Chapter XXVIII: Appendix

=Collection of Specimens of Wood.=--Waste pieces of all the common woods can easily be obtained at the wood working shops. Have some system about the size and shape of the specimens. Some kinds you may be able to get only in pieces of such shape as you can find among the odds and ends of the shops, and many rare foreign and tropical woods you can obtain only in quite small pieces, but even these will show the character of the wood and add value to the collection. Waste scraps of veneers of rare woods can be glued on blocks of pine.

The specimens will be most valuable if you can get them out so as to show a longitudinal section along the medullary rays (or through the heart), a longitudinal section at right angles to the medullary rays (or tangential to the annual rings), and a cross section (Fig. 693). It will be an advantage also to show not only the heartwood but the sapwood and bark. If you cannot get such large pieces of even the common woods, a collection of small flat blocks will be well worth making.

The specimens will show to best advantage if polished (one half of each side can be polished) or finished with a dull lustre, and they will be good objects on which to practise finishing (see _Finishing_ in Part V.).

All the information you can pick up about the strength, durability, toughness, elasticity, and uses of the various woods will be sure to come in play sooner or later. The gradations of hardness, density, weight, toughness, elasticity, etc., are almost endless.

Notice, therefore, the weight, colour, hardness, density, and characteristic odour of the specimens; the proportion of heart to sapwood, and the colour of each; the size and condition of the pith; the character of the grain, whether coarse or fine, close or open and porous; the number, arrangement, size, and colour of the medullary rays (when visible); the width and character of the annual rings (when visible), whether wide or narrow, with many or few ducts or resin canals. You will find many things to notice in some woods. Use a magnifying-glass if you can.

Notice also about the bark. Hunt up all the woody stems you can, compare the bark of the different specimens, noting its colour, taste, odour, surface, thickness, and the different ways it cracks and is cast off; and notice how easily you can learn to tell the common trees by the bark alone. Sections of small stems or branches will often show the character of the wood well.

Note what you can about the character and habits of the trees themselves; the height, diameter, age, and the shape and peculiarities of the leaves. In this connection, a collection of leaves will also be interesting to make. You can soon learn to tell the common trees by their leaves.

Notice how, in some trees, as the pines, spruces, firs, the stem grows right straight up to the top, forming a spire-shaped tree. This is called an _excurrent_ trunk (Lat., _excurrere_, to run out). Notice how, in other trees, like the elm, oak, etc., the stem branches again and again until it is lost in the branches. This is called a _deliquescent_ stem (Lat., _deliquescere_, to melt away).

Study the shape and arrangement of the different kinds of trees as shown in outline against the sky; best, perhaps, when the leaves are off. You can learn to tell the common trees by their outline. Do they look stout, firm, strong, and rugged, or delicate, yielding, and graceful? To a certain extent you can thus form an idea of the character of the wood, as in comparing the pine, with its comparatively light top and slender leaves, with the heavy growth which the trunk of the oak has to sustain in wind and snow.

=Preservation of Forests.=--Forests are of great value from their effect upon the climate, making it more equable. They tend to cause abundant and needed rainfall and to preserve the moisture when fallen, releasing it to the rivers gradually, and thus preventing abnormal freshets and extreme droughts. By absorbing and parting with heat slowly they cause the changes of temperature to be less sudden than in the open country. They temper the heat, and they serve as a protection, or "wind-break," to adjacent land. Trees, with other vegetation, are essential to the purification of the air. All this is in addition to the obvious uses of supplying fuel and wood for an almost endless variety of purposes, not to speak of the value of trees for shade and as features of the landscape.

The reckless rate at which the forests of the United States are being destroyed is becoming a serious matter, not merely because of depriving wood-workers of the materials with which to work, but because of the influence of the forests upon the climate, the soil, etc., upon which so much of the welfare of mankind depends. At the present rate of destruction many generations cannot pass before the supply of wood will be practically exhausted. It is every year becoming more difficult to obtain native lumber of the best quality and large size.

One of the most serious aspects of the matter, however, is in regard to the washing away of the soil, which owes not merely its origin but its preservation to the forest and other vegetable growths. Professor Shaler tells us that "it is in this action of the rain upon the bared surface of the ground that we find the principal danger which menaces man in his use of the earth."

The individual wood-worker may not have control of any forest or wood-lot, but he can at least use his influence indirectly, when opportunity offers, toward needed legislation to restrict, or at least regulate, the improvident waste now going on, and he can in many cases take advantage of Arbor Day to plant at least one tree toward preserving the balance required by nature.

=Common Woods and Some of their Characteristics.=--There are many things to be considered by the beginner when choosing his wood. Many of these points have been treated in Chapter III. (to which the reader is referred), but a few additional remarks about the various kinds may be of use.

One important thing, however, to be borne in mind before beginning, is to select straight-grained, plain, rather soft, and easily worked stock. With this and with _sharp_ tools you will have every chance of success, while with hard, crooked-grained wood and with _dull_ tools you will be well started on the road to discouragement and failure.

It may be remarked, incidentally, that beginning with soft woods, such as white pine, calls for even keener-edged tools than can be got along with for harder woods, like oak. This, however, though it may seem a disadvantage, is really a good thing, for it _compels_ one to keep his tools sharp. You will soon find that it is impossible to do even passable work in the softer woods without sharp tools, while with harder wood you may succeed by brute force in mauling the work into tolerable shape without being sufficiently impressed by the fact that your tools are dull and require sharpening.

Besides the familiar fact that the heartwood is usually better than the sapwood,[51] it may be useful to remember that, as a rule, the wood from a young tree is tougher than that from an old one; the best, hardest, and strongest in the young tree usually being nearest the heart, while in an old tree the heart, having begun to deteriorate, is softer and not as good as the more recently formed growths nearer the sapwood. If the tree is in its prime the wood is more uniformly hard throughout. The sapwood, as a rule, is tougher than the heartwood, though usually inferior in other respects; and timber light in weight is sometimes tougher than heavy wood, though the latter is often stronger and more durable and preferable for some purposes. The application of these statements varies much according to the kind of wood and different circumstances, for the growth and structure of trees is a very complex matter, and the diversities almost infinite.

It may be well to bear in mind, considering the great variety of purposes for which the amateur uses wood, the distinction between the _elasticity_ needed for such purposes as a bow or horizontal bar, and the _toughness_ required for the ribs of a canoe, or the wattles of a basket. In the former case the material must not merely bend without breaking, but must spring back (or nearly so) to its former shape when released, as with lancewood or white ash; while in the latter case it must bend without breaking, but is not required to spring back to its original form when released, as with many green sticks which can be easily bent, but have not much resilience. These two qualities are found combined in endlessly varying degrees in all woods. Elastic wood must necessarily have toughness up to the breaking-point, but tough wood may have but little elasticity.

Earliest of all trees, historically, come the pines--the conifers--and then the broad-leaved trees. The conifers, or needle-leaved trees, include the pines, firs, spruces, cypresses, larches, and cedars. As a rule they contain turpentine, have a comparatively straight and regular fibre and simple structure, are usually light, flexible, and elastic, and the wood is more easily split or torn apart than that from the broad-leaved trees, and is easily worked. The wood of the broad-leaved trees is more complex in structure than that of the conifers and, as a rule, harder, and for many purposes stronger and more durable.

Besides the woods in general use there are many which have merely a local value where they grow, and a long list could be made of the woods which have but very limited uses, as well as of those which, from their scarcity, hardness, small size, or other peculiarities are practically out of the question for the beginner or the amateur, except on rare occasions.

The following list makes no claim to completeness, but may be of some use to the beginner.

=Apple.=--This wood is used for turning, such as handles, etc., and for other small work. It is handsome, fine-grained, and somewhat hard.

=Ash.=--This is a valuable wood, of which there are a number of varieties. It is used for agricultural implements, carriage-building, floors, interior finish, cabinet-work, etc. Ash is flexible, tough, and elastic. It is good to stand a quick and violent strain, as that put on a horizontal bar in the gymnasium, although in time it becomes brittle. _White ash_ is the variety best suited for such purposes. It is good for oars and the like. Ash is of a rather coarse and usually straight-grained texture, and most varieties are not difficult to work.

=Basswood.=--The wood of the American linden, or basswood, is soft and light in substance, white or light brown in colour, is easily bent but not easily split, free from knots but prone to warp, and is used for cabinet-work, carriage-work, and for various minor articles. It can be obtained in boards of considerable width.

=Beech.=--This close-grained wood, hard, firm, strong, and taking a good polish, is extensively used for machine-frames, handles, plane-stocks, some kinds of furniture, and a variety of minor articles, but will not often be needed by the amateur. The medullary rays are noticeable.

=Birch.=--The birch, of which there are many species, is widely distributed in North America, and furnishes an important wood, which is used for a great variety of purposes,--for furniture, floors, interior finish, turning, and a long list of minor articles. It is close-grained, and most varieties are hard and strong, but not difficult to work, and are susceptible of being given a smooth satiny surface and a fine finish. The uses of the bark of the canoe birch are familiar to all. This tree is good not merely for canoes, but its wood is used for paddles, skis, and the like.

The _black birch_ is especially esteemed for furniture and interior work. It is of a beautiful reddish- or yellowish-brown colour, and much of it is beautifully figured with wavy and curly grain. It is frequently stained in imitation of mahogany, a deception much assisted by the resemblance in grain, and not easily detected if skilfully done.

=Black Walnut.=--Large black-walnut trees are practically almost as thoroughly exterminated in America as the bisons of the Western prairies. The wood can be obtained, however, though it is not abundant in very wide boards. It is durable, usually straight-grained, moderately strong and hard, not difficult to work, holds glue well, and can be given a fine finish. It holds its shape well, and is an excellent wood for many purposes in interior finishing, cabinet-work, and for various minor articles. It has been very extensively used for gun-stocks. Its sombre colour is not always admired, but it is an excellent wood for amateur work. When mottled or in the form of burl it is, of course, harder to smooth. The English and Italian varieties of walnut have long been used.

=Boxwood.=--This wood is distinguished for its extremely compact and even grain. It is hard and heavy, is used in turning, wood-engraving, and the like, but is not likely to be required by the amateur.

=Butternut.=--This wood, found in North America, has a rather coarsely marked grain, is soft, light, of a yellowish-brown colour, and when finished makes a handsome wood for furniture and interior work.

It is easily worked, but is not the easiest material for the amateur to smooth satisfactorily, because of the peculiar texture of the wood, which tends to "rough up" unless the tools are very keen.

=Buttonwood.=--See _Sycamore_.

=Cedar.=--This tree, found quite abundantly in the United States, furnishes a wood which is exceedingly durable, particularly where exposed to the alternations of moisture and dryness, as when inserted in the ground or in situations near the ground, and is very valuable for fence-posts, foundation-posts for buildings, railroad ties, shingles, pails, and the like. Some varieties of cedar are used for building purposes and interior fittings.

The varieties of _white cedar_ are light, of good grain and easy to work, soft, and not particularly strong, but durable and admirably adapted to such purposes as boat-building, for which it is largely used. _Red cedar_, which is in many respects similar to the other varieties, is distinguished by its colour and by its strong fragrance, which, being obnoxious to insects, makes it excellent for chests and closets. It is used for pencils.

=Cherry.=--This is a valuable wood for the amateur. It is found extensively in the United States. It is fine-grained, of moderate hardness, not difficult to work, and of a beautiful reddish-brown or yellowish-brown colour. It has a satin-like surface when smoothed, and can be given a beautiful finish. The _black cherry_ is especially esteemed. It can be obtained, so far as it has not been exterminated, in quite wide boards. Cherry mellows and grows richer in colour with age. The varieties having a wavy texture are especially beautiful. It is much used for cabinet-work, interior finish, and for many purposes. The beginner should select only the softer and straight-grained varieties, as some of the harder and denser kinds are exceedingly hard to smooth.

=Chestnut.=--The value of this wood to the amateur lies chiefly in its durability. It lasts well in or near the ground or exposed to the weather. It can be used for framing, for posts for a fence or to support a building, and for similar purposes. It is soft, coarse-grained, not very strong, but is not difficult to work.

=Cottonwood.=--This is a soft, light, close-grained wood, used for woodenware, boxes, pulp, etc.

=Cypress.=--This wood is found in North America, Mexico, parts of Asia and Europe. It is a valuable material, yellowish or yellowish-brown in colour, very durable when exposed to the weather or in contact with the soil, light, soft, easily worked, and is used for general lumber purposes for which pine is used, but to which it is superior for withstanding exposure. It is used for interior finish, doors, clapboards, shingles, cabinet-work, boat-building, posts, and a great variety of purposes. It takes a fine finish. The cypress of the Southern United States is of large size, and the wood is of beautiful figure and colouring. Valuable varieties are found upon the Pacific coast.

=Deal.=--See _Pine_ and _Spruce_.

=Ebony.=--The excessive hardness of ebony renders it unsuited for amateur work. It is also expensive. It is very hard and solid, with black heartwood and white sapwood, and is used for furniture, turning, and small articles.

=Elm.=--This useful wood, strong, tough, and durable, usually flexible, heavy and hard, is extensively used in some of its varieties for boat-building, the frames of agricultural implements, yokes, wheel-hubs, chairs, cooperage, and many other purposes. Some species are very good for continued exposure to wet. The _rock elm_ is a valuable variety, esteemed for flexibility and toughness as well as durability and strength.

=Fir.=--See _Pine_ and _Spruce_.

=Hemlock.=--This wood, valuable for its bark, is cheap, coarse-grained and subject to shakes, brittle and easily split, and somewhat soft, but not easy to work. It is unfit for nice work, but can be used for rough framing and rough boarding, for which its holding nails well renders it suitable.

=Hickory.=--This wood, found in the eastern parts of North America, is highly esteemed for its strength and great elasticity. It is hard, tough, heavy, and close-grained. It is largely used for carriage-work, agricultural implements, hoops, axe-helves, and the like. It is hard to work. The _shagbark_ is especially valued for timber.

=Holly.=--This wood is quite hard, close-grained, and very white, though it does not retain the purity of its colour. It is used for small articles of cabinet-work and for turning.

=Lancewood.=--The use of this wood for bows, fishing-rods, and such purposes has been extensive. It is distinguished for its elasticity.

=Lignum Vitæ.=--The extreme hardness, solidity, and durability of lignum vitæ make it of great value for pulley-sheaves, balls for bowling, mallets, small handles, and turned objects. It is too excessively hard for the beginner to use.

=Locust.=--The wood of the locust of North America is hard, strong, heavy, exceedingly durable, and of yellowish or brownish colour. It is a valuable wood, and is used extensively for posts for fences and for the support of buildings, for ship-building, and for other work to be subjected to exposure or to contact with the ground. It is used in turning, but not extensively for interior work.

=Mahogany.=--This highly valuable wood, which did not come into general use until the eighteenth century, is found in the West Indies, Mexico, Central America, and some other regions. It is very durable. The colour is found in a great variety of shades from golden-brown to deep reddish-brown. Some varieties are light and quite soft, even spongy, while others (the best) are very hard and heavy, close-grained, and strong. In some kinds the grain is quite straight, in others curved and twisted into an endless variety of crooked shapes, the latter being the most beautiful for ornamental work, but more liable to change of shape than the straight-grained varieties.

The straight-grained varieties change their shape but little,--less than most woods,--and are therefore excellently suited for the framework or structural parts of cabinet-work, for pattern-making, and the like. The so-called _baywood_ holds its shape well and is easily worked, but is not especially beautiful. The better grades of mahogany grow darker and richer in colour with age, but some varieties become bleached and lustreless with exposure.

It is of the greatest value for interior finishing, for furniture, and for cabinet-work generally, and is also used for many other purposes.

The term mahogany is used in commerce in a rather comprehensive way. Mahogany from San Domingo has long been highly esteemed, but is now difficult or impossible to obtain. The light-coloured variety known as _white mahogany_ is much valued for its beauty.

Mahogany is excellent for holding glue. It can be obtained in wide pieces, thus often saving the necessity of gluing. It can be given a beautiful dull finish or a high polish, as may be desired.

The beginner should only attempt the plain, softer, straight-grained kinds of mahogany at first. The other varieties require much skill to smooth and, in case of the harder pieces, even to work at all; and these, however beautiful they may be, should be deferred until considerable proficiency has been attained.

=Maple.=--The maple grows freely in the United States, and is much used for a great variety of purposes, the _sugar_ or _rock maple_ being especially esteemed. It is close-grained, hard, strong, heavy, and of a light yellowish-, reddish-, or brownish-white colour (sometimes almost white, though found in varying shades), and can be smoothed to a satin-like surface and be given a good finish. It can be stained satisfactorily. The curly or wavy varieties furnish wood of much beauty, the peculiar contortion of the grain known as "bird's-eye" being much admired. Maple is extensively used for cabinet-work and interior finishing, floors, machine-frames, work-benches, turning, and a great variety of miscellaneous articles.

There are a number of varieties of the maple. The beginner should confine himself at first to the softer and straight-grained specimens, as the other kinds are hard to work and to smooth.

=Oak.=--Of all the broad-leaved trees the oak is probably the most valuable, and has for ages stood as a type of strength. It is widely scattered in various parts of the world, and nearly three hundred varieties have been noted.

Oak is distinguished for its combination of useful qualities. It is hard, tough, elastic, heavy, durable, stiff (except after steaming, when it readily bends), and durable when exposed to the weather or to the soil. Oak is more or less subject to checking. It is strongly impregnated with tannic acid, which tends to destroy iron fastenings.

_American white oak._ This important variety is found in North America, and from it is obtained most excellent timber. It is used for a variety of purposes too great to be specified, from the construction of buildings and ships to furniture and agricultural implements, carriages, etc. It is an invaluable wood.

_British oak_ has long been held in the highest regard for its combination of valuable qualities, and has been used for more purposes than can be here mentioned.

The _live oak_, found in southern parts of North America, may be mentioned as a valuable wood, very strong, tough, and durable, which, before the introduction of iron and steel in ship-building, was extensively used in that business; but it is excessively hard and unsuited to amateur work.

Varieties of _red oak_ are extensively used, but, though valuable, are of inferior quality to the white oak. Other varieties largely used in England and on the Continent are seldom marketed in the United States.

=Pear.=--The wood of the pear tree is somewhat like that of the apple tree. It can be readily carved.

=Pine.=--First and foremost among the needle-leaved trees comes the pine, of which about seventy species are known. The _white pine_, known in England as yellow pine and also as Weymouth pine, is widely distributed in America, and is, or has been, our most valuable timber tree, but seems to be doomed to rapid extinction, at least so far as the wide, clear boards and planks of old-growth timber are concerned, which are now exceedingly hard to obtain.

There is no better wood for the beginner than clear white pine for all purposes to which it is suited.

It is light, stiff, straight-grained and of close fibre, easily worked, can be easily nailed, and takes a good finish. When allowed to grow it has reached a large size (as in the so-called "pumpkin" pine), furnishing very wide, clear boards, of beautiful texture and with a fine, satiny surface. It is of a light yellowish-brown colour, growing darker with time. It is soft, resinous, and of moderate strength. Pine is cut into lumber of many forms, and is used for inside finishing of houses, for many purposes of carpentry and cabinet-making, for masts and spars, for clapboards, shingles, and laths, doors, sashes, blinds, patterns for castings, and a long list of different purposes. It holds glue exceedingly well and takes paint well.

Other varieties, as the _sugar pine_, the _Canadian red pine_, the _yellow pine_, etc., grow in America. White pine is also found in Europe. The _Scotch pine_ or _Norway pine_, known also as _red_, _Scotch_, or _yellow fir_, and as _yellow deal_ and _red deal_,[52] is the common pine of the North of Europe, hence its name, _Pinus sylvestris_, pine of the forest. It is hard, strong, not very resinous, and is extensively used.

_Southern or Hard Pine._ This very important timber is found on the Southern Atlantic and Gulf coasts of the United States. It is very hard, heavy, and resinous, with coarse and strongly marked grain. It is durable, strong, and not easily worked by the beginner, and is hard to nail after seasoning. It is extensively used for girders, floor-timbers, joists, and many kinds of heavy timber work, including trestles, bridges, and roofs, for masts and spars, for general carpentry, floors, decks, and interior finish, railway cars, railway ties, and many other purposes, and, in addition, for the manufacture of turpentine.

Other varieties of hard pine are sold and used successfully for the same purposes, all under the common name of hard pine, Southern pine, Georgia pine, yellow hard pine, etc. Another variety of hard "pitch" pine (_Pinus rigida_), often confused with the Southern pine, is heavy, resinous, and durable, but not suited for the better class of work.

=Plum.=--This is a fine-grained, hard wood, used for turning, engraving, etc.

=Redwood.=--The two varieties of the giant _Sequoia_ of the Pacific coast are the _Sequoia sempervirens_ and the _Sequoia gigantea_ or _Wellingtonia_. The former, the most important tree of the Pacific coast, is of immense size (supposed to reach a height of even four hundred feet), red in colour, rather soft, light, and moderately strong, easily worked and finished, and very durable when exposed to the soil. It is used for general lumber purposes, carpentry, interior finish, posts, tanks, shingles, and a great variety of uses.

The _S. gigantea_ or _Wellingtonia_, which has the largest trunk in the world, is also red in colour, coarse-grained, rather weak, soft and light in texture, and of great durability when exposed to the soil. It is used for lumber and general building purposes, posts, shingles, etc. These are the "Big Trees," thought in some instances to be even five thousand years old, and of which the familiar stories are told about a stage-coach having been driven through a hollow tree, and about twenty-five people having danced at one time upon a stump.

=Rosewood.=--This wood, of handsome grain and colouring, has been much admired and extensively used for veneering. It is hard and heavy and of a peculiar texture, which seems oily to the touch. It is not well suited to amateur work, and is expensive.

=Satinwood.=--This handsome yellowish-brown wood is hardly to be considered by the amateur except for the occasional use of a small piece.

=Spruce.=--The wood of the spruce, of which there are a number of varieties, is quite abundant, is light and straight-grained, and comparatively free from large knots. It is largely used for many of the same purposes as white pine, to which it is inferior for interior finish and fine work, but superior in strength, hardness, and toughness. Both white and black spruce are extensively used for carpentry, interior finish, flooring, fencing, and inferior wood-work generally. It has the great disadvantage of curling and twisting and springing badly, and is not as nice to work as white pine. Spruce of good quality makes good paddles, spars, and the like, and is valuable for such work. The wood of the Norway spruce is known in England as _white deal_.

=Sycamore.=--This handsome wood, found in various parts of the world, and of a light yellowish or reddish-brown colour, is esteemed for interior work. The medullary rays are noticeable. It is rather hard, but not very difficult to work. It is not durable for outside work exposed to the weather. Known also as _Buttonwood_.

=Walnut.=--See _Black Walnut_.

=Whitewood.=--Like white pine, whitewood is an excellent wood for the early attempts of the beginner.

Whitewood, which is by no means white, but greenish- or brownish-yellow, is the name applied to the wood of the tulip tree. This tree attains a large size, thus furnishing wide boards, which are of such straight and even grain and so free from knots as to be of great use for many purposes. It is brittle and soft, but light and very easily worked. It is not, for most purposes, as reliable a wood as white pine, but is extensively used in the wood-working arts. It is more liable to warp and twist than pine. It takes a stain exceedingly well.

=Willow.=--An important use of this wood is for baskets. It will not often be required by the beginner, except for whistles.

=Yew.=--This wood, like lancewood, is distinguished for its elasticity, and is highly esteemed for bows and the like.

* * * * *

Many other woods can be alluded to, as catalpa (for posts and the like), elder (for various small articles), dogwood (for turning and the like), gum (for various common articles), hornbeam or ironwood (for mallets, handles, wheel-cogs, etc.), poplar (for pulp), sassafras (for posts, hoops, etc.), teak (from the East, strong and valuable), tupelo (hubs of wheels, etc.), and a great variety of others which cannot be specified, as they are but seldom required by the amateur and never needed by the beginner.

=Felling and Seasoning.=--A tree should usually be cut for timber at or near its maturity, as a young tree has too much sapwood and will not be as strong and dense or durable, while an old one is likely to get brittle and inelastic and the centre of the heartwood is liable to decay, being the oldest portion. A young tree, though softer and not so durable, furnishes a tougher and more elastic wood, and sometimes has a finer grain.

Trees differ so much, and the uses to which the wood is to be put are so various, that no exact ages can be set for cutting--probably from fifty to one hundred years for good timber, to make a rough statement. Some trees furnish excellent timber at a much greater age than one hundred years. Pine is thought to be ripe for cutting at about seventy-five or one hundred years of age, oak at from sixty to one hundred years or more, and the various other woods mature at different ages.

Midwinter, or the dry season in tropical regions, is usually preferred for felling, because the sap is quiet. Decay sets in more rapidly in the sapwood and between the wood and the bark during the period of active growth, because of the perishable nature of the substances involved in the growth. Midsummer is considered equally good by some.

The various methods of cutting the log into the lumber of commerce have been treated in Chapter III., to which the reader is referred. In this connection it will be noticed that, although boards cut through or near the middle are, as a rule, the best, when they contain the pith they are sometimes valueless in the centre, as well as when, in the case of an old tree, decay has begun at that point.

As the water evaporates gradually from green wood exposed to the air but protected from the weather, one might infer that in time it would evaporate entirely, leaving the wood absolutely dry, just as the water will entirely disappear from a tumbler or a tea-kettle. This is not so, however. The drying goes on until there is only about ten to twenty per cent. of moisture left, but no amount of open-air seasoning will entirely remove this small per cent. of moisture, the amount varying with the temperature and the humidity of the atmosphere. It can be got rid of only by applying heat, kiln-drying, baking, currents of hot air, vacuum process, or some artificial method of seasoning. After having completely dried the wood by any of these methods, if it is again exposed to the atmosphere, it absorbs moisture quite rapidly until it has taken up perhaps fifteen per cent., more or less, of its own weight. So you see that, though you may by artificial means make wood entirely dry, it will not stay in this unnatural condition unless in some way entirely protected from the atmosphere _at once_, but will reabsorb the moisture it has lost until it reaches a condition in harmony with the atmosphere. Recent investigations show that the very fibre or substance of the wood itself imbibes and holds moisture tenaciously, this being additional to the water popularly understood to be contained in the pores or cavities of the wood.

There are various other methods besides kiln-drying (referred to in