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Mechanical Antikythera mechanism

From Wikipedia, the free encyclopedia
The Antikythera mechanism (Fragment A - back)
The Antikythera mechanism (Fragment A - front)



The Antikythera mechanism (/ˌæntɨkɨˈθɪərə/ ANT-i-ki-THEER or /ˌæntɨˈkɪθərə/ ANT-i-KITH-ə-rə) is an ancient analog computer[1][2][3][4] designed to calculate astronomical positions. It was recovered in 1900–1901 from the Antikythera wreck,[5] but its significance and complexity were not understood until a century later. Jacques Cousteau visited the wreck in 1978[6] but, although he found new dating evidence, he did not find any additional remains of the Antikythera mechanism. The construction has been dated to the early 1st century BC. Technological artifacts approaching its complexity and workmanship did not appear again until the 14th century AD, when mechanical astronomical clocks began to be built in Western Europe.[7]

Professor Michael Edmunds of Cardiff University, who led a 2006 study of the mechanism, said:[8][9]

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.

—30 November 2006

The Antikythera mechanism is kept at the National Archaeological Museum of Athens. It is now displayed at the temporary exhibition about the Antikythera Shipwreck,[10] accompanied by reconstructions made by Ioannis Theofanidis, Derek de Solla Price, Michael Wright, the Thessaloniki University and Dionysios Kriaris. Other reconstructions are on display at the American Computer Museum in Bozeman, Montana, the Children's Museum of Manhattan in New York, in Kassel, Germany, and at the Musée des Arts et Métiers in Paris.

The mechanism was housed in a wooden box approximately 340 × 180 × 90 mm in size and comprised 30 bronze gears (although more could have been lost). The largest gear, clearly visible in fragment A, was approximately 140 mm in diameter and had 223 teeth. The mechanism's remains were found as 82 separate fragments of which only seven contain any gears or significant inscriptions.[11][12]

Origins and discovery

This machine has the oldest known complex gear mechanism and is sometimes called the first known analog computer,[13][14][15][16][17][18][19][20] although the quality of its manufacture suggests that it may have had undiscovered predecessors[21] during the Hellenistic Period. It appears to be constructed upon theories of astronomy and mathematics developed by Greek astronomers and is estimated to have been made around 100 BC. In 1974, British science historian and Yale University Professor Derek de Solla Price concluded from gear settings and inscriptions on the mechanism's faces that the mechanism was made about 87 BC and was lost only a few years later.[22] It is believed the mechanism was made of a low-tin bronze alloy (95% copper, 5% tin), but the device's advanced state of corrosion has made it impossible to perform an accurate compositional analysis.[23] All of the mechanism's instructions are written in Koine Greek,[9][not in citation given] and the consensus among scholars is that the mechanism was made in the Greek-speaking world.

Recent findings of The Antikythera Mechanism Research Project suggest the concept for the mechanism originated in the colonies of Corinth, since some of the astronomical calculations seem to indicate observations that can be made only in Corinth area of ancient Greece. Syracuse was a colony of Corinth and the home of Archimedes, which might imply a connection with the school of Archimedes.[24] Another theory states that coins found by Jacques Cousteau in the 1970s at the wreck site and dated to the time of the construction of the device, suggest that its origin may have been from the ancient Greek city of Pergamon.[25] Pergamon was also the site of the famous Library of Pergamum which housed many scrolls of art and science. The Library of Pergamum was only second in importance to the Library of Alexandria during the Hellenistic period. The ship carrying the device also contained vases that were in the Rhodian style. One hypothesis is that the device was constructed at an academy founded by the Stoic philosopher Posidonius on the Greek island of Rhodes, which at the time was known as a center of astronomy and mechanical engineering; this hypothesis further suggests that the mechanism may have been designed by the astronomer Hipparchus, since it contains a lunar mechanism which uses Hipparchus's theory for the motion of the Moon. Hipparchus was thought to have worked from about 140 BC to 120 BC. Rhodes was a trading port at that time.[26]

The mechanism was discovered in a shipwreck off Point Glyphadia on the Greek island of Antikythera. The wreck had been found in October 1900 by a group of Greek sponge divers. They retrieved numerous artifacts, including bronze and marble statues, pottery, glassware, jewelry, coins, and the mechanism itself, which were transferred to the National Museum of Archaeology in Athens for storage and analysis. The mechanism itself went unnoticed for 2 years: it was a lump of corroded bronze and wood and the museum staff had many other pieces with which to busy themselves.[26] On 17 May 1902, archaeologist Valerios Stais 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 to be prochronistic, too complex to have been constructed during the same period as the other pieces that had been discovered. Investigations into the object were soon dropped until Derek J. de Solla Price became interested in it in 1951.[27] In 1971, both Price and a Greek nuclear physicist named Charalampos Karakalos made X-ray and gamma-ray images of the 82 fragments. Price published an extensive 70-page paper on their findings in 1974.[26] It is not known how it came to be on the cargo ship, but it has been suggested that it was being taken to Rome, together with other treasure looted from the island, to support a triumphal parade being staged by Julius Caesar.[28]


Schematic of the artifact's known mechanism


The mechanism was operated by turning a small hand crank (now lost) which was linked via a crown gear to the largest gear (the 4 spoked gear visible on the front of fragment A (named b1)). This allowed setting of the date on the front dial. The action of turning the hand crank would also cause all interlocked gears within the mechanism to rotate, resulting in the calculation of the position of the Sun and Moon and other astronomical information, such as moon phases, eclipse cycles, and theoretically the locations of planets.


The mechanism is remarkable for the level of miniaturisation and the complexity of its parts, which is comparable to that of 14th-century astronomical clocks. It has at least 30 gears, although Michael Wright has suggested that the Greeks of this period were capable of implementing a system with many more gears. There is much debate that the mechanism may have had indicators for all five of the planets known to the ancient Greeks. No gearing for such a planetary display survives and all gears are accounted for, with the exception of one 63 toothed gear (r1) otherwise unaccounted for in fragment D.

Evans et al. suggest that to display the mean positions of the five classical planets would require only 17 further gears which could be positioned in front of the large driving gear and indicated using individual circular dials on the face.[29] Tony Freeth and Alexander Jones have modelled and published details of a version using several gear trains mechanically similar to the lunar anomaly system allowing for indication of the planets' positions as well as synthesis of the sun anomaly. Their system, they claim, is more authentic than Wright's model as it utilises the known skill sets of the Greeks of that period and does not add excessive complexity or internal stresses to the machine.[30]

The gear teeth were in the form of equilateral triangles with an average circular pitch of 1.6 mm, an average wheel thickness of 1.4 mm and an average air gap between gears of 1.2 mm. They were probably created from a blank bronze round using hand tools; this is evident because they are not all divided very evenly.[30] Due to advances in imaging and X-ray technology it is now possible to know the precise number of teeth and size of the gears within the located fragments. Thus the basic operation of the device is no longer a mystery and has been accurately replicated. The major unknown now regards the presence and nature of any planet indicators.

Known gear scheme


Gear chain diagram for the known elements of the mechanism. Hypothetical gears in italics.

The Sun gear is operated from the hand operated crank (connected to gear a1, driving the large four spoked mean sun gear, b1) and in turn drives the rest of the gear sets. The sun gear is b2 and it has 64 teeth.

The Moon train follows on from the sun train through gears b2/c1 * c2/d1 * d2/e2 then transferring through the freely rotating e3 to e5. The mechanism of e5/k1 * k2/e6 (all having 50 teeth) sits inside the ring gear e4 and on top of e3, k1 and k2 rotate with it and use it as an epicyclic platform.

Gear e3 rotates at a velocity which equals the difference between the number of sidereal months in one year (13.368) and the number of anomalistic months in one year (13.256) (ratio to sun: 0.1126). e5 rotates at the ratio of the sidereal month. Both e3 and e5 rotate in the same direction. k1 is mounted on e3 so rotates at an angular velocity equal to that of e5 minus e3. k1 and k2 are not coaxial and have their axes offset by about 1.1 mm. A pin protrudes from k1 and is used to drive k2 via a slot. Because of the offset axes, k2 rotates at a varying angular velocity depending on the position of k1's pin in k2's slot (an ω/t plot would be close to sinusoidal in form). e6 is larger in diameter than e5 in order to mesh with k2. This unusual arrangement of gears is to mimic the eccentricities of the moon's orbit.

The motion then passes through to e1/b3 and through the centre of the b2 and b1 gears and the sun indicator shaft to the moon spindle. The orbit of the moon follows the rotational velocity of the moon spindle with a total ratio to the sun gear of 13.368.

The system to indicate the phases of the moon utilises further gear combinations. Gear b0 is attached to the sun indicator shaft and through the bevel gear train b0/mb3 * mb2/ma1 the phase spindle rotates at a ratio of 12.368 to the sun, imitating the synodic month.

The Metonic train is driven from the sun gear through b2/l1 * l2/m1 * m2/n1. The total ratio for this train is 0.263.

The Olympiad train follows on from the Metonic. Gears n3/o1 with a total ratio to the sun gear of 0.25.

The Callippic train follows on from the Metonic. Gears n2/p1 * p2/q1 with a total ratio to the sun gear of 0.0132.

The Saros train is driven from the sun gear following: b2/l1 * l2/m1 * m3/e3 * e4/f1 * f2/g1. The total ratio for this train is 0.222.

The Exeligmos train follows on from the Saros train. Gears g2/h1 * h2/i1 with a total ratio to the sun gear of 0.018.

3sc Proposed planet indication schemes

Because of the large space between the mean sun gear and the front of the case and the size of and mechanical features on the mean sun gear it is very likely that the mechanism contained further gearing that has either been lost in or subsequent to the shipwreck or was removed before being loaded onto the ship. This lack of evidence and nature of the front part of the mechanism has led to numerous attempts to emulate what the Greeks of the period would have done and of course because of the lack of evidence many solutions have been put forward.

Wright proposal.
Evans et al. proposal.
Freeth et al. proposal.

Michael Wright was the first person to design and build a model with not only the known mechanism but also with his emulation of a potential planetarium system. He suggested that along with the lunar anomaly the deeper understood solar anomaly would also be indicated. He achieved this by the attachment of three meshing and equally sized gears to one of the spokes of the b1 mean sun gear. The farthest gear away from the central spindle was fitted with an offset pin over which an arm with a slot was fitted which in turn attached to the sun spindle, causing anomalous movement indicative of the solar anomaly.

The inferior planets are indicated using more gears attached to b1 or attached to a plate via the use of pillars which may have existed on b1. These gears ultimately drive disks protruding from which are pins over which arms with slots are placed. The arms are attached to the relevant planet indication spindle and through a combination of both the rotation of b1 and the action of the pin and slot mechanisms the planets' motions are synthesised and indicated on the front dial.

The superior planets are much more complex and their mechanisms require significant extra hardware. Each superior planet system is mounted on a separate 223 toothed main gear (the same tooth count as b1) which is mounted on a rectangular plate. This plate is mounted to the frame with wooden spacer blocks on each short end of the rectangular plate. These plates are vertically mounted together and attached to the mechanism as a whole. The individual main gears are driven by smaller transfer gears driven by b1, as all of these gears share the same tooth counts the ratio between b1 and superior gear is 1. Each superior system is very similar with the only differences being the size of the gears. The main gears and upper plate are free to rotate, while the central spindle gear is fixed. The main gear is driven by the b1 transfer gear and drives the smaller coaxial gear attached to its surface. This gear drives a larger transfer gear which drives two smaller gears, one of these is coaxial and on the other side of the upper plate, the other is on the same side of the upper plate and drives the pin carrier wheel which is on the other side of the upper plate. The smaller driven gear then drives the fixed gears on the top of the upper plate, the smaller of those (or in the case of the Mars mechanism the only one) drives the fixed spindle gear. Attached to the spindle is an arm with a slot which engages with the aforementioned pin carrier wheel. This whole system rotates with the mean sun gear and subtracts from that gear's angular velocity to make the required ratio and indicate it on the front face.[34][35][36]

Evans, Carman and Thorndike published a solution with significant differences from Wright's. Their proposal centred on what they observed as irregular spacing of the inscriptions on the front dial face which to them seemed to indicate an off centre sun indicator arrangement, this would simplify the mechanism by removing the need to simulate the solar anomaly. They also suggested that rather than accurate planetary indication (rendered impossible by the offset inscriptions) there would be simple dials for each individual planet showing information such as key events in each planet's cycle, initial and final appearances in the night sky and apparent direction changes. This system would lead to a much simplified gear system, with much reduced forces and complexity.

Their proposal used simple meshed gear trains and accounted for the previously unexplained 63 toothed gear in fragment D. They proposed two face plate layouts, one with evenly spaced dials and another with a gap in the top of the face to account for criticism regarding their not using the apparent fixtures on the b1 gear. They proposed that rather than bearings and pillars for gears and axles they simply held weather and seasonal icons to be displayed through a window.[29]

In a paper published in 2012 Carman, Thorndike and Evans proposed a system of epicyclic gearing with pin and slot followers.[37]

Freeth and Jones published their proposal in 2012 after extensive research and work they came up with a compact and feasible solution to the question of planetary indication. They also propose indicating the solar anomaly on a separate pointer to the mean sun wheel's date pointer. Their front panel display would be essentially the same as Wright's although instead of pointers with text they would use semi-precious stones for each of the indicated bodies. The materials to be used are in order from the centre outwards:

Unlike Wright's model however, this model has never been built and has only been operated as a computer simulation.

The system to synthesise the solar anomaly is very similar to that used in Wright's proposal. Three gears, one fixed in the centre of the b1 gear and attached to the sun spindle, the other fixed on one of the spokes (in their proposal the one on the bottom left) acting as an idle gear and the final positioned next to that one, the final gear is fitted with an offset pin and over said pin an arm with a slot which is in turn attached to the sun spindle inducing anomaly as the mean sun wheel turns.

The inferior planet mechanism is again similar to Wright's mechanism however it uses fewer gears. A gear is attached to the centre of b1 and meshes with another gear which uses b1 as an epicyclic platform (Venus uses the upper left spoke and Mercury the lower right). Attached to this gear is a plate to which a pin is fixed, a slotted arm goes over this pin and is attached to the indicator spindle, the spindle is rotated freely about the centre of b1 with anomaly induced by the pin and slot mechanism.

The superior planet mechanisms differ from Wright's but perform the same function using fewer gears. They all follow the same general principle of the lunar anomaly mechanism. All planet systems contain four gears: the input gear which is fixed, the pin gear, the slot gear and the output gear attached to the indicator shaft. Two mounted on offset axes using pin and slot systems and two mounted on the same axis, one driving and one being driven. All systems use ratios related to Babylonian astronomy. The superior planet gears are mounted on a sub-plate using metal bridges, which is in turn located in front of the inferior systems and attached to the wooden frame, the front dial plate is fixed on top of this.

There are in total 8 coaxial spindles of various sizes to transfer the rotation of the mechanism to the pointers. In total these additions require 18 new gears and because of the application of the sun anomaly the addition of a separate date pointer and of course the extra planet pointers giving a total of 47 gears and 8 pointers.[38]

4l Fragments


Of the 82 fragments that have been found seven of the fragments are significant and contain the majority of the mechanism and inscriptions. There are also 16 smaller parts that contain fractional and incomplete inscriptions.

The seven major fragments are listed below:

Fragment Size [mm] Weight [g] Gears Inscriptions
A 180 × 150 369.1 27 Yes
B 125 × 60 99.4 1 Yes
C 120 × 110 63.8 1 Yes
D 45 × 35 15.0 1
E 60 × 35 22.1 Yes
F 90 × 80 86.2 Yes
G 125 × 110 31.7 Yes

3sc Major fragments

Fragment A can be seen as the main fragment and contains the majority of the known mechanism. Clearly visible on the front is the large b1 gear, and under closer inspection further gears behind said gear (parts of the l, m, c and d trains are clearly visible as gears to the naked eye). The back of the fragment contains the rearmost e and k gears for synthesis of the moon anomaly, noticeable also is the pin and slot mechanism of the k train. It is noticed from detailed scans of the fragment that all gears are very closely packed and have sustained damage and displacement due to their years in the sea. The fragment is approximately 30 mm thick at its thickest point.

Fragment A also contains divisions of the upper left quarter of the Saros spiral and 14 inscriptions from said spiral. The fragment also contains inscriptions for the Exeligmos dial and visible on the back surface the remnants of the dial face itself. Finally, this fragment contains some back door inscriptions.

Fragment B contains approximately the bottom right third of the Metonic spiral and inscriptions of both the spiral and back door of the mechanism. The Metonic scale would have consisted of 235 cells of which 49 have been deciphered from fragment B either in whole or partially. The rest so far are assumed from knowledge of the Metonic cycle itself. This fragment also contains a single gear (o1) used in the Olympic train.

Fragment C contains parts of the upper right of the front dial face showing calendar and zodiac inscriptions. This fragment also contains the moon indicator dial assembly including the moon phase sphere in its housing and a single bevel gear (ma1) used in the moon phase indication system.

Fragment D contains at least one unknown gear and according to M.T.Wright possibly two. Their purpose and position has not been ascertained to any accuracy or consensus but lends to the debate for the possible planet displays on the face of the mechanism.

Fragment E was found in 1976 and contains 6 inscriptions from the upper right of the Saros spiral.

Fragment F was found in 2005 and contains 16 inscriptions from the lower right of the Saros spiral. It also contains remnants of the mechanism's wooden housing.

Fragment G is a combination of fragments taken from fragment C while cleaning.

3sc Minor fragments

Many of the smaller fragments that have been found contain nothing of value however a few have some inscriptions on them.

Fragment 19 contains significant back door inscriptions including one reading "...76 years...." which refers to the Callippic cycle. Other inscriptions seem to describe the function of the back dials. In addition to this important minor fragment, 15 further minor fragments have remnants of inscriptions on them.

5c Inscriptions

Computer-generated front panel of the Freeth model.

On the front of the mechanism, there is one dial with two confirmed pointers, but, due to references on the inscriptions, there might have been as many as eight pointers: one for the day of the year and the rest representing the orbital positions for Mercury, Venus, Sun, Mars, Jupiter, Saturn and the Moon; although no fragments have been found to confirm this. It has been confirmed that the pointer for the moon also rotates on its axis to show its phase along with its position, although it is not clear whether the Sun position pointer would have been separated from a date pointer, or whether any planetary positions might have been displayed.[24]

Since the purpose was to position astronomical bodies with respect to the celestial sphere, in reference to the observer's position on the Earth, the device was based on the geocentric model.[39]

4l Front face

The front dial has two concentric circular scales. The outer ring is marked off with the days of the 365-day Egyptian calendar, or the Sothic year, based on the Sothic cycle. On the inner ring, there is a second dial marked with the Greek signs of the Zodiac and divided into degrees. The calendar dial can be moved to compensate for the effect of the extra quarter day in the solar year by turning the scale backwards one day every four years. A 36514-day year was used in the Callippic cycle about 330 BC and in the Decree of Canopus in 238 BC. A few of the following months are inscribed, in Greek letters, on the outer ring:

  • Mecheir
  • Phamenoth
  • Pharmouthi
  • Pachon
  • Payni
  • Epeiph
  • Mesore
  • Epagomene
  • Thoth
  • Phaophi
  • Hathyr
  • Choiak
  • Tybi

In addition, the following Zodiac signs appear on the inner ring: 'ΟN', ΧΗΛΑΙ, ΣΚΟΡΠΙΟΣ. Thus, the complete Zodiac, which is believed to be tropical as opposed to sidereal, would be:

Front panel of a 2007 reproduction.
  • ΚΡIOΣ (Aries)
  • ΤΑΥΡΟΣ (Taurus)
  • ΔIΔΥΜΟΙ (Gemini)
  • ΚΑΡΚIΝΟΣ (Cancer)
  • ΛEΩΝ (Leo)
  • ΠΑΡΘEΝΟN (Virgo)
  • ΧΗΛΑΙ (Scorpio's Claw, i.e., Libra)
  • ΣΚΟΡΠΙΟΣ (Scorpio)
  • ΤΟΞΩΤΗΣ (Sagittarius)
  • ΑIΓOΚΕΡΩΣ (Capricorn)
  • YΔΡΟΧOΟΣ (Aquarius)
  • IΧΘΕIΣ (Pisces)

Other inscriptions on the front dial are:

  • {Κ} Evening
  • {Λ} The Hya{des se}t in the evening
  • Μ Taurus {be}gins to rise
  • {N} Vega rises in the evening
  • Θ {The Pleiad}es rise in the morning
  • Ο The Hyades rise in the morning
  • Π Gemini begins to rise
  • Ρ Altair rises in the evening
  • Σ Arcturus sets in the {morning}

Finally, the front dial includes a parapegma, a precursor to the modern day almanac, 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.

4l Rear face

Computer-generated back panel

In 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.[40] Inscriptions on the instrument closely match the names of the months on calendars from Illyria and Epirus in northwestern Greece and with the island of Corfu.[41][42]

On the back of the mechanism, there are five dials: the Metonic, the Olympiad, the Callippic, the Saros and the Exeligmos. The Metonic Dial is the main upper dial. It is a 19-year calendar with a total of 235 months. Each month is written over two or three lines within one of the 235 cells spread over a spiral with five turnings. The Corinthian months are:

  1. ΦΟΙΝΙΚΑΙΟΣ (Phoinikaios)
  2. ΚΡΑΝΕΙΟΣ (Kraneios)
  3. ΛΑΝΟΤΡΟΠΙΟΣ (Lanotropios)
  4. ΜΑΧΑΝΕΥΣ (Machaneus)
  5. ΔΩΔΕΚΑΤΕΥΣ (Dodekateus)
  6. ΕΥΚΛΕΙΟΣ (Eukleios)
  7. ΑΡΤΕΜΙΣΙΟΣ (Artemisios)
  8. ΨΥΔΡΕΥΣ (Psydreus)
  9. ΓΑΜΕΙΛΙΟΣ (Gameilios)
  10. ΑΓΡΙΑΝΙΟΣ (Agrianios)
  11. ΠΑΝΑΜΟΣ (Panamos)
  12. ΑΠΕΛΛΑΙΟΣ (Apellaios)

The Olympiad Dial is the right secondary upper dial. The dial is divided into four sectors, each of which is inscribed with a year number and the name of two Panhellenic Games: the "crown" games of Isthmia, Olympia, Nemea, and Pythia; and two lesser games: Naa (held at Dodona) and another games which has not yet been deciphered.[43] The years on each one of the four divisions are:

  1. LA (Year 1)
  2. LB (Year 2)
  3. LΓ (Year 3)
  4. L∆ (Year 4)

The names given to each of these four divisions are:

  1. ΙΣΘΜΙΑ, ΟΛΥΜΠΙΑ (corresponding to year 1)
  2. NEMEA, NAA (corresponding to year 2)
  3. ΙΣΘΜΙΑ, ΠΥΘΙΑ (corresponding to year 3)
  4. ΝΕΜΕΑ, undeciphered text (corresponding to year 4)

The Callippic Dial is the left secondary upper dial, which follows a 76-year cycle, quadrupling the Metonic dial.

The Saros Dial is the main lower dial. It is an 18-year calendar with a total of 223 lunar months. Each month is represented by one of the 223 cells spread over a spiral with four turnings. This dial predicts eclipses and the predictions are shown in the relevant months as glyphs, which indicate lunar and solar eclipses and their predicted times of day. There are 51 glyphs, specifying 38 lunar and 27 solar eclipses. The glyph times are still incomplete. Beneath each glyph is an index letter. Some of the index letters are:

  • Σ = ΣΕΛΗΝΗ (Moon)
  • Η = ΗΛΙΟΣ (Sun)
  • H\M = ΗΜΕΡΑΣ (of the day)
  • ω\ρ = ωρα (hour)
  • N\Y = ΝΥΚΤΟΣ (of the night)

Moreover, the divisions on the inside of the dial at the cardinal points indicate the start of a new full moon cycle.

The Exeligmos Dial is the secondary lower dial. It is a 54-year triple Saros dial. The labels on its three divisions are:

  • Blank, which represents the number zero.
  • H (number 8)
  • Iς (number 16)

So the dial pointer indicates how many hours must be added to the glyph times of the Saros Dial in order to get the exact eclipse times.

4l Doors

The mechanism has a wooden casing with a front and a back door. The Back Door appears to be the "Instruction Manual". On one of its fragments, it is written "76 years, 19 years" representing the Callippic and Metonic cycles. It is also written "223" for the Saros cycle. On another one of its fragments, it is written "on the spiral subdivisions 235" for the Metonic Dial. The Front Door also has inscriptions.[24][44]

5c Speculation about the mechanism's purpose

It is thought that the purpose of this device was to predict lunar and solar eclipses based on Babylonian arithmetic progression cycles. The inscriptions on the device also support suggestions of mechanical display of planetary positions.[45]

Derek J. de Solla Price suggested that the mechanism 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, which apparently were a specialty of the Rhodians. Pindar, one of the nine lyric poets of ancient Greece, said this of Rhodes:

The animated figures stand
Adorning every public street
And seem to breathe in stone, or
Move their marble feet.

—Pindar (trans. Rev. C. A. Wheelwright - 1830), Seventh Olympic Ode (95)

Arguments against the device having been on public display include the following:

  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 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 much information associated with well-known Mediterranean geographical locations).[citation needed][dubious ]

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.

5c Similar devices in ancient literature

Cicero's De re publica, a 1st-century BC philosophical dialogue, mentions two machines that some modern authors consider as some kind of planetarium or orrery, predicting the movements of the Sun, the Moon, and the five planets known at that time. They were both built by Archimedes and brought to Rome by the Roman general Marcus Claudius Marcellus 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 Gaius Sulpicius Gallus (consul with Marcellus' nephew in 166 BC, and credited by Pliny the Elder as the first Roman to have written a book explaining solar and lunar eclipses) gave both a "learned explanation" and a working demonstration of the device.

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.][46]

Pappus of Alexandria stated that Archimedes had written a now lost manuscript on the construction of these devices entitled On Sphere-Making.[47][48] The surviving texts from the Library of Alexandria describe many of his creations, some even containing simple drawings. One such device is his odometer, the exact model later used by the Romans to place their mile markers (described by Vitruvius, Heron of Alexandria and in the time of Emperor Commodus).[49] 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.[50] Whether this is an example of a device created by Archimedes and described by texts lost in the burning of the Library of Alexandria, or if it is a device based on his discoveries, or if it has anything to do with him at all, is debatable.

An odometer by Leonardo da Vinci based on the design by Roman engineer Vitruvius
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 (Divinarum Institutionum Libri VII), Claudian (In sphaeram Archimedes), and Proclus (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, "... 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..."[51]

It is unlikely that any one of these machines was the Antikythera mechanism found in the shipwreck since 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 device was almost certainly in the hands of Posidonius by that date. The scientists who have reconstructed the Antikythera mechanism also agree that it was too sophisticated to have been a unique device.

This evidence that the Antikythera mechanism was not unique 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 worlds, where mechanical devices which were complex, albeit simpler than the Antikythera mechanism, were built during the Middle Ages.[52] Fragments of a geared calendar attached to a sundial, from the 5th or 6th century Byzantine Empire, have been found; the calendar may have been used to assist in telling time.[53] In the Islamic world, Banū Mūsā's Kitab al-Hiyal, 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 texts preserved in monasteries. A geared calendar similar to the Byzantine device was described by the scientist al-Biruni around 1000, and a surviving 13th-century astrolabe also contains a similar clockwork device.[53] It is possible that this medieval technology may have been transmitted to Europe and contributed to the development of mechanical clocks there.[7]

5c Investigations and reconstructions

Reconstruction of the Antikythera mechanism in the National Archaeological Museum, Athens (made by Robert J. Deroski, based on Derek J. de Solla Price model)

The Antikythera mechanism is one of the world's oldest known geared devices. It has puzzled and intrigued historians of science and technology 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.[54]

4l Derek J. de Solla Price

Following decades of work cleaning the device, in 1951 British science historian Derek J. de Solla Price undertook systematic investigation of the mechanism.

Price published several papers on "Clockwork before the Clock".[55][56] and "On the Origin of Clockwork",[57] before the first major publication in June 1959 on the mechanism: "An Ancient Greek Computer".[58] This was the lead article in Scientific American and appears to have been initially published at the prompting of Arthur C. Clarke, according to the book Arthur C. Clarke's Mysterious World (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. 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.

In 1971, Price, by then the first Avalon Professor of the History of Science at Yale University, teamed up with Charalampos Karakalos, professor of nuclear physics at the Greek National Centre of Scientific Research "DEMOKRITOS". Karakalos took both gamma- and X-ray 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",[59] 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 against the Egyptian calendar. The upper rear dial displays a four-year period and has associated dials showing the Metonic cycle 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. 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.

4l Allan George Bromley

Professor Allan Bromley, a computer scientist of the University of Sydney improved on Price's reconstruction with the help of Frank Percival, a clockmaker. Having tested Price's theory using Meccano parts, he found that the mechanism was unworkable. Working with Percival, he improved the device by altering the function of the handle so that one complete rotation would correspond to a single day, which he considered to be the most obvious astronomical unit. Bromley worked with the same set of parts as Price, but suspected that a gap in the mechanism was originally home to several extra gears.[60]

Another breakthrough by Bromley concerned a train of gearing which appeared to have 15 and 63 teeth, for which Price had been unable to discover a purpose. Price considered these numbers to be too difficult to work with, and assumed that they should be corrected to 16 and 64, theorising that it could have operated a four-year cycle on the device. Bromley worked with the original count of 15 and 63 teeth, discovering that the train's cycle was four and a half years; four of such cycles equalled 18 years, a duration equal to the cycle of eclipses. With this gearing, the mechanism worked correctly, with the pointer moving into a new square for each new moon, as the handle is turned, meaning that each square on a dial represented one month. Over 223 months, or 18 years, the complete cycle is shown.[60]

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

4l 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. They used a technique called linear X-ray tomography 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.[61] Early results of this survey were presented in 1997, which showed that Price's reconstruction was fundamentally flawed.[62]

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. Wright's planetarium not only modelled the motion of the Sun and Moon, but also the Inferior Planets (Mercury and Venus), and the Superior Planets (Mars, Jupiter and Saturn).[63][64]

Wright proposed that the Sun and Moon could have moved in accordance with the theories of Hipparchus and the five known planets moved according to the simple epicyclic theory suggested by the theorem of Apollonius. 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.[65][66]

Wright also increased upon Price's gear count of 27 to 31[64] including 1 in Fragment C that was eventually identified as part of a Moon phase display.[67] 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,[68] allowing a new gearing scheme to be advanced.[69] This more accurate information allowed Wright to confirm Price's perceptive suggestion that the upper back dial displays the Metonic cycle 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 Months). 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.[70]

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 prediction.[71]

All these findings have been incorporated into Wright's working model,[70] 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.[70]

Finally, as an outcome of his considerable research,[61][70][72][73][74][75][76] Wright also conclusively demonstrated that Price's suggestion of the existence of a differential gearing arrangement was incorrect.[67][70]

In 2006 Wright completed what he believed to be an almost exact replica of the mechanism.[77]

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 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.

4l Antikythera Mechanism Research Project

The Antikythera Mechanism Research Project was launched in 2005,[78] a joint program between Cardiff University (M. Edmunds, T. Freeth), the National and Kapodistrian University of Athens (X. Moussas, Y. Bitsakis), the Aristotle University of Thessaloniki (J.H. Seiradakis), the National Archaeological Museum of Athens, X-Tek Systems UK[79] and Hewlett-Packard USA, initially funded by the Leverhulme Trust and supported by the National Bank of Greece Cultural Foundation.[80]

The mechanism's fragility precluded its removal from the museum, so the Hewlett-Packard research team[81] and X-Tek Systems had to bring their devices to Greece. HP built a 3-D 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.

The team announced in October 2005 that new pieces of the Antikythera mechanism had been found, making a total of 82 fragments.[citation needed] Most of the new pieces had been stabilized but were awaiting conservation. In May 2006, the team announced that the imaging system had allowed 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 on the function and purpose of the Antikythera mechanism. The first results were announced at an international conference in Athens in November and December 2006.[82]

4l Nature papers

3sc 2006

In November 2006, the science journal Nature published a new reconstruction of the mechanism by the Antikythera Mechanism Research Project, based on the high-resolution X-ray tomography described above.[83] 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, 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 together with pointers that indicated the position of the Sun, the Moon, 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, 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 cycle of 54 years and one day (essential in eclipse prediction, see Eclipse cycle). It also contains another spiral scale for the Metonic cycle (19 years, equal to 235 lunar months) and the Callippic cycle with a period of 1016 lunar orbits in approximately 76 years.

The Moon mechanism, using an ingenious train of gears, 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 appears to vary according to the theory of Hipparchus, and to a good approximation follows Kepler's second law for the angular velocity, being faster near the perigee and slower at the apogee.

3sc 2008

In July 2008, a paper providing further details about the mechanism was published in Nature.[24] In this paper 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 (and therefore also traditionally assumed for Corinth, Kerkyra, Epidamnos, 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; alternatively it could have been ordered by and customized for any of these markets and was being shipped.

Access to the full text of this 2008 paper requires a paid subscription. However, the submitted version can be downloaded.[84]

3sc 2010

Nature published another study in November 2010,[85] which suggests that the mechanism may 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.

The article concentrates on suggestions by James Evans, Christián Carman and Alan Thorndike that a simpler gearing system was used to display key events of displayed bodies. Their first suggestion is that the zodiac indicator dial was unevenly graduated to comply with the sun's anomalous progress through the sky. This system would simplify the sun's gear system. However the uneven graduation of the zodiac dial would lead to any planet indicators not being very accurate. To overcome this problem they suggest that each planet had a dial of its own and rather than showing precise location indication they simply show key events in each planet's cycle, such as initial and final appearances in the night sky and direction changes. This would supply the same information as a complex epicyclic gearing system but using much simpler gear trains.

The article also states that inscriptions are still being deciphered from x-ray images.

4l Tony Freeth and Alexander Jones's additions

In their 2012 article for the Institute for the Study of the Ancient World (ISAW) entitled The Cosmos in the Antikythera Mechanism they suggest that it is quite likely that the mechanism included gearing and indicators for the planets as well as possibly indicating solar anomalies.

They base their proposal on inscriptions detailing the motion of the five known planets as well as on the noticeable holes and brackets on the main driving gear.

They suggest that the mean sun wheel (b1) may have been utilised as a carrier for various gear trains and other hardware and they describe and simulate how this could have been possible. They also describe in detail the evidence they have found for additional fixings on the gear. These include bearings for shafts on some of the spokes, a recess and a raised flat area possibly used to attach fixings with solder or rivets and pillars around the edge of the wheel which were potentially used to hold a sub plate and fixing bridges. They also find evidence for a 1 mm hole drilled lengthwise into the spoke at the bottom left; this would have been a complex technical achievement at the time and they are unable to explain its purpose, but tentatively suggest something to do with lubrication.

Their model simulates the solar anomaly, inferior planets and superior planets and indicates their positions on the front face along with the date and lunar pointers.

Investigations reveal that their simulated mechanism is not particularly accurate, the Mars pointer being up to 38° out at times. This is due to the inaccuracies of the Greek theories of the planets and the lack of detailed knowledge by the same.

In short, the Antikythera Mechanism was a machine designed to predict celestial phenomena according to the sophisticated astronomical theories current in its day, the sole witness to a lost history of brilliant engineering, a conception of pure genius, one of the great wonders of the ancient world—but it didn’t really work very well!

—The Cosmos in the Antikythera Mechanism , 2012

5c Further planned research

The Woods Hole Oceanographic Institution in the United States received permission from the Greek Government in 2012 to conduct new dives around the deep shoals of Antikythera. Brendan Foley of the institute will be conducting a new survey of the debris field along with other archaeologists, including Theotokis Theodoulou of the Greek Ephorate of Underwater Antiquities.[86] The researchers are hoping to find other small pieces of the Antikythera mechanism on the sea floor. Additionally they hope to locate and survey the wrecks of other ships that foundered on the island's shoals.[86]

5c Latest research results

The divers who conducted the latest Antikythera shipwreck work in 2012, found artefacts that spread across the rocky sea floor on a steep slope between 35-60m deep, 200m away from the site excavated by J.Y.Cousteau. [87] The latest expedition objectives were to survey the entire underwater Antikythera coastline to 40m, relocate the shipwreck site and conduct a full underwater archaeology project by year 2015. [88]

Pictures on latest Antikythera shipwreck site work

5c Documentaries and popular culture

The National Geographic documentary series Naked Science had an episode dedicated to the Antikythera Mechanism entitled Star Clock BC (Season leaving Episode 2) that aired on January 20, 2011.

A documentary about the mechanism, called The World's First Computer, was produced in 2012 by the Antikythera mechanism researcher and film-maker Tony Freeth.[89][90]

The device was also a central artifact in the film Stonehenge Apocalypse (2010), where it was used as the object that saved the world from impending doom.[91]

A fully functioning Lego reconstruction of the Antikythera mechanism was built in 2010 by hobbyist Andy Carrol, and featured in a short film produced by Small Mammal in 2011.[92]

In 2012 BBC Four aired The Two-Thousand-Year-Old Computer. It documented the discovery and investigation of the mechanism.[93]

On 3 April 2013, a new episode of the science show NOVA, called "Ancient Computer", was broadcast on PBS. This is a rebroadcast of "The Two-Thousand-Year-Old Computer" under a different title.[94]

On May 25, 2010, the first episode of the History Channel series Ancient Aliens presented it as one of the many 'evidences' of ancient alien astronauts visiting earth and leaving behind technology.[95]

5c See also

5c References

  1. ^ The Antikythera Mechanism Research Project", The Antikythera Mechanism Research Project. Retrieved 2007-07-01 Quote: "The Antikythera Mechanism is now understood to be dedicated to astronomical phenomena and operates as a complex mechanical 'computer' which tracks the cycles of the Solar System."
  2. ^ BILL. SEAMAN; Otto E. Rössler (1 January 2011). Neosentience: The Benevolence Engine. Intellect Books. p. 111. ISBN 978-1-84150-404-9. Retrieved 28 May 2013. "Mike G. Edmunds and colleagues used imaging and high-resolution X-ray tomography to study fragments of the Antikythera Mechanism, a bronze mechanical analog computer thought to calculate astronomical positions" 
  3. ^ Eric G. Swedin; David L. Ferro (24 October 2007). Computers: The Life Story of a Technology. JHU Press. p. 1. ISBN 978-0-8018-8774-1. Retrieved 28 May 2013. "It was a mechanical computer for calculating lunar, solar, and stellar calendars." 
  4. ^ Washington Post Quote: Imagine tossing a top-notch laptop into the sea, leaving scientists from a foreign culture to scratch their heads over its corroded remains centuries later. A Roman shipmaster inadvertently did something just like it 2,000 years ago off southern Greece, experts said late Thursday.
  5. ^ pp. 5–8, Gears from the Greeks. The Antikythera Mechanism: A Calendar Computer from ca. 80 BC, Derek de Solla Price, Transactions of the American Philosophical Society, new series, 64, No. 7 (1974), pp. 1–70.
  6. ^ Lazos, Christos (1994). The Antikythera Computer (Ο ΥΠΟΛΟΓΙΣΤΗΣ ΤΩΝ ΑΝΤΙΚΥΘΗΡΩΝ),. ΑΙΟΛΟΣ PUBLICATIONS GR. 
  7. ^ a b In search of lost time, Jo Marchant, Nature 444, #7119 (30 November 2006),pp. 534–538,doi:10.1038/444534a
  8. ^ Johnston, Ian (30 November 2006). "Device that let Greeks decode solar system". The Scotsman. Retrieved 26 June 2007. 
  9. ^ a b The Guardian: Mysteries of computer from 65BC are solved. Excerpts: This device is extraordinary, the only thing of its kind," said Professor Edmunds. "The astronomy is exactly right ... in terms of historic and scarcity value, I have to regard this mechanism as being more valuable than the Mona Lisa." and One of the remaining mysteries is why the Greek technology invented for the machine seemed to disappear.
  10. ^ "The Antikythera Shipwreck: the Ship , the Treasures, the Mechanism". Antikythera Mechanism Research Project. 6 June 2012. Retrieved 16 April 2013. 
  11. ^ "Decoding The Antikythera Mechanism - Investigation of An Ancient Astronomical Calculator". Bibliotecapleyades.net. Retrieved 2012-11-13. 
  12. ^ Vetenskapens värld: Bronsklumpen som kan förutsäga framtiden. SVT. 17 october 2012.
  13. ^ Mark E. Rosheim (11 August 1994). Robot Evolution: The Development of Anthrobotics. John Wiley & Sons. p. 7. ISBN 978-0-471-02622-8. Retrieved 28 May 2013. "The Antikythera Mechanism (c. 87 BC) proves how sophisticated Greek technology was. and encrusted by twenty-one centuries of undersea exposure, X-ray examination revealed a complex mechanical computer in the Archimedean tradition of planetary construction." 
  14. ^ Harry Henderson (1 January 2009). Encyclopedia of Computer Science and Technology. Infobase Publishing. p. 13. ISBN 978-1-4381-1003-5. Retrieved 28 May 2013. "The earliest known analog computing device is the Antikythera mechanism." 
  15. ^ ORMUS The Secret Alchemy of Mary Magdalene ~ Revealed ~ [Part A]. ORMUS® USA/Japan. December 2007. p. 4. ISBN 978-0-9793737-0-1. Retrieved 28 May 2013. "Being one of the world's oldest known geared devices, a major article in Scientific American entitled “An ancient Greek computer,” [June 1959] the theory that the Antikythera mechanism is a device specifically designed for calculating sidereal..." 
  16. ^ Justin Pollard; Howard Reid (30 October 2007). The Rise and Fall of Alexandria: Birthplace of the Modern World. Penguin Group US. p. 120. ISBN 978-1-4406-2083-6. Retrieved 28 May 2013. "Price's meticulous study of the cogs, gear ratios, and inscriptions enabled him to put together a model of how the Antikythera mechanism worked and what it did. The mechanism was a hugely sophisticated analog computer for calculating the ..." 
  17. ^ http://www.forbes.com/sites/parmyolson/2012/10/24/could-this-have-been-the-worlds-first-computer/
  18. ^ Dimitris G. Angelakis (2006). Quantum Information Processing: From Theory to Experiment ; [proceedings of the NATO Advanced Study Institute on Quantum Computation and Quantum Information, Chania, Crete, Greece, 2- 13 May 2005]. IOS Press. p. 5. ISBN 978-1-58603-611-9. Retrieved 28 May 2013. "The Antikythera mechanism, as it is now known, was probably the world's first “analog computer” — a sophisticated device for calculating the motions of stars and planets. This remarkable assembly of more than 30 gears with a differential..." 
  19. ^ John Bolender (2010). The self-organizing social mind. MIT Press. p. 48. ISBN 978-0-262-01444-1. Retrieved 28 May 2013. "One feels an eerie excitement when hearing that the Antikythera mechanism of ancient Greece was a computer (figures 2.2 and 2.3)." 
  20. ^ "Discovering How Greeks Computed in 100 BC". The New York Times. 31 July 2008. Retrieved 27 March 2010. 
  21. ^ Martin Allen (27 May 2007). "Were there others? | The Antikythera Mechanism Research Project". Antikythera-mechanism.gr. Archived from the original on 21 July 2011. Retrieved 24 August 2011. 
  22. ^ Derek de Solla Price, "Gears from the Greeks. The Antikythera Mechanism: A Calendar Computer from ca. 80 B. C." Transactions of the American Philosophical Society, New Ser., Vol. 64, No. 7. (1974), pp. 1–70.
  23. ^ "What was it made of?". Antikythera Mechanism Research Project. 4 July 2007. Retrieved 16 May 2012. 
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  25. ^ http://www.cs.virginia.edu/~robins/Decoding_an_Ancient_Computer.pdf
  26. ^ a b c Marchant, J. In search of lost time. Nature [serial on the Internet]. (2006, Nov 30), [cited November 15, 2012]; 444(7119): 534-538. Available from: Academic Search Complete.
  27. ^ Haughton, Brian (26 December 2006). Hidden History: Lost Civilizations, Secret Knowledge, and Ancient Mysteries. Career Press. pp. 43–44. ISBN 978-1-56414-897-1. Retrieved 16 May 2011. 
  28. ^ "Ancient 'computer' starts to yield secrets". Archived from the original on 13 March 2007. Retrieved 23 March 2007. 
  29. ^ a b Solar Anomaly and Planetary Displays in the Antikythera Mechanism, Evans, James, Carman Christián C., and Thorndike Alan S. , Journal for the History of Astronomy, 02/2010, Volume 41, Issue 142, p.1-39, (2010)
  30. ^ a b The Cosmos in the Antikythera Mechanism, Freeth, Tony and Jones, Alexander R. ISAW Papers, Volume 4, (2012)
  31. ^ a b Freeth, T.; Bitsakis, Y.; Moussas, X.; Seiradakis, J. H.; Tselikas, A.; Mangou, H.; Zafeiropoulou, M.; Hadland, R. et al. (30 November 2006). "Decoding the ancient Greek astronomical calculator known as the Antikythera Mechanism". Nature. 444 Supplement (7119): 587. Bibcode:2006Natur.444..587F. doi:10.1038/nature05357. 
  32. ^ a b Freeth, Tony; Jones, Alexander; Steele, John M.; Bitsakis, Yanis (31 July 2008). "Calendars with Olympiad display and eclipse prediction on the Antikythera Mechanism". Nature. 454 Supplement (7204): 614. Bibcode:2008Natur.454..614F. doi:10.1038/nature07130. 
  33. ^ "Using Computation to Decode the First Known Computer". IEEE Computer Magazine. 2011-7. July 2011. 
  34. ^ a b The Antikythera Mechanism reconsidered - M. T. Wright - Interdisciplinary science reviews, 2007, VOL. 32, NO. 1
  35. ^ Presentation given to the NHRF in Athens, 6th March 2007 - M. T. Wright
  36. ^ The Antikythera Mechanism: a Review of the Evidence, and the Case for Reconstruction as a Planetarium. - M.T. Wright. - November 2006
  37. ^ "On the Pin-and-Slot Device of the Antikythera Mechanism, with a New Application to the Superior Planets," Journal for the History of Astronomy 43, 2012, 93_116
  38. ^ The Cosmos in the Antikythera Mechanism - Tony Freeth and Alexander Jones - 2012
  39. ^ "Does it favour a Heliocentric, or Geocentric Universe?". Antikythera Mechanism Research Project. 27 July 2007. Archived from the original on 21 July 2011. Retrieved 24 August 2011. 
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  84. ^ Calendars with Olympiad and Eclipse Prediction on the Antikythera Mechanism, url=http://www.antikythera-mechanism.gr/system/files/Antikythera_Nature2008_submitted.pdf
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5c Further reading

4l Books

  • James, Peter; Thorpe, Nick (1995). Ancient Inventions. New York: Ballantine. ISBN 0-345-40102-6. 
  • Marchant, Jo (6 November 2008). Decoding the Heavens: Solving the Mystery of the World's First Computer. William Heinemann Ltd. ISBN 0-434-01835-X. 
  • Price, Derek J. de Solla (1975). Gears from the Greeks: The Antikythera Mechanism – A Calendar Computer from ca. 80 BC. New York: Science History Publications. ISBN 0-87169-647-9. 
  • Rosheim, Mark E. (1994). Robot Evolution: The Development of Anthrobotics. John Wiley & Sons. ISBN 0-471-02622-0. 
  • Russo, Lucio (2004). The Forgotten Revolution: How Science Was Born in 300 BC and Why It Had To Be Reborn. Berlin: Springer. ISBN 3-540-20396-6. 
  • Steele, J. M. (2000). Observations and Predictions of Eclipse Times by Early Astronomers. Dordrecht: Kluwer Academic. ISBN 0-7923-6298-5. 
  • Steele, J. M. (1994). Robot Evolution: The Development of Anthrobotics. John Wiley & Sons. ISBN 0-471-02622-0. 
  • Stephenson, F. R. (1997). Historical Eclipses and the Earth's Rotation. Cambridge, UK: Cambridge Univ. Press. ISBN 0-521-46194-4. 
  • Toomer, G. J. (1998). Ptolemy's Almagest (trans. Toomer, G. J.). Princeton, New Jersey: Princeton Univ. Press. 

4l Journals

  • Bromley, A. G. (1985). "The Design of Astronomical Gear Trains". Horological Journal 128 (6): 19–23. 
  • Bromley, A. G. (1986). "The Design of Astronomical Gear Trains (b)". Horological Journal 128 (9): 10–11. 
  • Bromley, A. G. (1986). "Notes on the Antikythera Mechanism". Centaurus 29: 5. Bibcode:1986Cent...29....5B. doi:10.1111/j.1600-0498.1986.tb00877.x. 
  • Bromley, A. G. (1990). "The Antikythera Mechanism". Horological Journal 132: 412–415. 
  • Bromley, A. G. (1990). "The Antikythera Mechanism: A Reconstruction". Horological Journal 133 (1): 28–31. 
  • Bromley, A. G. (1990). "Observations of the Antikythera Mechanism". Antiquarian Horology 18 (6): 641–652. 
  • Charette, François (2006). "High tech from Ancient Greece". Nature 444 (7119): 551–552. Bibcode:2006Natur.444..551C. doi:10.1038/444551a. PMID 17136077. 
  • Edmunds, Mike & Morgan, Philip (2000). "The Antikythera Mechanism: Still a Mystery of Greek Astronomy". Astronomy & Geophysics 41 (6): 6–10. Bibcode:2000A&G....41f..10E. doi:10.1046/j.1468-4004.2000.41610.x.  (The authors mention that an "extended account" of their researches titled "Computing Aphrodite" is forthcoming in 2001, but it does not seem to have appeared yet.)
  • Freeth, T. (2002). "The Antikythera Mechanism: 1. Challenging the Classic Research". Mediterranean Archeology and Archeaometry 2 (1): 21–35. 
  • Freeth, T. (2002). "The Antikyhera Mechanism: 2. Is it Posidonius' Orrery?". Mediterranean Archeology and Archeaometry 2 (2): 45–58. 
  • Freeth, T. (2009). "Decoding an Ancient Computer". Scientific American 301 (6): 76–83. doi:10.1038/scientificamerican1209-76. PMID 20058643. . See also abstract.
  • Freeth, T.; Bitsakis, Y., Moussas, X., Seiradakis, J. H., Tselikas, A., Mankou, E., Zafeiropulou, M., Hadland, R., Bate, D., Ramsey, A., Allen, M., Crawley, A., Hockley, P., Malzbender, T., Gelb, D., Ambrisco, W., & Edmunds, M. G. (2006). "Decoding the ancient Greek astronomical calculator known as the Antikythera Mechanism". Nature 444 (7119): 587–591. Bibcode:2006Natur.444..587F. doi:10.1038/nature05357. PMID 17136087. 
  • Jones, A. (1991). "The adaptation of Babylonian methods in Greek numerical astronomy". Isis 82 (3): 440–453. doi:10.1086/355836. 
  • Morris, L.R. (1984). "Derek de Solla Price and the Antikythera Mechanism: An Appreciation". IEEE Micro 4: 15–21. doi:10.1109/MM.1984.291304. 
  • Price, D. de S. (1959). "An Ancient Greek Computer". Scientific American 200 (6): 60–67. doi:10.1038/scientificamerican0659-60. 
  • Price, D. de S. (1974). "Gears from the Greeks: The Antkythera Mechanism – A Calendar Computer from ca 80BC". Trans Am Philos. Soc., New Series 64 (7): 1–70. doi:10.2307/1006146. 
  • Price, D. de S. (1984). "A History of Calculating Machines". IEEE Micro 4: 22–52. doi:10.1109/MM.1984.291305. 
  • Spinellis, Diomidis (May 2008). "The Antikythera Mechanism: A Computer Science Perspective". Computer 41 (5): 22–27. doi:10.1109/MC.2008.166. 
  • Steele, J. M. (2000). "Eclipse prediction in Mesopotamia". Arch. Hist. Exact Sci. 54 (5): 421–454. doi:10.1007/s004070050007. 
  • Weinberg, G. D.; Grace, V. R., Edwards, G. R., Robinson, H. S;, Throckmorton, P., & Ralph, E. K. (1965). "The Antikythera Shipwreck Reconsidered". Trans Am Philos. Soc. 55 (New Series) (3): 3–48. doi:10.2307/1005929. JSTOR 1005929. 
  • Zeeman, E. C., (1986). "Gears From The Ancient Greeks". Proc. Roy. Inst. GB 58: 137–156.  (See also the slides from a lecture here [3], slide 22 is a view of how the mechanism for a model comes to replace actual reality).

4l Other

  • Cousteau, Jacques (1978). The Cousteau Odyssey: Diving for Roman Plunder (Tape). Warner Home Video/KCET, Los Angeles. 
  • Hellenic Ministry of Culture and the National Archaeological Museum, The Antikythera Mechanism Research Project
  • Rice, Rob S. (4–7 September 1997). "Physical and Intellectual Salvage from the 1st Century BC". USNA Eleventh Naval History Symposium. Thessaloniki. pp. 19–25.  see The Antikythera Mechanism

5c External links

5c Navigation menu

Mechanical Age

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Old Navigational Instruments

The Sextant is the most well known navigational instrument in the world and still in use to this very day.


Navigation is the art of getting from one place to another.
The first records of boats large enough to carry trading goods are from between 3500 B.C. to 3000 B.C., so we can safely assume that that time also marked the beginning of navigation. These first navigators had no choice but stay close to shore and navigated by sight of landmarks or other characteristics on land that they could see. They travelled mostly by day and went for a safe harbour to stay at anchor at night. They did however develope kind of rudimentary charts, which listed directions, showed crude drawings depicting landmarks and certain dangerous places like reefs, sandbanks or rocks in the water.

Early documents state that the more experienced mariners of the time were said to plot their course by using certain star constellations so most vessels followed the east/west movement of the sun or the track of the stars. However, the ancient navigator had no way to accurately determine longitude and therefore, once out of sight of land, had no idea how far east or west he was. So his estimates were made based upon the time it took to sail from A to B. This is the simplest form of navigation and it is called dead-reckoning; it is still used by navigators today.

To determine the distance travelled from one point to another, the navigator would multiply the time he sailed by the speed of the vessel. Of course these crude calculations were often way off because time was still measured with a sandglass and speed was estimated by watching pieces of seaweed or wood pass by the hull.

Staff Navigation (Left) Early Speed Determination Device (Right)

Another useful navigational instrument of the time, around 1500 B.C., was the sounding reed or sounding weight. This device was used to figure out water depths in coastal regions. Using a combination of depth soundings, the sun or stars and the wind rose, these early navigators had to guess where they were when land could not be seen. The development of better navigational tools was naturally motivated by commerce and trade. The Phoenicians were most likely the first of the Mediterranean navigators to sail from coast to coast and even at night. The earliest known systems to aid the navigator were bonfires set up on mountaintops or large rocks.

Sounding Weight (left) Early Compass (right)

The first successful exploratory ocean voyages were probably achieved by navigational mistakes. Some of the reasons being: the ship was blown off course by a storm or influenced by a strong current or an error through a calculation made by the navigator, the best example being Christopher Colombo. Close examinations of his journals reveal that he did not know how to calculate latitude properly, so some of his determinations were far too high. When he discovered the Americas he actually thought he had reached India which explains why the names West Indies and Indians are still around to this very day.

Navigational instruments like the ones below were highly priced possessions in the early days of navigation.

Gallery Access

Additional info about historical navigational instruments:


Italian Compass 1570 - The inner bowl with the compass face is mounted in a brass gimbal ring to reduce the effects of the ship's motion at sea. The soft iron needle is diamond-shaped and is fixed to the underside of the vellum and paper card. The compass face is divided into thirty-two points. Decorations on the north and east points were quite common up to the 19th century, wherby east for Europeans has been the direction of the Holy Land. Most early compasses were set in wooden bowls or boxes.  

The Sextant - The Sextant, not unlike some other navigational instruments, takes its name from its shape - the sixth part of a circle. Sextants for use in astronomy had been around since the 16th century but the marine version was developed around 1756/57 by Captain John Campbell, with the help of a London instrument maker named John Bird. The difference between a sextant and an octant is the lenght of its scale - up to 120 degrees but both work after the same principle.  

Persian Astrolabe 1660 - The astrolabe represents a mathematical likeness of the heavens and its Greek name is - "Star Taker". This amazing sophisticated scientific instrument has been crafted by Muhammad Mahdi al-Khadim al-Yazdi in brass and was used to solve astronomical problems and to show the positions of stars and planets at different dates, times and latitudes. The Persian calligraphy engraving reads a quotation from the Koran: "The world is decorated with stars".

Cross Staff circa 1700 - This particular Cross-Staff has been crafted by Thomas Tuttell, London, circa 1700.
The cross-staff was another instrument designed to measure the altitude of the sun or polar star. It made use of the properties of right-angled triangles, or trigonometry. The navigator or captain rested the main staff just below his eye and moved the cross until the bottom was aligned with the horizon level, and the top with the lower edge of star or sun. The position could then be read off on the scale in degrees and minutes. Cross-staves were mostly made of wood, but there are indications that some have been crafted in metall (brass) as well. Constantly looking at the sun with an instrument of this kind has often caused blindness.

Octant 1760 - The octant, also known as Hadley's quadrant, forms an eighth of a circle but the use of reflection doubles the angle, so that the scale reads up to 90 degrees. It has a radius of 17.75 inches (45.1 cm). Sir Isaac Newton developed the principle of the octant but is was not until 1731 when John Hadley demonstrated its use for marine purposes to the Royal Society in London. The use of mirrors to bring a reflected image of stars or the sun alongside the horizon, when viewed through the sight improved the accuracy of navigation considerably. This particular octant has been crafted by Benjamin Martin, London, circa 1760.


Spanish/Portuguese Astrolabe 1588 - The mariner's astrolabe has been developed by Arabic astronomers. Christopho Columbo used a similar astrolab design on his voyages to discover the "New World". It was a simplified version of an instrument for measuring the height of stars and the sun above the horizon level. This astrolabe has been discovered in southern Ireland were several ships of the Spanish Armada foundered.  

Mariner's Quadrant 1720/25 - The mariner's quadrant was one of the earliest devices developed for measuring angles, either of a star above the horizon level or the top of a hill in surveying. The name suggests, it consists of a quarter of a circle, with the curved edge divided into 90 degrees, a cord with an attached weight suspended from the point of the right-angle. The object was aligned through the sights on one edge, and the angle of elevation read off where the cord crossed the scale. This instrument is made of brass and its degree scale is subdivided for measurements to 30 minutes of arc.  

Gigantic Astronomical Sextant - Astronomical sextants had been in use since the 16th century.  

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