bark, outer covering of the stem of woody plants, composed of waterproof cork cells protecting a layer of food-conducting tissue—the phloem or inner bark (also called bast). As the woody stem increases in size (see cambium), the outer bark of inelastic dead cork cells gives way in patterns characteristic of the species: it may split to form grooves; shred, as in the cedar; or peel off, as in the sycamore or the shagbark hickory. A layer of reproductive cells called the cork cambium produces new cork cells to replace or reinforce the old. The cork of commerce is the carefully harvested outer bark of the cork oak (Quercus suber), a native of S Europe. The phloem (see stem) conducts sap downward from the leaves to be used for storage and to nourish other plant parts. "Girdling" a tree, i.e., cutting through the phloem tubes, results in starvation of the roots and, ultimately, death of the tree; trees are sometimes girdled by animals that eat bark. The fiber cells that strengthen and protect the phloem ducts are a source of such textile fibers as hemp, flax, and jute; various barks supply tannin, cork (see cork oak), dyes, flavorings (e.g., cinnamon), and drugs (e.g., quinine). The outer bark of the paper birch was used by Native Americans to make baskets and canoes.

bark or barque, sailing vessel with three masts, of which the mainmast and the foremast are square-rigged while the mizzenmast is fore-and-aft-rigged. Although the word was once used to mean any small boat, later barks were sometimes quite large (up to 6,000 tons). In addition to the standard three-masted bark there are also four-masted barks (fore-and-aft-rigged on the aftermast) and barkentines, or three-masted vessels with the foremast square-rigged and the other masts fore-and-aft-rigged. Large numbers of barks were employed in carrying wheat from Australia to England before World War I; and in 1926 the bark Beatrice sailed from Fremantle, Western Australia, to London in 86 days.

Abstract and figurative designs applied to nonwoven fabric made from bark. Also called tapa, the pieces are made by scratching or painting the designs. The most popular material is the inner bark of the paper mulberry tree. The bark is stripped off, soaked, and beaten until it is thin. Today hand-painted bark cloth is made in northern Australia, New Guinea, and parts of Melanesia. Styles and imagery vary by location, from naturalistic and stylized representations of human and animal forms to mythical beings, spirals, circles, and abstract motifs.

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Any member of the beetle family Scolytidae, many of which severely damage trees. Bark beetles are cylindrical, brown or black, and usually less than 0.25 in. (6 mm) long. A male and females (as many as 60 females with each male) bore into a tree and form a chamber where each female deposits her eggs. The emerging larvae bore away from the chamber, forming a characteristic series of tunnels. Different species attack particular trees, damaging roots, stems, seeds, or fruits. Some species transmit disease (e.g., elm bark beetles carry spores of the fungal Dutch elm disease).

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In woody plants, tissues outside of the vascular cambium. The term is also used more popularly to refer to all tissues outside the wood. The inner soft bark is produced by the vascular cambium; it consists of secondary phloem (food-conducting) tissue whose innermost layer transports food from the leaves to the rest of the plant. The layered outer bark contains cork and old, dead phloem. The bark is usually thinner than the woody part of the stem or root.

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BARK (Binär Aritmetisk Relä-Kalkylator, Swedish for "Binary Arithmetic Relay Calculator") was an early electromechanical computer. BARK was built using standard phone relays, implementing a 32-bit binary machine and could perform addition in 150 ms and multiplication in 250 ms. It had a memory with 50 registers and 100 constants. It was later expanded to double the memory. Howard Aiken stated in reference to BARK "This is the first computer I have seen outside Harvard that actually works."

BARK was developed by Matematikmaskinnämnen a few years before BESK. The machine was built with 8000 standard phone relays, 80 km of cable and with 175,000 soldering points. It was completed in February 1950 at a cost of 400.000 Swedish kronor, became operational on April 28, and was taken offline on September 22 1954. The engineers on the team led by Conny Palm were Harry Freese, Gösta Neovius, Olle Karlqvist, Carl-Erik Fröberg, G. Kellberg, Björn Lind, Arne Lindberger, P. Petersson and M. Wallmark.

External links

• http://www.algonet.se/~rittsel/dator/bark1.htm
• Tekn. lic. Olle Karlqvist in memoriam, memorial site of one of the engineers behind BARK and BESK