Atlas

An atlas is a collection of maps; it is typically a map of Earth or a region of Earth, but there are atlases of the other planets (and their satellites) in the Solar System. Furthermore, atlases of anatomy exist, mapping out the human body or other organisms. Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geographic features and political boundaries, many atlases often feature geopolitical, social, religious and economic statistics. They also have information about the map and places in it.

Etymology

The word atlas dates from 1636, first in reference to the English translation of Atlas, sive cosmographicae meditationes de fabrica mundi (1585) by Flemish geographer Gerhardus Mercator, who might have been the first to use this word in this way. A picture of the Titan Atlas holding up the world appeared on the frontispiece of this and other early map collections.

History

The first work that contained systematically arranged woodcut maps of uniform size, intended to be published in a book, thus representing the first modern atlas, was De Summa totius Orbis (1524–26) by the 16th-century Italian cartographer Pietro Coppo. Nonetheless, this distinction is conventionally awarded to the Flemish cartographer Abraham Ortelius who in 1570 published the collection of maps Theatrum Orbis Terrarum.

Atlas (computer)

The Atlas Computer was a joint development between the University of Manchester, Ferranti, and Plessey. The first Atlas, installed at Manchester University and officially commissioned in 1962, was one of the world's first supercomputers, considered to be the most powerful computer in the world at that time. It was said that whenever Atlas went offline half of the United Kingdom's computer capacity was lost. It was a second-generation machine, using discrete germanium transistors. Two other Atlas machines were built: one for British Petroleum and the University of London, and one for the Atlas Computer Laboratory at Chilton near Oxford.

A derivative system was built by Ferranti for Cambridge University. Called the Titan, or Atlas 2, it had a different memory organisation and ran a time-sharing operating system developed by Cambridge University Computer Laboratory. Two further Atlas 2s were delivered: one to the CAD Centre in Cambridge (later called CADCentre, then AVEVA), and the other to the Atomic Weapons Research Establishment (AWRE), Aldermaston.

Atlas (topology)

In mathematics, particularly topology, one describes a manifold using an atlas. An atlas consists of individual charts that, roughly speaking, describe individual regions of the manifold. If the manifold is the surface of the Earth, then an atlas has its more common meaning. In general, the notion of atlas underlies the formal definition of a manifold and related structures such as vector bundles and other fibre bundles.

Charts

The definition of an atlas depends on the notion of a chart. A chart for a topological space M (also called a coordinate chart, coordinate patch, coordinate map, or local frame) is a homeomorphism from an open subset U of M to an open subset of Euclidean space. The chart is traditionally recorded as the ordered pair .

Formal definition of atlas

An atlas for a topological space M is a collection of charts on M such that . If the codomain of each chart is the n-dimensional Euclidean space and the atlas is connected, then M is said to be an n-dimensional manifold.

Feint

Feint is a French term that entered English via the discipline of swordsmanship and fencing. Feints are maneuvers designed to distract or mislead, done by giving the impression that a certain maneuver will take place, while in fact another, or even none, will. In military tactics and many types of combat, there are two types of feints: feint attacks and feint retreats.

Attacks

A feint attack is designed to draw defensive action towards the point under assault. It is usually used as a diversion to force the enemy to concentrate more manpower in a given area, to weaken the opposing force in another area. Unlike a related diversionary maneuver, the demonstration, a feint involves actual contact with the enemy.

Retreats

A feint retreat is performed by briefly engaging the enemy, then retreating. It is intended to draw the enemy pursuit into a prepared ambush, or to cause disarray. For example, the Battle of Hastings was lost when Saxons pursued the Norman cavalry. This forfeited the advantage of height and the line was broken, providing the opportunity to fight in single handed combat on a neutral vantage point, a battle for which the Saxons were not ready. The Parthian shot is another example of a feint retreat, where mounted Parthian archers would retreat from a battle and then, while still riding, turn their bodies back to shoot at the pursuing enemy.