Until yesterday i thought that nothing direct is known about the "Archimedes's planetarium" - an elaborate ancient planetarium based on complex gear mechanism that could represent the geocentric motions of the seven classical planets (the sun, the moon and the first 5 planets in the solar system). I thought the only information known about this instrument was that Archimedes wrote a (now-lost) manuscript, entitled "on spheres-making", on the construction of such mechanisms, and the possibility of it related to the "Antikythera Planetarium" (discovered in 1902).

But yesterday i read the abstract of a recently published book "THE RECOVERED ARCHIMEDES PLANETARIUM" by the author GIOVANNI PASTORE, according to which an 2006 archeological excavation found a fragment of gear that might be a part, or relate to the planetarium of Archimedes. The book's abstract makes several claims that seem to me very interesting:

  • That in some aspects Archimedes's planetarium was even more advanced than the Antikythera Planetarium sinced it incorporated a special teeth's profile based on mathematical principles rediscovered only in the 17th and 18th century (in a youtube video the speaker mentions the teeth profile was based on the cycloid curve).
  • That Archimedes's device was actually a three dimensional planetrium while the Antikythera Planetarium was an analog computer with two dimensional display.
  • That a certain Roman general (i don't remember the name) deliberately attacked the Mecadonians in a dark night of lunar eclipse (in order to use the element of surprise). It suggests a conjecture that the Roman general knew earlier that there is going to be a lunar eclipse beacuse he saw the date calculated by Archimedes's device.

So, i'd like to know if anyone can tell something about the "gear of Olbia". Did someone here read this book? is it worth buying?


2 Answers 2


Let me cite an authority on Antikythera mechanism (Alexander Jones, "Portable cosmos"):

"A fragment of a gear, found in 2006 at Olbia, Sardinia, and accompanied by no related mechanical remains but in an archeological context reportedly dating to about 200 BC, has been claimed as part of the original planetarium of Archimedes; see Pastore 2006 and Pastore 2013. Its material is brass, and its teeth have rounded, roughly cycloidal shape. Contamination of the archeological context by an artifact of much more modern date is the most probable explanation of the fragment.

It seems that Giovanni Pastore makes too many far-reaching conclusions from a single piece of a wheel of doubtful origin.

By the way, Babylonian and Greek astronomers could predict lunar eclipses. And they needed no mechanisms for this. Clockwork toys demonstrating various astronomical phenomena were popular in 18 century, and their purpose was not science but entertaining rich sponsors. I suppose that the purpose of Antikythera mechanism and Archimedes planetarium was similar. Still it is highly interesting to know what kind of planet theory may have been used in Archimedes planetarium. Archimedes lived before Hipparchus, and we know from Ptolemy that Hipparchus had no planet theory.

  • $\begingroup$ the fact that Babylonian and Greek astronomers predicted lunar eclipses on a regular basis is a useful information, that's why I voted for you. But I like to hear possible hypotheses even if they aren't necessarily true hystorically. That is why I ask what useful scientific information is contained in this book. I like very much those kinds of sophisticated mechanisms (differential gears, epicyclic gear trains) , and curious to understand it's inner workings. So can you tell something about the book in addition? Did you read it? $\endgroup$
    – user2554
    Dec 17, 2018 at 18:01
  • $\begingroup$ @user2554: As you can guess from my ans, I have not read the book. And I am not going to buy it. If you like sophisticated mechanisms, I recommend you the book of Alexander Jones, who on my opinion is a serious researcher. $\endgroup$ Dec 17, 2018 at 20:05
  • $\begingroup$ @user2554: I did not write "on regular basis". On eclipse prediction, see my answer to this question: hsm.stackexchange.com/questions/368 $\endgroup$ Dec 17, 2018 at 20:14

The gear from Olbia has been confirmed as a legitimate find by the archaeologists who discovered it and later restored it; the same archaeologists, not Pastore, established its dating. I do not know on what basis Jones rejects the dating, but if it is only on the idea that the gear "seems too complex" for its dating, that would be the same reason to reject the Antikythera mechanism dating as a "contamination".

Regarding Pastore book, his arguments are summed up in the YouTube video (https://www.youtube.com/watch?v=hp-FXnjxNfw), I do not believe there is more than that


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