Roundel

A roundel in heraldry is any circular shape; the term is also commonly used to refer to a type of national insignia used on military aircraft, generally circular in shape and usually comprising concentric rings of different colours. In heraldry, a roundel is a circular charge. Roundels are among the oldest charges used in coats of arms, dating from at least the [...]

Round Table

The Round Table is King Arthur’s famed table in the Arthurian legend, around which he and his Knights congregate. As its name suggests, it has no head, implying that everyone who sits there has equal status. The table was first described in 1155 by Wace, who relied on previous depictions of Arthur’s fabulous retinue. The [...]

Notitia Dignitatum

The Notitia Dignitatum is a unique document of the Roman imperial chanceries. One of the very few surviving documents of Roman government, it details the administrative organisation of the eastern and westernempires, listing several thousand offices from the imperial court down to the provincial level. It is usually considered to be up to date for the Western empire in the 420s, [...]

Taijitu

Taijitu (a Chinese word that translates roughly as ‘diagram of ultimate power’) is a term which refers to any of the Chinese symbols for the concept of yin yang, and is sometimes extended to similar geometric patterns used historically by various cultures. The most recognized form is composed of two semi-circular teardrop-shaped curves of different colors, or [...]

Sesame street/Philip Glass: Geometry of circles

Spirograph

Spirograph is a geometric drawing toy that produces mathematical curves of the variety technically known as hypotrochoids and epitrochoids. The term has also been used to describe a variety of software applications that display similar curves, and applied to the class of curves that can be produced with the drawing equipment (so in this sense it may be regarded as a [...]

Vitruvian Man

 

The Vitruvian Man is a world-renowned drawing created by Leonardo da Vinci around the year 1487 It is accompanied by notes based on the work of Vitruvius. The drawing, which is in pen and ink on paper, depicts a nude male figure in two superimposed positions with his arms and legs apart and simultaneously inscribed in a circle and square. The drawing and [...]

ISO 216

ISO 216 specifies international standard (ISO) paper sizes used in most countries in the world today. It is the standard which defines the commonly available A4 paper size. The underlying principle is that when rectangles with width/length ratio  are cut or folded in half the rectangles thus formed retain the original width/length ratio.
 
The international ISO standard is based on the German DIN standard [...]

Bora (rings)

A Bora is the name given both to an initiation ceremony of Indigenous Australians, and to the site on which the initiation is performed. At such a site, young boys are transformed into men. The initiation ceremony differs from culture to culture, but often involves circumcision and scarification, and may also involve the removal of [...]

Carolingian cross

 

A variation of the Everlasting Cross is the Carolingian Cross, named after the Carolingian dynasty, a Frankish noble family that can be traced back to the seventh century. One member of this family, Pepin the Short, was crowned King of the Franks by the church, who saw this as a useful way to extend their authority over the [...]