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Antikythera mechanism

Antikythera mechanism

Overview
The Antikythera mechanism (icon or ˌ ) is an ancient mechanical computer
Analog computer
An analog computer is a form of computer that uses the continuously-changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved...

 designed to calculate astronomical
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 positions. It was recovered in 1900–1901 from the Antikythera wreck
Antikythera wreck
The Antikythera wreck is a shipwreck from the 1st or 2nd century BC. It was discovered by sponge divers off Point Glyphadia on the Greek island Antikythera in the early 1900s...

. Its significance and complexity were not understood until decades later. Its time of construction is now estimated between 150 and 100 BC. Technological artifacts of similar complexity and workmanship did not reappear in Europe until the 14th century, when mechanical astronomical clock
Astronomical clock
An astronomical clock 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.-Definition:...

s were built in Europe.

Jacques-Yves Cousteau
Jacques-Yves Cousteau
Jacques-Yves Cousteau was a French naval officer, explorer, ecologist, filmmaker, innovator, scientist, photographer, author and researcher who studied the sea and all forms of life in water...

 visited the wreck for the last time in 1978, but found no additional remains of the Antikythera mechanism.
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Encyclopedia
The Antikythera mechanism (icon or ˌ ) is an ancient mechanical computer
Analog computer
An analog computer is a form of computer that uses the continuously-changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved...

 designed to calculate astronomical
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 positions. It was recovered in 1900–1901 from the Antikythera wreck
Antikythera wreck
The Antikythera wreck is a shipwreck from the 1st or 2nd century BC. It was discovered by sponge divers off Point Glyphadia on the Greek island Antikythera in the early 1900s...

. Its significance and complexity were not understood until decades later. Its time of construction is now estimated between 150 and 100 BC. Technological artifacts of similar complexity and workmanship did not reappear in Europe until the 14th century, when mechanical astronomical clock
Astronomical clock
An astronomical clock 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.-Definition:...

s were built in Europe.

Jacques-Yves Cousteau
Jacques-Yves Cousteau
Jacques-Yves Cousteau was a French naval officer, explorer, ecologist, filmmaker, innovator, scientist, photographer, author and researcher who studied the sea and all forms of life in water...

 visited the wreck for the last time in 1978, but found no additional remains of the Antikythera mechanism. Professor Michael Edmunds of Cardiff University
Cardiff University
Cardiff University is a leading research university located in the Cathays Park area of Cardiff, Wales, United Kingdom. It received its Royal charter in 1883 and is a member of the Russell Group of Universities. The university is consistently recognised as providing high quality research-based...

 who led the most recent study of the mechanism said: "This device is just extraordinary, the only thing of its kind. The design is beautiful, the astronomy is exactly right. The way the mechanics are designed just makes your jaw drop. Whoever has done this has done it extremely carefully ... in terms of historic and scarcity value, I have to regard this mechanism as being more valuable than the Mona Lisa
Mona Lisa
Mona Lisa is a portrait by the Italian artist Leonardo da Vinci. It is a painting in oil on a poplar panel, completed circa 1503–1519...

."

The device is displayed at the National Archaeological Museum of Athens
National Archaeological Museum of Athens
The National Archaeological Museum in Athens houses some of the most important artifacts from a variety of archaeological locations around Greece from prehistory to late antiquity. It is considered one of the great museums in the world and contains the richest collection of artifacts from Greek...

, accompanied by a reconstruction made and donated to the museum by Derek de Solla Price
Derek J. de Solla Price
Derek John de Solla Price was a physicist, historian of science, and information scientist,credited as the father of scientometrics.-Biography:...

. Other reconstructions are on display at the American Computer Museum
American Computer Museum
The American Computer Museum is a museum of the history of computing located in Bozeman, Montana, USA. It was founded in May 1990 by Barbara and George Keremedjiev as a non-profit organization. The museum was originally intended to have been located in Princeton, New Jersey, but the location was...

 in Bozeman, Montana, the Children's Museum of Manhattan
Children's Museum of Manhattan
The Children’s Museum of Manhattan was founded by Bette Korman, under the name GAME , in 1973. With New York City in a deep fiscal crisis, and school art, music, and cultural programs eliminated, a loosely organized, group of artists and educators set up a basement storefront to serve Harlem and...

 in New York, and in Kassel
Kassel
Kassel is a town located on the Fulda River in northern Hesse, Germany. It is the administrative seat of the Kassel Regierungsbezirk and the Kreis of the same name and has approximately 195,000 inhabitants.- History :...

, Germany.

Origins



The mechanism is the oldest known complex scientific calculator. It contains many gear
Gear
A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....

s, and is sometimes called the first known analog computer
Analog computer
An analog computer is a form of computer that uses the continuously-changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved...

, although its flawless manufacturing suggests that it may have had a number of undiscovered predecessors during the Hellenistic Period
Hellenistic period
The Hellenistic period or Hellenistic era describes the time which followed the conquests of Alexander the Great. It was so named by the historian J. G. Droysen. During this time, Greek cultural influence and power was at its zenith in Europe and Asia...

.
It appears to be constructed upon theories of astronomy and mathematics developed by Greek astronomers and it is estimated that it was made around 150-100 BC
100 BC
Year 100 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Marius and Flaccus...

.

Consensus among scholars is that the mechanism itself was made in the Greek-speaking world. All the instructions of the mechanism are written in Koine Greek
Koine Greek
Koine Greek is the universal dialect of the Greek language spoken throughout post-Classical antiquity , developing from the Attic dialect, with admixture of elements especially from Ionic....

. One hypothesis is that the device was constructed at an academy founded by the Stoic
STOIC
STOIC was a variant of Forth.It started out at the MIT and Harvard Biomedical Engineering Centre in Boston, and was written in the mid 1970s by Jonathan Sachs...

 philosopher Posidonius
Posidonius
Posidonius "of Apameia" or "of Rhodes" , was a Greek Stoic philosopher, politician, astronomer, geographer, historian and teacher native to Apamea, Syria. He was acclaimed as the greatest polymath of his age...

 on the Greek island of Rhodes
Rhodes
Rhodes is an island in Greece, located in the eastern Aegean Sea. It is the largest of the Dodecanese islands in terms of both land area and population, with a population of 117,007, and also the island group's historical capital. Administratively the island forms a separate municipality within...

, which at the time was known as a center of astronomy and mechanical engineering, and that perhaps the astronomer Hipparchus
Hipparchus
Hipparchus, the common Latinization of the Greek Hipparkhos, can mean:* Hipparchus, the ancient Greek astronomer** Hipparchic cycle, an astronomical cycle he created** Hipparchus , a lunar crater named in his honour...

 was the engineer who designed it since it contains a lunar mechanism which uses Hipparchus's theory for the motion of the Moon. However, the most recent findings of The Antikythera Mechanism Research Project, as published in the July 31, 2008, edition of Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...

alternatively suggest that the concept for the mechanism originated in the colonies of Corinth
Ancient Corinth
Corinth, or Korinth was a city-state on the Isthmus of Corinth, the narrow stretch of land that joins the Peloponnesus to the mainland of Greece, roughly halfway between Athens and Sparta. The modern town of Corinth is located approximately northeast of the ancient ruins...

, which might imply a connection with Archimedes
Archimedes
Archimedes of Syracuse was a Greek mathematician, physicist, engineer, inventor, and astronomer. Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity. Among his advances in physics are the foundations of hydrostatics, statics and an...

.

It was discovered in a shipwreck
Shipwreck
A shipwreck is what remains of a ship that has wrecked, either sunk or beached. Whatever the cause, a sunken ship or a wrecked ship is a physical example of the event: this explains why the two concepts are often overlapping in English....

 off Point Glyphadia on the Greek
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

 island of Antikythera
Antikythera
Antikythera or Anticythera is a Greek island lying on the edge of the Aegean Sea, between Crete and Peloponnese. Since the 2011 local government reform it is part of the municipality of Kythira island....

. The wreck had been discovered in October 1900 and divers had retrieved numerous artifacts, most of them works of art, which had been transferred to the National Museum of Archaeology for storage. On 17 May 1902, archaeologist
Archaeology
Archaeology, or archeology , is the study of human society, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes...

 Valerios Stais
Valerios Stais
Valerios Stais was a Greek archaeologist. He was born in Kythera. He studied medicine and later archaeology. He became the director of the National Archaeological Museum of Athens in 1887 and held that post until his death. During that period he organized or participated in excavations in...

 was examining the finds and noticed that one of the pieces of rock had a gear wheel embedded in it. Stais initially believed it was an astronomical clock, but most scholars considered the device an anachronism
Anachronism
An anachronism—from the Greek ανά and χρόνος — is an inconsistency in some chronological arrangement, especially a chronological misplacing of persons, events, objects, or customs in regard to each other...

, too complex to have been constructed during the same period as the other pieces that had been discovered. However, investigations into the object were soon dropped until English
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 physicist Derek J. de Solla Price
Derek J. de Solla Price
Derek John de Solla Price was a physicist, historian of science, and information scientist,credited as the father of scientometrics.-Biography:...

 took an interest in it in 1951.

The circumstances under which it came to be on the cargo ship are unknown. Investigators have suggested that the ship could have been carrying it to Rome, together with other treasure looted from the island to support a triumphal parade
Roman triumph
The Roman triumph was a civil ceremony and religious rite of ancient Rome, held to publicly celebrate and sanctify the military achievement of an army commander who had won great military successes, or originally and traditionally, one who had successfully completed a foreign war. In Republican...

 being staged by Julius Caesar
Julius Caesar
Gaius Julius Caesar was a Roman general and statesman and a distinguished writer of Latin prose. He played a critical role in the gradual transformation of the Roman Republic into the Roman Empire....

.

Function


The device is remarkable for the level of miniaturization and for the complexity of its parts, which is comparable to that of 19th-century clocks. It has more than 30 gears, although Michael Wright (see below) has suggested as many as 72 gears, with teeth formed through equilateral triangles. When a date was entered via a crank (now lost), the mechanism calculated the position of the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 and Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 or other astronomical information such as the locations of planets. Since the purpose was to position astronomical bodies with respect to the celestial sphere
Celestial sphere
In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the Earth and rotating upon the same axis. All objects in the sky can be thought of as projected upon the celestial sphere. Projected upward from Earth's equator and poles are the...

, with reference to the observer's position on the surface of the Earth, the device was based on the geocentric model
Geocentric model
In astronomy, the geocentric model , is the superseded theory that the Earth is the center of the universe, and that all other objects orbit around it. This geocentric model served as the predominant cosmological system in many ancient civilizations such as ancient Greece...

.

The mechanism has three main dials, one on the front, and two on the back. The front dial has two concentric scales. The outer ring is marked off with the days of the 365-day Egyptian calendar
Egyptian calendar
The ancient civil Egyptian calendar had a year that was 360 days long and was divided into 12 months of 30 days each, plus five extra days at the end of the year. The months were divided into three weeks of ten days each...

, or the Sothic year, based on the Sothic cycle
Sothic cycle
The Sothic cycle or Canicular period is a period of 1,461 ancient Egyptian years or 1,460 Julian years...

. Inside this, there is a second dial marked with the Greek signs of the Zodiac
Zodiac
In astronomy, the zodiac is a circle of twelve 30° divisions of celestial longitude which are centred upon the ecliptic: the apparent path of the Sun across the celestial sphere over the course of the year...

 and divided into degrees. The calendar dial can be moved to compensate for the effect of the extra quarter day in the solar year (there are 365.2422 days per year) by turning the scale backwards one day every four years. Note that the Julian calendar
Julian calendar
The Julian calendar began in 45 BC as a reform of the Roman calendar by Julius Caesar. It was chosen after consultation with the astronomer Sosigenes of Alexandria and was probably designed to approximate the tropical year .The Julian calendar has a regular year of 365 days divided into 12 months...

, the first calendar of the region to contain leap year
Leap year
A leap year is a year containing one extra day in order to keep the calendar year synchronized with the astronomical or seasonal year...

s, was not introduced until about 46 BC, up to a century after the device was said to have been built.

The front dial probably carried at least three hands, one showing the date, and two others showing the positions of the Sun and the Moon. The Moon indicator is adjusted to show the first anomaly of the Moon's orbit. It is reasonable to suppose the Sun indicator had a similar adjustment, but any gearing for this mechanism (if it existed) has been lost. The front dial also includes a second mechanism with a spherical model of the Moon that displays the lunar phase
Lunar phase
A lunar phase or phase of the moon is the appearance of the illuminated portion of the Moon as seen by an observer, usually on Earth. The lunar phases change cyclically as the Moon orbits the Earth, according to the changing relative positions of the Earth, Moon, and Sun...

.

There is reference in the inscriptions for the planets Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

 and Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...

, and it would have certainly been within the capabilities of the maker of this mechanism to include gearing to show their positions. There is some speculation that the mechanism may have had indicators for all the five planets known to the Greeks. None of the gearing for such planetary mechanisms survives, except for one gear otherwise unaccounted for.

Finally, the front dial includes a parapegma, a precursor to the modern day almanac
Almanac
An almanac is an annual publication that includes information such as weather forecasts, farmers' planting dates, and tide tables, containing tabular information in a particular field or fields often arranged according to the calendar etc...

, which was used to mark the rising and setting of specific stars. Each star is thought to be identified by Greek characters which cross reference details inscribed on the mechanism.

The upper back dial is in the form of a spiral, with 47 divisions per turn, displaying the 235 months of the 19-year Metonic cycle
Metonic cycle
In astronomy and calendar studies, the Metonic cycle or Enneadecaeteris is a period of very close to 19 years which is remarkable for being very nearly a common multiple of the solar year and the synodic month...

. This cycle is important in fixing calendars.

The lower back dial is also in the form of a spiral, with 223 divisions showing the saros; it also has a smaller subsidiary dial which displays the 54 year "triple saros" or exeligmos
Exeligmos
An exeligmos is a period of 54 years, 33 days that can be used to predict successive eclipses with similar properties and location. For a solar eclipse, every exeligmos a solar eclipse of similar characteristics will occur close to the eclipse before it...

. (The saros, discovered by the Chaldea
Chaldea
Chaldea or Chaldaea , from Greek , Chaldaia; Akkadian ; Hebrew כשדים, Kaśdim; Aramaic: ܟܐܠܕܘ, Kaldo) was a marshy land located in modern-day southern Iraq which came to briefly rule Babylon...

ns, is a period of approximately 18 years 11 days 8 hours—the length of time between occurrences of a particular eclipse
Eclipse
An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer...

.)

The Antikythera Mechanism Research Project, with experts from Britain, Greece and the United States, detected in July 2008 the word "Olympia" on a bronze dial thought to display the 76-year Callippic cycle
Callippic cycle
In astronomy and calendar studies, the Callippic cycle is a particular approximate common multiple of the year and the synodic month, that was proposed by Callippus in 330 BC...

, as well as the names of other games in ancient Greece, and probably used to track dates of the ancient Olympic Games. According to BBC news:
The four sectors of the dial are inscribed with a year number and two Panhellenic Games
Panhellenic Games
Panhellenic Games is the collective term for four separate sports festivals held in ancient Greece. The four Games were:-Description:The Games took place in a four-year cycle known as the Olympiad, which was one of the ways the Greeks measured time...

: the "crown" games of Isthmia
Isthmian Games
The Isthmian Games or Isthmia were one of the Panhellenic Games of Ancient Greece, and were named after the isthmus of Corinth, where they were held...

, Olympia, Nemea
Nemean Games
The Nemean Games were one of the four Panhellenic Games of Ancient Greece, and were held at Nemea every two years ....

, and Pythia
Pythian Games
The Pythian Games were one of the four Panhellenic Games of Ancient Greece, a forerunner of the modern Olympic Games, held every four years at the sanctuary of Apollo at Delphi....

; and two lesser games: Naa (held at Dodona
Dodona
Dodona in Epirus in northwestern Greece, was an oracle devoted to a Mother Goddess identified at other sites with Rhea or Gaia, but here called Dione, who was joined and partly supplanted in historical times by the Greek god Zeus.The shrine of Dodona was regarded as the oldest Hellenic oracle,...

) and a second game which has not yet been deciphered.

Speculation about its purpose


Derek J. de Solla Price
Derek J. de Solla Price
Derek John de Solla Price was a physicist, historian of science, and information scientist,credited as the father of scientometrics.-Biography:...

 suggested that it might have been on public display, possibly in a museum or public hall in Rhodes. The island was known for its displays of mechanical engineering, particularly automata
Automaton
An automaton is a self-operating machine. The word is sometimes used to describe a robot, more specifically an autonomous robot. An alternative spelling, now obsolete, is automation.-Etymology:...

, which apparently were a speciality of the Rhodians. Pindar
Pindar
Pindar , was an Ancient Greek lyric poet. Of the canonical nine lyric poets of ancient Greece, his work is the best preserved. Quintilian described him as "by far the greatest of the nine lyric poets, in virtue of his inspired magnificence, the beauty of his thoughts and figures, the rich...

, one of the nine lyric poets
Nine lyric poets
The nine lyric poets were a canon of archaic Greek composers esteemed by the scholars of Hellenistic Alexandria as worthy of critical study.They were:*Alcman of Sparta...

 of ancient Greece, said this of Rhodes in his seventh Olympic Ode:
The animated figures stand
Adorning every public street
And seem to breathe in stone, or
Move their marble feet.


Arguments against it being on public display include:
  1. The device is rather small, indicating that the designer was aiming for compactness and, as a result, the size of the front and back dials is unsuitable for public display. A simple comparison with the size of the Tower of the Winds
    Tower of the Winds
    The Tower of the Winds, also called horologion , is an octagonal Pentelic marble clocktower on the Roman agora in Athens. The structure features a combination of sundials, a water clock and a wind vane...

     in Athens would suggest that the Antikythera mechanism manufacturer designed the device for mobility rather than public display in a fixed location.
  2. The mechanism had door plates that contained at least 2,000 characters, forming what members of the Antikythera mechanism research project often refer to as an instruction manual. The attachment of this manual to the mechanism itself implies ease of transport and personal use.
  3. The existence of this "instruction manual" implies that the device was constructed by a scientist and mechanic for use by a non-expert traveler (the text has a lot of information associated with well known Mediterranean geographical locations).


The device is unlikely to have been intended for navigation use because:
  1. Some data, such as eclipse predictions, are unnecessary for navigation.
  2. Damp, salt-laden marine environments would quickly corrode the gears, rendering it useless.


On 31 July 2008, scientists reported new findings in the journal Nature showing that the mechanism tracked the Metonic calendar, predicted solar eclipses, and calculated the timing of the Ancient Olympic Games. Inscriptions on the instrument closely match the names of the months on calendars from Illyria
Illyria
In classical antiquity, Illyria was a region in the western part of the Balkan Peninsula inhabited by the Illyrians....

 and Epirus
Epirus
The name Epirus, from the Greek "Ήπειρος" meaning continent may refer to:-Geographical:* Epirus - a historical and geographical region of the southwestern Balkans, straddling modern Greece and Albania...

 in northwestern Greece and with the island of Corfu
Corfu
Corfu is a Greek island in the Ionian Sea. It is the second largest of the Ionian Islands, and, including its small satellite islands, forms the edge of the northwestern frontier of Greece. The island is part of the Corfu regional unit, and is administered as a single municipality. The...

.

Similar devices in ancient literature


Cicero
Cicero
Marcus Tullius Cicero , was a Roman philosopher, statesman, lawyer, political theorist, and Roman constitutionalist. He came from a wealthy municipal family of the equestrian order, and is widely considered one of Rome's greatest orators and prose stylists.He introduced the Romans to the chief...

's De re publica
De re publica
De re publica is a dialogue on Roman politics by Cicero, written in six books between 54 and 51 BC. It is written in the format of a Socratic dialogue in which Scipio Africanus Minor takes the role of a wise old man — an obligatory part for the genre...

, a 1st century BC philosophical dialogue, mentions two machines that some modern authors consider as some kind of planetarium
Planetarium
A planetarium is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation...

 or orrery
Orrery
An orrery is a mechanical device that illustrates the relative positions and motions of the planets and moons in the Solar System in a heliocentric model. Though the Greeks had working planetaria, the first orrery that was a planetarium of the modern era was produced in 1704, and one was presented...

, predicting the movements of the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

, the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

, and the five planets known at that time. They were both built by Archimedes
Archimedes
Archimedes of Syracuse was a Greek mathematician, physicist, engineer, inventor, and astronomer. Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity. Among his advances in physics are the foundations of hydrostatics, statics and an...

 and brought to Rome by the Roman general Marcus Claudius Marcellus
Marcus Claudius Marcellus
Marcus Claudius Marcellus , five times elected as consul of the Roman Republic, was an important Roman military leader during the Gallic War of 225 BC and the Second Punic War...

 after the death of Archimedes at the siege of Syracuse in 212 BC. Marcellus had great respect for Archimedes and one of these machines was the only item he kept from the siege (the second was offered to the temple of Virtus). The device was kept as a family heirloom, and Cicero has Philus (one of the participants in a conversation that Cicero imagined had taken place in a villa belonging to Scipio Aemilianus in the year 129 BC) saying that Caius Sulpicius Gallus (consul with Marcellus' nephew in 166 BC, and credited by Pliny the Elder
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...

 as the first Roman to have written a book explaining solar and lunar eclipses) gave a "learned explanation" of it and demonstrated it working.
I had often heard this celestial globe or sphere mentioned on account of the great fame of Archimedes. Its appearance, however, did not seem to me particularly striking. There is another, more elegant in form, and more generally known, moulded by the same Archimedes, and deposited by the same Marcellus, in the Temple of Virtue at Rome. But as soon as Gallus had begun to explain, by his sublime science, the composition of this machine, I felt that the Sicilian geometrician must have possessed a genius superior to any thing we usually conceive to belong to our nature. Gallus assured us, that the solid and compact globe, was a very ancient invention, and that the first model of it had been presented by Thales of Miletus. That afterwards Eudoxus of Cnidus, a disciple of Plato, had traced on its surface the stars that appear in the sky, and that many years subsequent, borrowing from Eudoxus this beautiful design and representation, Aratus had illustrated them in his verses, not by any science of astronomy, but the ornament of poetic description. He added, that the figure of the sphere, which displayed the motions of the Sun and Moon, and the five planets, or wandering stars, could not be represented by the primitive solid globe. And that in this, the invention of Archimedes was admirable, because he had calculated how a single revolution should maintain unequal and diversified progressions in dissimilar motions.

When Gallus moved this globe it showed the relationship of the Moon with the Sun, and there were exactly the same number of turns on the bronze device as the number of days in the real globe of the sky. Thus it showed the same eclipse of the Sun as in the globe [of the sky], as well as showing the Moon entering the area of the Earth's shadow when the Sun is in line ... [missing text]
[i.e. It showed both solar and lunar eclipses.]


So at least one of Archimedes' machines, probably (considering Gallus' interests and the fact that
that portion of the De Republica seems to be concerned with astronomical prodigia and in particular eclipses) quite similar to the Antikythera mechanism, was still operated around 150 BC.

Pappus of Alexandria
Pappus of Alexandria
Pappus of Alexandria was one of the last great Greek mathematicians of Antiquity, known for his Synagoge or Collection , and for Pappus's Theorem in projective geometry...

 stated that Archimedes had written a now lost manuscript on the construction of these devices entitled On Sphere-Making. The surviving texts from the Library of Alexandria
Library of Alexandria
The Royal Library of Alexandria, or Ancient Library of Alexandria, in Alexandria, Egypt, was the largest and most significant great library of the ancient world. It flourished under the patronage of the Ptolemaic dynasty and functioned as a major center of scholarship from its construction in the...

 describe many of his creations, some even containing simple drawings. One such device is his odometer
Odometer
An odometer or odograph is an instrument that indicates distance traveled by a vehicle, such as a bicycle or automobile. The device may be electronic, mechanical, or a combination of the two. The word derives from the Greek words hodós and métron...

, the exact model later used by the Romans to place their mile markers (described by Vitruvius
Vitruvius
Marcus Vitruvius Pollio was a Roman writer, architect and engineer, active in the 1st century BC. He is best known as the author of the multi-volume work De Architectura ....

, Heron of Alexandria and in the time of Emperor Commodus
Commodus
Commodus , was Roman Emperor from 180 to 192. He also ruled as co-emperor with his father Marcus Aurelius from 177 until his father's death in 180. His name changed throughout his reign; see changes of name for earlier and later forms. His accession as emperor was the first time a son had succeeded...

). The drawings in the text appeared functional, but attempts to build them as pictured had failed. When the gears pictured, which had square teeth, were replaced with gears of the type in the Antikythera mechanism, which were angled, the device was perfectly functional. Whether this is an example of a device created by Archimedes and described by texts lost in the burning of the Library of Alexandria
Library of Alexandria
The Royal Library of Alexandria, or Ancient Library of Alexandria, in Alexandria, Egypt, was the largest and most significant great library of the ancient world. It flourished under the patronage of the Ptolemaic dynasty and functioned as a major center of scholarship from its construction in the...

, or if it is a device based on his discoveries, or if it has anything to do with him at all, is debatable.

If Cicero's account is correct, then this technology existed as early as the 3rd century BC. Archimedes' device is also mentioned by later Roman era writers such as Lactantius
Lactantius
Lucius Caecilius Firmianus Lactantius was an early Christian author who became an advisor to the first Christian Roman emperor, Constantine I, guiding his religious policy as it developed, and tutor to his son.-Biography:...

 (Divinarum Institutionum Libri VII), Claudian
Claudian
Claudian was a Roman poet, who worked for Emperor Honorius and the latter's general Stilicho.A Greek-speaking citizen of Alexandria and probably not a Christian convert, Claudian arrived in Rome before 395. He made his mark with a eulogy of his two young patrons, Probinus and Olybrius, thereby...

 (In sphaeram Archimedes), and Proclus
Proclus
Proclus Lycaeus , called "The Successor" or "Diadochos" , was a Greek Neoplatonist philosopher, one of the last major Classical philosophers . He set forth one of the most elaborate and fully developed systems of Neoplatonism...

 (Commentary on the first book of Euclid's Elements of Geometry) in the 4th and 5th centuries.

Cicero also said that another such device was built 'recently' by his friend Posidonius
Posidonius
Posidonius "of Apameia" or "of Rhodes" , was a Greek Stoic philosopher, politician, astronomer, geographer, historian and teacher native to Apamea, Syria. He was acclaimed as the greatest polymath of his age...

, "... each one of the revolutions of which brings about the same movement in the Sun and Moon and five wandering stars [planets] as is brought about each day and night in the heavens..."

It is unlikely that any one of these machines was the Antikythera mechanism found in the shipwreck because both the devices fabricated by Archimedes and mentioned by Cicero were located in Rome at least 30 years later than the estimated date of the shipwreck and the third one was almost certainly in the hands of Posidonius by that date. So we know of at least four such devices. The modern scientists who have reconstructed the Antikythera mechanism also agree that it was too sophisticated to have been a unique device.

It is probable that the Antikythera mechanism was not unique, as shown by Cicero's references to such mechanisms. This adds support to the idea that there was an ancient Greek tradition of complex mechanical technology that was later, at least in part, transmitted to the Byzantine and Islamic world
Islamic Golden Age
During the Islamic Golden Age philosophers, scientists and engineers of the Islamic world contributed enormously to technology and culture, both by preserving earlier traditions and by adding their own inventions and innovations...

s, where mechanical devices which were complex, albeit simpler than the Antikythera mechanism, were built during the Middle Ages
Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

. Fragments of a geared calendar attached to a sundial, from the 5th or 6th century Byzantine Empire
Byzantine Empire
The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

, have been found; the calendar may have been used to assist in telling time. In the Islamic world, Banū Mūsā
Banu Musa
The Banū Mūsā brothers , namely Abū Jaʿfar Muḥammad ibn Mūsā ibn Shākir , Abū al‐Qāsim Aḥmad ibn Mūsā ibn Shākir and Al-Ḥasan ibn Mūsā ibn Shākir , were three 9th-century Persian scholars of Baghdad who are known for their Book of Ingenious Devices on automata and mechanical devices...

's Kitab al-Hiyal
Book of Ingenious Devices
The Book of Ingenious Devices was a large illustrated work on mechanical devices, including automata, published in 850 by the three Persian brothers known as the Banu Musa working at the House of Wisdom in Baghdad, Iraq, under the Abbasid Caliphate...

, or Book of Ingenious Devices, was commissioned by the Caliph of Baghdad in the early 9th century AD. This text described over a hundred mechanical devices, some of which may date back to ancient Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 texts preserved in monasteries
Monastery
Monastery denotes the building, or complex of buildings, that houses a room reserved for prayer as well as the domestic quarters and workplace of monastics, whether monks or nuns, and whether living in community or alone .Monasteries may vary greatly in size – a small dwelling accommodating only...

. A geared calendar similar to the Byzantine device was described by the scientist al-Biruni
Al-Biruni
Abū al-Rayḥān Muḥammad ibn Aḥmad al-BīrūnīArabic spelling. . The intermediate form Abū Rayḥān al-Bīrūnī is often used in academic literature...

 around 1000, and a surviving 13th century astrolabe
Astrolabe
An astrolabe is an elaborate inclinometer, historically used by astronomers, navigators, and astrologers. Its many uses include locating and predicting the positions of the Sun, Moon, planets, and stars, determining local time given local latitude and longitude, surveying, triangulation, and to...

 also contains a similar clockwork device. It is possible that this medieval technology may have been transmitted to Europe and contributed to the development of mechanical clocks there.

Investigations and reconstructions


The Antikythera mechanism is one of the world's oldest known geared devices. It has puzzled and intrigued historians of science
History of science
The history of science is the study of the historical development of human understandings of the natural world and the domains of the social sciences....

 and technology
History of technology
The history of technology is the history of the invention of tools and techniques, and is similar in many ways to the history of humanity. Background knowledge has enabled people to create new things, and conversely, many scientific endeavors have become possible through technologies which assist...

 since its discovery. A number of individuals and groups have been instrumental in advancing the knowledge and understanding of the mechanism including: pioneering German Philologist Albert Rehm; Derek J. de Solla Price (with Charalampos Karakalos and his wife Emily); Allan George Bromley (with Frank Percival, Michael Wright and Bernard Gardner); Michael Wright and The Antikythera Mechanism Research Project.

Derek J. de Solla Price


Following decades of work cleaning the device, in 1951 British science historian Derek J. de Solla Price
Derek J. de Solla Price
Derek John de Solla Price was a physicist, historian of science, and information scientist,credited as the father of scientometrics.-Biography:...

 undertook systematic investigation of the mechanism.

Price published several papers on "Clockwork before the Clock". and "On the Origin of Clockwork", before the first major publication in June 1959 on the mechanism: "An Ancient Greek Computer". This was the lead article in Scientific American
Scientific American
Scientific American is a popular science magazine. It is notable for its long history of presenting science monthly to an educated but not necessarily scientific public, through its careful attention to the clarity of its text as well as the quality of its specially commissioned color graphics...

and appears to have been initially published at the prompting of Arthur C. Clarke
Arthur C. Clarke
Sir Arthur Charles Clarke, CBE, FRAS was a British science fiction author, inventor, and futurist, famous for his short stories and novels, among them 2001: A Space Odyssey, and as a host and commentator in the British television series Mysterious World. For many years, Robert A. Heinlein,...

, according to the book Arthur C. Clarke's Mysterious World
Arthur C. Clarke's Mysterious World
Arthur C. Clarke's Mysterious World is a thirteen part British television series looking at unexplained phenomena from around the world. It was produced by Yorkshire Television for the ITV network and first broadcast in September 1980....

(see end of chapter 3). In "An Ancient Greek Computer" Price advanced the theory that the Antikythera mechanism was a device for calculating the motions of stars and planets, which would make the device the first known analog computer
Analog computer
An analog computer is a form of computer that uses the continuously-changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved...

. Until that time, the Antikythera mechanism's function was largely unknown, though it had been correctly identified as an astronomical device, perhaps being an astrolabe
Astrolabe
An astrolabe is an elaborate inclinometer, historically used by astronomers, navigators, and astrologers. Its many uses include locating and predicting the positions of the Sun, Moon, planets, and stars, determining local time given local latitude and longitude, surveying, triangulation, and to...

.

In 1971, Price, by then the first Avalon Professor of the History of Science at Yale University
Yale University
Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...

, teamed up with Charalampos Karakalos, professor of nuclear physics
Nuclear physics
Nuclear physics is the field of physics that studies the building blocks and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those...

 at the Greek National Centre of Scientific Research "DEMOKRITOS". Karakalos took both gamma
Gamma ray
Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...

- and X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

 radiographs of the mechanism, which revealed critical information about the device's interior configuration.

In 1974, Price published "Gears from the Greeks: the Antikythera mechanism — a calendar computer from ca. 80 BC", where he presented a model of how the mechanism could have functioned.

Price's model, as presented in his "Gears from the Greeks", was the first theoretical attempt at reconstructing the device based on its inner structure revealed by the radiographs. According to that model, the front dial shows the annual progress of the Sun and Moon through the zodiac
Zodiac
In astronomy, the zodiac is a circle of twelve 30° divisions of celestial longitude which are centred upon the ecliptic: the apparent path of the Sun across the celestial sphere over the course of the year...

 against the Egyptian calendar
Egyptian calendar
The ancient civil Egyptian calendar had a year that was 360 days long and was divided into 12 months of 30 days each, plus five extra days at the end of the year. The months were divided into three weeks of ten days each...

. The upper rear dial displays a four-year period and has associated dials showing the Metonic cycle
Metonic cycle
In astronomy and calendar studies, the Metonic cycle or Enneadecaeteris is a period of very close to 19 years which is remarkable for being very nearly a common multiple of the solar year and the synodic month...

 of 235 synodic months, which approximately equals 19 solar years. The lower rear dial plots the cycle of a single synodic month, with a secondary dial showing the lunar year of 12 synodic months.

One of the remarkable proposals made by Price was that the mechanism employed differential gears, which enabled the mechanism to add or subtract angular velocities
Angular velocity
In physics, the angular velocity is a vector quantity which specifies the angular speed of an object and the axis about which the object is rotating. The SI unit of angular velocity is radians per second, although it may be measured in other units such as degrees per second, revolutions per...

. The differential was used to compute the synodic lunar cycle by subtracting the effects of the Sun's movement from those of the sidereal lunar movement.

Allan George Bromley


A variant on Price's reconstruction was built by Australian computer scientist Allan George Bromley
Allan Bromley (historian)
Allan George Bromley was an Australian historian of computing.Allan Bromley was an associate professor at the University of Sydney...

 of the University of Sydney
University of Sydney
The University of Sydney is a public university located in Sydney, New South Wales. The main campus spreads across the suburbs of Camperdown and Darlington on the southwestern outskirts of the Sydney CBD. Founded in 1850, it is the oldest university in Australia and Oceania...

 and Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...

 clockmaker Frank Percival. Bromley went on to make new, more accurate X-ray images in collaboration with Michael Wright.

Michael Wright


Michael Wright, formerly Curator of Mechanical Engineering at The London Science Museum and now of Imperial College, London, made a completely new study of the original fragments together with Allan George Bromley
Allan Bromley (historian)
Allan George Bromley was an Australian historian of computing.Allan Bromley was an associate professor at the University of Sydney...

. They used a technique called linear X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

 tomography
Tomography
Tomography refers to imaging by sections or sectioning, through the use of any kind of penetrating wave. A device used in tomography is called a tomograph, while the image produced is a tomogram. The method is used in radiology, archaeology, biology, geophysics, oceanography, materials science,...

 which was suggested by retired consultant radiologist, Alan Partridge. For this, Wright designed and made an apparatus for linear tomography, allowing the generation of sectional 2D radiographic images.
Early results of this survey were presented in 1997, which showed that Price's reconstruction was fundamentally flawed.

Further study of the new imagery allowed Wright to advance a number of proposals. Firstly he developed the idea, suggested by Price in "Gears from the Greeks", that the mechanism could have served as a planetarium
Planetarium
A planetarium is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation...

. Wright's planetarium not only modelled the motion of the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 and Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

, but also the Inferior Planets
Inferior and superior planets
The terms "inferior planet" and "superior planet" were originally used in the geocentric cosmology of Claudius Ptolemy to differentiate as 'inferior' those planets whose epicycle remained collinear with the Earth and Sun, compared to the 'superior' planets that did not.In the 16th century, the...

 (Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...

 and Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...

), and the Superior Planets
Inferior and superior planets
The terms "inferior planet" and "superior planet" were originally used in the geocentric cosmology of Claudius Ptolemy to differentiate as 'inferior' those planets whose epicycle remained collinear with the Earth and Sun, compared to the 'superior' planets that did not.In the 16th century, the...

 (Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

, Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

 and Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

).

Wright proposed that the Sun and Moon could have moved in accordance with the theories of Hipparchus
Hipparchus
Hipparchus, the common Latinization of the Greek Hipparkhos, can mean:* Hipparchus, the ancient Greek astronomer** Hipparchic cycle, an astronomical cycle he created** Hipparchus , a lunar crater named in his honour...

 and the five known planets moved according to the simple epicyclic theory suggested by the theorem of Apollonius
Apollonius of Perga
Apollonius of Perga [Pergaeus] was a Greek geometer and astronomer noted for his writings on conic sections. His innovative methodology and terminology, especially in the field of conics, influenced many later scholars including Ptolemy, Francesco Maurolico, Isaac Newton, and René Descartes...

. In order to prove that this was possible using the level of technology apparent in the mechanism, Wright produced a working model of such a planetarium.

Wright also increased upon Price's gear count of 27 to 31 including 1 in Fragment C that was eventually identified as part of a Moon phase display. He suggested that this is a mechanism that shows the phase of the Moon by means of a rotating semi-silvered ball, realized by the differential rotation of the sidereal cycle of the Moon and the Sun's yearly cycle. This precedes previously known mechanisms of this sort by a millennium and a half.

More accurate tooth counts were also obtained, allowing a new gearing scheme to be advanced. This more accurate information allowed Wright to confirm Price's perceptive suggestion that the upper back dial displays the Metonic cycle
Metonic cycle
In astronomy and calendar studies, the Metonic cycle or Enneadecaeteris is a period of very close to 19 years which is remarkable for being very nearly a common multiple of the solar year and the synodic month...

 with 235 lunar months divisions over a five-turn scale. In addition to this Wright proposed the remarkable idea that the main back dials are in the form of spirals, with the upper back dial out as a five-turn spiral containing 47 divisions in each turn. It therefore presented a visual display of the 235 months of the Metonic cycle (19 years ≈ 235 Synodic Month
Month
A month is a unit of time, used with calendars, which was first used and invented in Mesopotamia, as a natural period related to the motion of the Moon; month and Moon are cognates. The traditional concept arose with the cycle of moon phases; such months are synodic months and last approximately...

s). Wright also observed that fragmentary inscriptions suggested that the pointer on the subsidiary dial showed a count of four cycles of the 19-year period, equal to the 76-year Callippic cycle
Callippic cycle
In astronomy and calendar studies, the Callippic cycle is a particular approximate common multiple of the year and the synodic month, that was proposed by Callippus in 330 BC...

.

Based on more tentative observations, Wright also came to the conclusion that the lower back dial counted Draconic Months and could perhaps have been used for eclipse
Eclipse
An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer...

 prediction.

All these findings have been incorporated into Wright's working model, demonstrating that a single mechanism with all these functions could be built, and would work.

Despite the improved imagery provided by the linear tomography Wright could not reconcile all the known gears into a single coherent mechanism, and this led him to advance the theory that the mechanism had been altered, with some astronomical functions removed and others added.

Finally, as an outcome of his considerable research, Wright also conclusively demonstrated that Price's suggestion of the existence of a differential gearing arrangement was incorrect.

In 2006 Wright completed what he believes to be an almost exact replica of the mechanism.

Michael Wright's research on the mechanism is continuing in parallel with the efforts of the Antikythera Mechanism Research Project (AMRP). Recently Wright slightly modified his model of the mechanism to incorporate the latest findings of the AMRP regarding the function of the pin and slot engaged gears that brilliantly simulate the anomaly in the Moon's angular velocity. On 6 March 2007 he presented his model in the National Hellenic Research Foundation in Athens
Athens
Athens , is the capital and largest city of Greece. Athens dominates the Attica region and is one of the world's oldest cities, as its recorded history spans around 3,400 years. Classical Athens was a powerful city-state...

.

The Antikythera Mechanism Research Project


The Antikythera mechanism is now being studied by the Antikythera Mechanism Research Project, a joint program between Cardiff University
Cardiff University
Cardiff University is a leading research university located in the Cathays Park area of Cardiff, Wales, United Kingdom. It received its Royal charter in 1883 and is a member of the Russell Group of Universities. The university is consistently recognised as providing high quality research-based...

 (M. Edmunds, T. Freeth), the National and Kapodistrian University of Athens
National and Kapodistrian University of Athens
The National and Kapodistrian University of Athens , usually referred to simply as the University of Athens, is the oldest university in Southeast Europe and has been in continuous operation since its establishment in 1837. Today, it is the second-largest institution of higher learning in Greece,...

 (X. Moussas, Y. Bitsakis), the Aristotle University of Thessaloniki
Aristotle University of Thessaloniki
The Aristotle University of Thessaloniki is the largest Greek university, and the largest university in the Balkans. It was named after the philosopher Aristotle, who was born in Stageira, Chalcidice, about 55 km east of Thessaloniki, in Central Macedonia...

 (J.H. Seiradakis), the National Archaeological Museum of Athens
National Archaeological Museum of Athens
The National Archaeological Museum in Athens houses some of the most important artifacts from a variety of archaeological locations around Greece from prehistory to late antiquity. It is considered one of the great museums in the world and contains the richest collection of artifacts from Greek...

, X-Tek Systems UK and Hewlett-Packard
Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...

 USA, funded by the Leverhulme Trust
Leverhulme Trust
The Leverhulme Trust was established in 1925 under the will of the First Viscount Leverhulme, William Hesketh Lever, with the instruction that its resources should be used to support "scholarships for the purposes of research and education."...

 and supported by the Cultural Foundation of the National Bank of Greece
National Bank of Greece
The National Bank of Greece is the oldest and largest commercial banking group in Greece. The group has a particularly strong presence in Southeastern Europe and the Eastern Mediterranean...

.

The mechanism's fragility precluded its removal from the museum, so the Hewlett-Packard research team and X-Tek Systems had to bring their devices to Greece. HP built a 3-D
Three-dimensional space
Three-dimensional space is a geometric 3-parameters model of the physical universe in which we live. These three dimensions are commonly called length, width, and depth , although any three directions can be chosen, provided that they do not lie in the same plane.In physics and mathematics, a...

 surface imaging device, known as the "PTM Dome", that surrounds the object under examination. X-Tek Systems developed a 12 ton 450 kV microfocus computerised tomographer especially for the Antikythera Mechanism.

It was announced in Athens
Athens
Athens , is the capital and largest city of Greece. Athens dominates the Attica region and is one of the world's oldest cities, as its recorded history spans around 3,400 years. Classical Athens was a powerful city-state...

 on 21 October 2005 that new pieces of the Antikythera mechanism had been found. There are now 82 fragments. Most of the new pieces had been stabilized but were awaiting conservation.

On 30 May 2006, it was announced that the imaging system had enabled much more of the Greek inscription to be viewed and translated, from about 1,000 characters that were visible previously, to over 2,160 characters, representing about 95% of the extant text. The team's findings shed new light concerning the function and purpose of the Antikythera mechanism. Research is ongoing. The first results were announced at an international conference in Athens, November 30 and December 1, 2006.

Nature papers 2006 and 2008


On 30 November 2006, the science journal Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...

published a new reconstruction of the mechanism by the Antikythera Mechanism Research Project, based on the high resolution X-ray tomography described above. This work doubled the amount of readable text, corrected prior transcriptions, and provided a new translation. The inscriptions led to a dating of the mechanism to around 150 to 100 BC. It is evident that they contain a manual with an astronomical, mechanical and geographical section.

The new discoveries confirm that the mechanism is an astronomical analog calculator or orrery
Orrery
An orrery is a mechanical device that illustrates the relative positions and motions of the planets and moons in the Solar System in a heliocentric model. Though the Greeks had working planetaria, the first orrery that was a planetarium of the modern era was produced in 1704, and one was presented...

 used to predict the positions of celestial bodies. This work proposes that the mechanism possessed 37 gears, of which 30 survive, and was used for prediction of the position of the Sun and the Moon. Based on the inscriptions, which mention the stationary points of the planets, the authors speculate that planetary motions may also have been indicated.

On the front face were graduations for the solar scale and the zodiac
Zodiac
In astronomy, the zodiac is a circle of twelve 30° divisions of celestial longitude which are centred upon the ecliptic: the apparent path of the Sun across the celestial sphere over the course of the year...

 together with pointers that indicated the position of the Sun, the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

, the lunar phase, and possibly the planetary motions.

On the back, two spiral scales (made of half-circles with two centers) with sliding pointers indicated the state of two further important astronomical cycles: the Saros cycle
Saros cycle
The saros is a period of 223 synodic months , that can be used to predict eclipses of the Sun and Moon. One saros after an eclipse, the Sun, Earth, and Moon return to approximately the same relative geometry, and a nearly identical eclipse will occur, in what is referred to as an eclipse cycle...

, the period of approximately 18 years separating the return of the Sun, Moon and Earth to the same relative positions and the more accurate exeligmos
Exeligmos
An exeligmos is a period of 54 years, 33 days that can be used to predict successive eclipses with similar properties and location. For a solar eclipse, every exeligmos a solar eclipse of similar characteristics will occur close to the eclipse before it...

 cycle of 54 years and one day (essential in eclipse prediction, see Eclipse cycle
Eclipse cycle
Eclipses may occur repeatedly, separated by certain intervals of time: these intervals are called eclipse cycles. The series of eclipses separated by a repeat of one of these intervals is called an eclipse series.- Eclipse conditions :...

). It also contains another spiral scale for the Metonic cycle
Metonic cycle
In astronomy and calendar studies, the Metonic cycle or Enneadecaeteris is a period of very close to 19 years which is remarkable for being very nearly a common multiple of the solar year and the synodic month...

 (19 years, equal to 235 lunar months) and the Callippic cycle
Callippic cycle
In astronomy and calendar studies, the Callippic cycle is a particular approximate common multiple of the year and the synodic month, that was proposed by Callippus in 330 BC...

 with a period of 1016 lunar orbits in approximately 76 years.

The Moon mechanism, using an ingenious train of gears
Gear train
A gear train is formed by mounting gears on a frame so that the teeth of the gears engage. Gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, this provides a smooth transmission of rotation from one gear to the next.The transmission of...

, two of them linked with a slightly offset axis and pin in a slot, shows the position and phase of the Moon during the month. The velocity of the Moon varies according to the theory of Hipparchus, and to a good approximation follows Kepler's second law for the angular velocity
Kepler's laws of planetary motion
In astronomy, Kepler's laws give a description of the motion of planets around the Sun.Kepler's laws are:#The orbit of every planet is an ellipse with the Sun at one of the two foci....

, being faster near the perigee and slower at the apogee.

On 31 July 2008, a paper providing further details about the mechanism was published in Nature (Nature Vol 454, Issue 7204, July 31, 2008). In this paper, among other revelations, it is demonstrated that the mechanism also contained a dial divided into four parts, and demonstrated a four-year cycle through four segments of one year each, which is thought to be a means of describing which of the games (such as the ancient Olympics) that took place in two and four-year cycles were to take place in any given year.

The names of the months have been read; they are the months attested for the colonies of Corinth
Corinth
Corinth is a city and former municipality in Corinthia, Peloponnese, Greece. Since the 2011 local government reform it is part of the municipality Corinth, of which it is the seat and a municipal unit...

 (and therefore also traditionally assumed for Corinth, Kerkyra, Epidamnos
Epidamnos
The ancient Greek city of Epidamnos , later the Roman Dyrrachium was founded in 627 BCE in Illyria by a group of colonists from Corinth and Corcyra...

, and Syracuse, which have left less direct evidence). The investigators suggest that the device might well be of Syracusan design and so descend from the work of Archimedes
Archimedes
Archimedes of Syracuse was a Greek mathematician, physicist, engineer, inventor, and astronomer. Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity. Among his advances in physics are the foundations of hydrostatics, statics and an...

; alternatively it could have been ordered by and customized for any of these markets and was being shipped.

Nature published another study on 24 November 2010. The study interprets the mechanism to be based on computation methods used in Babylonian astronomy, not ancient Greek astronomy, implying that Babylonian astronomy inspired the Greek counterpart – including the mechanical constructs.

Andrew Carol, an Apple software engineer, built a replica of the mechanism out of 1,500 LEGO pieces, and has correctly predicted the Solar eclipse of April 8, 2024
Solar eclipse of April 8, 2024
A total solar eclipse will take place on April 8, 2024, visible as a partial eclipse across North America and Central America. With a magnitude of 1.0566, its longest duration of totality will be of four minutes and 28 seconds near the town of Nazas, Durango, Mexico, and the nearby city of Torreón,...

 as a demonstration of its accuracy.

There is also a 3D model simulator of Price's and the Antikythera Mechanism Research Project representations.

In fiction


The device is mentioned in Kim Stanley Robinson's
Kim Stanley Robinson
Kim Stanley Robinson is an American science fiction writer known for his award-winning Mars trilogy. His work delves into ecological and sociological themes regularly, and many of his novels appear to be the direct result of his own scientific fascinations, such as the fifteen years of research...

 novel Galileo's Dream
Galileo's Dream
Galileo's Dream is a science fiction novel with elements of historical fiction written by author Kim Stanley Robinson. It describes the life of 17th century scientist and astronomer Galileo Galilei, and the far-future society living on the Galilean moons he discovered.It was published in hardcover...

. on page 293: Cartophilus actually smiled at this. “You may be right. Whatever you call it, there’s one of them on the bottom of the Aegean, near Antikytherae. It’s likely to last a long time, too. It was disguised to look like an Olympic calendar, but that won’t be enough to explain it if it’s ever found

The device is one of a number of "entanglers" which are used for time travel.

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