This section, edited from the Encyclopedia Britannica first edition, refers to labels in the diagram below. (Open it in a second window on your screen for easy magnified reference.)
Armillary sphere diagram
The exterior parts of this machine are a compages [or framework] of brass rings, which represent the principal circles of the heavens:
The equinoctial A, which is divided into 360 degrees (beginning at its intersection with the ecliptic in Aries) for showing the sun's right ascension in degrees; and also into 24 hours, for showing its right ascension in time.
The ecliptic B, which is divided into 12 signs, and each sign into 30 degrees, and also into the months and days of the year, in such a manner that the degree or point of the ecliptic on which the sun appears, on any given day, stands over that day in the circle of months.
The tropic of CancerC, touching the ecliptic at the beginning of Cancer in e, and the tropic of CapricornD, touching the ecliptic at the beginning of Capricorn in f; each circle 231⁄2 degrees from the equinoctial circle.
The equinoctial colureG, passing through the north and south poles of the heavens at N and S, and through the equinoctial points in Aries and Libra, in the ecliptic.
The solstitial colureH, passing through the poles of the heavens, and through the solstitial points in Cancer and Capricorn, in the ecliptic. Each quarter of the equinoctial colure is divided into 90 degrees, from the equinoctial to the poles of the world, for showing the declination of the sun, moon, and stars; and each quarter of the solstitial colure, from the ecliptic as e and f, to its poles b and d, for showing the latitude of the stars.
In the north pole of the ecliptic is a nut b, to which is fixed one end of the quadrantal wire. To the other end is a small sun Y, which is carried around the ecliptic B—B, by turning the nut. In the south pole of the ecliptic is a pin d, on which another quadrantal wire is situated, with a small moon Ζ upon it, which may be moved around by hand. A mechanism causes the moon to move in an orbit which crosses the ecliptic at an angle of 51⁄3 degrees, to opposite points called the lunar nodes, and allows for shifting these points backward in the ecliptic, as the lunar nodes shift in the heavens.
Within these circular rings is a small terrestrial globe I, fixed on an axis K, which extends from the north and south poles of the globe at n and s, to those of the celestial sphere at N and S. On this axis the flat celestial meridian L is fixed, which may be set directly over the meridian of any place on the globe, so as to keep over the same meridian upon it. This flat meridian is graduated the same way as the brass meridian of the common globe, and its use is much the same.
To this globe is fitted the movable horizon M, so as to turn upon the two strong wires proceeding from its east and west points to the globe and entering the globe at the opposite points off its equator, which is a movable brass ring set into the globe in a groove all around its equator. The globe may be turned by hand within this ring, so as to place any given meridian upon it, directly under the celestial meridian L. The horizon is divided into 360 degrees all around its outermost edge, within which are the points of the compass, for showing the amplitude of the sun and the moon, both in degrees and points. The celestial meridian L passes through two notches in the north and south points of the horizon, as in a common globe: if the globe is turned around, the horizon and meridian turn with it. At the south pole of the sphere is a circle of 25 hours, fixed to the rings. On the axis is an index which goes around that circle, if the globe is turned around its axis.
The original diagram of Chinese scientist Su Song's book of 1092 showing the inner workings of his clocktower; a mechanically rotated armillary sphere crowns the top.
The globe assembly 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. The globe assembly slides in the upright piece R, in which is a screw at r, to fix it at any proper elevation.
In the box T are two wheels (as in Dr Long's sphere) and two pinions, whose axes come out at V and U; either of which may be turned by the small winch W. When the winch is put upon the axis V, and turn backward, the terrestrial globe, with its horizon and celestial meridian, keep at rest; and the whole sphere of circles turns round from east, by south, to west, carrying the sun Y, and moon Z, round the same way, and causing them to rise above and set below the horizon. But when the winch is put upon the axis U, and turned forward, the sphere with the sun and moon keep at rest; and the earth, with its horizon and meridian, turn round from horizon to the sun and moon, to which these bodies came when the earth kept at rest, and they were carried round it; showing that they rise and set in the same points of the horizon, and at the same times in the hour circle, whether the motion be in the earth or in the heaven. If the earthly globe be turned, the hour-index goes round its hour-circle; but if the sphere be turned, the hour-circle goes round below the index.
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.
To reset the sphere for use, one must first slacken the screw r in the upright stem R, and taking hold of the arm Q, move it up or down until the given degree of latitude for any place lies at the side of the stem R; then the axis of the sphere will be properly elevated, so as to stand parallel to the axis of the terrestrial globe, if the globe assembly is to be aligned to north and south by a small compass: once this is done, the user must count the latitude from the north pole, upon the celestial meridian L, down towards the north notch of the horizon, and set the horizon to that latitude. The user then must turn the nut b until the sun Y comes to the given day of the year in the ecliptic, and the sun will be at its proper place for that day.
To find the place of the moon's ascending node, and also the place of the moon, an ephemeris must be consulted to set them right accordingly. Lastly, the user must turn the winch W, until either the sun comes to the meridian L, or until the meridian comes to the sun (moving the sphere or globe at the user's discretion), and then set the hour-index to the XII, marked noon, the whole sphere will be reset. Then the user must turn the winch, and observe when the sun or moon rises and set sin the horizon. The hour-index will show the times thereof for the given day.[2]
Throughout Chinese history, astronomers have created celestial globes (Chinese:渾象; pinyin:húnxiàng) to assist the observation of the stars. The Chinese also used the armillary sphere in aiding calendrical computations and calculations.
According to Joseph Needham, the earliest development of the armillary sphere in China goes back to the astronomers Shi Shen and Gan De in the 4th century BC, as they were equipped with a primitive single-ring armillary instrument.[3] This would have allowed them to measure the north polar distance (declination) a measurement that gave the position in a xiu (right ascension).[3] Needham's 4th century BC dating, however, is rejected by British sinologist Christopher Cullen, who traces the beginnings of these devices to the 1st century BC.[4]
During the Western Han dynasty (202 BC–9 AD) additional developments made by the astronomers Luoxia Hong (落下閎), Xiangyu Wangren, and Geng Shouchang (耿壽昌) advanced the use of the armillary in its early stage of evolution. In 52 BC, it was the astronomer Geng Shouchang who introduced the first permanently fixed equatorial ring of the armillary sphere.[3] In the subsequent Eastern Han dynasty (23–220 AD) period, the astronomers Fu An and Jia Kui added the ecliptic ring by 84 AD.[3] With the famous statesman, astronomer, and inventor Zhang Heng (張衡, 78–139 AD), the sphere was totally complete in 125 AD, with horizon and meridian rings.[3] The world's first water-powered celestial globe was created by Zhang Heng, who operated his armillary sphere by use of an inflow clepsydra clock.
Subsequent developments were made after the Han dynasty that improved the use of the armillary sphere. In 323 AD the Chinese astronomer Kong Ting was able to reorganize the arrangement of rings on the armillary sphere so that the ecliptic ring could be pegged on to the equator at any point desired.[3] The Chinese astronomer and mathematician Li Chunfeng (李淳風) of the Tang dynasty created one in 633 AD with three spherical layers to calibrate multiple aspects of astronomical observations, calling them 'nests' (chhung).[3] He was also responsible for proposing a plan of having a sighting tube mounted ecliptically in order for the better observation of celestial latitudes. However, it was the Tang Chinese astronomer, mathematician, and monk Yi Xing in the next century who would accomplish this addition to the model of the armillary sphere.[5] Ecliptical mountings of this sort were found on the armillary instruments of Zhou Cong and Shu Yijian in 1050, as well as Shen Kuo's armillary sphere of the later 11th century, but after that point they were no longer employed on Chinese armillary instruments until the arrival of the European Jesuits.
In 723 AD, Yi Xing (一行) and government official Liang Ling-zan (梁令瓚) combined Zhang Heng's water powered celestial globe with an escapement device. With drums hit every quarter-hour and bells rung automatically every full hour, the device was also a striking clock.[6] The famous clock tower that the Chinese polymath Su Song built by 1094 during the Song dynasty would employ Yi Xing's escapement with waterwheel scoops filled by clepsydra drip, and powered a crowning armillary sphere, a central celestial globe, and mechanically operated manikins that would exit mechanically opened doors of the clock tower at specific times to ring bells and gongs to announce the time, or to hold plaques announcing special times of the day. There was also the scientist and statesman Shen Kuo (1031–1095). Being the head official for the Bureau of Astronomy, Shen Kuo was an avid scholar of astronomy, and improved the designs of several astronomical instruments: the gnomon, armillary sphere, clepsydra clock, and sighting tube fixed to observe the pole star indefinitely.[7] When Jamal al-Din of Bukhara was asked to set up an 'Islamic Astronomical Institution' in Khubilai Khan's new capital during the Yuan dynasty, he commissioned a number of astronomical instruments, including an armillary sphere. It was noted that "Chinese astronomers had been building [them] since at least 1092".[8]
The armillary sphere was used for observation in India since early times, and finds mention in the works of Āryabhata (476 CE).[9] The Goladīpikā—a detailed treatise dealing with globes and the armillary sphere was composed between 1380 and 1460 CE by Parameśvara.[9] On the subject of the usage of the armillary sphere in India, Ōhashi (2008) writes: "The Indian armillary sphere (gola-yantra) was based on equatorial coordinates, unlike the Greek armillary sphere, which was based on ecliptical coordinates, although the Indian armillary sphere also had an ecliptical hoop. Probably, the celestial coordinates of the junction stars of the lunar mansions were determined by the armillary sphere since the seventh century or so."[10]
Mythological figures within an armillary sphere in a fragmentary fresco from Stabiae, mid-1st century AD
The Greek astronomerHipparchus (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 ἀστρολάβοςastrolabos and κρικωτὴ σφαῖραkrikōtē sphaira "ringed sphere".[16] The English name of this device comes ultimately from the Latinarmilla (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.
In its simplest form, consisting of a ring fixed in the plane of the equator, the armilla is one of the most ancient of astronomical instruments. Slightly developed, it was crossed by another ring fixed in the plane of the meridian. The first was an equinoctial, the second a solstitial armilla. Shadows were used as indices of the sun's positions, in combinations with angular divisions. When several rings or circles were combined representing the great circles of the heavens, the instrument became an armillary sphere.[1]
Armillary spheres were developed by the Hellenistic Greeks and were used as teaching tools already in the 3rd century BC. In larger and more precise forms they were also used as observational instruments. However, the fully developed armillary sphere with nine circles perhaps did not exist until the mid-2nd century AD, during the Roman Empire.[17] Eratosthenes most probably used a solstitial armilla for measuring the obliquity of the ecliptic. Hipparchus probably used an armillary sphere of four rings.[17] The Greco-Roman geographer and astronomer Ptolemy (c.100– c.170 AD) describes his instrument, the astrolabon, in his Almagest.[17] It consisted of at least three rings, with a graduated circle inside of which another could slide, carrying two small tubes positioned opposite each other and supported by a vertical plumb-line.[1][17]
Persian and Arab astronomers such as Ibrahim al-Fazari and Abbas Ibn Firnas continued to build and improve on armillary spheres. The spherical astrolabe, a variation of both the astrolabe and the armillary sphere, was likely invented during the Middle Ages in the Middle East.[19] About 550 AD, Christian philosopher John Philoponus wrote a treatise on the astrolabe in Greek, which is the earliest extant treatise on the instrument.[20] The earliest description of the spherical astrolabe dates back to the Persian astronomer Nayrizi (fl. 892–902). Pope Sylvester II applied the use of sighting tubes with his armillary sphere in order to fix the position of the pole star and record measurements for the tropics and equator, and used armillary spheres as a teaching device.[21]
Korea
Korean celestial globe
Chinese ideas of astronomy and astronomical instruments were introduced to Korea, where further advancements were also made. Jang Yeong-sil, a Korean inventor, was ordered by King Sejong the Great of Joseon to build an armillary sphere. The sphere, built in 1433 was named Honcheonui (혼천의,渾天儀).
The Honcheonsigye, an armillary sphere activated by a working clock mechanism was built by the Korean astronomer Song Iyeong in 1669. It is the only remaining astronomical clock from the Joseon dynasty. The mechanism of the armillary sphere succeeded that of Sejong era's armillary sphere (Honŭi 渾儀, 1435) and celestial sphere (Honsang 渾象, 1435), and the Jade Clepsydra (Ongnu 玉漏, 1438)'s sun-carriage apparatus. Such mechanisms are similar to Ch'oe Yu-ji (崔攸之, 1603~1673)'s armillary sphere(1657). The structure of time going train and the mechanism of striking-release in the part of clock is influenced by the crown escapement which has been developed from 14th century, and is applied to gear system which had been improved until the middle of 17th century in Western-style clockwork. In particular, timing device of Song I-yŏng's Armillary Clock adopts the early 17th century pendulum clock system which could remarkably improve the accuracy of a clock.[22]
Tycho Brahe's zodiacal armillary sphere, from his Astronomiae Instauratae Mechanica (Wandesburg, 1598), p. 36.
Renaissance
Further advances in this instrument were made by Danish astronomer Tycho Brahe (1546–1601), who constructed three large armillary spheres which he used for highly precise measurements of the positions of the stars and planets. They were described in his Astronomiae Instauratae Mechanica.[23]
Armillary spheres were among the first complex mechanical devices. Their development led to many improvements in techniques and design of all mechanical devices. Renaissance scientists and public figures often had their portraits painted showing them with one hand on an armillary sphere, which represented the zenith of wisdom and knowledge.
The armillary sphere survives as useful for teaching, and may be described as a skeleton celestial globe, the series of rings representing the great circles of the heavens, and revolving on an axis within a horizon. With the earth as center such a sphere is known as Ptolemaic; with the sun as center, as Copernican.[1]
Young girl with an astronomical instrument, by Jan Gossaert, c. 1520-1540
Portrait in the frontispiece of Antoine Crespin's Propheties par l'astrologue du treschrestien Roy de France et de Madame la Duchesse de Savoye, Lyon, France, 1572
A representation of an armillary sphere is present in the modern flag of Portugal and has been a national symbol since the reign of Manuel I.
The Armillary sphere in Geneva
Paralympic Games
An artwork-based model of an Armillary sphere has been used since the March 1, 2014 to light the Paralympic heritage flame at Stoke Mandeville Stadium, United Kingdom. The sphere includes a wheelchair that the user can rotate to spark the flame as part of a ceremony to celebrate the past, present and future of the Paralympic Movement in the UK. The Armillary Sphere was created by artist Jon Bausor and will be used for future Heritage Flame events. The flame in the first-ever ceremony was lit by London 2012 gold medallist Hannah Cockroft.[24]
In the end of the 15th century, the armillary sphere became the personal heraldic badge of the future King Manuel I of Portugal, when he was still a Prince. The intense use of this badge in documents, monuments, flags and other supports, during the reign of Manuel I, transformed the armillary sphere from a simple personal symbol to a national one that represented the Kingdom of Portugal and in particular its Overseas Empire. As a national symbol, the armillary sphere continued in use after the death of Manuel I.
Celestial globes show the apparent positions of the stars in the sky. They omit the Sun, Moon, and planets because the positions of these bodies vary relative to those of the stars, but the ecliptic, along which the Sun moves, is indicated.
Hipparchus was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry, but is most famous for his incidental discovery of the precession of the equinoxes. Hipparchus was born in Nicaea, Bithynia, and probably died on the island of Rhodes, Greece. He is known to have been a working astronomer between 162 and 127 BC.
Right ascension is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the point in question above the Earth. When paired with declination, these astronomical coordinates specify the location of a point on the celestial sphere in the equatorial coordinate system.
A solstice is the time when the Sun reaches its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around 20–22 June and 20–22 December. In many countries, the seasons of the year are defined by reference to the solstices and the equinoxes.
Zhang Heng, formerly romanized Chang Heng, was a Chinese polymathic scientist and statesman who lived during the Eastern Han dynasty. Educated in the capital cities of Luoyang and Chang'an, he achieved success as an astronomer, mathematician, seismologist, hydraulic engineer, inventor, geographer, cartographer, ethnographer, artist, poet, philosopher, politician, and literary scholar.
An astrolabe is an astronomical instrument dating to ancient times. It serves as a star chart and physical model of visible half-dome of the sky. Its various functions also make it an elaborate inclinometer and an analog calculation device capable of working out several kinds of problems in astronomy. In its simplest form it is a metal disc with a pattern of wires, cutouts, and perforations that allows a user to calculate astronomical positions precisely. It is able to measure the altitude above the horizon of a celestial body, day or night; it can be used to identify stars or planets, to determine local latitude given local time, to survey, or to triangulate. It was used in classical antiquity, the Islamic Golden Age, the European Middle Ages and the Age of Discovery for all these purposes.
In astronomy, a planisphere is a star chart analog computing instrument in the form of two adjustable disks that rotate on a common pivot. It can be adjusted to display the visible stars for any time and date. It is an instrument to assist in learning how to recognize stars and constellations. The astrolabe, an instrument that has its origins in Hellenistic astronomy, is a predecessor of the modern planisphere. The term planisphere contrasts with armillary sphere, where the celestial sphere is represented by a three-dimensional framework of rings.
An astronomical clock, horologium, or orloj is a clock with special mechanisms and dials to display astronomical information, such as the relative positions of the Sun, Moon, zodiacal constellations, and sometimes major planets.
The torquetum or turquet is a medieval astronomical instrument designed by persons unknown to take and convert measurements made in three sets of coordinates: horizon, equatorial, and ecliptic. It is characterised by R. P. Lorch as a combination of Ptolemy's astrolabon and the plane astrolabe. In a sense, the torquetum is an analog computer.
Yi Xing, born Zhang Sui, was a Chinese astronomer, Buddhist monk, inventor, mathematician, mechanical engineer, and philosopher during the Tang dynasty. His astronomical celestial globe featured a liquid-driven escapement, the first in a long tradition of Chinese astronomical clockworks.
Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the twenty-eight mansions have been found on oracle bones unearthed at Anyang, dating back to the mid-Shang dynasty. The core of the "mansion" system also took shape around this period, by the time of King Wu Ding.
Su Song, courtesy name Zirong, was a Chinese polymathic scientist and statesman. Excelling in a variety of fields, he was accomplished in mathematics, astronomy, cartography, geography, horology, pharmacology, mineralogy, metallurgy, zoology, botany, mechanical engineering, hydraulic engineering, civil engineering, invention, art, poetry, philosophy, antiquities, and statesmanship during the Song dynasty (960–1279).
Colure, in astronomy, is either of the two principal meridians of the celestial sphere. The term is now rarely used and may be considered obsolete.
Medieval Islamic astronomy comprises the astronomical developments made in the Islamic world, particularly during the Islamic Golden Age, and mostly written in the Arabic language. These developments mostly took place in the Middle East, Central Asia, Al-Andalus, and North Africa, and later in the Far East and India. It closely parallels the genesis of other Islamic sciences in its assimilation of foreign material and the amalgamation of the disparate elements of that material to create a science with Islamic characteristics. These included Greek, Sassanid, and Indian works in particular, which were translated and built upon.
Zhang Sixun was a Chinese astronomer and mechanical engineer from Bazhong, Sichuan during the early Song dynasty. He is credited with creating an armillary sphere for his astronomical clock tower that employed the use of liquid mercury. The liquid mercury filled scoops of the waterwheel would rotate and thus provide the effect of an escapement mechanism in clockworks and allow the astronomical armillary sphere to rotate as needed.
The York Minster astronomical clock is a memorial to the airmen operating from bases in Yorkshire, Durham, and Northumberland who were killed in action during World War II, designed by R. Atkinson, and installed in York Minster in 1955.
A quadrant is an instrument used to measure angles up to 90°. Different versions of this instrument could be used to calculate various readings, such as longitude, latitude, and time of day. Its earliest recorded usage was in ancient India in Rigvedic times by Rishi Atri to observe a solar eclipse. It was then proposed by Ptolemy as a better kind of astrolabe. Several different variations of the instrument were later produced by medieval Muslim astronomers. Mural quadrants were important astronomical instruments in 18th-century European observatories, establishing a use for positional astronomy.
Astronomical rings, also known as Gemma's rings, are an early astronomical instrument. The instrument consists of three rings, representing the celestial equator, declination, and the meridian.
Catherine of Alexandria is a tempera painting created by Ieremias Palladas. Palladas was a monk associated with Saint Catherine's sacred monastery in Egypt also known as Mount Sinai. He was a painter and teacher. His nephew became the Patriarch of Alexandria. His name was Gerasimos Palladas. Ieremias was a Sinaitic monk because of his association with Saint Catherine's monastery on Mount Sinai. The monastery encloses the site where it is assumed by Christians that Moses saw the burning bush. Ieremias was one of the most influential figures of his time. The Patriarch of Jerusalem Nectarius wrote about the painter in his archives.
↑ Dirk L. Couprie, Robert Hahn, Gerard Naddaf: Anaximander in Context: New Studies in the Origins of Greek Philosophy, 2003, ISBN978-0-7914-5537-1, p. 179
↑ Emilie Savage-Smith (1993). "Book Reviews", Journal of Islamic Studies4 (2), pp. 296–299.
"There is no evidence for the Hellenistic origin of the spherical astrolabe, but rather evidence so far available suggests that it may have been an early but distinctly Islamic development with no Greek antecedents."
↑ Modern editions of John Philoponus' treatise on the astrolabe are De usu astrolabii eiusque constructione libellus (On the Use and Construction of the Astrolabe), ed. Heinrich Hase, Bonn: E. Weber, 1839, OCLC165707441 (or id. Rheinisches Museum für Philologie 6 (1839): 127–71); repr. and translated into French by Alain Philippe Segonds, Jean Philopon, traité de l'astrolabe, Paris: Librairie Alain Brieux, 1981, OCLC10467740; and translated into English by H.W. Green in R.T. Gunther, The Astrolabes of the World, Vol. 1/2, Oxford, 1932, OL18840299M repr. London: Holland Press, 1976, OL14132393M pp. 61–81.
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