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a device used to hold a ship or other floating craft in place in an open area of water. Two kinds of anchor are distinguished: ship anchors and special-purpose anchors. An anchor must be strong and easy to handle and must take and hold any ground well. Anchors may be described according to holding power, which is defined as the force that must be applied per unit of anchor weight to pull the anchor out of the ground when its shank is horizontal. The holding power depends on the design and weight of the anchor and on the type of bottom ground.
The first anchors, which appeared more than 4,000 years ago, took the form of a stone attached to a rope. Such an anchor may be called an anchor stone. The prototype of the admiralty anchor, the most commonly used anchor in the days of the sailing fleets, was developed about 3,000 years ago; it was fashioned from wood. The admiralty anchor (Figure 1) works in the following manner: the lower end of the shank, called the crown, and one end of the stock settle on the bottom; when an attempt is made to pull the anchor along the bottom, the entire length of the
stock comes to rest on the bottom, and one of the flukes digs into the ground. Anchors of this design are reliable and have good holding power (6–12 kilograms-force per 1 kilogram-force of anchor weight). Since, however, the stock and flukes set in mutually perpendicular planes, paying out the admiralty anchor and stowing it are difficult tasks. Use of the admiralty anchor often resulted in accidents involving its own ship or ships passing over the anchor.
Naval evolution, particularly the construction of larger ships, required the design of anchors that would be easy to handle and would have greater holding power. Virtually all anchors today are made with pivoting flukes and no stock. The most efficient and, consequently, most widely used anchor designs (Figure 2) were developed by the Englishman Hall, the Americans Baldt and Bayers, and the German Hein, whose design was modified at the request of the German firm Gruson. The anchor designed by the Soviet engineer I. R. Matrosov has given a good account of itself, and the holding power of the American Danforth anchor is rated at 200 or more kilograms-force. The world’s largest anchor, which was built in the United States in 1954, weighs 27.2 tons. Today’s anchors are made of cast or welded steel.
Permanent mooring anchors of various designs (Figure 3) are used for floating beacons, anchor buoys, dredges, and other structures that must be moored for lengthy periods of time. The anchor proposed by the English hydraulic engineer Mitchell is considered the best of this type.
Special-purpose anchors (Figure 4) are used in various situations. Sea anchors are used by small ships to reduce drift. The
simplest sea anchor consists of a canvas cone. Ice anchors, which are used by vessels navigating through ice, usually have one arm and are merely attached to the edge of an ice crack or to the edge of a hole cut in the ice. Special-purpose anchors are extremely varied in design and weight and may have several arms, as does the grapple, or may have none.
REFERENCESkriagin, L. N. Kniga o iakoriakh. Moscow, 1973.
What does it mean when you dream about an anchor?
Anchors generally convey positive connotations of security, stability, and a harbor against storms. Large bodies of water frequently symbolize the unconscious (or, sometimes, the emotions), making boats vehicles for negotiating the unconscious. Anchors may thus indicate a stable relationship with the unconscious or shelter against the “storms” of the emotions. Loss of an anchor indicates feeling adrift. Less positively, anchors may symbolize a resistance to change or a clinging to a sense of security. As with all dream symbols, the tone and setting of the dream indicate which interpretation is appropriate.
A hypertext browser usually displays a source anchor in some distinctive way, e.g. marked with a special symbol or drawn in a different colour, font or style. When the user activates the link (e.g. by clicking on it with the mouse), the browser displays the destination anchor to which the link refers. Some anchors only look different when the mouse is over them but this forces the user to hunt for them when they should be obvious.
In HTML, anchors are created with the <a..>..</a> construct. The opening "a" tag of a source anchor has an "href" (hypertext reference) attribute giving the destination in the form of a URL - usually a whole node or "page". E.g.
<a href="http://foldoc.org/"> Free On-line Dictionary of Computing</a>
Destination anchors are only used in HTML to name a position within a page using a "name" attribute. E.g.
The name or "fragment identifier" is appended to the URL of the page after a "#":
(Though it is generally better to break pages into smaller units than to have large pages with named sections).
anchor(1) See anchor tag.
(2) In desktop publishing, a format code that keeps a graphic near or next to a text paragraph. If text is added, causing the paragraph to move to a subsequent page, the graphic image is moved along with the anchor.
(3) In a GUI builder (development environment for creating a user interface), a format code that keeps a button, message or other interface control aligned to some part of the window. When the window is expanded, the corners of the control that are not anchored move with the window borders, but not the anchored corner. See user interface control.