1 Carbon tetrachloride is a clear, colorless, volatile liquid, having a specific gravity of 1.604 and a boiling point of 78 degrees C: It is non-inflammable, non-explosive, non-corrosive, and its vapors smother flame. It is a non-conductor and is particularly useful in the case of electrical fires, where water cannot be employed and where dry powders, such as sand, have previously been used. It is also serviceable in library fires, because it will extinguish flames produced by burning papers without injuring the papers as water would injure them. Solids. Flour, sand, and other solids are sometimes used in emergen- cies. Such materials are stored in cylinders and these "dry powder cylinders" are convenient and easily found receptacles for small quan- tities ofthe powders used. These cylinders are useful as far as they go but the y may do harm by causing a sense of security not warranted by the results obtained. The National Fire Protection Association reports as follows: "In view of the fa t ct that several so-called fire extinguishers, consist- ing generally of sheet-metal tubes filled with mixtures of bicarbonate of 1 Journal Industrial and Engineering Chemistry (January, 1910) ; Engineer- ing News (March 16, 1911); Quarterly National Fire Protection Association (January, 1911); Catalogues Pyrene Manufacturing Company; etc. WOOD AN AGENT IN CONFLAGRATIONS 289 soda and other materials in powdered form, have been widely advertised as suitable for use for fire-extinguishing purposes, we have to report that in our opinion all forms of dry-powder fire extinguishers are inferior for general use, that attempts to extinguish fires with them may cause delay in the use of water and other approved extinguishing agents, and therefore their introduction should not be encouraged." Methods or Devices for Applying Materials. Water is applied by steam fire engines and other devices commonly associated with the elaborate fire departments of cities. Tanks placed at high elevations are often useful where natural head is not available. Chemical engines, sprinklers, and fire pails are also employed. Chemical engines are tanks containing bicarbonate of soda dissolved in water, and commercial sulphuric acid (oil of vitriol) stored separately but also within the tank. The carbon dioxide which results when these compounds come together creates the force by which the contents of the extinguisher is discharged. 1 Automatic sprinkler systems consist of pipes arranged on the ceilings of rooms within the structures to be protected. Water- ways in these pipes are closed by small discs which are held in place by easily fusible solder. In case of fire the solder melts, water flows upon the fire, and an alarm is rung. There are many other important details, 2 some of which are noted later in the present chapter. Portable chemical fire extinguishers differ from the larger chemical engines that have been described in that they are easily carried from place to place, and very easily manipulated. The copper receptacle, coated with tin, is designed to hold about three gallons of water, and to resist a pressure of about four hundred pounds, although the pressure seldom exceeds eighty pounds. The quantities of acid and soda are adjusted so that the pressure, when they come together, is not greater than the cylinders can bear. The solution that leaves the extinguisher should be alka- line rather than acid, since acid solutions are more liable to damage the materials upon which they are thrown. Extin- 1 Requirements for Proper Installation of Chemical Fire Extinguishers (Published by The New York Fire Insurance Exchange, 19 13). 2 Rules and Requirements of the National Board of Fire Underwriters for Sprinkler Equipment, 1913. 290 ORGANIC STRUCTURAL MATERIALS guishers should be recharged at stated intervals; their contents should always be fresh and active. 1 The extinguishers become active when they are inverted. The stopper then drops away from the mouth of the acid flask. The acid mixes with the soda solution, and the conditions neces- sary for operation are obtained. Extinguishers should not be inverted until operators are in the presence of the fires, since the streams last only about eighty seconds. They should be stored in conspicuous places, where those who are to use them can find them easily. Care should be taken so their contents will not freeze. Fire pails are less effective than chemical extinguishers, because their contents cannot be propelled as accurately or as far. Fire pails should be painted red so that they can be identified if thoughtlessly removed from their accustomed places for othei service. They should always remain in the FIG. 46. Section same conspicuous and convenient places, and through portable fire care s h O uld be taken to prevent their contents extinguisher. . from freezing. The pails should be inspected frequently as a safeguard against leakage and evaporation. The value of fire pails has been described as follows : 2 A pail of water is the best fire extinguisher yet devised. It costs little; its use is understood by everyone; it is easily kept ready for use; and its effect, if used at the proper moment, may be better than the work of an entire fire department five minutes later. The value of fire pails has come to be recognized, not only by the insurance community and by practical firemen, but also by all other persons having a care for the safety of life and property. Accordingly, it is a common practice for property owners, of their own accord, to have pails of water ready, in 1 The directions that appear upon extinguishers of a certain approved type are as follows: "Fill the receptacle with two and one-half gallons of water, add two and one-half pounds bicarbonate soda; stir well to dissolve. Fill to acid line with four fluid ounces of sulphuric acid and place stopper in bottle, and bottle in cage. Screw cap down tight. Protect from freezing. If i used, clean well and recharge. Discharge, clean well and recharge yearly. Record date when charged." See also "Requirements for Proper Installation Chemical Fire Extinguishers" (Published by New York Fire Insurance Exchange, 1913). 2 " Requirements for Proper Installation of Fire Pails" (Published by The New York Fire Insurance Exchange, 1909). WOOD AN AGENT IN CONFLAGRATIONS 291 case of fire; in addition, the officers of local fire departments use their authority to bring this about, and fire insurance organizations have not been lacking in encouraging the insuring public to equip their premises with this simple means of fire protection. The New York Fire Insurance Exchange, in common with other in- surance organizations, has placed a premium on fire-pail equipments by granting a liberal reduction in rates, where the premises of an assured con- tain fire pails, maintained in a manner which assures a fair probability of their being ready for use when needed. Fire pails are useful only when they are filled, within easy reach, and near at hand; and in order to provide some guarantee of efficiency, the fire insurance community has been obliged to adopt certain rules regarding fire pails, and to make a proper observance of these rules a condition to granting the reduction in rates. These and similar fire insurance rules are the result of more than fifty years' experience with the insuring public, who, with the best of intentions, frequently install costly fire protection equipments,and then take no steps toward keeping them in condition for use when fire occurs. In the case of fire pails, for example, it has been found advisable to require that the pails be painted red, with the word "FIRE" or "FOR FIRE ONLY" in black letters of a certain size. The red color is useful because of its general association with fire; it helps to make the pail clearly visible when wanted; and, with the word "FIRE," is a constant reminder that the pail is there for a special purpose, the putting out of fire, and is not to be taken away or used for ordinary purposes. The placing at a medium height is devised to permit of grasping the pail with- out spilling half its contents; if a pail is placed more than five feet high, it is likely to be out of the reach of the average person; and if set lower than two feet, it is likely to be overlooked or to be knocked from its position. The use of an iron pail in preference to a pail of wood or other material, is a matter of service and economy, in addition to the greater likelihood that an iron pail will be found serviceable when suddenly wanted for use. The requirement of a stated number distributed in groups throughout the entire premises, is framed to provide that pails shall be within a hand's grasp, and not be distant anywhere from 50 to 200 feet at a time when a tiny flame is rapidly growing into a formid- able blaze. The insistence of a permanent setting, such as hooks or shelves, is intended to make sure that the pail will be given a fixed posi- tion, which will become familiar to the occupants who, in time of excite- ment, can rely on finding pails in a definite spot. The regular re-filling is a common-sense precaution to make sure that the pails shall contain water. Such rules as these are part of the usual discipline maintained in establishments which have in view a careful management of the property, and they are published in the belief that a proper observance of them will tend to reduce the loss suffered by the community from the effects of fire. 292 ORGANIC STRUCTURAL MATERIALS When fire pails are located where there is a liability of the water being frozen in cold weather, it is recommended that 2 pounds of chloride of calcium or salt (the chloride of calcium is preferable), be placed in each pail. For casks the quantity recommended is fifty pounds for each cask. It is necessary that the chloride of calcium or the salt be dissolved by thorough stirring. Organization. It should be remembered that fire losses are caused by failure and the misuse of apparatus as well as by its absence. The efficiency of the best apparatus is limited by the way in which it is used, and, for this reason, the highest efficiency is seldom obtained outside of large cities where there are paid fire departments. The danger from fire is less where those in charge of apparatus are taught how to use it before an actual emergency takes place. A plan of action should be formed and all details be considered before a fire takes place. SOME PRINCIPLES OF FIRE PROTECTION For completeness some space is given to the general field of Fire Protection. It was stated that the policy in Europe is to prevent fires, but that in this country, until recently, the principal demand has been for means to extinguish them, and that this difference explains why losses are so much greater in this country than in others. Fires may be prevented by eliminating the factors that are known to cause them, one of which is wood. One reason why preventive practices are emphasized in foreign countries is because wood is less plentiful in such coun- tries. These practices were not introduced suddenly, but grew, little by little, as local supplies of wood gradually decreased. It was the law of necessity that, in Europe, caused the substitu- tion of non-inflammable materials for wood, and already the same law is beginning to serve similarly in the United States. The conditions in Europe and in this country differ in that larger proportions of what may be called " final constructions" exist abroad where civilization is older. That which is regarded as mere neglect or misfortune here, is considered there more as though it were a crime. The police in Berlin have very real authority over every detail that is likely to increase danger from fires, while citizens of France are held legally responsible for fires that pass from their own homes to those of others: WOOD AN AGENT IN CONFLAGRATIONS 293 Preventive practices in the United States had their origin in the factory districts of New England, and some of the best and most modern details in this field have been evolved by manu- facturers in those sections. The National Fire Protection Asso- ciation, the National Board of Fire Underwriters, Factory Mu- tuals, and other organizations now exist to study causes and suggest methods by which fires may be prevented. The organizations alluded to occupy a field in this country that suggests the one occupied by paternal governments abroad. Very much has been accomplished by them already, but improve- ment to the point of the average conditions that exist in older countries cannot be hoped for for some time to come. Many structures that were erected to meet first needs in the United States have already given way to others, better and more per- manent, but much remains to be done. The rebuilding of a country is a very slow process. It will be remembered that the preceding section was devoted to a study of the material Wood when burning, and that the text was presented under the titles "Burning of Wood," "Attempts to Prevent Wood from Burning," and "Methods Used to Extin- guish Burning Wood." As distinct from this, the subject of Fire Protection is devoted to a study of burning Buildings and the parts of this subject will be grouped as they relate to (1) "Burning of Buildings," and (2) "Method by which Buildings are Prevented from Burning." Burning Buildings. Such fires may be classified as they originate within the buildings, or as they are transferred from without. The latter are known as "exposure fires," and a large proportion of the destruction that takes place in this country is of this type. The superiority of the average European building, from the fire standpoint, is shown by the fact that a larger proportion of the fires in Europe are confined to the buildings in which they start. Aside from fires due to warfare, the great conflagrations that have taken place in all Europe during several centuries have destroyed less property than those that have taken place in the United States alone during a single century. The destructive temperatures in burning buildings vary between 1,500 degrees Fahrenheit and perhaps 2,500 degrees Fahrenheit. Drafts and air currents must also be considered. Materials may be injured not only by heat, but, also by sudden 294 ORGANIC STRUCTURAL MATERIALS cooling, as when streams of water are applied to them suddenly while they are hot. Methods By Which Buildings Are Prevented From Burning. It is doubtless true that in the United States some general fires have been prevented by the presence of parks, streets, and other open spaces, and by the moderate heights of structures; but great fires, that have few counterparts in European history, have taken place in Portland, New York, Chicago, Boston, Jacksonville, Paterson, Baltimore, San Francisco, and Chelsea. The first real attempts to reduce fire losses came when brick and stone were used instead of wood for outside walls. Walls of brick and stone were made to support floors and roofs of wood, and buildings of this kind resisted better than those of the earlier type, because they offered more resistance to outside fires. 1 Later attempts included the use of iron and steel, but these materials were not protected as they are at the present time. The high conductivity of iron and steel, and their tendency to expand under comparatively small increases of temperature caused these unprotected beams and columns to bend and collapse even in very small fires. Buildings constructed in this manner were but little better than those of wood. Buildings are now designed to stand against both inside and outside fires. A fire may destroy the inflammable contents in a room or other section of such a building, but it will not normally reach over into another room or section of the building. Details relating to materials, design, special devices and the care of the buildings after they are erected are all important. It should be constantly remembered that the building may be strictly fire- proof but that its contents, as distinct from the building itself, may be inflammable, and that such contents, if too great in quantity, may cause the destruction of the building. Materials. It is obvious that the best way to prevent a structure from burning is to build it of something that will not burn. Yet it must be remembered that some materials that do not burn are not to be regarded as fireproof. A really fireproof material will not only resist the disintegrating and distorting influences due to high heat and sudden cooling, but it will not conduct heat. 1 $68,000,000 of the total loss in the United States in 1907 took place in buildings composed of brick, concrete, stone, and similar materials; while the loss in wooden buildings during the same year was over twice as much, or about $148,000,000. WOOD AN AGENT IN CONFLAGRATIONS 295 FIG. 47. Metals. Iron and steel are poor fireproof materials when used alone. This is because they warp and conduct heat, and it is only after they are protected by non-conducting substances that they become valuable in fireproof constructions. Natural Stones. Stones differ greatly in their ability to stand against heat. Granites disintegrate because they contain water, and because the component minerals do not have the same coefficients of expansion and contraction under heat and cold. Limestones lose their carbon diox- ide and are reduced to ordinary building lime under the influence of heat. Most sandstones stand against fire better than all limestones, and far better than all granites. Artificial Stones. The prop- erties of brick are influenced by the properties of the clays used in their manufacture. Good brick is one of the best of all fireproof materials. Enamelled brick is often very good. Terra cotta, whether used in bricks, or for ornamental work, or as a protective coating for iron and steel, is a very valuable fire-resisting material. Con- crete possesses the additional advantage that it can be laid without joints. Combinations. The best results are obtained by the use of all-metal members protected by brick, terra cotta, concrete, or other non-con- ducting materials. Hollow brick, terra cotta, and concrete, are used for walls, floors, and ceilings. Influence of Design, Special Devices, Etc. An ideal building has out- side walls of brick. Its frame is made of steel or iron covered with some material that will stand against heat. Floors and roofs are built of hollow tile, terra cotta, concrete, or other non-conducting or fire-resist- ing materials. All stairs, elevators, and dumbwaiters are enclosed by brick shafts with standard, tin-clad fire doors in all openings. Wells for light are enclosed by brick, and the windows in the wells are of wired glass in standard metal frames, and these materials are also used in outside windows. Standard fire doors, or their equivalents, are used in door openings. A low building is safer than a high building. An ideal building is restricted in height and floor areas so that all parts can be swept by fire streams under prevailing pressures. Heights and areas can be increased if the entire building is protected by automatic sprinklers. Roofs. Roofs are either fireproof, semi-fireproof, or inflammable. Roofs covered with slate, tile, and some special materials are in the first ;e protected by duplicate re doors. 296 ORGANIC STRUCTURAL MATERIALS group; while those made of tin or corrugated iron spread upon wood are in the second group. Shingled roofs, which are in the third group, are highly inflammable. A large proportion of all outside fires are caused by sparks lodging on roofs. Door Openings. Fire doors, designed to obstruct the passage of heat and flame through door openings, are used in pairs, one door being placed at each one of the two surfaces of the wall through which the opening extends. Automatic doors, that close when the heat becomes sufficient to fuse a link of special metal, are generally recommended. Latches, locks, hinges, slides, and other details are highly important. The efficiency of the standard fire door is expressed in the following quotation. 1 " Recent tests and investigations indicate that for openings of ordinary size the so-called standard tin-clad door and shutter, all things considered, furnishes the most reliable protection, particularly when the exposures are severe. The superiority of this type is very largely due to its efficiency as a non-conductor of heat. This offsets, in a large measure, inherent defects in other respects, such as the bulging of the plates by the gases generated from the inflammable materials now used in its construction, the falling down of the core after it has been reduced to charcoal, and its comparative lack of endurance under severe exposures." Window Openings. Water curtains and iron shutters were formerly used to protect window openings, but these devices have given way to standard fire shutters, and wired glass windows. Tin-clad fire shutters are similar to the standard fire doors that have been described; while the wired glass is used, as has been noted, in metal frames. The re- quirements of both inside and exposed fires must be recognized. The value of wired glass windows in resisting the action of moderate fires depends upon the character of the glass and sashes. Glass softens and drops away when a temperature of about 1,500 degrees F. is reached. Sashes and frames are made of hollow steel and other metal. There are three types : the pivoted sash, which is automatic, the double hung sash, and the casement sash. Locks, hinges, and other hardware are im- portant factors. Ordinary putty must not be used. 2 Fire Shutters. The principal difference between fire shutters and fire doors is noted in the rules prepared by the National Board of Fire 1 Abstract of Committee Report presented at annual meeting of National Fire Protection Association, New York City, May 23-25, 1905 (Engineering News, Vol. 53, No. 22). Also Rules and Requirements for the Construction and Installation of Fire Doors and Shutters recommended by the National Fire Protection Association (Edition of 1906). 2 Rules and Requirements of the National Board of Fire Underwriters for the Manufacture of Wired Glass and the Construction of Frames for Wired and Prism Glass used as a Fire Retardant. PLATE VIII. DETAILS OF TIN-CLAD FIRE DOOR -J-T- ^r-r (c) Method of Joining and Fastening Tin. (a) Application of Tin to Corners of Fire Door. (6) Method of Holding Layers of Core together by Clinched Nails. (d) The Completed Door. (Facing page 296.) WOOD AN AGENT IN CONFLAGRATIONS 297 Ell J Underwriters as follows: 1 " Construction to be the same as for fire doors, except that only two thicknesses of % inch boards are required. Layers of boards to be at right angles." Automatic Sprinklers. It is a important to have fires discovered and extinguished while they are small, and apparatus Designed with these ends in view may be properly classed among prevent ative devices. General information with respect to automatic and open sprinkler equipments, prepared by the National Board of Fire Underwriters, is as follows : 2 1. Preparation of Building. Many buildings require preparation for sprinkler equipment. All needless ceiling sheathing, hollow siding, tops of high shelving, needless partitions or decks should be removed. Necessary " stops" to check draft, necessary new partitions, closets, decks, etc., should be put in place so that the equipment may conform to the same. The top flooring should be made thoroughly tight. 2. Accessory Woodwork. Sprinkler equipments require accessory wood- work, dry pipe valve closets, ladders, anti-freezing boxing for tank pipes, etc. This work should be promptly at- tended to if not let with sprinkler contract. 3. Drapery and Sheathing. Paper or similar light inflammable ceiling sheathing is objectionable and unnecessary. Where floors leak dirt, an acceptable sheathing may be made of lath and plaster, matched boards or joined metal. All channels back of sheathing to be thoroughly closed between timbers or joists. Sheathing to be tightly put together and kept in repair. In mill bays, sheathing to follow contour of timbers without concealed space. 1 Rules and Requirements for the Construction and Installation of Fire Doors and Shutters as recommended by the National Fire Protection Association (Edition of 1906). 2 Rules and Requirements National Board of Fire Underwriters governing the Installation of Automatic and Open Sprinkler Equipments as recom- mended by the National Fire Protection Association (Edition of 1913). 3 This window was in Newark works of Sherwin-Williams Company. The picture shows appearance after fire had destroyed adjacent works of Consolidated Color and Chemical Company. The fire did not pass through this window, although the heat was sufficient to burn the paint from frame and sash (Insurance Engineering, November, 1907). FIG. 48. Wired glass window in metal sash. 3 298 ORGANIC STRUCTURAL MATERIALS 4. Vertical or Horizontal Drafts. Floor or wall openings tending to create vertical or horizontal drafts, or other structural defects that would prevent the prompt operation of automatic sprinklers by prevent- ing the banking up of the heated air from the fire, should -be properly "stopped" in order to permit specific control by the local sprinklers. Satisfactory curtain-boards and other draft-stops must be provided to overcome such structural defects. 5. Clear Space Below Ceilings. Full effective action of sprinklers re- quires about 24 inches wholly clear space below roofs or ceilings; this loss of storage capacity should be realized in advance of equipment. 6. Experienced Workmen Recommended. Sprinkler installation is a trade in itself. Insurance inspectors cannot be expected to act as work- ing superintendents, nor correct errors of beginners. Sprinkler work should be entrusted to none but fully experienced and responsible parties. 7. All Portions of Buildings to be Protected. Experience teaches that sprinklers are often necessary where seemingly least needed. Their protection is required not alone where a fire may begin, but also wherever any fire might extend, including wet or damp locations. 8. Degree of Protection. A maximum protection cannot be expected where sprinklers are at more or less permanent disadvantage, as in the case of stocks very susceptible to smoke and water damage, buildings having deep piles of hollow goods, excessive drafts, explosion or flash fire hazards, or large amounts of benzine or similar fluid. 9. Necessary Cut-offs. Sprinklers cannot be expected to keep out fire originating in unsprinklered territory. Stringent measures should be used to properly cut off all unsprinklered portions of buildings or exposures. 10. Communications. When a building fully equipped with sprink- lers communicates with another not so equipped, the openings must be protected by standard fire doors on both sides of the walls, one of which must be automatic. 11. Protection Against Exposures. The danger of sprinkler protection being impaired by exposure fires should be reduced by providing adequate shutters, wired glass or open sprinkler protection at exposed windows. Signals. There are automatic and non-automatic signals. An auto- matic thermostat alarm depends upon the opening and shutting of an electric circuit in a thermostat. Such alarms are used in connection with automatic sprinklers. Non-automatic alarms should be practical, conveniently located, and easily understood. Care or Maintenance of Structures. The contents of a building are as important as the building itself. The building may be composed of materials that will not burn, yet it may be injured or even destroyed by fires in contained oils, cotton, or similar stores. The quantity of such inflammable stores should always accord with the capacity of the WOOD AN AGENT IN CONFLAGRATIONS 299 building to resist fires and with its capacity to isolate them so that they will not spread from one section to another. Cleanliness and Order Are Imperative. Trash should not be permitted to accumulate. Oiled rags or waste should be destroyed, or kept in metal boxes. Matches should also be stored in metal boxes. Smoking must often be prohibited. Systematic inspection is usually necessary. Managers should be held responsible by night as well as by day. It is not enough for them to employ watchmen. They should be certain that such assistants, who are usually selected for physical rather than mental gifts, really perform their duties. Watchmen work alone and without direct superintendence, and, for this reason, their duties should be planned for them. Watchmen's Recorders. The services of watchmen are systematized by means of mechanical devices known as recorders that compel the watchmen to visit certain stations at certain stated intervals. These recorders are of three kinds. There are portable time recorders, station- ary time recorders, and central office recorders. 1 Portable Time Recorders. The recorder resembles an alarm clock and contains a paper dial, turned by clock movement, upon which an impres- sion is made whenever a key is used. There are several such keys, with but one recorder, which last is carried by the watchman, while the keys are chained at the several stations to be visited. The records shown by the paper dials indicate the time when each key was used. This system is simple and economical in its first cost, but it is objectionable because of the weight of the recorder and because of the fact that watch- men sometimes obtain duplicate keys. Stationary Time Recorders. In this system there is one key and sev- eral recorders. The watchman carries the key and the recorders are fixed at the stations. Some recorders contain paper record forms which are collected in the morning, and others are wired so that the records are received on a single dial in the superintendent's office. A stationary time recorder system is good because watchmen do not have to carry the more or less heavy recorders, and because it is difficult to tamper with the records. The weak points are the increased first cost, and the labor required to collect the records in the morning. When such labor is rendered unnecessary by connecting the recorders with the superin- tendent's office, there is extra cost for wiring. Central Office Systems. The central office system enables a superin- tendent, located at a central office, to reach and control the movements of his men at all times while they are on duty. 1 New York Fire Insurance Exchange Bulletin, No. 5. Also literature published by Newman Portable Clock Company, American Watch System, etc., etc. CHAPTER XII FAILURE OF WOOD BECAUSE OF ANIMAL LIFE. MARINE AND TERRESTRIAL FORMS. METHODS OF PROTECTION The forms of animal life that attack woods may be divided according to their habits or environment into marine woodborers 1 and terrestrial woodborers. The quantity of wood destroyed by marine woodborers is considerable, but the proportion is much smaller than it was when wood was used more extensively in marine constructions. The total value of wood destroyed by marine borers is much less than the total value of woods and living trees destroyed by terrestrial borers. MARINE WOODBORERS The harm done by these borers has not always been measur- able by direct costs, since it is recorded that owners of wooden ships once discriminated against harbors in which numbers of these pests were known to be -present. Most . perforations found in timbers that have been in sea water are attributed to the Teredo navalis, probably because this shipworm was one of the first to be studied and was the one selected for description in some of the earlier text-books. The Teredo navalis is worthy of the attention it receives, but it must not be forgotten that there are other marine woodborers. THE SHIPWORM (Teredo, Xylotrya, etc.). This is a general name that applies to several species of mollusks of the genus Teredo, together with other species in other genera. The mol- lusks known as shipworms are characterized by the fact that they bore in wood, and are represented, along the north-central Atlantic Coast, by species of the genus Xylotrya. Shipworms are widely distributed throughout the waters of the tropics, and are present in smaller numbers in cooler waters of temperate regions. They inhabit European waters from Sweden 1 The first part of this chapter is based upon the author's paper entitled "Marine Woodborers" published by the American Society of Civil Engi- neers (Transactions, Vol. XL, 1898). Some of the pictures prepared for the original paper are used with the permission of the said Society. 300 MARINE AND TERRESTRIAL WOODBORERS 301 to Sicily, and are also found in the vicinity of Bermuda, the West Indies, New Zealand, and Australia. In the United States they exist from Maine to Florida, and along the Pacific Coast as far north as Alaska. The United States Fish Commission reports their distribution in local waters to be as follows : Teredo navalis, between Florida and Cape Cod. Teredo norvegica, Cape Cod northward to Maine. Teredo megotara, New Bedford, south to South Carolina. Teredo dilatata, Massachusetts to South Carolina. Teredo thompsoni, Massachusetts. Xylophaga dorsalis, North Atlan- tic. Xylotrya fimbriata, Long Island Sound to Florida. Form. The form of the shipworm is shown in the picture. It is a long, worm-like organism of which the posterior end s remains at the outer surface of the timber, while the other or anterior end B occupies the inner extremity of the tunnel. The two horn-shaped structures s are the free extremities of other- wise united tubes, known as siphons, that pass throughout FlG 49 ._ The sh ip worm . the entire length of the ship- worm to the vital organs and boring shell at B. These horn- shaped extremities are the only parts of the shipworm that can extend outward beyond the wood, and are therefore the only parts that are evident to the casual observer. A general idea of the form of the shipworm may be gained by examining the ordinary long, or soft-shelled, clam (Mya arenaria) so familiar to residents of New England. This clam possesses a very long worm-like neck penetrated by two parallel tubes or siphons through one of which water, oxygen, and food pass in- ward, while through the other exhausted water and debris pass out. It is also helpful to examine the common razor clam (Ensis directus) which, besides siphons, possesses a powerful, muscular club-shaped foot or sucker that enables it to bore into the sand. The long and razor clams and the shipworm are all true mollusks, and each one suggests a worm only because the part that sur- rounds the siphons is soft and cylindrical. The parts of the shipworm that are important in the present connection are the body, siphons, collar, pallets, boring shell, foot, and lining shell. These parts will be considered separately. 302 ORGANIC STRUCTURAL MATERIALS The Body. The translucent substance of which the body is composed resembles the living substance in the body of the oyster. In some species, in addition to their normal functions of respiration, the gills perform the important office of sheltering the embryo. The nervous system is well developed. Vital organs, such as the liver, are protected by being enclosed within the boring shell. The stomach is not distin- guished by any peculiarity. There is a long intestine. 1 The Siphons. The siphons extend through almost the entire length of the body. One of them conveys the oxygen, water, and infusorial food to the digestive organs; while the other conveys the ex- hausted water, excretions, and wood particles from the excavation to the free water without. The siphons are joined together for most of their length, but separate as they pass outward at their extremities, s, and are then* capa- ble of being thrust out and with- drawn through the orifice in the wood. They are the only parts that can be seen from the outside of the wood. It will be noted that these extremities must always re- * * the orifice to the tunnel. When the conditions are favora- ble, the extremities of the siphons are extended out to their full length beyond the surface of the wood. Other- wise, they are withdrawn and there is then but little evidence that the shipworm is within the piece. The picture shows the siphons as they appeared fully extended after several consecutive days of warm weather. The Collar. The collar C is a muscular, wrinkled membrane that ex- tends around the posterior portion of the shipworm at the point of union between the siphon and the body proper, and forms a connection between the body and the calcareous lining of the tunnel. This is the only place at which the body of the shipworm is not free and separated from its surroundings. The collar in- cludes .several well-defined muscles and these act upon the small shells known as pallets by which the FlQ 51 _ p a u e t s . entrance to the perforation may be guarded. The Pallets. The two shells or plates, located at p and called pallets, are broad, slightly curved and flattened at the top and contracted at the wood. Sigerfoos (Circular Johns Hopkins University, June, 1896). PLATE IX. WORK OF THE SHIPWORM Surface of Wood recently Occupied by Shipworms. Life Size. Section Parallel to Face Shown in Preceding Figure. Life Size. Vertical Section through Preceding Figures. Life Size. (Facing page 302.) MARINE AND TERRESTRIAL WOODBORERS 303 the bottom where they pass under the collar. When the siphon ex- tremities are withdrawn into the body, the tops of the pallets are brought together over them and protect them. These shells are sometimes con- fused with the boring shells, which are quite distinct, and at the other end of the body. Details differ with species. The Boring Shell. The principal or boring shell B is small and very beautifully formed. The two parts together are nearly as long as they are broad, and present an irregular triangular appear- ance when observed from the side. They close tightly at the hinge and at the side opposite. As distinct from this, however, an open space at the top permits the body to emerge while a similar opening at the bottom is for the foot or sucker. The shells of young shipworms are much larger in proportion than those of older ship- worms, and when the worm is very young, it is for a short time entirely enclosed in its shell. The Foot. The foot, which in form resembles a pestle, is a short, stout, muscular organ, broadly truncated or rounded at the end, and so ar- ranged that it can exert a powerful suction upon anything to which it is attached. The extent to which this cupping action assists the exca- vating has probably been underestimated. The Calcareous Lining. Calcareous material deposited upon the woody surface of the tunnel forms a smooth lining along which the body of the shipworm can pass as it contracts or expands. This shell-like tube is distinct from the pallets and from the boring shell. Its thick- ness, which varies with species, is sometimes so slight that the shell is detached by the slightest shock, and many specimens, exhibited in museums, do not show the lining for this reason. The lining is some- times very thick. The shipworm can rarely advance through the wood very far in a straight line, but is forced to pass here and there so as to avoid obstacles such as cracks, knots, and the tunnels of its companions. In such cases, the linings are curved as they wind in and out, and often so many are present that almost the entire content of the wood is occupied. Shipworms avoid seams and joints in wood, possibly because of their effect upon the calcareous linings. FIG. 52. The boring shell. 304 ORGANIC STRUCTURAL MATERIALS Physiology. Shipworms live principally, if not wholly, upon organic particles obtained from sea water. Particles of wood are sometimes found in their intestines, and it is not certain that these particles, cut from the burrows, do FIG. 53. End view of dis- section shown in figure which follows. (Life size.) not serve in some minor way as food. It is certain, however, that the principal reason for the boring is to prepare a shelter. A shipworm can live for a short time out of water. But, since it derives its sus- tenance from the water, it must have access to it much of the time. It does not have to be submerged all of the time, and can live and work under such con- ditions as exist between tide levels. It has been known to live for about two weeks in timbers that have been transferred from the sea to fresh water, and could possibly have lived longer than two weeks. FIG. 54. Dissection showing calcareous lining in wood. (Life size.) MARINE AND TERRESTRIAL WOODBORERS 305 Many logs in a cargo of Central American woods recently received in New York, after a voyage of about two weeks, were found to be full of living shipworms that had gained entrance while the logs were waiting for shipment in the South. The shipworms were apparently in good condition when the timbers were removed from the hold of the ship. The wood itself, and the hold of the ship, contained considerable water, yet the logs were by no means submerged, and the fact exists that these particular specimens survived during a voyage of about two weeks. They were very numerous, so much so, that later the logs had to be removed from the yard because of the odor. Reproduction and Development. Most mollusks reproduce by means of eggs, which, in the case of some shipworms, are spheri- cal in shape and greenish yellow in color. Shipworms are very prolific, the eggs of a single specimen being numbered by the million. The eggs are very hardy and many survive and yield young shipworms. A shipworm can swim at the end of about three hours after hatching and has a well-developed shell before the end of the first day. The shipworm passes through several stages before it assumes the character and form of the adult. It is first covered with fine hairs or cilia, which enable it to swim. Soon most of the cilia are lost and the rudiments of a small bivalve shell appear. At first, this shell is heart-shaped and very small, yet it is large enough to enclose almost the entire body. The portion of the body that protrudes from the cell is fringed with cilia, and these enable it to continue to swim until it finally encounters a piece of wood. The results of some observations upon the shipworm (Xylotrya fimbriata) at Beaufort have been summarized by Professor Sigerfoos as follows: 1 "The free-swimming stage is reached in three hours, and a well- developed shell is formed in a day. We have no direct observations as to the time the ship larva is free-swimming. We may assume, I think, that it is at least a month, or it may be two. Most of its energies are devoted to locomotion during this period, but, after it has attached itself, all of its energies are devoted to forming its burrow and securing its food. Coming into contact with the wood, the larva throws out a sin- gle, long byssus thread for attachment and never again leaves its place. The newly attached larva is somewhat less than 0.25 mm. long. In twelve days it has attained a length of 3 mm.; in sixteen days, 6 mm.; Johns Hopkins Circular, June, 306 ORGANIC STRUCTURAL MATERIALS in twenty days, 11 mm.; in thirty days, 63 mm.; and in thirty-six days, about 100 mm., when it bears ripe eggs or sperm." The time of reproduction is important. In the vicinity of New York, this takes place principally during the month of May; but it may continue, although to a less extent, throughout the greater part of the summer. In tropical countries, it probably goes forward throughout the entire year. Although the extreme life limit of a shipworm is unknown, it is thought that individuals can live for several years under favorable conditions. A ship- worm may attain to a comparatively large size during a single season. Influence of Temperature and Water. In most cases ship- worms are more plentiful where the water is not cold, and, for this reason, wood is destroyed more continuously and more rapidly in the tropics and semi-tropics. In the United States destruction is most serious along the entire Pacific Coast, as well as along the coast of the South Atlantic and Gulf States. Some shipworms are found, although they are much less active, where it is often extremely cold, as in Maine and Alaska. Some shipworms thrive in pure sea water, while others do well in brackish, impure, or comparatively fresh waters. Sometimes the parts of timbers that are near the surface of the water are injured, and sometimes the parts that are down near the bottom. These and other differences are accounted for by the facts that there are many species of shipworms, and that differences some- times exist between the qualities of higher and lower layers of water. For example, when fresh water from a river meets the heavier water of the sea, shipworms may sometimes be found near the bottom where the water is actually salt. Some shipworms (Xylotrya fimbriata) survive in the brackish, polluted waters of New York Harbor, while other species that do not exist in these waters are present in the nearby ocean. Shipworms are very active along the north Pacific Coast but are said to be absent at some points near the mouth of the Columbia River because fresh water pre- dominates at these points. A vessel carrying hardwood logs was wrecked in the vicinity of the Gulf of Mexico. The logs were conveyed to the sheltered, but brackish, waters of a creek where they remained for about six weeks. The pieces were attacked as soon as they were placed in the creek and the results were so noticeable that some borings were measured and are said to have been six inches in length. The MARINE AND TERRESTRIAL WOODBORERS 307 wood that remained in the outer ocean was not injured. 1 The dis- crepancies between these incidents may be accounted for by the presence of different species of ship worms. The belief that shipworms are influenced by impurities in water was expressed in Holland as early as 1733. It was noticed that comparatively little rain fell in years when shipworms were quite plentiful, and it was thought that the diminished volumes of river water during these years permitted larger quantities of salt to exist in the waters near the mouths of the rivers. Analyses proved that the proportions of salt did vary during the dry and rainy seasons. Method of Attack. While the ship worm is yet very small, it settles upon the surface of the wood and almost immediately begins to clear away a place through which to burrow. There is some controversy as to the method by which the burrow is excavated, but it is quite certain that the foot assists the shell. The details are not perfectly understood, but the facts are that the hardest woods are penetrated and that surfaces are cut as smoothly as though a sharp chisel had been employed. Character of Excavation. A shipworm is very small when it enters a piece of wood, but once within develops rapidly and then never leaves its burrow. The perforation through which the shipworm enters is very small, but the diameter of the boring increases rapidly, the average being reached at a point quite near the perforation through which the shipworm entered. A shipworm grows principally in length and must therefore tunnel to secure space for the increasing length of its body. The shipworm does not encroach upon other tunnels because most of these tunnels are occupied by shipworms. It instinc- tively avoids knots, imperfections, bark, cracks, and lines of cleavage. Woods are not exempt from attack simply because they are hard. Wood may appear to be sound and yet be so weak that it can be crushed by the hand. As much as fifty per cent, of the weight of a piece may be removed without much evidence upon the out- side. Failures often come suddenly and without warning. The tops of piles thought to be in good condition are seen floating away. A freight train on the Louisville and Nashville Railway 1 Reported to the writer by Messrs. Nesmith and Constantine of New York, 1897. 308 ORGANIC STRUCTURAL MATERIALS crushed through a trestle that had been standing about ten months and that had been frequently inspected. Size of Borings. The size of a boring depends upon that of the shipworm that made it, and the size of the shipworm depends upon its age and species. Five inches and as many feet may be regarded as minimum and maximum lengths. One-quarter of FIG. 55. End of log of Panama mahogany destroyed in one season. an inch is a small diameter from which measurements have been made up to one and one-eighth inches. 1 It is safer to disregard minimum possibilities in such a connection. Rapidity of Work. Evidence upon this subject is seldom ac- companied by statements of conditions under which the results were accomplished, so it is sometimes hard to associate the boring 1 Measured by the writer in a specimen from the North Pacific Coast. PLATE X. WORK OF SHIPWORM LARGE BORINGS The large circle near the top of the picture shows a boring actually in. in diameter. (Facing page 308.) L MARINE AND TERRESTRIAL WOODBORERS 309 with the species that made it. The species of the woodborer, the location of the piece, the season, and the kind of wood in which the boring exists are all important. Conditions that influence the growth of the ship worm influence the speed with which it works. Generally speaking, cold retards while heat expedites the work of excavation. A six-inch burrow may be driven in as many weeks so that a one-foot pile attacked on all sides can be destroyed in that length of time. On the contrary, other pieces remain practically intact for many years. Wood has been found to contain shipworms after a submergence of eight days (United States Annual Report of Scientific Discovery of 1857). Six-inch piles were destroyed at Aransas Pass in six weeks; other piles in the same locality have lasted as long as three or four months (Report, Chief of Engineers, U. S. A., 1888, pp. 13, 14). Piles have been destroyed in one hundred days in Mobile Bay (Annual Report, Chief of Engineers, U. S. A., 1879, p. 937) . Piles on the line of the Louis- ville and Nashville Railroad sometimes have to be replaced after six months service (Transactions, Am. Soc. C. E., Vol. XXXI, p. 221, Montfort). Unpainted spar buoys have a life of about one year in the vicinity of Cape Cod (Report to United States Fish Commission by Captain Edwards). Piles have been destroyed in the harbor of Galves- ton in three years (Report, Chief of Engineers, U. S. A., 1868, p. 512). Piles have lasted as long as twelve years in the harbor formed by the Delaware Breakwater (Annual Report, Chief of Engineers, U. S. A., 1871, p. 667). Field of Attack. The fact that a shipworm lives upon micro- scopic life present in sea water outside its burrow, makes it necessary for its siphon extremities to be located at the entrance to its burrow. This end of the shipworm being fixed as to posi- tion, the wood is removed inward from the surface to a distance measured by the increasing length of the shipworm. The small portals to the burrows that are evident upon the outside of the timber (see Plate IX) do not necessarily mark the exact content of wood that is destroyed within; since, although one end of the shipworm must remain at the entrance to its burrow, the other can reach upward into the wood above the water, or downward into that below the mud. Shipworms have been known to work under pressures caused by twenty or twenty- five feet of water. Woods Subject to Attack. Immunity is sometimes claimed for some particular wood; but it is usually found that such a 310 ORGANIC STRUCTURAL MATERIALS claim, based upon local conditions, is not generally substantiated. It is safer to assume that all ordinary woods may be attacked by these forms. Doubt may be felt with regard to some woods that contain repellent gums, resins, or bitter essences, and some palms that have open, porous structure; yet very few woods such as these are used in American constructions. Woods are not safe simply because they are hard. Osage Orange, which is a very hard wood, has failed in several instances where it has been used for piles. A Commission appointed in Holland to investigate this question reported as follows: "Although we do not know with any certainty whether among exotic woods there may not be found those which resist the shipworm, we can affirm that hardness is not an obstacle that prevents the mollusk from perforating its galleries." THE LIMNORIA (Limnoria lignorum). -This isopod crusta- cean, which has other names as the wood flea, sand flea, gribble, and boring gribble, is the prin- cipal one of several similar forms that attack woods when in sea-water. The Limnoria is much smaller than the shipworm, FIG. 56. The Limnoria. but it usually occurs in larger numbers and in some localities is almost equally destructive. The Limnoria is found along the Atlantic Coast from Nova Scotia to Florida. It exists sparingly in Long Island Sound; but is abundant along the Coast of Massachusetts, and very destruc- tive in the Bay of Fundy. It is also active in the north Pacific, as in Puget Sound and the Straits of San Juan de Fuca. It is said to exist upon the coast of Great Britain and in other European waters. Form and Physiology. The Limnoria is about as large as a grain of rice. The nearly straight sides are, in a general way, parallel to one another, while the ends are rounded. The upper and lower surfaces are flattened, the former being covered with small hairs to which more or less dirt often adheres. The body is made up of fourteen segments. To each of the seven segments that follow the head is attached a pair of short, stout legs ter- minating in claws, the shape of which suggests the small claws of the lobster. MARINE AND TERRESTRIAL WOODBORERS 311 The body of the Limnoria is grayish in color, and sometimes resembles the color of the wet wood so much that it is difficult to distinguish it. The Limnoria can swim, creep "backward and forward, as well as jump backward by means of its tail. When touched, it rolls itself into a ball, and in this particular, as well as in general appearance, it resembles the common sow-bug. The Limnoria differs from the ship worm in that quite certainly iib is a vegetarian. The shipworm is sustained, at least for the most part, by microscopic life drawn from the sea water, but the Lim- noria devours wood. Its tunnel affords both food and shelter. Influence of Temperature and Water. Limnoria are plentiful in some regions in the North where shipworms can exist but spar- ingly because of the cold. Limnoria require pure sea water and are seldom found in the comparatively fresh waters encountered near the mouths of rivers. Method of Attack. Character of Excavation. The Limnoria attacks the wood by means of its mandibles or jaws. It prefers wet wood and succeeds in making a very clean-cut excavation. The work of the Limnoria differs from that of a shipworm in that its tunnels terminate on the surface of the wood where they can be plainly seen, whereas those of the shipworm are for the most part concealed within the wood. The body of the shipworm cannot emerge from the wood within which it has located, while that of the Limnoria can pass freely in and out. The Limnoria frequently works in conjunction with the shipworm. It attacks the surface, while the shipworm takes away from the interior of the woodwork. The numberless, smooth, clean-cut galleries are close together and the partitions that separate them are so thin that they can- not long resist the action of the waves. Later, the partitions are either washed away by the waves, or they decay. Fresh sur- faces are then exposed and these are destroyed in the same man- ner. Layer after layer is removed until the timber is destroyed. The Limnoria can penetrate knots, but sometimes avoids them, when such hard portions stand out in relief as the other parts are destroyed. Size of Borings. The Limnoria is very small, but notwith- standing this fact, it is very destructive. The multitude of these woodborers compensates for their size. Each may be assumed to be from one-sixth to one-fourth inch in length and about one-sixteenth of an inch in diameter. The tunnels are about 312 ORGANIC STRUCTURAL MATERIALS one-half of an inch in length and about one-tenth of an inch in diameter. Rapidity of Work. The Limnoria does not work as rapidly as the shipworm. The number of individual workers must in this FIG- 57. Knot showing surface from which work of Limnoria has been removed by waves. (Reduced.) case be taken as a measure of the rapidity of destruction. The number of tunnels is more important than their depth. The thickness of a piece of timber may be reduced from one-fourth of an inch to as much as an inch in a year. Much wood used in marine constructions is in the form of piles that are necessarily exposed on all sides. The effective diameters of such pieces are, PLATE XI. WORK OF THE LIMNORIA MARINE AND TERRESTRIAL WOODBORERS 313 therefore, reduced twice as rapidly as indicated by the figures noted. Field of Attack. The depredations of Limnoria are confined to a limited distance above and below the low-water mark. Where the variations of the tides are extensive, as in the vicinity of the Bay of Fundy, the range of the Limnoria is correspondingly great. It has been found, although rarely, at a depth of forty feet. Woods Subject to Attack. Most woods used by American con- structors in waters where these forms are prevalent are subject to attack by them. THE CHELURA (Chelura terebrans). It is of ten stated that the Chelura is among the active enemies of woods; but efforts made to discover work actually per- formed by it have proved un- fruitful, and it is not known where this form exists as a specimen and where it exists as a real pest. It is probable FlQ . 53. The Chelura. that some results attributed to the Chelura were actually caused by the Limnoria. The Chelura is also known as the wood shrimp. Form and Physiology. The Chelura is an amphipod crusta- cean. The form differs strikingly from that of the Limnoria, except in size, and resembles that of the ordinary shrimp. The body is semi-translucent and spotted or mottled with pink. There are three pairs of caudal stylets, the last of which is nearly as long as the body. The Chelura swims actively upon its back, and, like the sand-hopper, can project itself to a considerable distance when placed upon dry land. The Chelura resembles the Limnoria in that it also is a vegetarian. Its burrow affords both residence and food. Method of Attack. Character of Excavation. The work of the Chelura and that of the Limnoria resemble one another in so many particulars that the suspicion is warranted that the two forms have been confused with one another. In both cases, the wood is attacked from without, and numerous tunnels are driven until the weakened layer succumbs to the action of the waves. A new surface is exposed and this is eventually destroyed in the same manner. The few specimens observed do not warrant wide generalizations, but it is possible that the Chelura prefers the ofter portion of the annual layer, and that the tunnels are 314 ORGANIC STRUCTURAL MATERIALS curved, because these points were noticed in the few specimens available. Size of Borings. The Chelura is somewhat larger than the Limnoria. The specimens seen were about one-third of an inch in length. The burrows were a little larger than those of the Limnoria. Field of Attack. The specimens observed were found at Prov- incetown, in wood located about ten feet below the low-water level. MISCELLANEOUS. Fresh-water Woodborers. The work of a fresh-water woodborer (Sphceroma destructor Richardson) in trestles of the Florida East Coast Railway resembles the work of the Limnoria, save that the burrows of the fresh-water borer are larger than those of the Limnoria. A yellow pine pile was reduced by them from a diameter of sixteen inches to one of seven and one-half inches in eight years. 1 Several kinds of fresh- water woodborers, some of them very large, have been found in Australian rivers. 2 Barnacles (Lepas antifera). Barnacles do not injure wood. On the contrary, they protect such parts as are covered by them from the attacks of marine woodborers. Barnacles attach themselves, singly or in clusters, to floating or submerged wood-work and are disliked by ship owners because bottoms covered in such a manner cannot move as rapidly through the water. Stone-borers. Stone-borers are interesting be- cause they show the power of forms that are apparently feeble. The pholas or piddock (Pholas dactylus) is a typical species of the molluscan family Pholadidse, which includes other stone- borers as well. The pholas bores in stone by 59 so as to " tne Barnacle(Le- pas antifera re- excavation. The long foot or pestle, similar to " that of the teredo > is then thrust out and rubbed against the stone. The process is assisted by particles of sand or rock. 3 1 See report by Harriet Richardson (Biological Society, Washington, May 13, 1897). 2 Correspondence Professor Charles Hedley, Sydney, Australia. 3 A cargo of marble wrecked in the North Atlantic was destroyed in one year by a boring sponge (Cliona sulfurea Vcrrill). The shells of live oysters are often attacked. PLATE XII. WORK OF THE CHELURA V bJO E o -fj bfi fl 1 a I o I | -M o MARINE AND TERRESTRIAL WOODBORERS 315 FIG. 60. Stoneborer in sandstone. (Life size.) PROTECTION FROM MARINE WOODBORERS Many of the attempts made to protect woods from the attacks of marine woodborers have failed, but some have succeeded. The methods usually considered are as follows: Removal During the Breeding Season. This method, which may be used to protect such objects as buoys, bathing houses, and rowboats, is applicable only where the breeding season is short, as in the North. Change of Water. Wooden vessels attacked by sea wood- borers are sometimes hauled into fresh or muddy waters. In the past several attempts have been made to protect special woodwork by surrounding it with fresh water. Use of Selected Woods. The few woods for which claims have been made are not generally employed in construction, and it is not urged that any one of these woods is always exempt. Thus far evidence favors palm and palmetto, probably because these woods have loose, open structures. External Coatings. This form of treatment is good because applications can be limited to the parts of timbers exposed to attack. The parts much above the high-water mark and those much below the mud line do not have to be protected. External coatings are defective in that they ultimately succumb to blows from waves, ships, and other floating objects. (a) The bark sometimes left upon logs protects them as long as the bark remains intact. This is explained by the reluctance of shipworms to cross seams. The bark is soon loosened and re- moved by the waves, 316 ORGANIC STRUCTURAL MA TE RIALS (6) Planks joined closely over the surface of woodwork will protect it from ship worms as long as the planks remain. (c) Copper and other metals have been used to enclose piles as well as the bottoms of wooden vessels. These coatings are expensive but do protect against all forms of marine woodborers as long as they remain intact. (d) Teredo-nails or worm-nails, said to have originated with the Romans, resemble ordinary carpet, upholstery, anc( thumb tacks, in that they have short spikes and large, flat heads. These nails are driven close together until the wood is enclosed by the heads. Experiments with teredo-nails have been made by the New York Department of Docks. 1 (e) Paraffin, tar, asphalt, paints, and other mixtures have been used to protect woods from marine woodborers, but usually do not remain long in place, since the coatings that are not softened by the water are likely to be removed by erosion. This form of protection should be frequently inspected. (/) Coatings are sometimes reinforced by wire net or by burlap. A paraffin mixture reinforced by burlap has been used to protect piles by the California State Board of Harbor Commissioners, the Northern Pacific Railway, and the Great Northern Railway. The bark was removed and the surface of the pile covered with a mix- ture of powdered limestone, clay, and paraffin. It was then wrapped in burlap; another coat of the compound was applied and wooden battens were nailed up and down to keep the coatings in place. 2 (g) Portland-cement mortar has been applied to piles after they had been driven. This is a good method in that the cement can be limited to the parts that are in danger; but it has not proved adequate because the cement being comparatively brittle is in danger of being cracked and destroyed. The cement is applied in several ways. Piles are sometimes encircled by sewer pipes, the spaces between the pipes and piles being filled with cement. Sometimes iron moulds, which are removed as soon as the cement is set, are employed. 3 1 See "Transactions American Society of Civil Engineers" (Vol. XXXI, p. 235). The " Dutch Waterstaat" specifies that nails must be well forged and not brittle. Diameters must be 3 cm. and lengths must be 4 cm. One kilogram must contain from thirty to thirty-four nails. 2 "Engineering News," February 8, 1894. 3 The Louisville and Nashville Railroad treated four thousand piles in this way, at an average cost of $1.25 per foot of length (Transactions American Society of Civil Engineers, Vol. XXXI, p. 225), MARINE AND TERRESTRIAL WOODBORERS 317 (h) Piles are also enclosed by sand. Sewer pipes are used and the spaces between pipes and piles are filled with sand instead of cement. The cost is less than for cement, while imperfections, serious enough to permit the sand to escape, are revealed by the settlement of the sand at the top. Piles treated in this manner are said to have been sound after twenty years of service. 1 FIG. 61. Piles protected by pipes and sand. 2 (i) Protection is sometimes afforded naturally by oysters, barnacles, and other forms. Preservatives Applied Within Woods. Of the many mixtures that have been used to repel the attacks of marine woodborers, creosote alone deserves attention. Experience has shown that sufficient quantities of good coal-tar creosote, well applied to 1 Transactions American Society Civil Engineers, Vol. XXXI, p. 221. 2 Photograph by Lockjoint Pipe Company. 318 ORGANIC STRUCTURAL MATERIALS appropriate woods, will protect the woods from marine wood- borers during terms that may be measured by the durability of the creosote. Creosoted piles have stood against the attacks of /, shipworms for as long as forty years. The failures that have taken place were, in almost every case, due to poor or insufficient , T creosote, or to poor methods of application. V ~J\&&+^t \yLk~Jubve Substitution. Substitution is not protection, but, in this / connection, it is well to remember that other materials can often be used in place of wood. If iron had not so largely replaced wood in marine constructions, sea woodborers would require more attention than they now receive. TERRESTRIAL WOODBORERS The total losses caused by terrestrial woodborers are enor- mous. Many trees are completely destroyed by them. But, as distinct from trees, woods in construction do not suffer unduly from these pests. The losses in this direction are less than from fire or from rot. If plant products, growing and in storage, be included with live stock, the losses due to depredations of insects in general would compare with the yearly expenditures of the National Government. It has been esti- mated that the total injury to agricultural products in the United States by insects amounts to $700,000,000. annually. 1 Terrestrial woodborers are too numerous for any save the most general notice. Most of them are insects, and it is, therefore, well to remember that all insects are grouped according to the way in which they develop from the egg to the adult. First, some insects develop with what is known as complete metamorphosis; second, others develop with incomplete metamorphosis; and third, still others develop without any metamorphosis. In the first case the egg liberates the larva, sometimes popularly known as "worm," which changes to the pupa, which in turn changes to the adult or imago. The Colorado potato beetle is an example. The egg, the thick larva, the pupa, and the adult beetle may often be observed upon a single potato plant. In the second case the egg liberates a form that closely resembles the adult, and this form, known as the nymph, changes directly 1 Marlatt (United States Department of Agriculture Year Book, 1904, p. 461); also "Insect Injuries of Forest Products," Hopkins (United States Department of Agriculture Year Book, 1904, p. 381) ; " Guide to the Study of Insects," Packard. PLATE XIII. WORK OF LARV.E OF BEETLES " BOOK WORMS" Corner of Book Cover, Tarry town, New York. Perforations Reduced One-half. Whitewood Bureau Drawer-Bottom, New York City. Life Size. Yellow Pine Base-Board, New York City. Life Size. (Facing page 318.) MARINE AND TERRESTRIAL WOODBORERS 319 to the adult. The locust is one of the forms that develop with incomplete metamorphosis; the nymph of the locust is like the adult, save that it has no wings. In the third case, the egg liberates a form that resembles the adult in practically all re- spects save size. Development without metamorphosis takes place in but a single order of insects (Thysanura). The bristle- tails are examples. Some insect woodborers attack the bark or wood of living trees while others are associated with woods that are ready for, or already in, construction. Some prefer sound and healthy woods, and others prefer those that are moist and decayed. Some insects are particularly associated with certain species of trees, and among these are groups known as hickory borers, elm borers, and the like. There are several hundred insect enemies of oak alone. BEETLES (Order Coleoptera). Beetles form what is known to naturalists as an Order. 1 This one includes almost one hundred thousand species; besides which, others are frequently discovered. Beetles undergo a complete metamorphosis. The larvae are sometimes called grubs. Beetles have two horny sheaths or wing- covers that meet in a straight line down the back over a single pair of wings. Their mouths are formed for biting, and are some- times so powerful as to be able to make an impression upon soft metal. Most wood- boring beetles attack live trees, but some at- tack woods in construction. Most of those tion^in sheet-lead that attack woods do so while they are in the roof made by adult larval condition, but some are harmful after they have become adults. It is common to refer to all woods that have been injured by beetles and other insects as " worm-eaten woods," even although the adult, as distinct from the larva, was responsible for the borings noticed. The family Scolytidse includes many forms that attack trees. Some bore in twigs and are known as "twig beetles," others bore in roots and are known as "root beetles," and still others attack bark and are known as "bark beetles." Some members of this family cut symmetrical grooves upon the outer surfaces of the 1 The animal kingdom is divided into Phyla, Classes, Orders, Families, Genera, Species, and Individuals, the importance being in the order named. 320 ORGANIC STRUCTURAL MATERIALS sapwood of trees and are known as "engraver beetles." The powder-post beetles include many enemies of seasoned woods that attack house-trim, flooring, spokes, tool handles, and the like. The larvae of some beetles attack the paste, covers, and leaves of books as well as woodwork, and are often known as "book- worms." The worm-eaten appearance of furniture is often due to them. An instance is on record of a bedpost destroyed thus in three years. The name bookworm is not confined to any par- ticular species but applies to any form of insect life that attacks the covers, leaves, or paste of books. 1 Summary. Although very numerous, beetles are principally harmful to living trees, and for this reason protective measures are almost wholly in the hands of growers, foresters, and horticul- turists. The total amount of wood in construction that is injured by beetles is comparatively small. Engineers seldom attempt to protect woods from the attacks of beetles. 2 MOTHS AND BUTTERFLIES (Order Lepidoptera) .Moths and butterflies undergo complete metamorphosis. Both forms possess four membranous, scaly wings, and in both cases the larva are often known as caterpillars. Butterflies fly by day, while moths fly by night, and there are also differences in the ways in which the wings are folded. Adult moths and butterflies do not attack trees or woods in construction, but the larvae of some species of both are very destructive. With few exceptions, liv- ing trees, as distinct from woods in construction, suffer from their attacks. The Gypsy Moth (Porthetriadispar). 3 The destruction accom- plished by the larvae of this species, by their habit of feeding on 1 The silver fish (Lepisima saccharina] often attacks paper. 2 " Insects Injurious to Forest Products," Hopkins (United States Depart- ment of Agriculture Year Book, 1904, pp. 387-388); "A Revision of the Powder-Post Beetles of the Family Lyctidae," Kraus and Hopkins (United States Bureau of Entomology, Technical Series No. 20, Part 3, 1911); "Principal Household Insects," Howard and Marlatt (United States Divi- sion of Entomology, Bulletin No. 4, pp. 76-78); etc., etc. 3 See also "The Gypsy Moth," Forbush and Fernald (Massachusetts State Board of Agriculture, 1896); "Report on the Field Work against the Gypsy Moth and the Brown-Tail Moth," Rogers and Burgess (United States Bureau of Entomology, Bulletin No. 87, 1910); "Insects Affecting Park and Woodland Trees" (New York State Museum, Vol. I, pp. 79-84); "The Importation into the United States of the Parasites of the Gypsy Moth and Brown-Tail Moth," Howard and Fiske (United States Bureau of Ento- mology, Bulletin No. 91, 1911); etc., etc. MARINE AND TERRESTRIAL WOODBORERS 321 leaves, has been so great that, in Europe, it has been referred to as "the plague," and, in the past, it has been thought to be a scourge sent by the Almighty as a penalty for wrong-doing. The Gypsy Moth was brought to the United States in 1868, but remained unrecognized until 1889. The work of the National Government and of the different States in combating this pest has produced encouraging results. The Goat Moth (Cossus ligmperda). The young, which are said to remain in a larval condition for as long as three years, possess wedge-shaped heads with large, trenchant jaws, equipped with powerful muscles that enable them to cut into very hard woods. The Carpenter Worm is the larva of a beautiful gray moth (Prionoxystus robinice) with wings that spread over a distance of about three inches. The full grown larva, which is about two and one-half inches long, sometimes bores into trunks of oaks, ma- ples, and locusts to such an extent that such woods have very little value later. Summary. The larvae of moths and butterflies are among the most dreaded insect enemies of living trees. Woods in construction are seldom injured. Pro- tective measures are in the hands of for- esters and horticulturists. 1 TERMITES (Order Isoptera) .Ter- mites are called " white ants" because they are of a dingy, white color, and be- cause they live in communities as true ants do. Termites have thick waists and develop with incomplete metamorphosis, ite(Termesbellicosus). . * ' (Natural size.) whereas true ants have slender waists and develop with complete metamorphosis. The mouths of ter- mites are formed for biting. The American termite (Termes 1 See also "The Gypsy Moth," Forbush and Fernald (Massachusetts State Board of Agriculture, 1896); "Report on the Field Work against the Gypsy Moth and the Brown-Tail Moth," Rogers and Burgess (United States Bureau of Entomology, Bulletin No. 87, 1910); "Insects Affecting Park and Woodland Trees" (New York State Museum, Vol. 1, pp. 79-84); "The Importation into the United States of the Parasites of the Gypsy Moth and Brown-Tail Moth," Howard and Fiske (United States Bureau of Ento- mology, Bulletin No. 91, 1911); etc., etc. FIG. 63. Queen ter- 322 ORGANIC STRUCTURAL MATERIALS flavipes), the European termite (Termes lucifugus), and the African termite (Termes bellicosus) are important species. Termites are encountered in the Northern States in hot-house plants, dead stumps, and under stones. They have destroyed live trees as far north as in the vicinity of Boston, but are more plentiful in the Southern States, and are very destructive in the tropics, where they occupy a position among land woodborers that compares with that held by shipworms among marine wood- borers. Although termites sometimes attack live plants they seem to prefer tissues within which life processes have ceased, and house timbers, railway ties, and other structural pieces, as well as dead stumps, books, and papers, are subject to attack by them. A floor in the National Museum at Washington was undermined sev- eral times by a colony of termites that could not be located, until it became necessary to replace the floor by one of cement. Termites have destroyed frame buildings in Washington and Baltimore. A school library in North Carolina was destroyed during the summer vacation. Humboldt explains the rarity of old books in Spain by the fact that termites are so active in that country. It is seldom urged that any wood is always exempt from the attacks of termites; but some, such as teak and redwood, seem to be more fortunate than others in this respect. Railway ties are not often attacked by termites, not because of the kinds of wood that are used but because of the disturbance caused by passing trains. Redwood stave pipes have resisted termites and other insects in the United States as long as the pipes remained wet. Some methods employed to protect woods from termites are as follows: (a) Decayed wood that is likely to attract or shelter colonies of termites, should be removed. (6) When discovered, colonies of termites should be destroyed by the liberal use of steam, hot water, kerosene, or other agencies, (c) Saturation with good coal-tar creosote has preserved timbers from attack. REFERENCES. "Dangers from White Ants," Hagen (American Natural- ist, July, 1876, pp. 401-410); "Manual," Comstock (pp. 95-97); "Insects Injurious to Forest Products," Hopkins (United States Department of Agriculture, Year Book, 1904, p. 389); "Important Philippine Woods," Ahern (p. 91); "Principal Household Insects," Howard and Marlatt (United States Division of Entomology, Bulletin No. 4, pp. 70-76); "The White Ant," Marlatt (United States Division of Entomology, Circular No. 50, Second Series). PLATE XIV. WORK OF LARGE CARPENTER ANT * ' * - ' (a) Pine Shingle from House on Long Island. (6) Fence Post from New York City. (Facing page 322.) MARINE AND TERRESTRIAL WOODBORERS 323 (d) As far as possible endangered structures should be surrounded by cleared spaces, and these should be covered with asphalt or gravel, (e) In the tropics, tables and other kinds of furniture are sometimes protected by placing the legs in small vessels contain- ing oil. (/) Books and papers endangered by termites should be frequently inspected, (g) It is often best to replace woodwork with stone or metal. FIG. 64. Termites (Termes flavipes). Queen, nymph of winged female y worker, and soldier. (Enlarged.) Marlatt (U. 8. Division of Entomology, Circular No. 50). Summary. Adult termites are the principal terrestrial wood- borers that attack woods in construction. Termites are occasion- ally active in the North, but are often exceedingly active in the tropics and semi-tropics. It is safest to replace wood by iron or stone wherever termites are known to be unduly active. THE CARPENTER-BEE (Xylocopavirginica). The carpenter- bee, which resembles the ordinary bumble-bee in size and appear- ance, is equipped with powerful jaws, and often attacks telegraph poles, fence posts, and house timbers. The tunnels thus formed may be one foot or more in length, and are used by the bees as nesting places. Some wasps attack wood. THE LARGE CARPENTER ANT (Camponotus herculeanus pennsylvanicus) . As distinct from the termite this is a true ant, and like other ants -it develops with complete metamorphosis. It seldom attacks sound trees, but does often attack some of those 324 ORGANIC STRUCTURAL MATERIALS that have been wounded or are diseased, and also, sometimes, attacks woods in construction. McCook states that carpenter ants were responsible for "at least one accident" that occurred in connection with the wooden trestle bridges formerly used by the Pennsylvania Railroad Company. 1 Ants offer one of the most perfect illustrations of communistic society. The State declares war, provides food, cares for the children, and owns all the property. Patriotism, loyalty, courage, and never-failing indus- try are exhibited. War, pillage, slavery, and disregard for the rights of other communities pre- vail. There are many species of ants, and each one is character- ized by some peculiarity. Some are road builders; others live in large mounds; and some bore in decayed trees . Most ants tunnel . METHODS OF PROTECTION Injury from insects can- not be completely controlled. Man has not yet succeeded in eliminating a single species of insects. But as distinct from this, the enormous losses that now result from this cause would be greater than they are if man had remained in- active. It is estimated that losses due to the Hessian fly have been re- duced over $100,000,000 annually, and also that the rotation of corn with oats and other crops has reduced the damage done by root worms to the corn crop of the Mississippi Valley about $100,000,000 annually. $15,000,000 to $20,000,000 are saved annually by protecting apple trees from insects by means of sprays. Defensive practice is almost wholly in the hands of foresters and horticulturists and is directed toward the protection of trees. Engineers seldom attempt to protect woodwork from insects other than termites, and the methods used to protect wood from these FIG. 65. Tunnel of carpenter-bee in yellow-pine grape-arbor post, New York City. 1 ''Nature's Craftsman," McCook (pp. 126, 127). PLATE XV. HIGH POWER SPRAYING APPARATUS IN ACTION From "Report of Field Work against Gypsy Moth and Brown-Tail Moth," Rogers & Burgess (United States Bureau of Entomology, Bulletin 87). (Facing page 324.) MARINE AND TERRESTRIAL WOODBORERS 325 insects resemble those used to protect it from marine woodborers and from rot. The value of birds as defensive agents against insects is beyond estimate. When birds are destroyed insects increase proportionately. This value of birds in maintaining the balance set by nature should be recognized by all. Some insects that prey upon other insects should be noted also. Some of these helpful insects directly destroy those that are harmful, while others destroy the harmful insects indirectly by depositing their eggs on, or in their bodies. These predaceous and parasitic insects are natural agents of great value in insect control. CHAPTER XIII PROTECTIVE METHODS SEASONING The term seasoning refers to certain processes designed to re- move water from woods. Woods dry, shrink, and otherwise improve by these processes. Improvement Caused by Drying. The influence of moisture upon wood has already been considered. 1 Dry wood is stronger than green wood and much less liable to decay. All woods should be shrunk before they are finally placed in position. Improvement Caused by Alteration. Experience shows that other changes take place when woods are seasoned. Von Schrenk believes that albuminous substances, and possibly tannin, resins, and other incrusting materials are altered or recombined during these processes. 2 The reasons are not clear, but the facts are that additional changes do take place and that they are of such a nature as to suggest the changes that take place in fruits when they are " cured." It is often hard to season wood without injuring it somewhat. This is because of (1) irregularities that exist in the arrangement of the wood-elements, and (2) irregularities that exist in the dis- tribution of the moisture; as, for example, the difference in the amount of moisture in the sapwood and in the heartwood of a green log. It is easy to dry wood, but it is not always easy to dry it so that every part will shrink together. All methods are not 1 See Index. 2 "Seasoning of Timber" (United States Bureau of Forestry, Bulletin No. 41, p. 9). REFERENCES. "Timber," Roth (United States Division of Forestry, Bulletin No. 10, 1895); " Seasoning of Timber," von Schrenk (United States Bureau of Forestry, Bulletin No. 41, 1903); "Kim-Drying Hardwood Lumber," Dunlap (United States Forest Service, Circular No. 48, 1906); "Principles of Drying Lumber at Atmospheric Pressure," Tiemann (United States Forest Service, Bulletin No. 104, 1912). See also catalogues of the B. F. Sturtevant Company, the Morton Dry Kiln Company, the Standard Dry Kiln Company, the American Blower Company, etc. "The Theory of Drying, etc.," Tiemann (United States Department of Agriculture, Bulletin No. 509, March, 1917). i( 326 PRESERVATION OF WOOD SEASONING 327 suitable for all woods. Judgment and experience are required to select the proper method in any particular case. Three groups of processes are employed to season woods. They are natural-seasoning, water-seasoning, and kiln-seasoning. NATURAL SEASONING. Just as certain fruits will either cure or rot, according to the way in which they are exposed to the weather, so, also, will certain woods. When woods are exposed under certain conditions in the open air, water is expelled and the changes that have been de- scribed take place. The details of exposure are important. A few woods do FIG. 66. Close-piling. This en- courages rot. well under almost all con- ditions, but the rule is that close piling and contact with the ground encourage rot. Tim- bers should be raised from the ground and should be so piled that the air can circulate between them and they should re- main in these positions during intervals that depend upon their shapes and sizes. While it is often assumed that the best results are those obtained from natural sea- soning, it should be remem- bered that the best results are not invariably thus ob- tained. The pieces within a pile may be well seasoned, FIG. 67.- permits and checked from having dried too rapidly. From two to four years must often pass be- fore woods are completely dried by the natural method. It is expensive to hold stock so long, and it is dangerous because of fires. However, wood is normally improved, even although the process is not carried through to the end. The extreme form of natural seasoning is practiced with pieces intended for musical and mathematical instruments, and 328 ORGANIC STRUCTURAL MATERIALS wood engravings. On the other hand, most railway ties and other large construction pieces receive a minimum of attention. It seldom happens that these large pieces are completely sea- soned; but the improvement that takes place while they are piled waiting for use is ordinarily very great, and, with this in view, such pieces should be piled loosely so that the air can cir- culate between them. Natural seasoning requires so much time that it is usually combined with some other method. Before woods are thus seasoned they are often soaked in water; and sometimes drying commenced by this method is completed in a kiln. Natural seasoning, air seasoning, and yard-drying mean the same. WATER SEASONING. Logs are often stored under water. The tendency to crack that exists when they are exposed to the hot sun, and the danger from insects and from rot, are counter- acted as long as they remain thus submerged. Woods keep safely under water, and, at the same time, undergo changes that render them more durable after they have been removed from the water. They dry rapidly when brought again into contact with the air, and are then durable in proportion as they have been washed by the water. Water seasoning is usually combined with natural seasoning. The water acts, first by excluding the air, and second by leach- ing out impurities. There is no reason why wood should ever decay while it remains under water. The softening or physical disintegration that may eventually take place is not decay. Logs are sometimes found buried deep in the mud of swamps. Pieces cut from such logs are often particularly prized because in the course of immersion they have been so thoroughly cleansed and rendered durable, and also because they have lost much of the natural tendency to warp. KILN SEASONING. Kiln seasoning originated with at- tempts to prevent warping and checking in special pieces. In the United States, nearly all hardwoods, save those in large con- struction pieces, are now cured by this method. Drying pro- ceeds rapidly and details can be controlled in kilns as they cannot be in natural-seasoning or in water-seasoning. There are many details and combinations, but the factors that influence design and operation in all cases are temperature, mois- ture, and circulation. PRESERVATION OF WOOD SEASONING 329 Temperature Heat may be dry or wet. In both cases, high tem- peratures should be avoided. Dry heat in excess of two hundred and twelve degrees is sufficient to expel some of the volatile constituents of the wood, which then becomes weak and brittle. The equivalent of this temperature in moist heat is not known. Temperatures of from one hundred degrees to one hundred and twenty degrees Fahrenheit are used in connection with green oak and some other difficult woods, while temperatures of from one hundred and sixty degrees to one hun- dred and eighty degrees Fahrenheit are employed with pine and cedar. The temperature of the entire charge must be raised to a point at which the drying is to take place. The surface of wood heated in warm, dry air is liable to shrink before the heat has penetrated and acted upon FIG. 68. A kiln for drying wood. the moisture that is within. Wet heat or steam adds to the moisture but assists because it keeps the surface soft and swollen until the heat has penetrated to the interior. Moisture. Natural moisture or sap must be distinguished from moisture that may be absorbed after the tree has been cut down. Most of the natural moisture is in the outer sapwood and this moisture is often retained, or even added to, with advantage, so that the outer wood will not shrink before the heat has penetrated to the moisture further in. This is particularly necessary in the case of oaks and other woods char- acterized by complex cellular arrangements. Ability to season woods successfully in kilns depends upon ability to manipulate the moisture. Heat, circulation, and the kilns themselves are designed or directed with this end in view. Some processes include the addition of steam while others use only the moisture that has been evaporated from the wood. In other processes the moisture from the wood is removed by condensation upon the surfaces of pipes filled with cold water. Moisture is sometimes introduced by piling snow upon the lumber as it enters the "greenwood ends" of the kilns. Pieces must be piled so as to facilitate the escape of the moisture. Circulation. The air within a kiln does not remain motionless. On the contrary, it moves naturally because of the heat, or else the move- ment is induced by means of fans, and, in both cases, drying may be 330 ORGANIC STRUCTURAL MATERIALS hastened or retarded by hastening or retarding the circulation of the air currents. Air currents may pass in at the bottom and out through the sides of the kilns, or they may pass through the kilns from one end to the other. Forms of Kilns. The principal features of all kilns are (1) the drying chambers in which the wood is stored, 1 (2) the fur- naces for heating air or making steam, and (3) the devices for causing the air to circulate within the drying chambers. There are kilns within which charges remain stationary, and others within which charges move through from end to end. FIG. 69. Interior of a drying chamber. When the wood remains stationary, in what is known as a " charge kiln" or " apartment-kiln," the moisture in the air is removed little by little, and the mass is finally exposed to a current of warm, dry air. When the charge moves forward, in what is known as a " progressive-kiln/' it advances through an air- current that contains most moisture near the entrance or "green- wood end" and least moisture at the other extremity where the wood emerges. Kilns are also grouped according to the origin of the draft, which may be natural, if caused by pipes or radiators placed beneath the drying chambers; or it may be forced if the draft, heated outside the kiln, is forced in by a fan. As stated already, 1 Drying chambers are from fifteen feet to one hundred and fifty feet in length and from ten feet to thirty feet in width. They are usually built of wood, but may be built of brick, or of concrete, as shown in the preceding picture. PRESERVATION OF WOOD SEASONING 331 the air currents may pass in at the bottom and out through the sides of the kilns, or they may pass through from end to end. Kilns designed for natural draft are often known as "moist- air kilns," and those designed for forced draft as " hot-blast kilns," but these names refer to details of operation, rather than -t-r FIG. 70. A scheme for a radiator kiln. to methods of construction, since moist air may be used in kilns of either kind, regardless of the source of the draft. FIG. 71. A scheme for a blower kiln. Natural-draft kilns and forced-draft kilns are also sometimes referred to as " radiator-kilns" and " blower-kilns " respectively. A scheme for a radiator or moist-air kiln designed for progressive operation is shown in the picture. The pieces that are to be seasoned are arranged upon trucks, which are then rolled into the kiln until it is 332 ORGANIC STRUCTURAL MATERIALS full. After a sufficient time in the kiln, one truck with its charge is removed from the " dry-wood end," the others are moved forward, and a new charge is admitted at the "greenwood end" of the kiln. The ventilator shaft at the right is often dispensed with. The general direc- tion followed by the air currents is shown by the arrows. A scheme for a blower-kiln is also shown. The humidity is main- tained by using the same air repeatedly. The saturated air drawn from the "greenwood end" at the left of the picture, deposits part of the moisture upon the cold water coils located at the left of the fan, The air then passes on through the fan and is re-heated by the steam pipes toward the right. The air is relatively dry and warm as it re-enters the dry end of the kiln. 1 Operation. The several parts of the process employed within a kiln of any kind may be grouped as they relate (1) to prepara- tion and (2) to drying. First, the temperature of the charge must be raised to the point at which the drying is to take place, while the surfaces of the pieces that make up the charge remain or are rendered soft and permeable. Second, the drying is forced by means of the draft, but at such a rate that the moisture from within the pieces can move out fast enough to replace the moisture that escapes from their surfaces. Preparation. The charge or apartment kiln both prepares and then dries the wood before it is removed. Once within this kiln the wood is not removed until the process is completed. In the progressive system the wood is sometimes, but not always, prepared before it is admitted to the drying chamber. The auxiliary kiln, that is here sometimes used, should be placed as near as possible to the greenwood end of the prin- cipal kiln so that the charge will not be unduly chilled during transfer. Drying. The draft must be held back until the heat has penetrated within the pieces. Even then, it must not be forced unduly, or the surface moisture will escape too rapidly, and cause the surface wood to shrink before that inside has had time to dry. Case-hardening, honey- combing, checking, warping, or twisting may then result. Difficulties. In kilns, where drying is hastened, the difficulties that have been mentioned in connection with slower methods of seasoning become more pronounced. The situation has been expressed as follows : 2 "In drying chemicals or fabrics, all that is required is to provide heat enough to vaporize the moisture and circulation enough to carry off the \From United States Forest Service; Circular No. 48. 2 "Kiln-Drying Hardwood Lumber," Dunlap (United States Forest Serv- ice, Circular No. 48, p. 5.). PRESERVATION OF WOOD SEASONING 333 vapor, and the quickest and most convenient means to these ends may be used. In drying wood, whether in the form of standard stock or finished product, the application of the requisite heat and circulation must be carefully regulated throughout the entire process, or warping and checking are almost certain to result. Moreover, wood of different shapes and thicknesses is very often differently affected by the same treatment. Finally, the tissues composing the wood, which vary in form and physical properties and which cross each other in regular directions, exert their own peculiar influence upon its behavior during drying. With our native woods, for instance, summer wood and spring FIG. 72. Auxiliary kiln for preliminary treatment. wood show distinct tendencies in drying, and the same is true in less degree of heartwood as contrasted with sapwood. Or, again, pro- nounced medullary rays further complicate the drying problem. Plain oak and quartered oak require different treatment. Even in mahogany and similar tropical woods, which are outwardly more homogeneous, various kinds of tissues are differentiated." The presence of knots, windshakes, frostshakes, and other defects add to the problem, which is to dry without distortion rather than simply to dry. The comparatively simple cellular structure of coniferous woods makes it easier to dry the woods of that series. The broadleaf woods as a group are more difficult, and some of them, such as the oaks, are particularly hard to dry. 334 ORGANIC STRUCTURAL MATERIALS Time Required. The time required to kiln-season lumber depends upon the sizes, shapes, and species of the individual pieces. Some operators dry one-inch white oak planks in four or five days, while others require one or two weeks for the same woods, and still others need twice as long. Plain oak and mahogany dry with about the same speed; these woods require less time than quartered oak, and longer than ash, birch, and basswood. PROTECTION OF SEASONED WOODS. Dry woods should remain dry. Woods suffer if their cell structures expand and contract too frequently. The cell structures may remain healthy, but they separate more easily from one another, and eventually the piece as a whole is weakened. The influence of moisture upon the fungi that cause disease will be remembered. Seasoned woods that are to be exposed to the weather should be protected by coatings applied to their surfaces, or by antiseptics introduced within them. CHAPTER XIV PROTECTIVE METHODS INTERNAL TREATMENT PRESERVATIVE COMPOUNDS APPLIED WITHIN WOODS Preservative compounds are applied within woods to produce results of several kinds. Sometimes, the object is to increase resistance to decay; sometimes, it is to repel the attacks of teredos and other live woodborers, and sometimes, the object is to retard fires. Preservatives within woods remain where paints on the outside would soften or be rubbed away. Paints would fail if applied to woods used in marine positions or in rail- way ties, whereas preservatives injected within woods have suc- ceeded in such positions. Preservative chemicals were first applied within woods in England. The diminished supply of wood, and the early rotting of their wooden ships, caused the English to practice within this field more than one hundred years ago. The beginning of real activity, however, was connected with the development of rail- ways (1830-1840). REFERENCES. "Antiseptic Treatment of Timber," Boulton (Proceedings Institution of Civil Engineers, London, 1884); "The Preservation of Tim- ber," Report of Committee (Transactions American Society of Civil Engi- neers, 1885); "Wood Preservation," Flad (United States Forest Service, Bulletin No. 1, 1887); "Preservation of Railroad Ties," Curtis (Transactions American Society of Civil Engineers, Vol. XLII, 1899); "Proposed Method of Preservation of Timber with Discussion," Kummer (Transactions Ameri- can Society of Civil Engineers, Vol. XLIV, 1900); "Hand-book of Timber Preservation," Samuel M.Rowe (Author's Edition, 1900); "Preservation of Railway Ties in Europe," Chanute (Transactions American Society of Civil Engineers, Vol. XLV, 1901); "Timber Tests and Discussions" (Transactions American Society of Civil Engineers, Vol. LI, 1903) ; " Decay of Timber," von Schrenk (United States Bureau of Plant Industry, Bulletin No. 14); "Recent Progress in Timber Preservation," von Schrenk (United States Department of Agriculture, Yearbook, 1903); "The Inspection of Treatment for the Protection of Timber by the Injection of Creosote Oil," Stanford (Transac- tions American Society of Civil Engineers, Vol. LVI, 1905); "The Preserva- tion of Structural Timber," Weiss (McGraw-Hill Book Co., 1915); Bulletins of American Railway Engineering Association; "Handbook" (1916) and other Publications of the American Wood Preservers Association; also, other Publications of United States Department of Agriculture; etc., etc. 335 336 ORGANIC STRUCTURAL MATERIALS The field of wood preservation has not been occupied to the same extent in the United States as in Europe. Woods have been more plentiful in the United States, where, consequently, the demands for construction have hitherto been along extensive, instead of intensive, lines. A study of the subject of wood preservation from a local stand- point was inaugurated by the American Society of Civil Engi- neers in 1880, and the report issued by this Society five years later is yet recognized as text. The study thus commenced was continued by the United States Department of Agriculture, which, having organized a Division of Forestry, issued its first bulletin in 1887. The situation in the United States today sug- gests the situation as it was in England some years ago; save that English engineers were obliged to learn from the beginning, whereas Americans have profited from successes and failures of a century of European practice. The price of wood is advancing in the United States; and, dependent upon this, the practice of wood preservation is rapidly becoming more general. Prior to 1901 only fifteen timber pre- serving plants were in operation, while, during the six successive years, this number was increased to fifty. 1 Nearly ten per cent, of the total number of railway ties recorded as having been pur- chased during 1905 received preservative treatment of some kind. A French authority states that one hundred and sixty-seven wood-preserving substances or processes were tried or introduced prior to 1874, 2 while Weiss enumerates two hundred and sixty- eight patents granted in the United States alone in this field since that year. 3 Most processes and chemicals included in these and other lists have, however, been abandoned. In 1885, the Com- mittee of the American Society of Civil Engineers reported fully upon only four preservatives and processes; and, in spite of the time that has elapsed since this report was rendered, these four are yet regarded as the most important. It is hardly probable that many methods now unknown will be successfully introduced in the future, because years must elapse before the efficiency of a material or a method can be proved by (United States Forest Service, Circular No. 43, p. 6). Weiss enumerates one hundred and ten wood-preserving plants as existing in the United States in 1914 (pp. 255-258). 2 "Traite de la conservation desbois," Paulet (Paris, 1874). 3 "Preservation of Structural Timber," Weiss (1915). PRESERVATIVES APPLIED WITHIN WOODS 337 actual tests. Woods are more costly and chances less war- ranted than in former years. As distinct from the development of new practices, however, it is probable that in the future more attention will be given to perfecting practices already known, and, that results obtained in the United States, will ultimately be more uniformly satisfactory than at the present time. The subject is one that requires attention along three lines, namely: the materials used to preserve woods, the processes used to force such materials into the woods, and the woods that will best receive and respond to the preservative materials thus used. PRESERVATIVE MATERIALS Salt, formaldehyde, lime, sulphate of iron, tannin, oils, arsenic, and many other substances have been tried or considered for preserving woods. Of this entire series copper sulphate, zinc chloride, mercury bichloride, and creosote, either separately or in combinations, have succeeded best; while of this smaller list, zinc chloride and creosote are now most used. 1 ir The following list is taken from "Handbook on Wood Preservation" (American Wood Preservers' Association, p. 27, 1916). It enumerates some of the substances which have been proposed as means of protecting wood against destruction by fire, fungi, and woodborers : Aluminum sulphate Petroleum oils Animal oils Potassium carbonate Barium carbonate Potassium nitrate Barium sulphate Resins Borax Sodium carbonate Cedar oil Sodium chloride Copper sulphate Sodium fluoride Creosotes (coal-tar, Sodium muriate water-gas-tar, wood, Sodium sulphate petroleum) Sulphuric acid Crude oil Tannin Fish oil Tar Glue Tartaric acid Gums (various) Vegetable oils Iron sulphate Wax Lime hydrate Whale oil Linseed oil Zinc chloride Magnesium sulphate Zinc sulphate Mercuric bichloride Molasses and low syrups 338 ORGANIC STRUCTURAL MATERIALS Wood preservatives may be divided as they do, or do not, dissolve in water. First, the salts of metals dissolve in water, and, for this reason, eventually escape if used where it is wet; but second, creosote, which is an oily mixture, does not dissolve in water. Creosote is much more permanent in its effects than are the salts of metals. It should be remembered that the influence of any chemical may continue for a short time after the removal of the chemical. TANNIN (CnHioOg). Tannin is an antiseptic and coagulant. Tannin and tannic acid are the same. 1 Tannin is present in parts of many trees and doubtless influences the natural dura- bility of woods. It is used in the preparation of leather, as well as in the artificial preservation of woods, although, in the latter case, it is used only in combination with other substances. Tannin serves in this connection, together with glue, in what are known as the "zinc tannin processes." The leather-like solids which result during these processes from the action of the tannin upon the glue, fill up the pores of the wood and retard the escape of zinc chloride, which is soluble in water. COPPER SULPHATE (CuSO 4 .5H 2 O). This is the blue vitriol of commerce. Chapman experimented with wood soaked in copper sulphate as early as 1816. Boucherie, who concerned himself with methods for forcing preservatives into woods rather than with the preservatives themselves, after employing various antiseptics, finally pronounced in favor of copper sulphate; and in consequence of this, the name of Boucherie is associated with copper sulphate and also with the process used for introducing it into wood. Copper sulphate is a very valuable wood antiseptic but it dissolves readily in water and escapes easily from the wood. It is decomposed when brought into contact with iron. Very little of it is now used in wood preservation in the United States. MERCURY BICHLORIDE (HgCl 2 ). The application of mer- cury bichloride in wood preservation was first suggested by John Howard Kyan in England in 1833. Mercury bichloride is the most active of all wood preservatives in use. Very small quantities are effective, and because the quantities needed are so small the actual cost, although considerable, is not as great as at first appears. It dissolves in boiling water, and once within the 1 In the strictly chemical sense, tannic acid is not a true acid, but an anhy- dride of an acid, belonging to the class of phenols. Tannin is therefore the more nearly correct name. The two terms refer to the same substance. PRESERVATIVES APPLIED WITHIN WOODS 339 wood, resists the actual moisture of reasonably dry places much longer than do copper sulphate and zinc chloride. On the other hand, mercury bichloride attacks iron; 1 in spite of the small quantities necessary it is comparatively costly, and it is very poisonous to human beings. 2 ZINC CHLORIDE (ZnCl 2 ). Zinc chloride, which is obtained by dissolving metallic zinc in hydrochloric acid, is a cheap and very good wood preservative, its toxic effects upon wood-destroying fungi being about equal to those of creosote ; also it has an affinity for wood fiber into which it penetrates to a considerable depth. Its chief fault is that it attracts water and dissolves easily in it. Experience shows, however, that it will remain in timber in reasonably dry locations for many years. It cannot be used in marine constructions, but has caused railway ties which would normally fail in four or five years to remain sound for ten or more years. Many million pounds of zinc chloride are now used annually in the United States in treating wood. Zinc chloride is the cheapest wood preservative practically available in this country, and in spite of defects that have led most European railways to cease using it, is highly regarded as an antiseptic that meets some temporary American conditions. Burnett first called attention to the value of zinc chloride as a wood preservative in 1838. CREOSOTE. 3 The name creosote applies to products derived 1 The reaction is as follows: Fe + HgCl 2 = FeCl 2 + Hg. 2 The antidote, when this active poison is taken into the stomach, is fresh milk or else egg water made by dissolving three or four raw eggs in one quart of water. 3 REFERENCES. "Coal-tar and Ammonia," Lunge; "Causes Underlying the Limited Production of Creosote in the United States" (Forestry and Irri- gation, October, 1906, pp. 482-484); "Fractional Distillation of Coal-tar Creosote," Dean and Bateman (United States Forest Service, Circular No. 80); "Quantity and Character of Creosote in Well-preserved Timbers," Alleman (United States Forest Service, Circular No. 98); "The Analysis and Grading of Creosotes" (United States Forest Service, Circular No. 112); "Volatilization of Various Fractions of Creosote after their Injection into Wood," Teesdale (United States Forest Service, Circular No. 188); "Modi- fication of the Sulphonation Test for Creosote," Bateman (United States Forest Service, Circular No. 191). Other Publications of the United States Forest Service. Manual, 1911, and other Publications American Railway Engineering Association. Proc. American Wood Preservers' Association. Specifications American Telephone and Telegraph Company. "Coal-tar Distillation," Warnes (D. Van Nostrand Company, 1914). "Preservation of Structural Timber," Weiss (McGraw-Hill Company, 1915). 340 ORGANIC STRUCTURAL MATERIALS from water-gas tar and wood; but, in construction, unless other- wise noted, it now refers principally to a mixture distilled from coal-tar. Coal-tars vary and the mixtures obtained from them during distillation vary also. It is, therefore, particularly un- fortunate that there can be no chemical formula for creosote. The value of creosote as a wood preservative was suggested by Bethell in 1838. Tar oil, heavy oil of tar, dead oil of tar, and coal-tar creosote are different names for the same material. Water-gas-tar and wood creosotes are antiseptics, but their success with woods is not to be compared with that which has followed the use of coal-tar creosote. Wood creosote has a sweet- ish, burning taste, with an odor that resembles that of smoked FIG. 73. Cross-section of pole, showing penetration of creosote. meat or fish. 1 Beef cured in wood-smoke owes much of its flavor, as well as its durability, to the influence of the volatile wood creo- sote present in the smoke. All creosote, whether made from wood, water-gas tar, or coal-tar, is poisonous to human beings. Coal-tar creosote stands by itself among the wood preserva- tives. The others dissolve in water, but creosote, in addition to being an antiseptic, is nearly insoluble in water. Creosote pre- vents rot, and also protects wood from the attacks of terrestrial and marine woodborers. The salts of metals do not materially lessen the porosity of wood, but creosote, in sufficient quantities, fills and stiffens within the cell-structures, shuts off the air, with- 1 For references with regard to wood creosote, see " Report on Wood Creo- sote Oil," Bixby (United States Forestry Bulletin No. 1); United States Dispensatory; "The Preservation of Structural Timber," Weiss (p. 86). PRESERVATIVES APPLIED WITHIN WOODS 341 out which fungi cannot live, and is the only preservative in com- mon use that keeps wood-fibers dry. No real difference of opinion exists with regard to the value of creosote, the use of which depends almost entirely upon its availability and cost. In Europe, where creosote is compara- tively plentiful and cheap, engineers use it for ties and in almost all wood-work that requires preservation. Americans now use it to prevent rot in railway ties, mud sills, bridge timbers, and pav- ing blocks, and to protect timbers designed for marine construc- tions from teredos and limnoria. Creosote is not yet used as widely in this country for ties as it is abroad, but its use as a tie preservative is increasing. As manipulated in gas works, mineral coal yields illuminating gas, ammoniacal liquid, coal-tar, and coke. Of these, the tar, which is a sticky black substance, is separated by distillations conducted between certain temperatures, into (1) light oils, that is oils lighter than water, (2) middle oils, (3) heavy oils, that is oils heavier than water, and (4) residue or pitch. The variable mixture obtained during the third dis- tillation is called creosote. This is also shown on the diagram. Coal Gas Ammoniacal Tar Coke Liquid Light Oils Middle Oils Heavy Oils or Pitch Creosote The list that follows, although incomplete, is sufficient to show the complex nature of coal-tar. 1 As a matter of fact, almost two hundred definite chemical compounds can be separated when this material is subjected to destructive distillation. When coal-tar is submitted to distillation and rectification, it yields, among others, the following products in varying proportions: 1 1. Solids. Naphthalene, methyl-naphthalene, acetyl-naphthalene diphenyl, fluorene, anthracene, phenanthrene, fluoranthene, methyl- anthracene, retene, chrysene, pyrene, picene, and carbazol. 2. Liquids. These may be neutral hydrocarbons, acids, ethers of acids, or their bases. The neutral hydrocarbons are benzene, toluene, methyl- toluene, and iso-xylene, pseudocumene, mesitylene, and cymene. The acid constituents are phenol, orthocresol, paracresol, metacresol, phlorol, rosolic acid, pyrocatechin, and creosote, consisting of the methyl ethers of pyrocatechin and its homologues. There are also present, 1 " Coal-tar and Ammonia," Lunge (London) United States Dispensatory; "Coal-tar Distillation," Warnes (D. Van Nostrand Company, 1914). 342 ORGANIC STRUCTURAL MATERIALS probably in combination with the ammonia of the ammoniacal liquor, acetic, butyric, carbonic, hydrocyanic, sulphocyanic, and hydrosul- phuric acids. The bases are ammonia, methylamine, ethylamine, phenylamine, pyridine, picoline, lutidine, collidine, leucoline, iridoline, cryptidine, acridine, coridine, rubidine, and viridine. 3. Gases, (a) Illuminating gases. Acetylene, ethylene, propylene, butylene, allylene, crotonylene, terene, and vapors of benzene, styrolene, naphthalene, methyl-naphthalene, fluorene, fluoranthene, hexane, hep- tane, and octane. (6) Heating and diluting gases. Hydrogen, marsh- gas (methane), carbon monoxide, (c) Impurities. Carbon dioxide, ammonia, cyanogen, methyl-cyanide, sulphocyanic acid, hydrogen sul- phide, carbon disulphide, carbon oxysulphide, and nitrogen. A highly prized creosote is obtained as a by-product from Newcastle coals burned in the vicinity of London. This creosote, known as " London oil," is thick and heavy. The English Midland districts pro- duce lighter creosotes, known as "country oils." German creosote is much employed. Much, but not all, good creosote now used in this country is imported, the United States not yet having met the demand for this product. Also, much American creosote contains an excess of naphthalene. Chemical, physical, and physiological results are brought about by the several ingredients that make up creosote. The wood is acted upon by the carbolic acid, cresylic acid, and associated antiseptics. The cells are treated by, or filled with thick, gummy oil and naphthalene, and the creosote, as a whole, is like camphor in that it is disliked by the lower forms of life. 1 It should be noted that creosotes differ in their behavior when under water. Thick London oils have resisted disintegration in marine posi- tions for forty years, while some American creosotes, applied under con- ditions that prevail in some parts of this country, have failed after having been exposed to the action of water for a few months. 2 Creosote should be thick, since thin oil is correspondingly less stable. The specific gravity should be greater than that of water. The influ- ence of temperature is important, because some of the ingredients, relied upon to solidify within the wood when they have cooled, do not distil save at high temperatures. Tidy wrote upon this subject as follows: 3 1 " Descriptions of Creosote Best Suited for Creosoting Timber," Tidy (Appendix 7); Boulton on "Antiseptic Treatment of Timber," the Institu- tion of Civil Engineers, London; "Coal-tar and Ammonia," Lunge (Third Edition, London, pp. 473-477). 2 "Changes which take place in Coal-tar Creosote during Exposure," von Schrenk, Fulks, and Kammerer (American Railway Engineering Association, Bulletin No. 93, November, 1907). 3 "Antiseptic Treatment of Timber," Boulton (The Institution of Civil Engineers, London, p. 51). PRESERVATIVES APPLIED WITHIN WOODS 343 "Believing strongly as I do in the value of those constituents of the oil that are the most difficult to volatilize, I have deemed it right to sug- gest a clause to the effect that the creosote shall contain at least 25 per cent, of matters that distil over at about 600 degrees Fahrenheit/' 1 The ingredients or groups of ingredients in coal-tar creosotes that are thought in the United States to exert much influence in wood preserva- tion are light oils, naphthalene, anthracene, or anthracene oils and tar acids. French engineers attribute much to the presence of tar acids, while in England, credit is given to acridine. Because of the complex nature of creosote and difficulties connected with analyses, most specifi- cations omit mention of all but a few of the components and confine themselves to important characteristics and reactions that indicate the genuineness of creosote as a whole. 2 Mixed Coal-tar Creosotes. Pine resin has been used to thicken creosote designed for the treatment of paving blocks. 3 Coal-tar is often mixed with pure creosote, the defense being that the supply of pure creosote is insufficient. Other materials or mixtures are also used with pure creosote. It is needless to say that when pure coal-tar creosote, free from the mixture of other substances, is specified that creosote only should be employed. The fact that creosote is so variable renders the more neces- sary some form of specification or control. It is unfortunate that some compounds yet sold as creosote have so little to commend them beyond the name, since failures during this more or less for- mative period tend to retard the use of the legitimate mixture. The properties of creosote are of vital importance. It should not be forgotten, however, that there are other factors that exert an equal influence upon the preservation of wood by creosote. The method of application is one of these factors. This should be such that deep impregnation, and the wide diffusion of the creosote, particularly through the outer parts of the timber, result. A poor quality of creosote well injected may yield better results than a good quality of creosote poorly injected. 1 Report of Tidy (Boulton on "Antiseptic Treatment of Timber," the Institution of Civil Engineers, London, p. 51). 2 About 55,000,000 gallons of creosote were used in the wood-preserving plants of the United States during the year 1908. Of this amount, about thirty per cent, was produced in this country, while the balance, about seventy per cent., was imported principally from England, Germany, and Canada. 3 See Creo-Resinate Process. 344 ORGANIC STRUCTURAL MATERIALS Specifications for creosotes are of two kinds. First, certain properties that the creosote should possess are specified; and second, methods of analysis by which the existence of these prop- erties is proved or the properties measured, are specified. It is needless to say that these two fields depend upon one another and that the specifications often overlap. Specifications for Creosote. Creosote, once purchased largely on faith, is now bought under more or less rigidly enforced speci- fications. Controlling items regardless of the purposes for which the oil is to be used relate, principally, (1) to its origin, (2) to the limits of the distillation ranges, (3) to its specific gravity, and sometimes (4) to the percentages of several constituents. (1) The origin of creosote is controlled by securing it from reputable dealers. (2) The determination of the temperatures between which certain fractions of the original bulk distil is of fundamental importance, since slight changes cause considerable variations to take place in the results of the analysis. (3) It is usually specified that creosotes should have specific gravities of from 101 to 112. (4) The percentages of cer- tain components as tar acids and naphthalene are sometimes stated. English practice is based upon the Tidy specification, 1 which is as follows: 1. " Creosote should be completely liquid at a tem- perature of 100 degrees Fahrenheit, no deposit afterwards taking place until the oil registers a temperature of 93 degrees Fahren- heit." 2. "The creosote should contain at least twenty-five per cent, of constituents that do not distil over at a temperature of 600 degrees Fahrenheit." 3. " The creosote shall yield a total of eight per cent, of tar acids." 2 Of the specifications employed in the United States those pre- pared by The American Railway Engineering Association, The American Telephone and Telegraph Company, and The United States Forest Service, are, on the whole, most important. 1 See Boulton on "Antiseptic Treatment of Timber" (The Institution of Civil Engineers, London, p. 51). Several characteristic European speci- fications appear with Chanute's paper "Preservation of Railway Ties in Europe" (Trans. American Society of Civil Engineers, Vol. XIV). 2 Some American and foreign specifications are shown in comparison with one another in a paper entitled, "Changes which take place in Coal-tar Creo- sote during Exposure," von Schrenk, Fulks and Kammerer (American Railway Engineering Association, Bulletin No. 93, November, 1907). PRESERVATIVES APPLIED WITHIN WOODS 345 The specification prepared by The American Railway Engi- neering Association is as follows: Standard Grade of Creosote Oil (Also Known as No. 1 Oil). The oil used shall be the best obtainable grade of coal-tar creosote; that is, it shall be a pure product obtained from coal-gas tar, or coke-oven tar, and shall be free from any tar, oil or residue obtained from petroleum or any other source, including coal-gas tar or coke-oven tar; it shall be completely liquid at thirty-eight (38) degrees Centigrade and shall be free from suspended matter; the specific gravity of the oil at thirty-eight (38) degrees Centigrade shall be at least 1.03. When distilled by the common method that is, using an eight (8) ounce retort, asbestos- covered, with standard thermometer, bulb one-half (^) inch above the surface of the oil the creosote, calculated on the basis of the dry oil, shall give no distillate below two hundred (200) degrees Centigrade, not more than five (5) per cent, below two hundred and ten (210) degrees Centigrade, not more than twenty-five (25) per cent, below two hundred and thirty-five (235) degrees Centigrade; and the residue above three hundred and fifty-five (355) degrees Centigrade, if it exceeds five (5) per cent, in quantity, shall be soft. The oil shall not contain more than three (3) per cent, water. In addition to the above standard specification, the two following grades can be used in cases where the higher-grade oil cannot be pro- cured. It should be understood that where it is necessary to purchase grades No. 2 and No. 3 consideration should be given to the use of a greater quantity of creosote oil per cubic foot. Specification for No. 2 Grade Creosote Oil. The oil used shall be the best obtainable grade of coal-tar creosote; that is, it shall be a pure product obtained from coal-gas tar, or coke-oven tar, and shall be free from any tar, oil or residue obtained from petroleum or any other source, including coal-gas tar or coke-oven tar; it shall be completely liquid at thirty-eight (38) degrees Centigrade and shall be free from suspended matter; the specific gravity of the oil at thirty-eight (38) degrees Centi- grade shall be at least 1.03. When distilled by the common method that is, using an eight (8) ounce retort, asbestos-covered, with standard thermometer, bulb one-half (^) inch above the surface of the oil the creosote, calculated on the basis of the dry oil, shall give not more than eight (8) per cent, distillate below two hundred and ten (210) degrees Centigrade, not more than thirty-five (35) per cent, below two hundred and thirty-five (235) degrees Centigrade; and the residue above three hundred and fifty-five (355) degrees Centigrade, if it exceeds five (5) per cent, in quantity, shall be soft. The oil shall not contain more than three per cent, water. 346 ORGANIC STRUCTURAL MATERIALS Specification for No. 3 Grade Creosote Oil. The oil shall be the best obtainable grade of coal-tar creosote; that is, it shall be a pure product obtained from coal-gas tar or coke-oven tar and shall be free from any tar, oil or residue obtained from petroleum or any other source, including coal-gas tar or coke-oven tar; it shall be completely liquid at thirty- eight (38) degrees Centigrade and shall be free from suspended matter; the specific gravity of the oil at thirty-eight (38) degrees Centigrade shall be at least 1.025. When distilled by the common method that is, using an eight (8) ounce retort, asbestos-covered, with standard ther- mometer, bulb one-half (^) inch above the surface of the oil the creosote, calculated on the basis of the dry oil, shall give not more than ten (10) per cent, distillate below two hundred and ten (210) degrees Centigrade, not more than forty (40) per cent, below two hundred and thirty-five (235) degrees Centigrade; and the residue above three hundred and fifty- five (355) degrees Centigrade, if it exceeds five (5) per cent, in quantity, shall be soft. The oil shall not contain more than three (3) per cent, water. The specification of the American Telephone and Telegraph Company 1 is as follows : General. The material desired under these specifications is that known as dead oil of coal-tar, or coal-tar creosote, obtained through the distillation of gas tar produced by the destructive distillation of bitu- minous coal, either in the manufacture of coal gas, or in the manufacture of coke by the by-product process. It shall be without adulteration. Information shall be furnished on request as to the origin of the oil and the names of the parties through whose hands it may have passed. A copy of any analysis of the oil that may have been made prior to its use shall also be furnished. The right is reserved to take representative samples of the oil and test the same wherever desired. Requirements. All dead oil of coal-tar furnished under these speci- fications shall conform to the following requirements : First. The oil shall have a specific gravity of at least one and three one-hundredths (1.03) at thirty-eight degrees Centigrade (38C.). Second. The oil shall be thoroughly liquid at a temperature of thirty- eight degrees Centigrade (38C.). Third. When one hundred grams of the oil are distilled in accordance with the requirements of the specifications for the analysis of dead oil of coal-tar or coal-tar creosote hereinafter referred to (a) Not more than five (5) per cent, shall distil off up to 205C. (b) Not more than thirty-five (35) per cent, shall distil off up to 235C. (c) The fraction coming over between 210C. and 235C. shall solidify on cooling to 20C. (d) -Not more than eighty (80) per cent, shall distil off up to 315C. 1 Specification No. 3,340, dated March 11, 1911 (in force April, 1912). PRESERVATIVES APPLIED WITHIN WOODS 347 (e) The oil shall not contain more than 1 two (2) per cent, of water. (/) The quantity of tar acids present in the fractions distilling below 300C. shall not exceed eight (8) per cent, (measured by volume) of the total sample distilled. (gr) The sulphonation residue from the fraction distilling between 300C. and 360C. shall not exceed twenty-five one hundredths (0.25) cubic centimeters. Fourth. The oil shall be free from acetic acid and acetates. Fifth. The constituents of the oil insoluble in benzol shall not exceed one (1.0) per cent, by weight. Thermometer Sheet Asbestos should rest against Glass Neck must never Touch Cork Stopper Retort Asbestos Sheet Wire Gauze Bunseu Burner FIG. 74. Apparatus for analysis of creosote used by American Telephone and Telegraph Co. Analysis. The oil shall be analyzed in accordance with the methods outlined in the Specifications for the Analysis of Dead Oil of Coal-tar or Coal-tar Creosote. 1 NOTE. When unseasoned timber is being treated for the Telephone Company by the cylinder pressure process, using steam for seasoning, the oil may contain not more than five (5) per cent, of water. But in case more than two (2) per cent, of water is present in the oil, the quantity of the preservative added to the timber shall be increased by an amount sufficient to ensure that the required amount of oil computed on a water- free basis has been taken up by the timber. 348 ORGANIC STRUCTURAL MATERIALS The United States Forest Service Specification for Creosote gives much attention to methods of analysis. 1 Specifications for Analysis of Creosote. The importance of details in analyzing creosotes has been mentioned. The methods and devices employed in determining the proportions of creosote separated between certain temperatures, the methods of measur- ing viscosity, and those employed to determine other properties, influence the results obtained. This is partly shown in the quo- tation that follows: 2 "The most important part of a creosote analysis is the fractional distillation, since by this operation an approximate determination is made of the relative proportions of the most important substances in tar oil. There has been considerable divergence of opinion as to the best way of carrying out the fractionation of tar oils, some recommend- ing a retort as a distilling vessel and certain temperatures for taking fractions, others recommending a distilling flask and a different set of temperatures." The shape of the distilling vessel is important, since it exerts an influence upon the quantities and the constituents of the parts, or fractions that are distilled. It is also necessary to decide upon the limits of temperature and the number of these limits that are to isolate, or divide the parts or fractions. The forms that follow show methods of reporting analyses. The first and second forms have been used to report the results of analyses in which the oil was divided into ten and eleven frac- tions, while the last form was used to report an oil that ran high in naphthalene. l " Standard Method for Analysis of Coal-tar Creosote," von Schrenk, Fulks, and Kammerer (American Railway Engineering Association, Bulletin No. 65). See also American Railway Engineering Association Manual, 1911, p. 441. "The Fractional Distillation of Coal-tar Creosote," Dean and Bateman (United States Forest Service, Circular No. 80). 2 United States Forest Service, Trade Bulletin No. 13; other references are United States Forest Service Circular No. 80; American Railway Engineer- ing Association Bulletins No. 65 and No. 72; Specifications of the American Telephone and Telegraph Company, New York Telephone Company; also sources enumerated in preceding footnote. PRESERVATIVES APPLIED WITHIN WOODS ANALYSIS OF DEAD OIL OF COAL TAR 349 Sample No. 1 Manufactured by : Purchased from : Date: 191 . SUMMARY OF RESULTS Specific Gravity at 38C. : Condition at 38C. : FRACTIONATION Weight of retort Weight of retort and oil Fraction number Temperature Per cent. Weight of vessel Weight of vessel and contents Weight of contents ! 1 170C. 2 170C. to 205C. 3 205C. to 210C . 4 210C. to 235C. 5 235C. to 245C. 6 245C. to 270C. 7 270C. to 300C. 8 300C. to 315C. 9 315C. to 360C. 10 Residue (in retort) Total per cents, found: Loss per cent. : Oil distilling below 205C. : Oil distilling below 235C. : Oil not distilling below 315C: Water: Sulphonation residue: Tar acids : Insoluble in benzol : Acetic acid or acetates : Condition of naphthalene fraction (210-235) when cooled to 20C. Per cent. Per cent. Per cent. Per cent. Cubic centimeters Cubic centimeters Per cent. 350 No. 2 ORGANIC STRUCTURAL MATERIALS Creosote . DISTILLATION No. 23 50 Date 3/ I/ 17 Analyst No. Temp. Flask Flask Dist. Per cent. Character 1 170 49.53 47.34 2.19 0.876 1. Water some naph. 2 170-205 47.11 45.49 1.62 0.648 2. Light oil some naph. 3 205-210 42.80 40.77 2.03 0.812 3. Light oil some naph. 4 210-235 86.45 51.97 34.48 13.792 4. Nearly solid. 5 235-245 71.44 46.34 25.10 10.040 5. Solid. 6 245-255 68.80 49.18 19.62 7.848 6. Semi-solid. 7 255-270 70.90 48.78 22.12 8.848 7. Very thin paste. 8 270-285 60.40 44.73 15.67 6.268 8. Very thin paste. 9 285-300 59.59 41.02 18.57 7.428 9. Thin paste. 10 300-320 80.82 52.38 28.44 11.370 10. Thick paste. 11 320-350 98.32 50.37 47.95 17.180 11. Solid. Res idue 128.55 97.32 31.23 12.492 Remarks: Oil almost liquid 99.608 No. 3. REPORT OF TEST OF COAL-TAB CREOSOTE Date: July 10, 1917. Analyst Sample from overflow pipe. Temperature, 48C. Oil supplied by Boiling, 210C. Specific gravity, 1 . 021. Melting point, 46C. Weight Retort 104.71 gr. Retort and Contents, 204.47 gr. Contents, 99.76 gr. Retort and Residue, 120 . 73 Residue, 16 . 02 gr. DISTILLATION Temp. Fraction Tube Weight of tube and contents Con- tents Per cent, ol whole -170 170-205 205-210 210-235 235-240 240-270 270-316 Phenols,hydrocarbonsand water Phenols and cresols 22.44 18.89 20.25 20.90 12.91 19.85 17.44 22.33 22.39 27.43 67.75 18.50 31.01 26.37 0.09 3.50 7.18 46.85 5.59 11.16 8.93 0.09 3.50 7.20 46.94 5.60 11.19 8.95 16.06 0.47 Phenols and naphthalene .... Naphthalene . ... Naphthalene and anthracene oil Anthracene oil Anthracene Residue Loss Total 100.00 Time : ( 40 to 210 29 min. 235 to 270 27 min. \ 210 to 235 21 min. 270 to 316 29 min. Percentage of naphthalene 53.34 per cent, (obtained by adding half of the percentage of the phenols and naphthalene, and naphthalene and anthracene oil fractions to the percentage of the naphthalene fraction). PRESERVATIVES APPLIED WITHIN WOODS 351 Required Quantities of Creosote. These depend upon the way in which the wood is used. For example, large quantities of creosote cannot be used in paving blocks because of the possi- bility that such blocks will annoy pedestrians by "bleeding" or giving up creosote when exposed to the sun. On the other hand, timbers that are to be submerged in marine positions require considerable quantities of creosote. Practices differ with localities, woods, and the uses for which the woods are intended. In the United States, railway ties are sometimes treated with quantities as small as six or eight pounds to the cubic foot, although the usual local practice is to treat them with ten or more pounds to the cubic foot. Depending upon a wide range of conditions, piles are usually made to receive from twelve to twenty-four pounds to the cubic foot. An eastern wood preserver advises as follows : "In this section of the country (New York) it is customary to subject a railroad tie to a treatment of eight to twelve pounds of creosote per cubic foot of wood. If we figure that a standard tie of seven inches by nine inches by eight feet six inches is being used, this would make a total injection of thirty to forty-four pounds of creosote oil into each tie, depending upon the treatment used. The treatment, of course, depends upon the conditions under which the tie is to be used, whether the con- ditions are severe or mild." "In northern waters, twelve to sixteen pounds of creosote oil per cubic foot of wood is considered sufficient for the protection of the piling. However, in the south, where the piling is subject to the ravages of the teredo, etc., it is considered good practice to creosote the piling to point of refusal, which is from twenty to twenty-four pounds per cubic foot." It should be remembered that some engineers believe that much of the value of creosote depends upon the fact that it keeps wood- fiber dry, and, therefore, think that it should be used in compara- tively large quantities, as in the so-called " full-cell" processes;- while others regard its antiseptic value more exclusively, and, in ties, use smaller quantities, as in the " empty-cell" processes. Distribution of Creosote. Experience has shown that the distribution of creosote throughout every part of every piece is impracticable and unnecessary, but that the thorough penetra- tion into the sapwood and outer parts is of vital importance. It is fortunate that sapwood, because of its comparative porosity, and because of its position upon the outside of the timber, receives creosote so much more easily than heartwood receives it. 352 ORGANIC STRUCTURAL MATERIALS The tendency of preservatives to lodge near surfaces indicates the desirability of framing timbers before they are treated. Europeans bore ties before they are treated, and finally insert- wooden dowels into the borings; these dowels, and not the ties, receive the spikes. MISCELLANEOUS MATERIALS. Several proprietary wood- preserving compounds are in existence; these, although recom- mended for ties, are principally used for small pieces, or for fresh exposures where timbers are cut and framed upon the ground. Carbolineum, woodiline, spiritine, and others are of this group. Carbolineum. The base of this mixture is understood to be a modified coal-tar creosote that differs from ordinary creosote in that the lower distilling fractions have been largely removed. Several compounds are sold under the name " Carbolineum." 1 Avenarius Carbolineum. This mixture, invented by Avenar- ius in Germany, in 1869, has been upon the market since 1876. An analysis furnished by the manufacturer, published by Filsinger in the "Chemicker Zeitung" of April 18, 1891, and referred to in Lunge's " Coal-tar and Ammonia," is as follows: ANALYSIS Color Red brown. Specific Gravity at 62 degrees F 1 . 128 Viscosity at 62 degrees F. (water 1) 10.00. Mineral matter 0. 03 per cent. Flashing point 270 degrees F. Burning point 370 degrees F. Begins to distil at 445 degrees F. Distils from 445 degrees to 520 degrees F 10. 6 Vol. per cent. Distils from 520 degrees to 570 degrees F 12.0 Vol. per cent. Naphthalene (at 410 degrees to 446 degrees F.) No separation. Phenols (carbolic acid aac. Seubert) 0.00 per cent. Residue a clear red-brown thick fluid. Avenarius Carbolineum is described by the manufacturers as follows : 2 "To give a short definition for Avenarius Carbolineum, we would say that it is a liquid oil from the very highest boiling and least volatile fractions distilled from coal-tar. It is of course a mixture of oils and 1 The name "Carbolineum" was registered by Richard Avenarius at the Patent Office in Washington, see No. 14,048. The American Telephone & Telegraph Company purchase "Carbolineum" under the specifications included in the Appendix. 2 Correspondence, February 24, 1912, quoted by permission. PRESERVATIVES APPLIED WITHIN WOODS 353 not a single substance, but this mixture is rigidly controlled and the composition of this product held is more constant than any other oily wood preservative, insuring uniformity of composition and certainty of action." PROCESSES USED TO INTRODUCE PRESERVATIVES WITHIN WOODS The process is quite as important as the material. The im- pregnation must be deep and well distributed through the outer parts of the pieces, and the wood must not be injured by the proc- esses used to secure this impregnation and distribution. Within limits, the same process may be used to introduce any preserva- tive through any species of wood, but, in practice, certain proc- esses have become more or less associated with certain preserva- tives. The process may be considered as it includes (1) the preparation, and (2) the impregnation of the wood. Europeans once prepared practically all woods that were to receive preservatives by first steaming them. But, at the pres- ent time, much of the best European practice excludes the application of steam save to woods that are to receive watery solutions. The woods that are to receive creosotes are usually prepared by drying. In the United States, early practices included preparatory steaming, and it is yet thought to be better to steam the imperfectly seasoned woods that are presented in such quantities for treatment in the United States, than to hold them in the yard until they are dry. The second part of the preservative process, that is, the part during which woods prepared by drying or by steaming are brought into contact with the preservative, may be carried out in many ways : woods may be dipped into or soaked in the preserva- tive, or the preservative may be applied with a brush, or may be forced into the wood by pressure applied within a cylinder. Regardless of details, all methods employed to introduce chem- ical compounds within woods may be grouped as they are (1) Superficial Processes, (2) Non-pressure Processes, and (3) Pres- sure Processes. SUPERFICIAL PROCESSES Many attempts have been made to introduce preservatives into woods without the assistance of pressure, and several of these attempts have yielded more or less final and satisfactory results. 354 ORGANIC STRUCTURAL MATERIALS DIPPING, SOAKING, BRUSH APPLICATIONS. These methods are often applied to small pieces such as shingles and fence posts, and sometimes to larger pieces such as telegraph poles; but, in the latter case, they are normally considered where treatment is to be confined to It, Sabin (Author's edition, 1917), Journal Indus- trial and Engineering Chemistry (American Chemical Society) . Assistance was received from the Sherwin-Williams Company, the F. W. DeVoe and C. T. Raynolds Company, the Dixon and the Detroit Graphite Companies, the Heath and Milligan Manufacturing Company, etc. CHAPTER XVI Adhesives: Cattle Glues, Fish Glues. "Glue, Gelatine, Isinglass, Ce- ments, and Pastes," Dawidowsky (Sampson Low, Marston, Searle & Rivington, London, 1884); "Glue and Glue Testing," Samuel Rideal (Scott, Greenwood & Sons, London, 1900); "Glues and Gelatine," Fernbach (Van Nostrand Company, 1907); Files of Scientific American, Woodcraft, etc., etc. Assistance was received from Messrs. Armour & Company, the Ameri- BIBLIOGRAPHY 445 can Glue Company, the Russia Cement Company, the Studebaker Corpora- tion, Schmitt Brothers, The Flint & Homer Company, and other manu- facturers and users of glue. CHAPTER XVII Indiarubber: Its Sources, Properties, and Uses. "Crude Rubber and Compounding Ingredients," Pearson (Indiarubber Publishing Company, New York, 1909); Files of Indiarubber World, Journal of Society of Chemical Industry; "The Culture of the Central American Rubber Tree," Cook (United States Bureau of Plant Industry Bulletin No. 49); "Rubber Cultivation for Porto Rico," Cook (United States Division of Botany, Circular No. 28); "Indiarubber" (Special Consular Reports, United States Government Printing Office, 1892); "Guayule, A Rubber Plant of the Chihuahuan Desert." Lloyd (Carnegie Institution, Bulletin No. 129); "Indiarubber and Gutta Percha," Seeligmann, Torrilhon and Falconnet (Scott, Greenwood & Company, London, 1910); "Rubber," Schidrowitz (Methune & Company, London, 1911) ; " Der Kautschuk und Seine Priifung," Hinrichsen and Memmler (Leipzig, Hirsel 1910); "Synthetic Caoutchouc, A Review Compiled from the Literature," Barrows (The Chemical Engi- neer, September, 1911, p. 355); "Production and Polymerization of Butad- iene, Isoprene and their Homologues," W. H. Perkin, Jr. (Journal Society Chemical Industry, Vol. 31, p. 616, 1912); "Les Produits pour le Fabrica- tion du Caoutchouc Synthetique," Ditmar ("Le Caoutchouc et la Gutta Percha," Paris, Vol. IX, p. 6458, 1912); "Les Caoutchoucs Artificiels," L. Ventou-Duclaux (Dunot and Pinat, Paris, 1912); "Die Synthese des Kautschuks," Ditmar (Theo. Steinkopff, Dresden and Leipzig, 1912); "The Business Aspect of Synthetic Rubber," Hinrichsen (Scientific American, August 3, 1912, p. 99); "Chemistry of the Rubber Industry," Potts (Con- stable and Company, London, 1912); "Natural and Synthetic Rubber," F. M. Perkin (Journal Royal Society Arts, London, Vol. 61, p. 86, 1913); "Review of Pioneer Work on Synthesis of Rubber," Pond (Journal Ameri- can Chemical Society, January, 1914, p. 165); "The Chemistry of Rubber," Porritt (D. Van Nostrand Company, New York, 1915). Assistance was received from the Birmingham Iron Foundry, Mr. Thomas A. Cashman, Dr. Earl F. Farnau of New York University, and others. INDEX PAGE 269 PAGE Algaroba 168 Abies 65, 72 Allardyce Process (Wood Pres- balsamea 72, 73, 169 ervation 371 concolor . 76 Alligatorwood 188 grandis 72, 74 Amber . 385, 386 lowiana 76 Amber, black 386 magnified 72, 75 American Railway Eng. Assn. : nobilis 72, 77 Spec, for Creosote . . 344, 345, 346 taxifolia... 70 American Telephone & Tele- Abietene 60 graph Co. : Abrasion 241, 256 Spec, for Application of Creo- Resistance to 241 sote, 358, 359, 360, 365, Acacia 166 366, 367, 368, 370 False 166 Spec, for Creosote 346, 347 Three-thorned 167 Spec, for Open Tank Process 358, Acer 133 359 dasycarpum 135 Ammonium phosphate (fire re- macrophyllum 137 tardant) .... 282, 283, 284 negundo 138 Ancona Auvergne 141 pseudo-platanus 133, 156 Angiosperms 4, 102, 247 rubrum 136 Animal Life, Woods Destroyed saccharinum 134,135,272 by 225, 300-325, 340 saccharum 40, 133, 134, 246 Anime 386 Adhesives, 159, 206, 208, 337, 403, Annual Deposit (see Annual 404, 405, 406, 407, 408, Rings, Bands or Layers). 409, 410, 411, 412, 413, 414, Annual Rings, Bands or Layers, 5, 6, 415, 416, 417, 418, 419, 420 10, 11, 29, 30, 34, 35, 36, 37, Aesculus 183 46, 102, 260 calif ornica 183, 185 Ant, Black Carpenter 323 flava 185 White 321 glabra 183, 184 Antiseptic Treatment of Wood, 322, hippocastanum 183,184 327,328,329,330,331,335, octandra 183, 185 336, 337, 353, 354, 355, 356, Agathis australis 63 357,358,359,360,361,362, Age, Woods Destroyed by. 266, 267 363, 364, 365, 366, 367, 368, Ailanthus 172 370, 371, 372, 373, 374 Ailanthus glandulosa 172 Antiseptics, Wood, 262, 265, 335, 338, Alburnum 37 339, 340, 341, 342, 343, 344, Alcohol. . . . 381, 387, 424, 425, 426 345, 346, 347, 348, 349, 350, Aleuritesfordii 214, 380 351, 352, 353 447 448 INDEX PAGE Apple 92, 126, 127, 213 American Crab 127 Narrowleaf Crab 127 Oregon Crab .. . 127 Sweet Crab 127 Apple-tree 116, 127 Osage 204 Arborvitse 85, 86, 89, 90 Giant 90 Arbutus 195 menziesii 195, 197 texana 197 xalapensis 197 Arctostaphylos 197 glauca 197 pungens 197 tomentosa. 197 Arundinaria 231 Arundo 231 Asbestos 284, 285, 401 Asbestos Paints 284, 285, 401 Ash, 3, 30, 38, 120, 121, 122, 125, 126, 275 American 121 Black 120,122,124,138 Blue 123, 125,248 Brown 122,124 Cane 121 Green 120, 125,248 Hoop 124 (Mineral) 17, 236, 281 Mountain 126 Oregon 126,248 Prickly 126 Pumpkin 248 Red 122 River 122 Second Growth 120 Stinking 138 Sugar 138 Swamp 124,125 Water 124,125,138 White 120, 121, 125, 248, 273 Yellow 126 Aspen 169 Large American 172 Largetooth 172, 248 Quaking 172 Associated Compounds 26, 235 PAGE Attalea excelsa 426 Attempts to Prevent Wood from Burning 282 Automatic Sprinklers, 289, 295, 297, 298 Avenarius Carbolineum, 352, 388, 389 B Bacteria 13, 42, 268, 269 Balluck 218 Balm 174 Balm of Gilead 73, 169, 174 Balsa 214,246 Balsam, 68, 73, 76, 169, 174, 275 Canada 72, 73 He 66 Poplar 169, 174 White 76 Balsam-tree 76 Bamboo, 4, 7, 165, 224, 225, 230, 232 Bambusa 230, 231 vulgaris 232 Bands, Rings or Layers, Annual, 5, 6, 10, 11,29,30,34,35,36,102 Banded Trunks and Woods, 5, 6, 9, 29, 30, 34, 43, 44, 102, 169, 224 Barium Sulphate (Pigment) 382, 383 Bark 30,38,39,176,224 Fungous Diseases of 272 Green 38 Inner or Fibrous 38 Barnacles 314 Bass 170 Basswood. 169, 170, 176, 248, 275 Common 176 White 176 Yellow 176 Bast 38, 176 Fibers 38, 176 Hard 38 Soft 38 Bastard Cut 40 Bay, Rose 195 Bay-tree 196 California 196 Bayonet, Spanish 228 Bay wood 208 INDEX 449 PAGE Bead Tree 214 Beantree 181 Bebeeru 201 Bee, Carpenter 323 Beech, 19, 30, 152, 153, 248, 275, 375 Blue 154,248 European 152 North American 152 Red 153 Ridge 153 Water 154,157 White 153 Beetles 56, 64, 318, 319, 320 Attacks by 318,319 Colorado Potato 318 Beetree 170,176 Benzine 381 Benzol 381 Bethell Process (Wood Preser- vation) % . 363, 370, 371 Betula 159 alba 159 lenta 159,164,202 lutea 159, 163 nigra 162 papyrifera 159, 160, 161 populifolia 160 Biberine 200 Bibiru 201 Big-bud 147 Bigtree 77, 101 Birch, 43, 155, 159, 162, 248, 275, 375 Black 162,164 Blue 162 Canoe 161 Cherry 164 European 159 Gray 160, 163 Large White 161 Mahogany 164 Oldfield 160 Paper 159, 160, 161 Poplar-leaved 160 Poverty 160 Red 162 River 162, 164 Silver 161,163 Small White.. . 160 PAGE Birch, Swamp 163 Sweet 159,164,202 Water 162 White 160,161 Yellow 159,163 Bismarck Brown, Pigment 388 Bitternut 146 Black Carpenter Ant 323 Blackjack 248 Black Scale 214 Blackwood 215 Bled Woods 46, 47 Blisted 188 Blister Rust 48, 50 Bloodwood 215 Blowdown (see Windfall} . . 65, 121 Bluing in Wood. ... 42, 56, 251, 268 Boards 40 Bodark 204 Bodock 204 Boiling Process (Wood Preser- vation) 372 Boisd'Arc 202,204 Bois puant 157, 180 Boleau 161 Bookworms 320 Bordered Pits 18, 20 Borers, Stone 314 Wood (see Marine and Land Woodborers) . Boring Gribble, 310, 311, 312, 313 Bot in Wood (see Decay] ... 42, 268 Botanical and Common Names . 2 Boucherie Process (Wood Pres- ervation) 372, 373 Bow-wood 204 Box 62, 191,216 Dogwood False 193 Boxelder 34,133,138 Boxwood 191, 193, 197 American 191 New England 193 Branches, System of 8, 9 Brashwood. 42, 267 Broadleaf Trees and Woods, 4, 5, 6, 29, 43, 44, 102, 103, 169, 333 Brown, Bismarck (Pigment) . . . 388 Brush Method (Wood Preserva- tion) . . 354 450 INDEX PAGE Buckeye 183, 185 Big 185 California 185 Fetid 184 Large 185 Ohio 184 Stinking 184 Sweet 185 Yellow 185,248 Bullnut 147 Burl 124, 139 Burnett Process (Wood Preser- vation) 368, 369, 371 Burning Woods 281, 236 Burr (see Burl). Butadiene 435 Butterflies and Moths 320 Summary 321 Butternut, 139, 140, 141, 143, 210, 248 Buttonball 156, 157, 158 Buttonball-tree 157, 158 Button wood -. . . 157, 158 Buxus 191 sempervirens 191 Cabbage Tree 227 Cajeput 196 Calamus rudentum 232 Calathaea 426 Calcium Carbonate in Wood. . 22 Calcium in Wood 22 Calcium Oxalate in Wood 22 Calico Bush 195 Callitris quadrivalvis 387 i Cambium, 10, 11, 22, 34, 39, 224, 228 j Cork 39 Layer 10, 11 Camphor Tree 198 Camponotus herculeanus penn- sylvanicus 323 Canada Balsam 72, 73 Canal, Resin 23, 25, 26, 28 Canals, Primary 26 Secondary 26 Canker in Wood 42 Canoewood.. . 171 PAGE Caoutchouc (see Indiarubber}, 423, 432 Carbolic Acid 342 Carbolineum 352, 388, 389 Avenarius 352, 388, 389 Carbon 9, 234, 236, 281, 288 Dioxide 9, 288 in Wood 9, 234,236, 288 Pigment 384 Tetrachloride 288 Card Process (Wood Preser- vation) 371 Car Painting 400 Pullman Company Specifica- tion 400 Care of Structures 298, 299 Carpenter Ant 32% Bee 323 Worm 321 Carpinus 154 caroliniana 154 Carya 145,146,147, 148 alba 145,246 olivceformis 148 porcina 146 tomentosa 147 Casein 389 Cassia Bark 198 Castanea 149,273 dentata 108, 150, 151 pumila 149, 151 vesca var. americana 150 vulgaris 149 vulgaris var. americana 150 Castanopsis chrysophylla . . . 149, 151 Castilla alba 427 elastica 213, 427 Catalpa, 30, 179, 180, 181, 207, 246,. 273, 275 Common 179 Hardy 179, 180, 181, 248 Western 180 Catalpa 179 bignonioides 181 catalpa 179, 181 speciosa 179, 180, 181, 246 Catawba 181 Tree 181 Caterpillars 320 INDEX 451 PAGE Cattle Glues, Application of 159, 408 Manufacture of 404, 405 Properties of, 405, 406, 407, 408, 409, 410, 411, 417, 418, 419, 420 Protection of 410 Sources of. 404 Testing of 417, 418, 419, 420 Cedar, 3, 43, 85, 87, 88, 89, 90, 92, 95, 207, 209, 386 Atlantic Red 89 Australian Red 209 Bastard 94,214 California Post 94 California White 94 Canoe 86, 90 Cuban 209 Eastern 85 Giant 72,90 Giant Red 90 Incense 86, 87, 94, 97, 272 Lebanon 85 Mexican 209 Northern White 275 Oil 380 Oregon 92 Pacific Red 90 Pencil 87 Port Orford 86,92 Post 91,94 Red, 85, 86, 87, 90, 94, 97, 209 Southern 85 Southern Red 85 White 275 Spanish 86,207,209 Swamp 91 Toon . 209 Western 85,88,90 Western Red 88, 275 White, 85, 86, 89, 91, 92, 94, 214 Yellow 86,88,93 Cedrela 206,207 australis 209 odorata 207, 209 Blanco 209 toona Roxburgh 209 Cedrus . . 85 PAGE Cells, Companion 38 Epithelium 25, 26 Parenchyma 38, 39 Pith-ray 19 Wood (see Wood Elements). Cell Structures (see Wood Ele- ments). Cellular Structure of Wood, 17, 32 Cellulose. . 9, 17, 234, 235, 270, 281 Celluloid 434 Celtis occidentalis 152 Cendre 87 Census Experiments upon Woods 33,257,261 Central Office System 299 Ceraostomella pilifera (fungus) . . 272 Cercocarpus ledifolius 207 parvifolius 207 parvifolius betuloides 207 Chamcecyparis 85, 95 lawsoniana 86, 92 nootkatensis 93 nutkcensis 93 nutkatensis 86 thyoides 86, 91 Charring (Wood Preservation) 373, 401 Checks in Wood (see Defects in Wood). Chelura 313,314 Excavations 313 Field of Attack 314 Method of Attack 313 Physiology of 313 Size of Borings 314 Chelura terebrans 313 Chemical, Composition of India-rubber, 431, 432, 433, 434 Composition of Wood, 9, 13, 26, 37, 38, 39, 233, 234, 235, 237, 281 Compounds Applied within Woods (See Preserva- tion of Wood). Elements in Wood, 13, 26, 234, 281 Fire Extinguishers 289, 290 Chemicals, Processes to Introduce within Woods 335, 353-375 452 INDEX PAGE Chene etoile 109 Vert 116 Cherry 30,159,202 Black 205,248 Choke 205 Red 248 Rum 205 Whiskey 205 Wild 202,205 Wild Black 202,205 Chestnut, 30, 108, 149, 150, 151, 273, 275 Blight 149, 150, 2Y2, 273 Evergreen 149 North American 149 China 214 China-berry 214 China Wood Oil 214, 380 China Wood Oil Tree 214, 380 Chinquapin 149, 151 California 149 Common 149 Goldenleaf 149 Western 149 Chlorophyll 9, 13, 38, 235, 268 Chloroxylon 215 swietenia 215 Chrome green Pigment 382 yellow Pigment 382 Cigar Tree 180, 181 Indian 181 Cinnamomum 198 camphora 198 cassia 198 zeylanicum 198 Cinnamon Tree 198 Citronella 380 Citrus aurantium 127 trifoliata 127 Cladrastis tinctoria 126 Clam, Long 301 Razor 301 Softshelled 301 Classifications, Fundamental, 1, 4, 5, 6 Coach Painting 400 Coatings for Woods . 377, 400 Coefficient of Elasticity, 33, 238, 239, 261 PAGE Coefficient of Rupture. .33, 239, 261 Coffee 152 Coffeebean 152 Coffeebean-tree . 152 Coffeenut 152 Coleoptera 319 Colophony. 388 Color Defined 251 Color of Wood 251 Coloring Matter in Wood ... 17, 251 Common and Botanical Names . 2 Companion Cells 38 Comparison, Woods with Stones and Metals xvii, 1, 2, 255 Compounds Associated with Woods 26 Associated with Wood-ele- ments 17,26 Inorganic 26, 236 Organic 26, 234 Conductivity (Defined) 248 of Wood 237,248 Cone-bearers (see Conifers). Cones (see Conifers) 44 Confederate Pintree 167 Conflagrations Influenced by Wood 277,280,294 Coniferae (see Conifers). Coniferous Trees (see Conifers) Woods (see Conifers). Conifers, 4, 5, 6, 20, 30, 34, 43, 44, 102 Conservation xvii Consumption of Wood 1 Convolvulus scoparius 214 Copal 386 Manila 386 Sierra Leone 386 South American 386 Zanzibar 386 Copper Sulphate, Effect upon Wood . 337,338, 374 Cork 246 Cork Cambium 39 Corkwood, Missouri 246 Corky Layer 39 Cornel 193 Flowering 193 Cornus.. . 191 INDEX 453 PAGE Cornus, florida 191, 193 Cortex 38,39,224 Cossus ligniperda 321 Cotonier 157 Cotton Tree 173 Cottonwood, 30, 169, 173, 174, 275, 375 Balm 174 Balsam 174 Big 173 Black 175,248 Broadleaved 173 Yellow 173 Cotton Wool 234 Cotyledon 4, 9 Cracks in Wood, (see Defects in Wood) 40 Creoaire Process (Wood Preser- vation) 374 Creo-resinate Process (Wood Preservation 372 Creosote, 281, 317, 318, 322, 337, 339, 340, 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, 351, 375, 376 Analysis of 344, 348, 349, 350 Constituents of 341, 342 Distribution of 351 Effects upon Wood 340, 341 Mixed 343 Required Quantities of 351 Sources of 341 Specifications, 344, 345, 346, 347, 348, 349, 350 Cresylic Acid 342 Cross-surfaces of Wood 39 Croton lacciferus 387 Crude Sap 11,235 Cryptogams 269 Cucumber 175 Cucumber-tree 169, 171, 175 Cupressus 95 macrocarpa 95 Cup Shakes in Wood (see De- fects in Wood) 41 Cut, Bastard 40 Quartered 39, 40, 334 Tangential 24,40 Cycadaceoe 4 PAGE Cylinders, Use of 360 Cynoxylonfloridum 193 Cypress, 3, 85, 86, 87, 94, 95, 97, 246, 272, 275 Alaska 93 Alaska Ground 93 American ... 96 Bald. 96,97 Black 96, 97 Common 95 Deciduous 97 Evergreen 95 Lawson 92 Monterey 95 Nootka 93 Nootka Sound 93 Red 96,97 Sitka 93 Southern 97 Swamp 86, 97 White.. 96,97 Yellow 93,96 Cyst 25 D Doedalea vorax (fungus) . 96, 97, 272 Dagger, Spanish 228 Dalbergia nigra 214 sissoo 213 Dammara 62, 387 australis 63, 221, 387 orientalis 387 Date, Plum 203 Wild 226 Deal 59 White 64 Decay in Wood, 42, 96, 265, 266, 268, 269, 270, 271, 272, 273, 274, 275, 276 Deciduous Trees and Woods, 4, 6, 43, 103 Defects in Woods . . 40, 41, 42, 333 Deformation in Woods 237 Dendrocalamus 231 Dendroctonus piceaperda 64 ponderosa 56 Density of Woods, 237, 244, 246, 247 Density Rule 46, 260 Density Test 46, 245, 260 454 INDEX PAGE Deposit, Annual, (see Annual Ring Bands or Layers). Springwood 30, 31, 35, 36 Summer-wood. . . 30, 31, 35, 36 Destruction Woods, by Age, 266, 267 by Ants 321, 323, 324 by Bees 323 by Beetles 319, 320 by Chelura 313 by Decay (see Decay in Woods'). by Exposure 267 by Fire, 277, 280, 281, 282, 283, 284, 285, 286 by Limnoria. . . 310, 311, 312, 313 b y Miscellaneous Wood- borers 314 by Moths and Butterflies, 320, 321 by Shipworms, 225, 300, 307, 308, 309, 310, 315, 316, 317, 318 by Termites 321, 322, 323 by Use 267 Destructive Temperatures 293 Diaporthe parasitica (fungus), 149, 150, 272, 273 Dicotyledons, 4, 5, 6, 30, 34, 43, 102, 169 Dicotyledonous Trees and Woods (see Dicotyledons') . Diffuse-porous Woods 30, 31 Diospyros 202 chloroxylon 202 ebenaster 202 ebenum 202, 246 mespiliformis 202 virginiana 202,203 Dipping Method (Wood Preser- vation) 354 Direct Physiological Properties . 233 Disease, Bark. . . . 149, 150, 272, 273 Black Scale 214 Blister Rust 48,50 Chestnut Bark, 149, 150, 272, 273 Foliage... 272 Roots 272 Trunks and Trees. . 268, 271, 272 Woods (see Decay in Woods). Distortion of Wood 264 Distribution of Species 16 PAGE Dogwood 191, 193 Flowering 191, 193, 248 Poison : 193 Doors, Fireproof, 284, 285, 295, 296, 402 Dote in Wood 42, 268 Douglas Fir 25, 246 Douglas Tree 71 Dragon-tree 224 Driers 379,380 Japan 380 Dry Rot in Wood 42, 268, 274 Duct 21 Resin (Wood Element), 23, 25, 26, 28 Durability of Wood, 266, 274, 275, 276 Duramen 37 E Ebenaceoe 202 Ebonite 434 Ebony 202,246 Green 202 Madagascar 202 Mexican 202 Edge-grained Woods 40 Edging 40 Elaborated Sap 11, 37, 235 Elasticity (Denned) 240 Modulus of 33, 238, 239, 261 of Wood 18,33,237,240 Electrical Conductivity of Wood 248 Elements, Chemical, in Wood, 13, 17, 26, 234, 281 Wood (Cell-Structures), 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,29,30,31,32,34,38,39, 44, 102, 224, 225, 237, 247, 248, 249, 252 Elm, 3, 43, 92, 102, 128, 129, 132, 248 American 129 Cliff 130 Cork 130,132 Corky 132 False 152 Hickory 130 Moose.. . 131 INDEX 455 PAGE Elm, Mountain 132 Red 131,132 Redwooded 131 Rock 130, 131 Slippery 129 Small-leaved 132 Wahoo 132 Water 129 White 129 Wing 132 Winged 132 Witch 132 Empty Cell Processes (Wood Preservation), 351, 362, 363, 369 Enamelled Paints 378, 398 Encena 117 Endogen 6, 7, 224 Endothia gyrosa (fungus), 149, 150, 272, 273 Endothia gyrosa var. parasitica (fungus), 149, 150, 272, 273 Entandrophragma candollei 206 Enzyme 270 Epidermis 39 Epithelium Cells 25 Eppinger & Russell Specification, 364 Erosion (Soil) 14, 15 Eucalypt, Giant 223 Eucalyptus, 26, 216, 217, 218, 219, 220, 221, 222, 223, 248 Blue Gum 248 Eucalyptus 216 amygdalina 216, 223 colossea 221 corynocalyx 223 diversicolor 216, 221 globulus 216,217,218 gomphocephala 216, 222 leucoxylon 246 macrorrhyncha 223 marginata 216, 220 resinifera 223 rostrata 216, 219 viminalis 223 Euphorbiacece 214 Evergreen Trees and Woods (see also Coniferous Trees and Woods) ... 4 6, 43, 44, 81 PAGE Examinations, Microscopical, 30, 31, 247 Exogen 5, 6 Experiments (see Tests). Physical, Woods, 33, 243, 251, 252, 255, 256, 257, 258, 259, 261 Railroad Spikes 242 Exposure, Woods Destroyed by, 266, 267, 268, 273, 274, 275, 276 External Preservative Treat- ment of Woods, 266, 273, 274, 282, 284, 285, 286, 315, 316, 317, 324, 334, 377 to 401, 410 Fagus 152 americana 19, 152, 153 atropunicea 153 ferruginea 153 grandifolia 153 sylvatica 152 Families (Defined) 3 Fastenings for Woods 237, 242 Feather-cone 77 Ferns 269 Ferrell Process (Wood Preser- vation) 374 Fever Tree 218 Fibers, Wood, 18, 19, 20, 22, 25, 30, 102, 247 Wood-parenchyma. ... 19, 22, 24 Fibrous Bark 38 Ficus elastica 213, 427 sycomorus 156 Fig Tree 156 Figures Relating to Physical Properties of Woods, 33, 257, 258, 259 Fillers, Wood 384, 385, 396, 397 Fir 3,43,64,65,70,72 Balm of Gilead 73 Balsam 72,73,76 California Red 75 California White 76 Colorado White 76 Common Balsam 73 Concolor White 76 Dantzic . . 59 456 INDEX PAGE Fir, Douglas 70, 71, 246, 275 Golden 75 Great Silver 74 Lowland 74 Magnificent 75 Memel 59 Noble 72,77 Noble Red 77 Noble Silver 77 Northern 59 Oregon White 74 Prince Albert's 79 Red 70,71,72,75,77,78 Red-bark 75 Rigi 59 Scots 59 Scottish 59 Silver 72,74,76 Stettin 59 Swedish 59 Tree 73 Western Hemlock 79 Western White 74 White 64,74,76 Yellow 70,71,74 Fire, Apparatus, 280, 287, 288, 289, 290, 291, 292 Burning Woods 236, 281 Coatings 284, 285, 286 Application 284, 286 Extinguishers, Chemical. 289, 290 Sprinklers 297, 298 Extinguishing Materials 288 Losses 278,279,280 Indirect 278 Pails 290,291,292 Protection 280,282,284,292 Retardants 282, 283 Risks 15 Signals 298 To Extinguish 280, 287 Underwriters' Specifications- 297 Woods Destroyed by 277 Fireproof Buildings 294 Doors 284, 285, 295, 296, 402 Materials 294, 295 Paints 284,285,402 Shutters 285,295,296 Windows.. . 296 PAGE Fireproof ed Woods . . . 282, 286, 402 Fires in Buildings, Prevention . . 294 First-growth Woods 120 Fish Glues, Application of 414 Manufacture of 411, 412 Properties of 413 Sources of 411 Fistulse 21 Flax 38, 379 Flax Fiber (see Cellulose) 234 Flea (Wood flea) 310 Floods 14 Foliage, Fungous Diseases of ... 272 Forest Service, National, Speci- fication for Creosote . . 348 Forest Top-soil 13 Forests 13, 14, 15 Influence on Erosion 14, 15 on Rainfall 14, 15 on Streamflow 14, 15 Value of 13 Forestry 15 Formalin 408, 410 Forms of Trees 12, 13 Fossil Resin 62, 386, 387 Fraxinus 120 americana 120, 121 lanceolata 120, 125 nigra 120, 124 oregona 126 pennsylvanica 122, 125 pennsylvanica var. lanceolata. . 125 pubescens 122 quadrangulata 123 sambucifolia 124 viridis 125 Fresh Water Wood-borers 314 Frost Shakes in Wood 41, 333 Full Cell Processes, Wood Pres- ervation, 351, 361, 362, 363, 368, 369, 371 Fundamental Classifications, 1, 4, 5, 6 Fungi, 13, 42, 64, 96, 149, 150, 262, , 263, 268, 269 Bread 269 Fungous Diseases 267, 273 Bark 149, 150, 272, 273 Contagion 276 Foliage.... 272 INDEX 457 PAGE Fungous Roots 272 Structural Woods 273, 274, 275, 276 Trees and Woods. . . 268, 271, 273 Trees.. . 271 Gallic Acid 104,119 Gelatine 403, 404, 410, 411 Genereso 210 Genus 3, 32 Gleditsia 165 triacanthos 165, 167 Glues, 159, 206, 208, 337, 389, 403, 404, 405, 406, 407, 408, 409, 410,411, 412,413,414,415, 416, 417, 418, 419, 420 Action of 410 Appearance of 408, 413 Application of . .159, 337, 408, 414 Cattle, 403, 404, 405, 406, 407, 408, 413, 417, 418, 419, 420 Failure of 407 Fish. 159, 337, 403, 411, 412, 413, 414, 420 Liquid (see Fish Glues) . Specifications 408, 409, 417 Tests 417,418,419,420 Uses of 414 Woods, Prepared for 408, 414 Gnetacece 4 Gopher Plum 189 Wood 95,126 Grain of Wood 26, 27, 28, 39 Graphite 384, 434 Greenheart 200, 201, 246, 275 Black 201 Gray 201 Yellow... 201 Gribble 310, 311, 312, 313 Boring 310, 311, 312, 313 Growth, Length 9, 12 Thickness 9 Tree 9,12,32 Guadua 231 Guajac 191 Guajacum 191, 194 arboreum 194 officinale 191, 194 PAGE Guajacum, sanctum. . . 191, 194, 246 Guayule (Indiarubber), 213, 426, 427 Gum (Excretions), 25, 37, 62, 165, 234,235,385 Gum (Trees), 186, 188, 190, 216, 218, 219, 220, 221, 222, 223 Gum, Black.. . . 19, 76, 187, 190, 248 Blue 216, 217, 218, 248 California Red 186 Cotton 21, 189 Mahogany 220 Manna 223 Red, 102, 141, 186, 187, 188, 216, 219, 223, 248 Sour 187, 189, 190 Star-leaved 188 Sugar 223 Sweet 31, 186, 188 Tree 186, 188,216 Tree, Yellow 190 Tupelo 186, 189, 190 Water 186,248 White 221,222 Gumbo file 199 Gymnocladus dioicus 152 Gymnosperms 4 H Hackberry 152 Hackmatack 83,84 Hard Bast 38 Hardhack 155 Hardness (Defined) 241 Hardness of Wood, 18, 237, 241, 245 Hardshell 146 Hardwood Mfrs.' Asso. Specif. 42 Trees and Woods 4, 6, 43, 102 Hardwoods 4, 6, 43, 102 Hasselmann Process (Wood Preservation) 374 Hayford Process (Wood Preser- vation) 364 ; Hazel 186, 188 ! Heart Shakes in Wood (see De- fects in Wood) 41 Heartwood 25, 34, 37, 38, 47, 246, 247, 262, 351 Heat, Conductivity of Wood . . 248 Effect upon Wood, 266, 329, 361 458 INDEX PAGE Hedge 204 Hedge-plant 204 Hemlock, 3, 43, 44, 65, 78, 79, 80, 275, 375 Alpine 78 Bastard 70 Black 79 Carolina 80 Eastern 78 Southern 80 Spruce 78, 80 True Black 78 Western 78,79 Hevea brasiliensis 213, 427 Hevea rubber, 213, 422, 424, 425, 427 Heyderia decurrens 94 Hickory, 3, 4, 30, 43, 92, 140, 144, 145, 147, 246 Bitternut 248 Black 146, 147 Broom 146 Brown 146 Common 147 Hard Bark 147 Mocker Nut . . . 147 Nut 147 Nutmeg 248 Pecan 148 Pignut 146 Red 146,147 Scalybark 145 Second-growth 120, 144 Shagbark 145,248 Shellbark 145,248 Switchbud 146 Upland.. 145 White 92, 145, 146, 147 Whiteheart 147 Hicoria 144 alba 147 glabra 146 ovata 145 pecan 148 HogNut 147 Holly 30, 191, 192, 248 American 192 European 191 White.. . 192 PAGE Honey 167 Pod 168 Shucks 167 Horizontal Wood-structure .... 26 Hornbeam 154, 155 Hop 155 Horse Chestnut 183 American 183 California 185 Humus 13, 14 Husk 38 Hygroscopicity 251 Identification of Trees and Woods 17,27, 28, 29, 30, 31, 32, 36 Idioblasts 22 Ilex 191 aquifolium 191 opaca 191, 192 Impact Testing Machine 245 Importance of Wood 1 Indian Bean 180, 181 Indian Cigar Tree 811 Indiarubber, 213, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 432, 433, 434, 435 Chemical Composition of, 431, 432, 433, 434 Classification Due to Form . . 429 Crude 427,428,433 Fresh 427,428 Grades of 426 Guayule 213,426,427 Latex, 421, 422, 423, 424, 425, 426 Para 213, 423,424,427 Physical Properties of 431 Plantation 428 Preparation of 429, 430, 431 Properties of . . . 431, 432, 433, 434 Pure 423,432 Purification of 429, 430, 431 Reclaimed 427,428 Refined 427,428 Shrub 213,427 Sources of 213,426,427 Synthetic 435 INDEX 459 PAGE Indiarubber, Uses of 434 Vulcanized 430, 431, 433, 434 Wild 428 Indiarubber Tree 213, 427 Assam 213,427 Central American 427 Hevea .... 213, 422, 424, 425, 427 Indiarubber Vine 427 Ink, Printer's 380 Inlaid Work 191, 192, 416, 417 Inorganic Compounds in Wood, 26, 236 Inorganic and Organic Mate- rials, Comparison, xvii, xviii, 233, 234, 236, 237, 255, 281 Insects, 318 Associated with Fungi 271 Hosts ,of Micro-organisms. . . 271 Woodborers, 318, 319, 320, 321, 322, 323, 324, 325 Woods Protected from . '. 324, 325 Inside Growth 6, 7, 9, 224 Internal Preservative treat- ment of Woods, 266, 282, 283, 284, 317, 322, 334, 335 to 376 Introduction xvii Ironbark 216, 223, 246 Iron Oxide Pigments 383 Ironwood 154, 155, 168, 194 Isinglass 411 Isoprene 435 Isoptera 321 Japan 380, 381 Jarrah 216,220 Jenicero 210 Joints, Wood and Glue, 410, 411, 414 Joshua-tree 228, 229 Juglans 139 australis 141 calif arnica 140 cinerea 139, 140, 141, 143 insularis 141 nigra 19, 21, 22, 23, 139, 142 regia 139, 141,209 rupestris 140 PAGE Juniper 83, 85, 87, 88, 91, 94 Bush 87 California 88 Red 87 Western 88 Juniperus 85 barbadensis 85, 86 calif ornica 88 occidentalis 88 scopulorum 85, 86 virginiana 85, 86, 87 K Kalmia latifolia 195 Kalsomine 389 Karri 216,220,221 Kauri Pine 62, 63, 387 Kauri (Resin) . 62, 63, 385, 387, 388 (Tree) 62, 63, 387 Khaya 206 grandifolia . 206 senegalensis 206 Kiln Drying of Wood (Wood Preservation) 327, 328 329, 330, 331, 332, 333, 334 Kilns, Forms of 330, 331, 332 Knots (see Defects), 41, 42, 43, 45, 333 Encased 42 Large 43 Loose 42 Pin 43 Pith 42 Rotten 43 Round 43 Sound 42 Spike 43 Standard 43 Kyan Method (Wood Pre- servation) 355 Lamella, Middle (Wood Ele- ments) 18 Land Life, W'oods Destroyed by, 266, 309, 310, 313, 318, 320, 322 460 INDEX PAGE Land and Marine Woodborers, 225, 300, 301, 302, 303, 304, 305, 306,307,308,309,310,311, 312, 313, 314, 315, 316, 317, 318, 320, 321, 322, 323, 324, 325 Landolphia dawei 427 heudelotii 427 kirkii 427 owariensis 427 thollonii 427 Larch 70, 77, 81, 82, 83, 84, 96 American 83 Black 83 Eastern 81 European 81,82 Great Western 84 Red 83 Red American 84 Western 81, 84 Larix 81 americana 81, 83, 84 europcea 81, 82 laricina 83 occidentalis 81, 84 Latex (Indiarubber), 421, 422, 423, 424, 425, 426 Laurel 195, 196, 197 Big 195 California 195, 196 Great 193, 195 Madrona 195,197 Mountain 195, 196 Laurelwood 197 Layers, Cambium (see also Cam- bium} 10, 11 Bands, or Rings, Annual, 5, 6, 10, 11, 29, 30, 34, 35, 36, 39, 46, 102, 260 Corky 39 Concentric 5 Lead, Oxide, Pigment 380 Red, Pigment 383 White, Pigment 378, 382 Leaf -system of Tree 9 Leaves 9 Leguminosce 165 Leitneria floridana 246 Length-growth of Trees 9, 12 PAGE Lepas antifera 314 Lepidoptera (Insects) 320 Lepisima saccharina (Beetle) . . . 320 Leverwood 155 Libocedrus 85 decurrens 86, 94 Lichens 269 Life, Animal, Woods Destroyed by 266,300 Light, Influence of 12, 13 Lignin 11, 17, 234, 235, 270, 281 Lignumvitae, 26, 191, 194, 201, 246, 275 Lime 170 Ogeechee 189 Lime Tree, Black 176 Smooth-leaved 176 Limetree 170, 176, 189 Wild 189 Limnoria. . . 310, 311, 312, 313, 340 Effects of Temperature and Water 311 Excavations 311 Field of Attack 313 Form and Physiology of 310 Methods of Attack 311 Rapidity of Attack 312 Size of Borings 311 Woods Subject to Attack. ... 313 Limnoria lignorum 310 Lin, Black 175 Lind 170 White 176 Linden 170,176 American 176 Linn 176 Linoxyn 379,383 Linseed Oil 379, 380, 383, 389 Liquidambar 186, 188 Liquidambar 186 styraciflua 141, 186, 188 Liriodendron 169 tulipifera 169, 171, 175 Litharge 383,434 Live Oak 105, 116, 118, 246 Locality of Species 16 Locust 165,166,167,246 Black, 30, 165, 166, 167, 248, 275, 375 INDEX 461 PAGE Locust, Green 166 Honey. . . . 165, 166, 167, 168, 248 Honey Shucks 167 Pea-flower 166 Post 166 Red 166 Sweet. 167 Thorn 167 Thorny 167 White 166 Yellow 166 London, Brighton & South Coast Railway Spec. (Creosote) 364 Long Clam 301 Longshucks 55 Lowry Process (Wood Preser- vation) 370, 371 j Lumber (defined) 17 Rolled 41 Lumen 18, 19 Lysiloma sabicu 213 M Madura aurantiaca 204 Madeira 208 Madrona.... 195, 197 Mexican 197 Madrone 197 Madrone-tree 197 Madrove 197 Magnolia 169, 175, 195, 248 Mountain 175 Magnolia 169, 195 acuminata 169, 175 fcetida 195 Mahogany, 152, 159, 202, 206, 208, 216, 220, 246, 396, 416 African 206,212 | American 163 Birchleaf 207 Central American 206 East Indian 206 Frontera 206, 208 Honduras 206, 208 ! Mexican 208 Mountain 164, 207 PAGE Mahogany, Philippine 206 Primavera 207 Red 206,223 Spanish 206,208 Valley 207 White 143,207,210 Maintenance of Structures 298 Mammoth Tree 101 Manzanita 197 Maple, 3, 4, 30, 43, 102, 133, 137, 156, 246, 248, 375 Ash-leaved 138 Birdseye 40, 133 Black 134 Blister 133 Broad-leaved 137 Curly 40, 133 Cut-leaved 138 European 133 Hard 40,133,134 Negundo 138 Oregon 137 Red 136 Red River 138 River.. 135 Rock 134 Silver 129, 135 Soft 133,135,136,272 Sugar 133,134 Swamp 135, 136 Three-leaved 138 Water 135, 136 White 135, 136, 137 Marine and Land Wood-borers, 225, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 320, 321, 322, 323, 324, 325, 340 Marine Life, Woods Destroyed by, 225, 266, 309, 310, 315, 322 Woods Protected from, 315, 316, 317, 318, 320, 322, 323, 324, 325 Marsonia ochroleuca (fungus) . . 272 Mastic 388 Materials, Associated with Wood, 235 462 INDEX PAGE Materials, Chemical Composi- tion of Wood, 9, 13, 26, 37, 38, 39, 233, 234, 235, 237, 281 Fireproofing 294 Fire retardants 282, 283 Inorganic, 17, 233, 234, 236, 237, 255, 281 Organic, 9, 11, 19, 37, 234, 235, 236 Physical Properties of, 33, ' 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 255, 256, 257, 258, 259, 260, 261 Physiological Properties of. . .233 Wood Preservatives, 337, 338, 339, 340, 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, 351, 352 Measurements, Physical Proper- ties .... 251, 252, 255, 256 Medulla , 37 Medullary Ray 24, 40 Meliacea 207 Melia azedarach 214 Mercury Bichloride 337, 338 Merisier 163 Rouge 163 Mesquite 165, 168, 275 Screwpod 165 Metals xvii, 277, 295 and Woods, Comparison xvii, 2, 255 Metal Coatings, 273, 286, 295, 316, 400 Micro-organisms, Soil 275 Microscopes 31 Microscopic Examinations, 30, 31, 32, 247 Microtomes 31, 32 Middle Lamella (Wood Ele- ment) 18 Mildew (see also Decay) 42 In Foliage 272 In Wood 42,268 Mineral Matter in Wood, 17, 236, 281 Missouri Corkwood 246 Mock Orange 204 Mocker Nut.. . 147,248 PAGE Moduli and Weights of Woods, 33, 238, 239, 261 Moisture in Woods, 17, 26, 234, 237, 245, 246, 252, 258, 262, 263, 264, 265, 329 Mollusk (see also Shipworm), 225, 330 Monocotyledons, 4, 5, 6, 7, 224, 230 Morus 182 alba 182 celtidifolia 182 rubra 182 Mosses 269 Moths and Butterflies 320, 321 Goat 321 Gypsy 320 Mould in Wood 268 Movement, Sap 11 Mucilage (Defined) 62 Mulberry 182 Black 182 Mexican 182 Red 182,248,275 Tree, Virginia 182 White 182 Murier Sauvage 182 Mya arenaria 301 Myrtle-tree 196 N Nails, Teredo 316 Worm 316 Names, Common and Botanical, 2, 47 Naphthalene 341, 342 National Forest Serv. Exper., 33, 258, 259, 260, 261 Natural Seasoning 276, 327 Naval Stores 15, 47, 53, 58 Nectandra 200 rodioei 200,201,246 Nectria cinndbarina (fungus) . . . 269 Needleleaf Trees and Woods, 4, 6, 29, 36, 43, 44 Negundo aceroides 138 Neowashingtonia filamentosa. . . 226 Nettle-tree 152 Nogal 141 INDEX 463 PAGE Nomenclature, Trees and Woods 2,47 Non-banded Trunks and Woods 6,9,29,224 Non-coniferous Trees and Woods 6,43,102,103 Non-durable Woods 275 Non-porous Woods 30, 31 Non-pressure Processes (Wood Preservation) 353, 355 Non-seedbearing Plants 269 Noyer 141 Nyssa 186 aquatica 21, 186, 189 multiflora 190 ogeche 189 sylvatica 19, 187, 190 o Oak, 3, 4, 5, 21, 24, 30, 43, 102, 104, 151, 152, 333, 334 African 212 Basket 107 Black 105,112,115 BlackLive 118 Box 109 Box White 109 Brash 109 British 119 Bur 105,110,248 California Live 105, 117 California Post Ill California White Ill Canyon 118 Canyon Live 118 Chestnut 105, 108, 119 Coast Live 117 Common 119 Cork 246 Cow 105,107,248 Dantzic 119 Durmast 119 Dyer's 115 English 104, 119 Evergreen 117 Garry 248 Golden-cup 118 Highland Live 118 PAGE Oak, Indian 212 Iron 109,118 Live 105,116,118,246 Maul 118 Mossycup 110 Mossycup White 110 Mountain 108 Oregon White Ill Overcup 109, 110, 248 Overcup White 110 Pacific Post 105, 111 Pin 32, 105, 113 Post 105,109,248 Quarter-Sawn 24, 39, 40, 334 Quercitron 115 Red, 20, 32, 105, 112, 114, 119, 150, 246, 275, 375 Rigi 119 Rock 108 Rock Chestnut 108 Scrub v. 110 Spanish 105,112,114 Spotted 115 Stave 106 Swamp Ill, 113,375 Swamp Chestnut 107, 108 Swamp Spanish 113 Swamp White. 107, 248 Tanbark 108,115 Valley Ill, 248 Valparaiso 118 Water 113 Water Spanish 113 Weeping. Ill Western White Ill White, 19, 22, 28, 31, 105, 106, 109, 111, 246, 248, 275, 375 Yellow 105, 115 Yellow-bark 115 Ochroma lagopus 214, 246 Oil 79,80,378,381,385 Boiled 379, 480 Cedar 380 China Wood 214, 379, 380 Citronella 380 Elaeococca 380 Linseed 379, 380, 383, 389 Lithographic 380 Non-solidifying 379, 381 464 INDEX PAGE Oil, Nut 143 Raw 379,380,392 Rubber 379 Sandal Wood 380 Solidifying 379, 380 Tung 214,379,380 Volatile 379, 381 Walnut 379 Oils, Paints and Varnishes 377 Oldfieldia 211 africana 211, 212 Olea europcea 127 Olive 127 California 196 Olive Tree 189 Wild 189 One-berry 152 Open Tank Process (Wood Pres- ervation), 355, 356, 357, 358, 359, 360 Orange 127 Mock 204 Osage 92, 202, 204, 248, 275 Oreodaphne 196 Oreodoxa regia 6, 225 Organic and Inorganic Materials, Comparison, xvii, 1, 233, 355 Organic Compounds in Woods, 9, 11, 19, 37, 234, 235, 236 Organic Origin, Influence upon Properties of Woods, 233, 234, 235, 262, 264 Osage 204 Apple Tree 204 Orange 92, 202, 204, 248, 275 Ostrya 154 virginiana. 154, 155 Outside-growing Trunks 5, 6 Oxygen in Wood 234, 281 Ozonium omnivorum (fungus) . . 272 Padus serotina 205 Paint, Application of, 389, 390, 391, 392, 393, 394, 395, 398, 399, 400 Asbestos 284,401 Casein 389 Covering Capacity 394 PAGE Paint, Denned 377 Durability of 398 Enamel 378, 398 Failure of 389, 390, 391 Fireproof 284, 285, 402 Miscellaneous Applications, 388, 389 Pigments, 378, 381, 382, 383, 384 Preparation of Woods to Re- ceive 402 Priming for 380, 390, 393 Removal of 390, 391 Sprayed 391 Upon New Surfaces 390 Upon Old Surfaces 390 Water 389 Waterglass 285, 401 Woods Prepared For 402 Painting, Car 400 Coach 400 Ship... 399 Palm 4,7,224,225 Arizona 226 California Fan 226 Date 226 Desert , 226 Fanleaf 225,226 Nut 426 Royal 6,225 Sargent 225 Washington 225, 226 Palmacece 225 Palmetto 225,227 Cabbage 225,227 Mexican 225, 227 Prickly Thatch 227 Silktop 225,227 Silver Thatch 227 Silvertop 225 Paraffine 281, 316 Parasites (see Bacteria) 269 Parenchyma Cells .... 24, 30, 38, 39 Ray 30 Paris White, Pigment 389 Parthenium argentatum 427 Paulownia 180 Paulownia tomentosa 180 Pear 127 Tree, Wild 190 INDEX 465 PAGE Pecan 148 Nut 148 Pecan-tree 148 Pecanier 148 Peckiness 93, 272 Penetrability 247 Pepper 213 California 213 Longleaved 213, 214 Pepperidge 190 Peppermint Tree 216, 223 Perishable Woods 275 Persimmon 30, 202, 203, 248 Black 193 Mexican 193 Peruvian Mastic 213 Phanerogams 269 Phloem 24, 34, 38 Phoe.nix dactylifera 226 Pholas 314 Pholas dactylus 314 Phosphorus in Wood 234 Phyllosticta acericola (fungus) . . 272 Physical Properties, India- rubber 431 Woods, 18, 26, 33, 237-265 Physiological Processes of Trees, 8, 9, 10, 11, 12, 13, 233 Influence upon Properties of Wood, 8, 9, 10, 11, 12, 233 Picea 64,65 alba 64,66,67 canadensis 67 engelmanni 64, 68 excelsa 64 mariana 66 nigra 64, 66, 67 rubens 64, 66 sitchensis 69 Piddock 314 Pieces, Edge-grained 40 Quarter-sawn 24, 39, 40, 334 Rift-grained 40 Straight-grained 40 Vertical-grained 40 Pigment, in Wood 17, 37 Barium Sulphate . . 382, 383, 434 Bismarck Brown . . . 388 PAGE Pigment, Bone Black 384 Carbon 384 Chrome Green . . 382 Yellow 382 Graphite.. . .' 384 Iron Oxide 378, 383 Ivory Black 384 Litharge 383,434 Paris White.... 389 RedLead 383 Silica 383 White Lead 378,382 Zinc White 378, 382, 434 Pignut 146 Water 248 Pin, Knot 43 Rot 94 Pine, 3, 5, 30, 43, 44, 45, 49, 65, 67, 70, 72 Alaska 79 American White 48 Arizona Flexilis 49 Bastard 47,53,55,60,76 Bhotan 60 Big 50,56 Black 55,58 Black Norway 58 Black Slash 55 Blister 73 Brown 52 Bull 47, 49, 54, 55, 56, 60, 272 Canadian Red 57 Carolina 54 Common Yellow 54 Cornstalk 55 Cowdie 63 Cuban. . 46, 47, 53, 261 Dantzic 45, 59 Digger 60 Fat...'. 62 Finger Cone 51 Fir 73 Florida 52 Florida Longleaved 52 Florida Yellow 52 Foothills Yellow 56 Foxtail 55 Frankincense 55 Georgia (see Longleaf Pine) . 466 INDEX PAGE Pine, Georgia Heart 52 Georgia Longleaved 52 Georgia Pitch 52 Georgia Yellow 52 Gigantic 50 Ginger 92 Gray 60 Grayleaf 60 Great Sugar 50 Hard,45 ; 46, 47, 52, 54, 57, 58,61,70 Heart 52 Heavy 56 Heavy-wooded 56 Indian 55 Jack 60 Jersey 61 Kauri 62, 63, 387 Limber 49 Limber-twig 49 Little Sugar 50, 51 Loblolly. . . .46, 53, 55, 60, 261, 275 Lodgepole 60,275 Longleaf, 2, 28, 31, 46, 47, 52, 53, 261, 275 Longleaved 56, 58 Longleaved Pitch 52 Longleaved Yellow 52 Longschat 55, 58 Long Straw 52 Longstraw 55 Marsh 60 Meadow 53, 55, 60 Mexican White 46 Montana Black 56 Monterey 60 Mountain 51 Mountain Wey mouth 51 Murray 60 North Carolina 54, 55, 60 North Carolina Pitch 52 North Carolina Yellow 54 Northern 45,48,59 Norway 57 Nut 46 Old Field 54,55 Oregon 46,47,70,71 Pacific 70 Parry's 46 Patternmaker's . 48 PAGE Pine, Pifion 20 Pitch 47,52,53,54,56,58 Pond 60 Poor 54 Puget Sound 71 Pumpkin 48 Red 56,57,71 Rigid 58 Rocky Mountain 49 Rocky Mountain White 49 Rosemary 52, 54, 55 Sabine 60 Sap 55,58 Scotch 59 Scrub 60 Shade 50 She 53 She Pitch 53 Shortleaf 46, 47, 54, 55, 261 Shortleaved Yellow 54 Shortshat 54 Silver 46,51,73 Slash 53,54,55 Soft 45,48,51 Southern 2,52 Southern Hard. ...... 46, 52, 261 Southern Hard Dense 261 Southern Hard Sound 260 Southern Heart 52 Southern Pitch 52 Southern Yellow 52, 56, 260 Spruce. ..... 47, 48, 53, 54, 55, 60 Stone. 60 Sugar 45,46,50 Swamp 53, 55 Tamarack 60 Texas Longleaved 52 Texas Yellow 52 Torch 55 Turpentine 52 Virginia 55 Virginia Yellow 54 Western Pitch 56 Western White 46, 51 Western Yellow, 20, 23, 25, 50, 56, 275 Weymouth 48 White, 45, 46, 48, 49, 50, 51, 58, 59, 64, 68, 171, 246 INDEX 467 PAGE Pine, White Blister Rust 48, 50 Whitebark 46 Yellow. ... 2, 47, 52, 54, 55, 56, 58 Yew 66 Finite 50 Pinus 45, 65 albicaulis 46 caribtea 53 cembra 60 cembroides 46 divaricata 60 echinata 46, 47, 54 edulis 20 excelsa 60 flexilis 46,49 glabra 60 heterophylla 46,47,53 lambertiana 45, 46, 50 mitis 54 monticola 46, 51 murrayana -. . . 60 palustris, 2, 5, 46, 47, 52, 53, 246 ponderosa 20, 23, 25, 56, 272 quadrifolia 46 radiata 60 resinosa 57 rigida 58 sabiniana 60 serotina 60 strobiformis 46 strobus 45, 48, 59, 171, 246 sylvestris 45, 59 tceda 46, 47, 53, 55 taxifolia 70 virginiana 61 Piquant Amourette 167 Pistacia lentiscus 388 Pitch 53,54,64 Tubes 64 Pith 24,34,37 Cavity 24,34,37 Knot 42 Ray 22, 24, 26, 40, 249 Ray Cells 19 Ray Primary 24 Ray Secondary 24 Pits 18, 19, 20, 21, 102 Bordered.. 20 PAGE Pits, Simple 18, 19, 20, 23, 102 Plane, American 156 Common 156 Oriental 156 Tree 156,157 Planks 40 Plants, Non-Seedbearing 269 Seedbearing 4, 269 Plaqueminier 203 Platane 157 Platanus 156 occidentalis 156, 157, 158, 246 orientalis 156 racemosa 156, 158 Plum, Date 203 Gopher 189 Polished Wood, Specification for 398,400 Surfaces, 395, 396, 397, 398, 399, 400 ; Polymerization 435 Polyporus carneus 86 Polyporus juniperus 86 Poplar 3, 73, 169, 171, 172 Balsam 169 Bay 186 Blue 171 Carolina 173 Hickory 171 Large 172 Largetooth 172 Necklace 173 Tulip 171 White 171, 172 Yellow 171,248 I Popple 171,172 I Populus 169 balsamifera 73, 169, 174 deltoides 173 grandideritata-, 172 monilifera 173 tremuloides 169, 172 trichocarpa 174 i Pores 21, 30, 247, 249, 375 j Porosity (Defined) 247 Wood 37, 237, 247, 248 Porthetria dispar 320 j Possumwood 203 * Potassium in Wood . . . 234 468 INDEX PAGE Powell Process (Wood Preserva- tion) 374 ; Preference for Wood 2 \ Preparation of Wood for Fire Coatings 284 ' Glue 408 i Internal Preservative Treat- ment 353, 374 i Paints, Oils and Varnishes, 284, j 402 Seasoning 328 Test Pieces 255, 256 j Preservatives, Wood, 265, 317, 335, 337, 338, 339, 340, 341, 342, \ 343,344,345,346,347,348, j 349, 350, 351, 352, 353, 375, 377, 379, 380, 381 Pressure, Influence upon Preser- vative Treatment. . . . 361 Prickly Thatch 227 Pride of India 214 Primary, Canal 26 Pith-Ray 24 Resin-duct 25 Wall 19 Wood 10 PrimaVera 207,210 Principles of Fire Protection, 292, 293, 294, 295, 296, 297, 298, 299 Prionoxystus robinice 321 Properties of Structural Mate- rials xvii, 1 Properties of Woods, Chemical Composition, 9, 26, 233, 234, 235. 281 due to Organic Origin, 233, 234, 235 Physical, (see Physical Prop- erties of Wood}, 263, 264,265 Physiological, 8, 9, 10, 11, 12, 233 Special 233 Prosopis 165 juliflora 165, 168 odorata . 165 Protection of Glue 410 Protection of Wood Allardyce Process 371 PAGE Protection of Wood Bethell Process 363, 371 Boiling Process 372 Boucherie Process 372 Brush Applications 354 Burnett Process 368 Card Process 371 Charring 373 Creoaire Process 374 Creo-resinate Process 372 Dipping Brush and Soaking Applications 354 Empty Cell Processes, 351, 361, 362, 369, 370, 371 External Treatment, 284, 285, 286, 315, 377, 378, 389, 390, 391, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402 Ferrell Process 374 from Burning, 282, 283, 284, 285, 286 from Rot 273, 274, 275, 276 from Wood Borers, 309, 310, 313, 315,316,317,318,320,321, 322, 323, 324 Full Cell Processes, 351, 361, 362, 363, 368, 369 Hasselmann Process 374 Hayford Process 364 Internal Treatment, 282, 283, 284, 317, 318, 335, 336, 337, 351, 352, 353, 354, 355, 356, 357. 358, 359, 360, 361, 362, 363, 364, 365, 366, 367, 368, 369, 370, 371, 372, 373, 374, 375 Kyan Process 355 Lowry Process 370 Miscellaneous Processes 373 Non-pressure Processes . .353,, 355 Open Tank Process, 355, 356, 357, 358, 359, 360 Powell Process 374 Pressure Processes. 353,360-373 Robbins Process 373 Ruping Process .... 361, 369, 371 Rutgers Process 371 Seasoned Woods, 266, 276, 334, 377, 402 INDEX 469 Protection of Wood, Seasoning, 326, 327, 328, 329, 330, 331, 332, 333, 334 Seeley Process 373 Superficial Processes .... Thilmany Process Vulcanizing Wellhouse Process Woods that Respond to . Zinc Chloride Process . . . Zinc Creosote Process . . . Zinc Tannin Protoplasm 11, 19,37 Prunus 202 serotina Pseudophcenix sargentii Pseudotsuga douglasii 71 macrocarpa mucronata 1 taxifolia 47, 71 Pterocarpus erinaceus 214 santalinus 215 Pterocarya caucasica 141 Pullman Specif., Car Paint- ing 400 Putty 393 Pyrus augustifolia 127 communis 127 coronaria.. . 127 PAGE 326 Ouercus obtusiloba PAGE . . 109 332 palustris 105, 113 pedunculata . . 105, 119 373 353 374 prinus pubescens robur . . . 105, 108 ... 119 . . 105 373 371 374 368 371 371 robur intermedia robur var. pedunculata . 3, robur var. sessiliflora rubra 3,20, 105, 112, sessiliflora stellata . .. 119 104, 119 104, 119 150, 246 105, 119 . 109 236 tinctoria ... 115 202 triloba . 114 205 velutina 105, 115 225 virens ... 116 70 virginiana 105, 116, 246 71 wislizeni ... 118 70 ,246 R mains . . 127 rivularis. . .127 Q Quartered Surfaces . . 24, 39, 40, 334 Quartz Ground, Pigment 383 Quercus. 3,21,104 agrifolia 105 117 alba 3, 19, 22, 105, 106, 246 chrysolepis 105, 118 cuber 246 digitata 105, 114 falcata 114 garryana 105, 111 lobata Ill macrocarpa 110 michauxii 105, 107 minor 105, 109 Racine Boats 411 Radial Surfaces of Wood 39 Railroad Spikes, Holding Power 242 Railway Eng. Assn. Specif, for Creosote 344,345 Rainfall 14 Range of Species. . 16 Rattan 232 Ray Parenchyma 301 Ray-tracheid 24 Razor Clam 301 Recorders, Watchmen's 299 Red Flower 136 Red Lead Pigment 383 Redwood, 27, 36, 46, 72, 86, 98, 99, 100, 101, 208, 275 California 101 'Coast 101 Common 98, 99, 101 Curly 98 Giant 101 Mammoth 98, 99, 101 Resilience, Wood 237, 241 Resin, 2, 4, 17, 25, 26, 44, 45, 46, 47, 57, 62, 234, 235, 246, 247, 385, 386, 387, 388, 432 Amber 385, 386 Anime 386 470 INDEX PAGE Resin, Canal (see Resin Ducts) Copal 386 Dammar 385, 387, 388 Duct ... 23, 24, 25, 26, 28, 45, 247 Primary 25 Secondary 25 Fossil 62,385,386,387 Fresh-product 62 Guajac 191 Kauri 62, 63, 385, 387, 388 Mastic 385,388 Pine 388 Sandarach 387 Semi-Fossil 62 Shellac 387, 392, 397 Solvents 378, 379, 380, 381 Varnish. ... 62, 385, 386, 387, 388 Zanzibar 386 Resonance (Denned) 249 Wood 237,249 Rhapis flabelliformis 232 Rhododendron 195 maximum 193, 195 Rift-grained Pieces 40 Rigidity (Denned) 239 Wood 237,239 Rings, Bands, or Layers, Annual, 5, 6, 10, 11, 29, 30, 34, 35, 36, 37, 102, 360 Ring-porous Woods 30, 31 Robbins Process (Wood Preser- vation) 373 Robinia 165 pseudacacia 165, 166, 246 Roble 210 Rolled Lumber 41 Root, Diseases 272 Fungi...' 272 I\mgous Diseases 272 Rot, Southern 272 System of Tree 8 Rose Bay 195 Rosewood 214 African 214 Brazilian 214 California 215 Canary 214 Rosin.. 388,434 Rot, Black Scale 214 PAGE Rot, Chestnut Bark 149, 150 Dry 42,268, 274,401 Pin 94 Red 86 Soft 42 Wet 42, 268, 274 White 86, 121 Wood 268, 273, 274, 275, 276 Rotary-cut 40 Rotten Knot 43 Round Knot 43 Rubber, (see Indiarubber). Oil 379 Tree 213,427 Rueping Process (Wood Preser- vation) 361, 369, 371 Rule, Density 46, 260 Rupture, Modulus of. . 33, 239, 261 RustinWood 42,268 Rutgers Process (Wood Preser- vation) 371 Sabal mexicana 225, 227 palmetto 225, 227 Sabicu 213 Sagwan 212 Salix . . . 177 alba 177, 178 caprea 177 fluviatilis 177 fragilis 177 nigra 178 russeliana 177 Sand Flea 310 Sandalwood 215 Oil 380 Red 215 Sandarach 387 Sanderswood 215 Santalin 215 Santalum 215 album 215 ! Sap, 11, 20, 21, 37, 38, 235, 262, 263 Circulation of 11, 20,21 Crude 11,235 Effect upon Properties, 26, 262, 263 Elaborated 11,37,235 Movement.. ... 11, 20, 21 INDEX 471 PAGE Saprophytes 269 Sapwood, 25, 34, 37-, 38, 47, 120, 144, 246, 247, 262, 351 SasifraxTree , 199 Sassafac 199 Sassafrac 199 Sassafras 198,199 Calif ornian 196 Sassafras 198 officinale 199 sassafras 199 Satinwood 215 East Indian 215 Savin 87 Saxifrax 199 Schcefferiafrutescens 193 Schinus molle 213 terebinthifolius 214 Scolytidce 319 Season, Influence upon Cutting, 262, 263 Seasoned Woods, Protection of, 266, 276, 334, 377, 402 Seasoning of Woods, 266, 276, 326, 327, 328, 329, 330, 331, 332, 333, 334, 402 Air 327 Kiln-drying, 328, 329, 330, 331, 332, 333, 334 Natural 327 Water 327, 328 Yard Drying.. 327 Secondary, Canals 26 Pith-ray 24 Resin-duct 25 Wall 19 Wood 10 Second-growth Woods 120, 144 Seedbearing Plants 269 Seeley Process (Wood Preserva- tion) 373 Semi-vulcanite 434 Sequoia, 27, 36, 86, 98, 99, 100, 101 Sequoia 86,98 sempervirens 98, 101 washingtoniana 98, 101 Shagbark 145 Shakes (Defects) 41 Shapes of Trees 12, 13 PAGE Shawneewood 180 Shellac. 385, 387, 390, 392, 397, 398 Shellbark 145 Shinglewood 90 Ship-painting 399 Shipworm, 98, 225, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 340 Boring Shell 303 Calcareous Lining 303 Collar 302,303 Excavations 307 Field of Attack. 309 Foot 303 Form 301 Influence of Temperature and Water 306 Method of Attack 307 Pallets 302 Protection from 315 Rapidity of Work 308 Reproduction and Develop- ment 305 Siphon 302 Size of Borings 308 Woods, Subject to Attack,309, 310 Shutters, Fire. . . 284, 285, 295, 296 Sieve Tubes 38 Signals, Fire 298 Silica, Pigment 383 Silverbell 248 Silver Fish 320 Thatch 227 Simmon 203 Simple Pits 18, 19, 20, 23, 102 Sipiri 201 Sissoo 213 Slab 40 Slash-cut Pieces 40 Slice-cut Pieces 40 Smoking Bean 181 Soaking (Preservation of Wood) 354 Soft Bast 38 Soft Rot 42,268 Softshelled Clam 301 Softwoods 4, 6, 30, 43, 44 Sorbus 126 americana. . . 126 472 INDEX PAGE Sorbus, sambucifolia 126 Sound, Conductivity of Wood . . 248 Special Properties of Woods . . . 233 Sound Knot 42 Southern Creosoting Co., Specif. 364 Soymida 206 febrifuga 206 Spanish Bayonet 228 Dagger 228 Spar Varnish 386 Special Properties of Woods . . . 233 Species 3, 16 Defined 3 Distribution of 16 Number of 3 Specifications, Analysis of Creo- sote, 346, 347, 348, 349, 350 Amer. Railway Engr. Assn. (Defects) 42 Amer. Society for Testing Materials (Defects) ... 42 Application of Cattle Glue, 408, 409 Application of Creosote, 358, 359, 360, 364, 365, 366, 367, 368, 370 Application of Fish Glue. . . 414 Application of Paint, 391, 392, 393, 394, 398, 400 Automatic Sprinklers 297 Car Painting '. 400 Creosote, 344, 345, 346, 347, 348, 349, 350 Defects in Wood 42 Density Rule for Grading Southern Hard Pine . . 260 Hardwood Mfrs. Assn. of the U. S. (Defects) 42 Open Tank Process (Wood Preservation) 358 Pacific Coast Lumber Mfrs. Assn. (Defects) 42 Wood Polishing 398, 400 Yellow Pine M|rs. Assn. (De- fects) 42 Zinc Tannin Process (Wood Preservation) 371 Specific Gravity of Wood . . 237, 244 Specimens, Wood Testing, 252, 255, 256 PAGE Sphceroma destructor 314 Spice-tree 196 Spike Knot 43 Spikes, Holding Power 242 Spiral (Wood-element) 20 Spiritine 352 Spores Fungi 269 Spot in Foliage 272 Spring Deposit 30, 31, 35, 36 Spring Wood (see Spring Deposit) . Sprinklers, Automatic, 289, 295, 297, 298 Spruce, 28, 29, 43, 44, 46, 64, 65, 66, 67, 70, 71, 72, 80 Big Cone 70 Black 60,64,66,67 Blue 66 Bog 67 California Hemlock 79 Cat 67 Cork-barked Douglas 71 Destroying Beetle 64 Double 66,67 Douglas 47, 64, 70, 71 Engelmann's 68 Great Tideland 69 He Balsam 66 Hemlock 78,80 Kauri 64 Menzies 69 Mountain 68 Norway 64 Pine 66 Prickly 60 Red 64,66,70 Single 67,73 Sitka 69,275 Skunk 67 Tideland 69 Water 66 Western 69 White 60, 64, 66, 67, 68, 275 Stains for Wood 388, 398 Standard, Knot 43 Moisture in Wood 252 Star Shakes (see Defects in Wood) 41 Steam, Influence upon Wood, 361, 362 INDEX 473 PAGE Stinkwood 190 Stone-borers 314 Stones, Building xvii, 277, 295 Stones and Woods, Comparison', xxii, 1,255 Stores, Naval 15, 47, 53, 58 Straight-grained Pieces 40 Streamflow 14 Strength (Defined) 237 Strength of Wood Influenced by Moisture 262,264 Strength of Sapwood and Heart- wood 37 of Woods, 33, 37, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 267 Stringybark 216, 223 Structure, Wood (see Wood Structure) . Structures, Maintenance of. ... 298 Suberin 39 Sugarberry 152 Sugar Cane 224 Sugar Tree 134 Sulphur in Wood 236 Sumach 193 Summer Deposit 30, 31, 35, 36 Summerwood (see Summer De- posit) . Summer-felled Wood 262, 263 Sunlight, Influence on Tree. . 12, 13 Supeira 201 Superficial Processes (Wood Preservation) 353 Surface Treatment of Woods, 284, 315, 377, 389, 390, 391, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402 Surfaces, Cross (Wood) 39 Quarter-sawn (Wood) 24, 39, 40, 334 Radial (Wood) 39 Tangential (Wood) 39 Swamps 83, 85, 86 Cedar - 85 Cypress 86 Tamarack 83, 86 PAGE Swietenia 206, 207 mahagoni 206, 207, 208, 246 Sycamore, 30, 156, 157, 158, 246, 248, 275 California 156, 158 System, Central Office 299 Tabebuiadonnell-smithii. . . 207, 210 Tacmahac 174 Tamarack 60, 81, 83, 84 Red 83 Swamp 86 Western 84 White 83 Tanbark 2 Tangential Surfaces 24, 39 Tannic Acid (see Tannin). Tannin, 37, 203, 234, 235, 337, 338 Tar (see Naval Stores).. . 46, 47, 316 Taxodium 95 distichum 96, 97, 246 Taxus 92 bacata 20 brevifolia 92 floridana 92 Teak 211,212 African....'. 211,212 Burma *. . . 212 Indian 212 Malabar 212 Tectona 211 grandis 211,212 Teek 212 Telephone & Tel. Co. Specif, for Creosote 346,347 Temperatures, Destructive 293 Effect upon Wood 293, 329 Teredo, (see Shipworm). Teredo Nails 316 Teredo dilatata 301 megotara 301 navalis 300, 301 norvegica 301 thompsoni 301 Termes bellicosus 322 flavipes 322 lucifugus . 322 474 INDEX PAGE Termites 201,321 Protection from 322 Summarized 323 Woods Destroyed by 322 Terrestrial Woodborers, 18,300, 318, 319, 320, 321, 322, 323, 324, 325 Woods Destroyed by, 319, 320, 321, 322, 323, 324 Woods Protected from 324 Test, Density 46, 245, 260 Test Machine, Impact 245 Test-pieces, Wood 252, 255, 256, 258, 259 Tests, "Fireproof ed Woods, "286, 287 Glues 417, 418, 419, 420 Woods, Physical Properties of, 33, 242,243,244,251,252,255, 256, 257, 258, 259, 261 Woods, Natl. Forest Service, 33, 258, 261 Woods, U. S. Census, 33, 257, 261 Woods, Watertown Arsenal . . 33 Tewart 222 Thickness-growth of Trees. . . 10, 12 Thilmany Process (Wood Pres- ervation) 374 Thorn 167 Thorny Locust 167 Thrinaxmicrocarpa 225, 227 parviflora 225,227 Thuya 85 gigantea 86, 90 occidental 86,89 plicata 90 Thysanura 319 Tidy Specif, for Creosote 344 Tiel 170 Tieltree. . .170 americana heterophylla Timber (Defined) .. 170,176 176 17 Tooart 222 Toothache Trees Top-soil Influence upon Rot . . . Torchwood 126 13, 14 275 21 Torus . ... 18,20 PAGE Toxylon 202 pomiferum 202, 204 Tracheae (Wood Elements) .... 21 Tracheal-tubes (Wood Ele- ments) 21 Tracheid (Wood Elements), 11, 19, 20, 22, 23, 24, 25, 30, 44, 102, 247 Tree (Defined) 8 of Heaven 172 Yucca 229 Trees and Woods, Banded (see Trunks and Woods, Banded). Broadleaf, 4, 5, 6, 29, 43, 44, 102, 103, 169, 333 Coniferous, 4, 5, 6, 20, 29, 43, 44, 102 Deciduous 4, 6, 43, 103 Dicotyledonous, 4, 5, 6, 30, 34, 43, 102, 169 Evergreen. 4, 5, 6, 20, 34, 43, 44, 102 Hardwood 4, 6, 43, 102 Identification of, 17, 27, 28, 29, 30, 31, 32, 36 Monocotyledonous, 4, 5, 6, 7, 224, 230 Needleleaf, 4, 5, 6, 20, 29, 36, 43, 44, 102 Non-banded 6, 9, 29, 224 Softwoods 4, 6, 43, 44 Trees, Forms of 12, 13 Fungous Diseases 271 Influence of Sunlight 12, 13 Inside-growing 6, 7, 9, 224 Leaf Systems of 9 Length-growth of 9 Number of 3 Outside-growth of, 5, 6, 9. 29, 30, 34,43,44, 102,169,224 Physiology of, 8, 9, 10, 11, 12, 13 Root System of 8 Shapes of 12,13 Thickness-growth of 10, 12 Trunk System of 9 Trichophyton tonsurans (fun- gus) 270 Trunks 9,16,34 Fungous Diseases of 272 INDEX 475 PAGE Trunks and Woods, Banded, 5, 9, 29, 30, 34, 43, 44, 102, 169, 224 Non-banded 6, 9, 29, 224 Tsuga 65, 78 canadensis 80 caroliniana 80 heterophylla 78 mertensiana 78, 79 Tuart 216,222 Tubes (see Wood Elements] 21 Pitch 64 Sieve 38 Tulip 102 Tulip-tree 169, 171, 175 Tung Oil 214, 379, 380 Tree 214 Tupelo 189,190,275 Large 189 Sour 189 Swamp 189 Turpentine, 2, 25, 46, 47, 53, 54, 57, 60, 62, 381, 399, 435 Venice 62,82 Xyloses 21, 247, 248, 375 U Ulmus alata americana fulva .... 128 .... 132 .... 129 .. 3,131 pubescens 129, 131 racemosa 130 thomasi 130 Umbellularia calif ornica. . . 195, 196 Umbrella Tree 214 ; Unbled Woods 46,47 j United States Census, Exper., 33, ! 257, 261 Unknown Tree 152 j Use, Wood Destroyed by 266 Uses of Wood. . 2 Variety (Botanical) 3 Varnish, xviii, 377, 378, 379, 385, 386, 387, 388, 395, 396 Application of, 395, 396, 397, 398, 399 Japan 380,381 PAGE Varnish, Oil 62, 378, 385 Resins 62, 385, 386, 387 Spar 386 Spirit 62,378,385 Woods to Receive 402 Varnishes, Oils, and Paints .... 377 Vasa 21 Veneer 40, 414, 415, 416, 417 Veneers, Rotary Cut 169 Veneered Work, Appearance of . 417 Economy of 417 Preparation of 416 Stability of 417 Uses of 414 Venice Turpentine 62, 82 Vertical Grain in Woods 26 Grain Pieces 40 Vessels, 19, 21, 28, 30, 44, 247, 375 Vessel-segments 21 Vitse 29 Vitality of Wood 267 Vulcanite 434 Vulcanite-semi 434 Vulcanization, Ihdiarubber, 430, 431, 434 Vulcanization (Wood Preserva- tion) 373,430,431,434 Vulcanized Rubber.. . . 430, 431, 434 W Wahoo 132 Wain 40 Wall (Wood Element) 19 Walls, Primary 19 Secondary 19 Walnut, 3, 19, 21, 22, 139, 142, 143, 144, 145 American 140 Arizona 140 Austrian 141 Black, 19, 21, 22, 23, 30, 139, 140, 142, 188, 248 California 140 Caucasian 141 Circassian 139, 141, 186, 215 Dwarf 140 English 139,141,209 European 139, 141 476 INDEX PAGE Walnut, French 141 Italian 141 Little 140 Mexican 140 Oil ; 379 Persian 141 Royal 139, 141 Russian 141 Satin 141, 186,188 Shagbark 145 Sweet 145 Turkish 141 Western 140 West Indian 141 White 139,140,143,210 Washingtonia filifera 225, 226 Watchman's Recorders 299 Water in Wood, 17, 26, 234, 237, 245, 246, 252, 258, 262, 263, 264, 265, 329 Paints 389 Seasoning of Wood 327, 328 Waterglass, Paint 285, 401 Watertown Arsenal Experi- ments 33,257,261 Weathering of Woods 267 Weights of Woods, 18, 33, 237, 244, 245, 246, 247, 261, 267 Weights and Moduli for Woods (Summaries) 33, 261 Wellhouse Process (Wood Pres- ervation) 371 Wet Rot in Wood 42, 268, 274 Whahoo 132 White, Ant (see Termite) Lead Pigment 378, 382 Pine Blister Rust 48,50 Whitewash 389 Whitewood ... 46, 169, 171, 173, 176 Whiting 389 Wickup . 176 Wild Date 254 Willow 177, 178,213 Basket 177 Bedford 177 Black 178 Crack 177 Desert 248 Goat.. . 177 PAGE Willow, Longleaf 177 Osier 177 Sandbar , 177 Swamp 178 White 177,178 Windfalls 65, 121 Windows, Fireproof 296 Wind Shakes in Wood (Defects), 41, 333 Winter Felled Wood 262, 263 Wired Glass. 296. 297 Wood, Banded, 5, 6, 9, 29, 30, 34, 43, 44, 102, 169, 224 Bled 46,47 Broadleaf, 4, 5, 6, 29, 36, 43, 44, 102, 103, 169, 333 Cells (see Wood Elements). Chemical Composition of, 9, 13, 26, 37, 38, 39, 233, 234, 235, 236, 237, 281 Coloring Matter in, 17 Coniferous, 4, 5, 6, 26, 29, 30, 34, 36, 43, 44, 102, 103 Consumption of 1, 2 Deciduous 4, 6, 43, 103 Defects in 40, 41, 42, 43, 333 Defined 17 Density of 237,244 Destroyed, by Age 266, 267 by Ants , 321,323,324 by Bees 323 by Beetles 319,320 by Chelura 313 by Decay (see Decay in Woods) . by Exposure 267 by Fire, 277, 280, 281, 282, 283, 284, 285, 286 byLimnoria.. 310,311,312,313 by Miscellaneous Wood- borers 314 by Moths andButterflies, 320, 321 by Shipworms, 225, 300, 307, 308, 309, 310, 315, 316, 317, 318 by Termites 321, 322, 323 by Use 267 Dicotyledonous, 4, 5, 6, 30, 34, 36, 43,102,169 INDEX 477 PAGE Wood. Diffuse-porous 30, 31 Durable 266, 274, 275, 276 Elements, 11, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 34, 38, 39, 44, 45, 102, 224, 225, 237, 247, 248, 249, 252, 375 Evergreen 4, 6, 43, 44, 81 First-growth 120 Flea 310 Hard (see Broadleaf Woods). Heart 25, 34, 37, 247, 351 Hygroscopicity 251 Identification of 17, 27, 32, 36 Importance of....xvii, xviii, 1 Monocotyledonous, 4, 5, 7, 224, 230 Needleleaf (see Coniferous Woods). Nomenclature 2, 47 Non-Banded 6, 9, 29,224 Non-Durable (see Perishable Woods). Non-Coniferous (see Broadleaf Woods). Non-Porous 30, 31 Parenchyma 24, 30 Physical Properties of, 18, 26, 33, 237, 251-265 Porous 30, 31, 37 Prepared for Fire Coatings . . . 284 for Glue.. . 408 for Internal Preservative Treatment 353, 374 for Paints and Other Coat- ings 284,402 for Seasoning '. 328 for Test Pieces 255, 256 Preservatives (see Preserva- tives of Wood). Primary 10 Protected from Burning, 282, 283, 284, 285, 286 from Rot. . . . 273, 274. 275, 276 from Woodborers, 309, 310, 313, 315, 316, 317, 318, 320, 321, 322, 323, 324 Wood, Sapwood, 25, 34, 37, 38, 47, 120, 351 144, 246, 247, 262, PAGE Wood, Secondary 10, 19 Second-growth 120, 144 Soft 4, 6, 20, 30, 38, 43, 44 Special Properties of 233 Spring 35 Summer 35 Vitality of 267 Woodborers, Land, .300, 318, 319, 320, 321, 322, 323, 324. 325 Marine, 95, 225, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 31.1, 312, 313, 314, 315, 316, 317, 318, 340 Miscellaneous 314 Protection from, 315, 316, 317, 318, 320, 321, 322, 323, 324, 325 Woods and Trees (see Trees and Woods). Wool, Cotton 234 Worm, Carpenter 321 Nails 316 X Xanthoxylum americana 126 clava-herculis 126 cribrosum 215 Xylem 24,34 Xylocopa virginica 323 Xylophaga dorsalis 301 Xylotrya 300 fimbriata 301, 305, 306 Yearly Bands, Rings, or Layers (see Annual Rings, Bands or Layers). Yellow Bark 121 Yellow Pine Mfrs. Asso. Specif. . 42 Yellow-wood 193, 204, 205 Yew 20, 92 California . 92 Florida 92 Oregon .- 92 Western 92 Yucca 224, 228, 229 Aloe-leaf . . .228 478 INDEX PAGE Yucca, Breadfruit 228 Cactus 229 Mohave 228 Schott 228 Tree 229 Yucca 228 aloifolia 228 arborescens 228, 229 brevifolia 228, 229 constricta 228 gloriosa 228 PAGE Yiicca, macrocarpa 228 mohceuensis 228 treculeana 228 Z Zanzibar 386 Zinc Chloride Processes 368, 371 Creosote Process 371 Oxide 382, 434 Tannin Process Specif 371 White Pigment 378, 382, 434 REC'D Lt OCT8 '64.5 TA.4 . 3C5844 UNIVERSITY OF CALIFORNIA LIBRARY