A drawer ( / d r ɔːr / DROR ) is a box -shaped container inside a piece of furniture that can be pulled out horizontally to access its contents. Drawers are built into numerous types of furniture, including cabinets , chests of drawers (bureaus), desks , and the like.
89-410: Drawers can be built in various ways using a variety of materials, including wood , various wood composites , sheet metal , and plastic . Wooden drawers are often crafted with a seamless front face, concealing the end grain from the side panels. The corners may feature dovetail joints for added strength or aesthetic appeal,, with half-blind dovetail joints commonly used at the front corners to conceal
178-407: A commercial industry involved in the research and development , engineering , production, and servicing of military material, equipment, and facilities. Many industrialized countries have a domestic arms industry to supply their own military forces, and some also have a substantial trade in weapons for use by their citizens for self-defense, hunting, or sporting purposes. Contracts to supply
267-428: A construction material , for making tools and weapons , furniture and paper . More recently it emerged as a feedstock for the production of purified cellulose and its derivatives, such as cellophane and cellulose acetate . As of 2020, the growing stock of forests worldwide was about 557 billion cubic meters. As an abundant, carbon-neutral renewable resource, woody materials have been of intense interest as
356-433: A closed forest, and in the manufacture of articles where strength is an important consideration such "second-growth" hardwood material is preferred. This is particularly the case in the choice of hickory for handles and spokes . Here not only strength, but toughness and resilience are important. The results of a series of tests on hickory by the U.S. Forest Service show that: Weapon A weapon , arm , or armament
445-405: A given country's military are awarded by governments, making arms contracts of substantial political importance. The link between politics and the arms trade can result in the development of a " military–industrial complex ", where the armed forces, commerce, and politics become closely linked. According to research institute SIPRI, the volume of international transfers of major weapons in 2010–2014
534-401: A heavy piece of pine is compared with a lightweight piece it will be seen at once that the heavier one contains a larger proportion of latewood than the other, and is therefore showing more clearly demarcated growth rings. In white pines there is not much contrast between the different parts of the ring, and as a result the wood is very uniform in texture and is easy to work. In hard pines , on
623-405: A large log the sapwood, because of the time in the life of the tree when it was grown, may be inferior in hardness , strength , and toughness to equally sound heartwood from the same log. In a smaller tree, the reverse may be true. In species which show a distinct difference between heartwood and sapwood the natural color of heartwood is usually darker than that of the sapwood, and very frequently
712-400: A log is on the outside, it is more or less knotty near the middle. Consequently, the sapwood of an old tree, and particularly of a forest-grown tree, will be freer from knots than the inner heartwood. Since in most uses of wood, knots are defects that weaken the timber and interfere with its ease of working and other properties, it follows that a given piece of sapwood, because of its position in
801-858: A major driver of cultural evolution and human history up to today since weapons are a type of tool that is used to dominate and subdue autonomous agents such as animals and, by doing so, allow for an expansion of the cultural niche, while simultaneously other weapon users (i.e., agents such as humans, groups, and cultures) are able to adapt to the weapons of enemies by learning, triggering a continuous process of competitive technological, skill, and cognitive improvement ( arms race ). The use of objects as weapons has been observed among chimpanzees , leading to speculation that early hominids used weapons as early as five million years ago. However, this cannot be confirmed using physical evidence because wooden clubs, spears, and unshaped stones would have left an ambiguous record. The earliest unambiguous weapons to be found are
890-466: A number of issues around the potential ongoing risks from deployed weapons, the safe storage of weapons, and their eventual disposal when they are no longer effective or safe. Strange and exotic weapons are a recurring feature or theme in science fiction . In some cases, weapons first introduced in science fiction have now become a reality. Other science fiction weapons, such as force fields and stasis fields , remain purely fictional and are often beyond
979-481: A pretty definite relation between the rate of growth of timber and its properties. This may be briefly summed up in the general statement that the more rapid the growth or the wider the rings of growth, the heavier, harder, stronger, and stiffer the wood. This, it must be remembered, applies only to ring-porous woods such as oak, ash, hickory, and others of the same group, and is, of course, subject to some exceptions and limitations. In ring-porous woods of good growth, it
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#17328559032541068-712: A secret hiding place behind it. Another way uses full extension drawers, which have full-extension drawer slides, also called telescoping slides, a kind of linear-motion bearing § Compound slides that support the drawer even when the drawer is pulled entirely out of the cabinet. A drawer slide or drawer runner is the part of a drawer that allows it to move. There are various types of slide mechanisms with different features, for different uses, at different price points. Examples of uses are in home furniture hardware, office appliances, and industrial equipment, including kitchen cabinets , oven slides , rails for sliding doors , and fridge slides (for coolers ). A good slide rail
1157-631: A source of renewable energy. In 2008, approximately 3.97 billion cubic meters of wood were harvested. Dominant uses were for furniture and building construction. Wood is scientifically studied and researched through the discipline of wood science , which was initiated since the beginning of the 20th century. A 2011 discovery in the Canadian province of New Brunswick yielded the earliest known plants to have grown wood, approximately 395 to 400 million years ago . Wood can be dated by carbon dating and in some species by dendrochronology to determine when
1246-460: A source of weakness. In diffuse-porous woods the pores are evenly sized so that the water conducting capability is scattered throughout the growth ring instead of being collected in a band or row. Examples of this kind of wood are alder , basswood , birch , buckeye, maple, willow , and the Populus species such as aspen, cottonwood and poplar. Some species, such as walnut and cherry , are on
1335-564: A tree is first formed as sapwood. The more leaves a tree bears and the more vigorous its growth, the larger the volume of sapwood required. Hence trees making rapid growth in the open have thicker sapwood for their size than trees of the same species growing in dense forests. Sometimes trees (of species that do form heartwood) grown in the open may become of considerable size, 30 cm (12 in) or more in diameter, before any heartwood begins to form, for example, in second growth hickory , or open-grown pines . No definite relation exists between
1424-423: A type of imperfection known as a knot. The dead branch may not be attached to the trunk wood except at its base and can drop out after the tree has been sawn into boards. Knots affect the technical properties of the wood, usually reducing tension strength, but may be exploited for visual effect. In a longitudinally sawn plank, a knot will appear as a roughly circular "solid" (usually darker) piece of wood around which
1513-484: A wooden object was created. People have used wood for thousands of years for many purposes, including as a fuel or as a construction material for making houses , tools , weapons , furniture , packaging , artworks , and paper . Known constructions using wood date back ten thousand years. Buildings like the longhouses in Neolithic Europe were made primarily of wood. Recent use of wood has been enhanced by
1602-605: A worldwide crusade in the 1920s. Poison gas did not win battles, and the generals did not want it. The soldiers hated it far more intensely than bullets or explosive shells. By 1918, chemical shells made up 35 percent of French ammunition supplies, 25 percent of British, and 20 percent of American stock. The “Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous, or Other Gases and of Bacteriological Methods of Warfare”, also known as
1691-437: Is a season check in the knot, as is often the case, it will offer little resistance to this tensile stress. Small knots may be located along the neutral plane of a beam and increase the strength by preventing longitudinal shearing . Knots in a board or plank are least injurious when they extend through it at right angles to its broadest surface. Knots which occur near the ends of a beam do not weaken it. Sound knots which occur in
1780-401: Is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants . It is an organic material – a natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or more broadly to include
1869-456: Is also greatly increased in strength thereby. Since the latewood of a growth ring is usually darker in color than the earlywood, this fact may be used in visually judging the density, and therefore the hardness and strength of the material. This is particularly the case with coniferous woods. In ring-porous woods the vessels of the early wood often appear on a finished surface as darker than the denser latewood, though on cross sections of heartwood
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#17328559032541958-428: Is an important consideration. The weakening effect is much more serious when timber is subjected to forces perpendicular to the grain and/or tension than when under load along the grain and/or compression . The extent to which knots affect the strength of a beam depends upon their position, size, number, and condition. A knot on the upper side is compressed, while one on the lower side is subjected to tension. If there
2047-599: Is any implement or device that is used to deter, threaten, inflict physical damage, harm, or kill . Weapons are used to increase the efficacy and efficiency of activities such as hunting , crime (e.g., murder ), law enforcement , self-defense , warfare , or suicide . In a broader context, weapons may be construed to include anything used to gain a tactical, strategic, material, or mental advantage over an adversary or enemy target. While ordinary objects such as sticks , rocks , bottles , chairs , and vehicles can be used as weapons , many objects are expressly designed for
2136-422: Is dark colored and firm, and consists mostly of thick-walled fibers which form one-half or more of the wood. In inferior oak, this latewood is much reduced both in quantity and quality. Such variation is very largely the result of rate of growth. Wide-ringed wood is often called "second-growth", because the growth of the young timber in open stands after the old trees have been removed is more rapid than in trees in
2225-426: Is defined by smoothness, tight tolerance and load capacity. A soft-close mechanism is a special feature that slows the drawer's velocity in the last part of closing, then closes it automatically. The user gives the drawer a gentle push to engage the mechanism, and the drawer closes smoothly and quietly without the possibility of slamming. See also: Guide rail and Linear-motion bearing Wood Wood
2314-560: Is difficult to control completely, especially when using mass-produced kiln-dried timber stocks. Heartwood (or duramen ) is wood that as a result of a naturally occurring chemical transformation has become more resistant to decay. Heartwood formation is a genetically programmed process that occurs spontaneously. Some uncertainty exists as to whether the wood dies during heartwood formation, as it can still chemically react to decay organisms, but only once. The term heartwood derives solely from its position and not from any vital importance to
2403-399: Is in the walls, not the cavities. Hence the greater the proportion of latewood, the greater the density and strength. In choosing a piece of pine where strength or stiffness is the important consideration, the principal thing to observe is the comparative amounts of earlywood and latewood. The width of ring is not nearly so important as the proportion and nature of the latewood in the ring. If
2492-486: Is known as secondary growth ; it is the result of cell division in the vascular cambium , a lateral meristem, and subsequent expansion of the new cells. These cells then go on to form thickened secondary cell walls, composed mainly of cellulose , hemicellulose and lignin . Where the differences between the seasons are distinct, e.g. New Zealand , growth can occur in a discrete annual or seasonal pattern, leading to growth rings ; these can usually be most clearly seen on
2581-431: Is laid down on the outside of the wood previously formed, it follows that unless a tree materially increases its production of wood from year to year, the rings must necessarily become thinner as the trunk gets wider. As a tree reaches maturity its crown becomes more open and the annual wood production is lessened, thereby reducing still more the width of the growth rings. In the case of forest-grown trees so much depends upon
2670-470: Is more complex. The water conducting capability is mostly taken care of by vessels : in some cases (oak, chestnut, ash) these are quite large and distinct, in others ( buckeye , poplar , willow ) too small to be seen without a hand lens. In discussing such woods it is customary to divide them into two large classes, ring-porous and diffuse-porous . In ring-porous species, such as ash, black locust, catalpa , chestnut, elm , hickory, mulberry , and oak,
2759-431: Is the rule. Some others never form heartwood. Heartwood is often visually distinct from the living sapwood and can be distinguished in a cross-section where the boundary will tend to follow the growth rings. For example, it is sometimes much darker. Other processes such as decay or insect invasion can also discolor wood, even in woody plants that do not form heartwood, which may lead to confusion. Sapwood (or alburnum )
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2848-492: Is the trafficking of contraband weapons and ammunition . What constitutes legal trade in firearms varies widely, depending on local and national laws. In 2001, the United Nations had made a protocol against the manufacturing and trafficking of illicit arms. This protocol made governments dispose illegal arms, and to licence new firearms being produced, to ensure them being legitimate. It was signed by 122 parties. There are
2937-413: Is the younger, outermost wood; in the growing tree it is living wood, and its principal functions are to conduct water from the roots to the leaves and to store up and give back according to the season the reserves prepared in the leaves. By the time they become competent to conduct water, all xylem tracheids and vessels have lost their cytoplasm and the cells are therefore functionally dead. All wood in
3026-400: Is then known as the latewood or summerwood. There are major differences, depending on the kind of wood. If a tree grows all its life in the open and the conditions of soil and site remain unchanged, it will make its most rapid growth in youth, and gradually decline. The annual rings of growth are for many years quite wide, but later they become narrower and narrower. Since each succeeding ring
3115-461: Is usually the latewood in which the thick-walled, strength-giving fibers are most abundant. As the breadth of ring diminishes, this latewood is reduced so that very slow growth produces comparatively light, porous wood composed of thin-walled vessels and wood parenchyma. In good oak, these large vessels of the earlywood occupy from six to ten percent of the volume of the log, while in inferior material they may make up 25% or more. The latewood of good oak
3204-460: The Geneva Protocol , was issued in 1925 and was accepted as policy by all major countries. In 1937, poison gas was manufactured in large quantities but not used except against nations that lacked modern weapons or gas masks. Many modern military weapons, particularly ground-based ones, are relatively minor improvements to weapon systems developed during World War II. World War II marked perhaps
3293-537: The Schöningen spears , eight wooden throwing spears dating back more than 300,000 years. At the site of Nataruk in Turkana, Kenya, numerous human skeletons dating to 10,000 years ago may present evidence of traumatic injuries to the head, neck, ribs, knees, and hands, including obsidian projectiles embedded in the bones that might have been caused by arrows and clubs during conflict between two hunter-gatherer groups. But
3382-572: The arquebus were much more powerful than human-powered weapons. Firearms became increasingly important and effective during the 16th–19th centuries, with progressive improvements in ignition mechanisms followed by revolutionary changes in ammunition handling and propellant. During the American Civil War , new applications of firearms, including the machine gun and ironclad warship , emerged that would still be recognizable and useful military weapons today, particularly in limited conflicts . In
3471-401: The grain of the rest of the wood "flows" (parts and rejoins). Within a knot, the direction of the wood (grain direction) is up to 90 degrees different from the grain direction of the regular wood. In the tree a knot is either the base of a side branch or a dormant bud. A knot (when the base of a side branch) is conical in shape (hence the roughly circular cross-section) with the inner tip at
3560-429: The resin which increases the strength when dry. Such resin-saturated heartwood is called "fat lighter". Structures built of fat lighter are almost impervious to rot and termites , and very flammable. Tree stumps of old longleaf pines are often dug, split into small pieces and sold as kindling for fires. Stumps thus dug may actually remain a century or more since being cut. Spruce impregnated with crude resin and dried
3649-578: The trireme , were in use by the 7th century BC. During the first First Punic War , the use of advanced warships contributed to a Roman victory over the Carthaginians. European warfare during post-classical history was dominated by elite groups of knights supported by massed infantry (both in combat and ranged roles). They were involved in mobile combat and sieges , which involved various siege weapons and tactics. Knights on horseback developed tactics for charging with lances , providing an impact on
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3738-409: The 19th century, warship propulsion changed from sail power to fossil fuel -powered steam engines . Since the mid-18th century North American French-Indian war through the beginning of the 20th century, human-powered weapons were reduced from the primary weaponry of the battlefield to yielding gunpowder-based weaponry. Sometimes referred to as the "Age of Rifles", this period was characterized by
3827-563: The 4th century BC. Cavalry developed once horses were bred to support the weight of a human. The horse extended the range and increased the speed of attacks. Alexander's conquest saw the increased use of spears and shields in the Middle East and Western Asia as a result Greek culture spread which saw many Greek and other European weapons be used in these regions and as a result many of these weapons were adapted to fit their new use in war In addition to land-based weaponry, warships , such as
3916-433: The addition of steel and bronze into construction. The year-to-year variation in tree-ring widths and isotopic abundances gives clues to the prevailing climate at the time a tree was cut. Wood, in the strict sense, is yielded by trees , which increase in diameter by the formation, between the existing wood and the inner bark , of new woody layers which envelop the entire stem, living branches, and roots. This process
4005-418: The annual rings of growth and the amount of sapwood. Within the same species the cross-sectional area of the sapwood is very roughly proportional to the size of the crown of the tree. If the rings are narrow, more of them are required than where they are wide. As the tree gets larger, the sapwood must necessarily become thinner or increase materially in volume. Sapwood is relatively thicker in the upper portion of
4094-442: The beginning of the implementation of firearms in western warfare. Guns and rockets were introduced to the battlefield. Firearms are qualitatively different from earlier weapons because they release energy from combustible propellants , such as gunpowder , rather than from a counterweight or spring. This energy is released very rapidly and can be replicated without much effort by the user. Therefore, even early firearms such as
4183-449: The border between the two classes, forming an intermediate group. In temperate softwoods, there often is a marked difference between latewood and earlywood. The latewood will be denser than that formed early in the season. When examined under a microscope, the cells of dense latewood are seen to be very thick-walled and with very small cell cavities, while those formed first in the season have thin walls and large cell cavities. The strength
4272-458: The cell walls are composed of micro-fibrils of cellulose (40–50%) and hemicellulose (15–25%) impregnated with lignin (15–30%). In coniferous or softwood species the wood cells are mostly of one kind, tracheids , and as a result the material is much more uniform in structure than that of most hardwoods . There are no vessels ("pores") in coniferous wood such as one sees so prominently in oak and ash, for example. The structure of hardwoods
4361-435: The central portion one-fourth the height of the beam from either edge are not serious defects. Knots do not necessarily influence the stiffness of structural timber; this will depend on the size and location. Stiffness and elastic strength are more dependent upon the sound wood than upon localized defects. The breaking strength is very susceptible to defects. Sound knots do not weaken wood when subject to compression parallel to
4450-445: The competition of the trees in their struggle for light and nourishment that periods of rapid and slow growth may alternate. Some trees, such as southern oaks , maintain the same width of ring for hundreds of years. On the whole, as a tree gets larger in diameter the width of the growth rings decreases. As a tree grows, lower branches often die, and their bases may become overgrown and enclosed by subsequent layers of trunk wood, forming
4539-412: The contents being dumped on the floor. There are at least two ways to make the full interior of a drawer visible, while still being completely supported by the cabinet. One way places the back of the drawer such that it is fully visible when the drawer hits the stop -- the interior of such a drawer is much shorter than the sides of the drawer. That visible back of the drawer may be a false back that conceals
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#17328559032544628-433: The contrast is conspicuous (see section of yew log above). This is produced by deposits in the heartwood of chemical substances, so that a dramatic color variation does not imply a significant difference in the mechanical properties of heartwood and sapwood, although there may be a marked biochemical difference between the two. Some experiments on very resinous longleaf pine specimens indicate an increase in strength, due to
4717-498: The development of ancient weapons. It was not the introduction of early Iron Age swords , however, as they were not superior to their bronze predecessors, but rather the domestication of the horse and widespread use of spoked wheels by c. 2000 BC . This led to the creation of the light, horse-drawn chariot , whose improved mobility proved important during this era. Spoke-wheeled chariot usage peaked around 1300 BC and then declined, ceasing to be militarily relevant by
4806-426: The development of firearms for infantry and cannons for support, as well as the beginnings of mechanized weapons such as the machine gun . Artillery pieces such as howitzers were able to destroy masonry fortresses and other fortifications, and this single invention caused a revolution in military affairs , establishing tactics and doctrine that are still in use today. An important feature of industrial age warfare
4895-428: The development, production, stockpiling, proliferation, and usage of weapons, from small arms and heavy weapons to weapons of mass destruction . Arms control is typically exercised through the use of diplomacy, which seeks to impose such limitations upon consenting participants, although it may also comprise efforts by a nation or group of nations to enforce limitations upon a non-consenting country. Arms trafficking
4984-415: The end of a log, but are also visible on the other surfaces. If the distinctiveness between seasons is annual (as is the case in equatorial regions, e.g. Singapore ), these growth rings are referred to as annual rings. Where there is little seasonal difference growth rings are likely to be indistinct or absent. If the bark of the tree has been removed in a particular area, the rings will likely be deformed as
5073-409: The end of this period revolutionized warfare. Formations of musketeers , protected by pikemen , came to dominate open battles, and the cannon replaced the trebuchet as the dominant siege weapon . The Ottoman used the cannon to destroy much of the fortifications at Constantinople which would change warfare as gunpowder became more available and technology improved The European Renaissance marked
5162-652: The enemy formations, and then drawing more practical weapons (such as swords ) once they entered melee. By contrast, infantry, in the age before structured formations, relied on cheap, sturdy weapons such as spears and billhooks in close combat and bows from a distance. As armies became more professional, their equipment was standardized, and infantry transitioned to pikes . Pikes are normally seven to eight feet in length and used in conjunction with smaller sidearms (short swords). In Eastern and Middle Eastern warfare, similar tactics were developed independent of European influences. The introduction of gunpowder from Asia at
5251-403: The exact mechanisms determining the formation of earlywood and latewood. Several factors may be involved. In conifers, at least, rate of growth alone does not determine the proportion of the two portions of the ring, for in some cases the wood of slow growth is very hard and heavy, while in others the opposite is true. The quality of the site where the tree grows undoubtedly affects the character of
5340-422: The fingers on the bottom side of its front. Some drawers can be locked, notably in filing cabinet and desk drawers. Drawer slides often have a mechanism to keep the drawer from accidentally being pulled fully from its enclosure. With the simplest kinds of mounting, the drawer cannot be pulled out sufficiently to see the full interior, without pulling the drawer completely out of the cabinet, often leading to
5429-505: The grain. In some decorative applications, wood with knots may be desirable to add visual interest. In applications where wood is painted , such as skirting boards, fascia boards, door frames and furniture, resins present in the timber may continue to 'bleed' through to the surface of a knot for months or even years after manufacture and show as a yellow or brownish stain. A knot primer paint or solution (knotting), correctly applied during preparation, may do much to reduce this problem but it
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#17328559032545518-412: The greater the water content, the greater its softening effect. The moisture in wood can be measured by several different moisture meters . Drying produces a decided increase in the strength of wood, particularly in small specimens. An extreme example is the case of a completely dry spruce block 5 cm in section, which will sustain a permanent load four times as great as a green (undried) block of
5607-464: The interpretation of warfare at Nataruk has been challenged due to conflicting evidence. The earliest ancient weapons were evolutionary improvements of late Neolithic implements, but significant improvements in materials and crafting techniques led to a series of revolutions in military technology . The development of metal tools began with copper during the Copper Age (about 3,300 BC) and
5696-472: The interwar period (between WWI and WWII) with the continuous evolution of weapon systems by all major industrial powers. The major armament firms were Schneider-Creusot (based in France), Škoda Works (Czechoslovakia), and Vickers (Great Britain). The 1920s were committed to disarmament and the outlawing of war and poison gas, but rearmament picked up rapidly in the 1930s. The munitions makers responded nimbly to
5785-412: The joint. To secure the bottom piece, a groove is typically cut into the four vertical sides to hold the drawer bottom in place. One or two handles or drawer pulls are commonly attached to the front face of the drawer to facilitate pulling it out from its enclosure. In some cases, drawers may have another means by which to pull it, including holes cut in the front face or a hollowed-out area to insert
5874-407: The larger vessels or pores (as cross sections of vessels are called) are localized in the part of the growth ring formed in spring, thus forming a region of more or less open and porous tissue. The rest of the ring, produced in summer, is made up of smaller vessels and a much greater proportion of wood fibers. These fibers are the elements which give strength and toughness to wood, while the vessels are
5963-572: The manufacture, sale, transfer, possession, modification, and use of small arms by civilians. Countries that regulate access to firearms will typically restrict access to certain categories of firearms and then restrict the categories of persons who may be granted a license for access to such firearms. There may be separate licenses for hunting, sport shooting (a.k.a. target shooting), self-defense, collecting, and concealed carry, with different sets of requirements, permissions, and responsibilities. International treaties and agreements place restrictions on
6052-480: The moisture content of the air) retains 8–16% of the water in the cell walls, and none, or practically none, in the other forms. Even oven-dried wood retains a small percentage of moisture, but for all except chemical purposes, may be considered absolutely dry. The general effect of the water content upon the wood substance is to render it softer and more pliable. A similar effect occurs in the softening action of water on rawhide, paper, or cloth. Within certain limits,
6141-453: The most frantic period of weapon development in the history of humanity. Massive numbers of new designs and concepts were fielded, and all existing technologies were improved between 1939 and 1945. The most powerful weapon invented during this period was the nuclear bomb ; however, many other weapons influenced the world, such as jet aircraft and radar , but were overshadowed by the visibility of nuclear weapons and long-range rockets. Since
6230-542: The other hand, the latewood is very dense and is deep-colored, presenting a very decided contrast to the soft, straw-colored earlywood. It is not only the proportion of latewood, but also its quality, that counts. In specimens that show a very large proportion of latewood it may be noticeably more porous and weigh considerably less than the latewood in pieces that contain less latewood. One can judge comparative density, and therefore to some extent strength, by visual inspection. No satisfactory explanation can as yet be given for
6319-404: The plant overgrows the scar. If there are differences within a growth ring, then the part of a growth ring nearest the center of the tree, and formed early in the growing season when growth is rapid, is usually composed of wider elements. It is usually lighter in color than that near the outer portion of the ring, and is known as earlywood or springwood. The outer portion formed later in the season
6408-605: The point in stem diameter at which the plant's vascular cambium was located when the branch formed as a bud. In grading lumber and structural timber , knots are classified according to their form, size, soundness, and the firmness with which they are held in place. This firmness is affected by, among other factors, the length of time for which the branch was dead while the attaching stem continued to grow. Knots materially affect cracking and warping, ease in working, and cleavability of timber. They are defects which weaken timber and lower its value for structural purposes where strength
6497-461: The point of being able to ensure the destruction of the Earth by 100 fold, a new tactic had to be developed. With this realization, armaments development funding shifted back to primarily sponsoring the development of conventional arms technologies for support of limited wars rather than total war . The arms industry is a global industry that involves the sale and manufacture of weaponry. It consists of
6586-411: The properties of the wood. Certain rot-producing fungi impart to wood characteristic colors which thus become symptomatic of weakness. Ordinary sap-staining is due to fungal growth, but does not necessarily produce a weakening effect. Water occurs in living wood in three locations, namely: In heartwood it occurs only in the first and last forms. Wood that is thoroughly air-dried (in equilibrium with
6675-412: The purpose; these range from simple implements such as clubs , axes , spears , and swords to complicated modern firearms , tanks , intercontinental ballistic missiles , biological weapons , and cyberweapons . Something that has been repurposed, converted, or enhanced to become a weapon of war is termed weaponized , such as a weaponized virus or weaponized laser . The use of weapons has been
6764-516: The rapidly shifting strategic and economic landscape. The main purchasers of munitions from the big three companies were Romania, Yugoslavia, Greece, and Turkey – and, to a lesser extent, Poland, Finland, the Baltic States, and the Soviet Union. Realistic critics understood that war could not really be outlawed, but its worst excesses might be banned. Poison gas became the focus of
6853-541: The realization of mutual assured destruction (MAD), the nuclear option of all-out war is no longer considered a survivable scenario. During the Cold War in the years following World War II, both the United States and the Soviet Union engaged in a nuclear arms race . Each country and their allies continually attempted to out-develop each other in the field of nuclear armaments. Once the joint technological capabilities reached
6942-603: The realms of known physical possibility. At its most prosaic, science fiction features an endless variety of sidearms , mostly variations on real weapons such as guns and swords . Among the best-known of these are the phaser used in the Star Trek television series, films, and novels, and the lightsaber and blaster featured in the Star Wars movies, comics, novels, and TV series. In addition to adding action and entertainment value, weaponry in science fiction sometimes becomes
7031-468: The reverse is commonly true. Otherwise the color of wood is no indication of strength. Abnormal discoloration of wood often denotes a diseased condition, indicating unsoundness. The black check in western hemlock is the result of insect attacks. The reddish-brown streaks so common in hickory and certain other woods are mostly the result of injury by birds. The discoloration is merely an indication of an injury, and in all probability does not of itself affect
7120-453: The same size will. The greatest strength increase due to drying is in the ultimate crushing strength, and strength at elastic limit in endwise compression; these are followed by the modulus of rupture, and stress at elastic limit in cross-bending, while the modulus of elasticity is least affected. Wood is a heterogeneous , hygroscopic , cellular and anisotropic (or more specifically, orthotropic ) material. It consists of cells, and
7209-494: The same type of tissue elsewhere, such as in the roots of trees or shrubs. In a living tree, it performs a mechanical-support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients among the leaves , other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, woodchips , or fibers . Wood has been used for thousands of years for fuel , as
7298-430: The tree, may well be stronger than a piece of heartwood from the same tree. Different pieces of wood cut from a large tree may differ decidedly, particularly if the tree is big and mature. In some trees, the wood laid on late in the life of a tree is softer, lighter, weaker, and more even textured than that produced earlier, but in other trees, the reverse applies. This may or may not correspond to heartwood and sapwood. In
7387-445: The tree. This is evidenced by the fact that a tree can thrive with its heart completely decayed. Some species begin to form heartwood very early in life, so having only a thin layer of live sapwood, while in others the change comes slowly. Thin sapwood is characteristic of such species as chestnut , black locust , mulberry , osage-orange , and sassafras , while in maple , ash , hickory , hackberry , beech , and pine, thick sapwood
7476-416: The trunk of a tree than near the base, because the age and the diameter of the upper sections are less. When a tree is very young it is covered with limbs almost, if not entirely, to the ground, but as it grows older some or all of them will eventually die and are either broken off or fall off. Subsequent growth of wood may completely conceal the stubs which will remain as knots. No matter how smooth and clear
7565-461: The wide introduction of aircraft into warfare and naval warfare with the introduction of aircraft carriers . Above all, it promised the military commanders independence from horses and a resurgence in maneuver warfare through the extensive use of motor vehicles. The changes that these military technologies underwent were evolutionary but defined their development for the rest of the century. This period of innovation in weapon design continued in
7654-418: The wood formed, though it is not possible to formulate a rule governing it. In general, where strength or ease of working is essential, woods of moderate to slow growth should be chosen. In ring-porous woods, each season's growth is always well defined, because the large pores formed early in the season abut on the denser tissue of the year before. In the case of the ring-porous hardwoods, there seems to exist
7743-410: Was technological escalation – innovations were rapidly matched through replication or countered by another innovation. World War I marked the entry of fully industrialized warfare as well as weapons of mass destruction ( e.g. , chemical and biological weapons ), and new weapons were developed quickly to meet wartime needs. The technological escalation during World War I was profound, including
7832-434: Was 16 percent higher than in 2005–2009, and the arms sales of the world's 100 largest private arms-producing and military services companies totaled $ 420 billion in 2018. The production, possession, trade, and use of many weapons are controlled. This may be at a local or central government level or by international treaty. Examples of such controls include: All countries have laws and policies regulating aspects such as
7921-616: Was followed by the Bronze Age , leading to the creation of the Bronze Age sword and similar weapons. During the Bronze Age, the first defensive structures and fortifications appeared as well, indicating an increased need for security. Weapons designed to breach fortifications followed soon after, such as the battering ram , which was in use by 2500 BC. The development of ironworking around 1300 BC in Greece had an important impact on
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