A quincunx (/ˈkwɪn.kʌŋks/) is a geometric pattern consisting of five points arranged in a cross, with four of them forming a square or rectangle and a fifth at its center. It forms the arrangement of five units in the pattern corresponding to the five-spot on six-sided dice, playing cards, and dominoes. It is represented in Unicode as U+2059⁙FIVE DOT PUNCTUATION or (for the die pattern) U+2684⚄DIE FACE-5.
The quincunx was originally a coin issued by the Roman Republic c. 211–200 BC, whose value was five twelfths (quinque and uncia) of an as, the Roman standard bronze coin. On the Roman quincunx coins, the value was sometimes indicated by a pattern of five dots or pellets. However, these dots were not always arranged in a quincunx pattern.
The Oxford English Dictionary (OED) dates the first appearances of the Latin word in English as 1545 and 1574 ("in the sense 'five-twelfths of a pound or as'"; i.e. 100 old pence). The first citation for a geometric meaning, as "a pattern used for planting trees", dates from 1606. The OED also cites a 1647 reference to the German astronomer Kepler for an astronomical/astrological meaning, an angle of 5/12 of a whole circle. Jackson (1821) states that the word refers to the pattern of trees in an orchard, but then uses it more abstractly for a version of the orchard-planting problem involving patterns of points and lines in the plane (for which the quincunx pattern provides the optimal solution for five points).
In heraldry, groups of five elements (charges) are often arranged in a quincunx pattern, called in saltire in heraldic terminology. The flag of the Solomon Islands features this pattern, with its five stars representing the five main island groups in the Solomon Islands. Another instance of this pattern occurred in the flag of the 19th-century Republic of Yucatán, where it signified the five departments into which the republic was divided.
Quincunxes are used in modern computer graphics as a pattern for multisample anti-aliasing. Quincunx antialiasing samples scenes at the corners and centers of each pixel. These five sample points, in the shape of a quincunx, are combined to produce each displayed pixel. However, samples at the corner points are shared with adjacent pixels, so the number of samples needed is only twice the number of displayed pixels.
The quincunx as a tattoo is known as the five dots tattoo. It has been variously interpreted as a fertility symbol, a reminder of sayings on how to treat women or police, a recognition symbol among the Romani people, a group of close friends, standing alone in the world, or time spent in prison (with the outer four dots representing the prison walls and the inner dot representing the prisoner).Thomas Edison, whose many inventions included an electric pen which later became the basis of a tattooing machine created by Samuel O'Reilly, had this pattern tattooed on his forearm.
The first two stages of the Saturn V super heavy-lift rocket had engines in a quincunx arrangement.
Early African American scientist Benjamin Banneker describes a dream in which he is asked to measure the shape of the soul after death. The answer is "quincunx". Research locates his ancestry in Senegal, where the quincunx is a common religious symbol.
Various literary works use or refer to the quincunx pattern for its symbolic value:
The English physician Sir Thomas Browne in his philosophical discourse The Garden of Cyrus (1658) elaborates upon evidence of the quincunx pattern in art, nature and mystically as evidence of "the wisdom of God". Although Browne wrote about quincunx in its geometric meaning, he may have been influenced by English astrology, as the astrological meaning of "quincunx" (unrelated to the pattern) was introduced by the astronomer Kepler in 1604.
James Joyce uses the term in "Grace", a short story in Dubliners of 1914, to describe the seating arrangement of five men in a church service. Lobner argues that in this context the pattern serves as a symbol both of the wounds of Christ and of the Greek cross.
The Quincunx is the title of a lengthy and elaborate novel by Charles Palliser set in 19th-century England, published in 1989; the pattern appears in the text as a heraldic device, and is also reflected in the structure of the book.
In the first chapter of The Rings of Saturn, W. G. Sebald's narrator cites Browne's writing on the quincunx. The quincunx in turn becomes a model for the way in which the rest of the novel unfolds.
Séamus Heaney describes Ireland's historical provinces as together forming a quincunx, as the Irish word for province cúige (literally: "fifth part") also explicates. The five provinces of Ireland were Ulster (north), Leinster (east), Connacht (west), Munster (south) and Meath (center, and now a county within Leinster). More specifically, in his essay Frontiers of Writing, Heaney creates an image of five towers forming a quincunx pattern within Ireland, one tower for each of the five provinces, each having literary significance.