Zodiac: a band 18 o wide that is centered on the ecliptic. The zodiac comes from the Greek word for "circle of animals" that form the various constellation of stars in the eclilptic. The constellation of animals aries (the ram), taurus (the bull), cancer (the crab), leo (the lion), scorpius (the scorpion), and capricornus (the capricorn) were named at least a thousand years before by Babylonian and Chaldean astronomers. Since Roman times we also have constellation of libra (scales) and the representation of people in the form of aquarius (the water carrier), gemini (the twins), virgo (the virgin), and sagittarius (the archer). Brashear, Ronald (May 1999). "Astronomiæ instauratæ mechanica by Tycho Brahe: Introduction". Special Collections Department. Smithsonian Institution Libraries . Retrieved July 11, 2020. The Symonds papers are held by Winterthur Museum in the USA. With the Symonds papers is an album of photographs labelled ‘Furniture Sandridgebury No 1’. Symonds wrote a ‘Portrait of a Collector’ about Percival Griffiths, in Country Life, June 13, 1952. R W Symonds’ book ‘English Furniture from Charles II to George II’ (1929) is illustrated with items from the Sandridgebury collection. In the foreword Griffiths writes of his experience and philosophy as a collector. See also 'Intuitively Collected', by Simon Houfe, Country Life 27 December 1990.

The metal rings, usually made of brass or bronze, are referred to as armilla, which is Latin for bracelet. Armilla were prestigious armbands awarded to Roman soldiers for distinguished gallantry. The whole fabric is supported on a pedestal N, and may be elevated or depressed upon the joint O, to any number of degrees from 0 to 90, by means of the arc P, which is fixed in the strong brass arm Q, and slides in the upright piece R, in which is a screw at r, to fix it at any proper elevation. Equinoctial colure: meridian or great circle that passes through the celestial poles and the two equinoxes (first point of Aries and first point of Libra). The Greek astronomer Hipparchus ( c. 190– c. 120 BC) credited Eratosthenes (276–194 BC) as the inventor of the armillary sphere. [11] [12] [13] [14] [15] Names of this device in Greek include ἀστρολάβος astrolabos and κρικωτὴ σφαῖρα krikōtē sphaira "ringed sphere". [16] The English name of this device comes ultimately from the Latin armilla (circle, bracelet), since it has a skeleton made of graduated metal circles linking the poles and representing the equator, the ecliptic, meridians and parallels. Usually a ball representing the Earth or, later, the Sun is placed in its center. It is used to demonstrate the motion of the stars around the Earth. Before the advent of the European telescope in the 17th century, the armillary sphere was the prime instrument of all astronomers in determining celestial positions. And so, by this construction, the machine is equally fitted to show either the real motion of the earth, or the apparent motion of the heavens.About it rotate a set of rings representing the heavens – the celestial sphere – with one complete revolution approximating 24 hours.

The British Museum has a collection of several armillary sphere rings that are incredibly well-crafted and detailed. When closed, they look like any other ring, but as the different bands are fanned out, the rings take on a unique quality. Built with anywhere between two to eight moving bands, these intricate pieces of jewelry would need to have been executed by skilled craftsmen. The Arctic Circle E, and the Antarctic Circle F, each 23 1⁄ 2 degrees from its respective pole at N and S. Prime Vertical: the great circle that passes through the zenith and nadir, and intersects the horizon at its east and west points. An armillary sphere (variations are known as spherical astrolabe, armilla, or armil) is a model of objects in the sky (on the celestial sphere), consisting of a spherical framework of rings, centered on Earth or the Sun, that represent lines of celestial longitude and latitude and other astronomically important features, such as the ecliptic. As such, it differs from a celestial globe, which is a smooth sphere whose principal purpose is to map the constellations. It was invented separately, in ancient China possibly as early as the 4th century BC and ancient Greece during the 3rd century BC, with later uses in the Islamic world and Medieval Europe. Antarctic Circle: This small circle forms the southernmost latitude on earth at which the center of the sun’s disk travels completely around the horizon for a full 24 hours on the December solstice (summer solstice in the Southern hemisphere). Currently the latitude of the Antarctic Circleis 66 o 33.8’ S. The latitude of the Antarctic Circlevaries from67.9 o S and 65.5 o Sover about 41,000 years. The Antarctic Circleis moving north toward the equator at about 50 feet per year.

Used by astronomers to study and make calculations, these pieces of jewelry were considered tokens of knowledge.

The armillary sphere was reintroduced in the national arms and in the national Flag of Portugal in 1911.

An armillary sundial also called an armillary sphere is a representation of both the terrestrial globe and celestial sphere. Often highly decorated, these are beautiful sundials. Dirk L. Couprie, Robert Hahn, Gerard Naddaf: Anaximander in Context: New Studies in the Origins of Greek Philosophy, 2003, ISBN 978-0-7914-5537-1, p. 179 Williams, Henry Smith (2004). A History Of Science. Whitefish, MT: Kessinger Publishing. ISBN 1-4191-0163-3.

Inscriptions or zodiac symbols were often used as decorative elements on the bands.

Equinoctial: refers to the celestial equator. The term equinoctial refers to the fact that the vernal and autumnal equinoxes occur when the sun passes through this great circle. The celestial equator is a projector of the earth’s equator onto the celestial sphere. The hour markings of the armillary sundial are inscribed on the inner surface of this ring. It is believed that the Greek astronomer Hipparchus invented the armillary sphere around 200BC, to decipher how the heavens and stars moved around the earth. His sphere had a ball representing the earth in the centre, and four overlapping rings circling the globe. The equinoctial colure G, passing through the north and south poles of the heaven at N and S, and through the equinoctial points Aries and Libra, in the ecliptic.

Zenith: in the horizon coordinate system, it is the position directly overhead on the celestial sphere. The zenith’s altitude is 90 o. Colure is one of two principal meridians (great circles) on the celestial sphere—equinoctial colure and solstitial colure.

Tropic of Cancer: This small circle (also called the Northern Tropic) forms the northernmost latitude on earth at which the noontime sun can cross the zenith. This occurs around June 21 and is called the summer solstice in the northern hemisphere. A corresponding circle, also called the Tropic of Cancer, is formed by the projection of the earth’s Tropic of Cancer onto the celestial sphere. In ancient times, the sun passed through the zodiacal constellation of Cancer at this time of year — thus its name Cancer. The word “tropic” derives from the Greek word meaning turn — referring to the point on the sky where the sun changes direction and begins moving south as winter approaches in the northern hemisphere. Today, while precession (the wobble of the earth on its axis) has shifted the summer solstice into the constellational of Taurus, the solstitial sun remains in the astrological sign of Cancer, which is unaffected by precession. The Tropic of Cancer is currently at latitude 23 o 26.2’ N (23.44 o N). Like the obliquity, the latitude of the Tropic of Cancer varies from22.1 o Nand 24.5 o Nover about 41,000 years. The Tropic of Cancer is moving south toward the equator at about 50 feet per year. Arctic Circle: This small circle forms the northernmost latitude on earth at which the center of the sun’s disk travels completely around the horizon for a full 24 hours on the June solstice (summer solstice in the Northern hemisphere). Currently the latitude of the Arctic Circleis 66 o 33.8’ N.The latitude of the Arctic Circlevaries from67.9 o N and 65.5 o Nover about 41,000 years. The Arctic Circleis moving south toward the equator at about 50 feet per year.