Antikythera Mechanism

Has anyone on here ever drawn bronze wire down to 0.3mm if so how strong was it?

SOD:

Isn't the time on the Smiths timer witnessed by the notch at the 12 o'clock position?

Dave, there seems to be a misunderstanding of the Mechanism (which made me think I was missing something) As I understand it, none of the dials or hole rings move when the thing is cranked. All that happens is that the related "pointers"move - except the calendar dial is manually moveable for adjustment.

dave8

Edited By david bennett 8 on 20/11/2021 00:16:46

Edited By david bennett 8 on 20/11/2021 00:18:21

Edited By david bennett 8 on 21/11/2021 02:19:54

Edited By david bennett 8 on 21/11/2021 02:22:48

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Sorry, Dave … I honestly don’t understand the logic of your choice.

[ mostly because you started with a false premise ]

MichaelG.

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P.S. __ If you really want to labour this [which I do not think is really appropriate] … you might find this interesting : 

https://www.hermetic.ch/cal_stud/cassidy/err_trop.htm

Edited By Michael Gilligan on 21/11/2021 07:57:22

Michael G, I also do not wish to labour the point, but I would be interested ro know my false premise, and I doubt the extra decimal points would be relevant to a mechanism like this .

dave8

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O.K. Dave

You clearly stated, with [it appeared] some confidence:

"We now know the actual solar year is 365.24 days. Over 4 years the error would be 0.96 days."

... but that is, in fact, quite contrary to what "we now know"

What we do know is that the solar year varies from place to place and from time to time.

That's what I was hinting-at when I wrote:

"... pick a number"

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I do agree that additional decimal places are likely irrelevant to the construction of the mechanism ... but if we were to use anything for 'reverse engineering' , then Hipparchus’s figure would be near-contemporaneous and [rounded to two decimals] gives 0.99 rather than 0.96

MichaelG.

Michael, thanks for your views. Finally, what in your opnion is the purpose of the ring of holes?

dave8

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Until we can be more confident of the number of holes in the full circle, I am content to remain agnostic

MichaelG.

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Ref. __ https://www.merriam-webster.com/dictionary/agnostic

Edited By Michael Gilligan on 21/11/2021 20:28:47

As a general comment,to summarise, a solar dial with a 365.25 geared pointer, would give a very accurate leap-year correction by advancing  the year dial  one hole  in a 354 hole ring every 4 years.

dave8

Edited By david bennett 8 on 23/11/2021 00:38:52

Edited By david bennett 8 on 23/11/2021 00:43:55

Edited By david bennett 8 on 23/11/2021 00:46:28

Edited By david bennett 8 on 23/11/2021 00:51:43

dave8

Edited By david bennett 8 on 23/11/2021 02:38:30

Edited By david bennett 8 on 23/11/2021 02:43:29

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354/365 = 0.97 [rounded to two decimal places]

’though the favoured Metonic explanation also makes good use of 354

MichaelG.

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Ref. __ https://www.scientificamerican.com/article/antikythera-mechanism-eclipse-olympics/

… as one digestible source

Ref. __ https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjn6fne7630AhXGUMAKHSmJBuYQFnoECB8QAQ&url=https%3A%2F%2Fosf.io%2Fpreprints%2Fsocarxiv%2Ffzp8u%2Fdownload&usg=AOvVaw2Hf3gjn3t2ysykR9uvvn_G

… should [hopefully] link to a recent ‘preprint’

Edited By Michael Gilligan on 23/11/2021 07:13:01

Good find Michael G

From the first Scientific American link you posted.
If this image is from the Antikythera find it appears to show a larger fragment. Maybe it is an assembly of found pieces? However even if it is it may enable a more precise centre point to be derived, Even if just a "feature" arc is used if the holes are not visible. it might improve the accuracy of the calculations for the hole circle. By knowing the radius of a feature arc and then measuring the distance from the feature arc to the hole circle arc, a more accurate radius for the hole circle might be obtained. I firmly believe that the mechanism was accurately made with true concentric circles.

Maybe there is a better copy of this image available?

Slideshow Link

Regards
John

[ posted in error … I will try again later ]

MichaelG.

Edited By Michael Gilligan on 05/12/2021 18:52:08

John,I too believe the dials were made truly circular, but when they were broken, distortion of their circularity is likely due to the release of locked in stresses. A cast bronze ring, possibly quenched, probably hammered to harden and refine the structure, then machined, would have severe internal stess. 350+ holes in the calendar ring backing plate would add to it. When such a ring is broken, the apparent original center would be in doubt. (I cannot find any data relating to this stress release distortion) ( then there's the problem of centuries of sea-water corrosion)

dave8

Edited By david bennett 8 on 06/12/2021 17:22:07

Edited By david bennett 8 on 06/12/2021 17:31:07

This guy Chris has made one. Just delete if his YT channel has been linked before. He has done a good job of recreating tools etc to make it al happen, apart from using sheet material it seems. I found it interesting and the precision possible with such basic hand tools.

https://www.youtube.com/c/Clickspring/videos

Some newer data, 

https://www.youtube.com/watch?v=MkKgdq57uOo

https://bhi.co.uk/antikytheramechanism/

Edited By Neil Lickfold on 08/01/2022 09:11:49

For info. Neil

That guy Chris is one of the authors of the paper which is being discussed.

MichaelG.

Thanks Michael, If my posting is not needed, then it should be deleted.

Eight pages into a complex thread, Neil

… I would say your reference is well worth keeping, for the benefit of new readers.

MichaelG.

I have just found this article in 'Scientific American'. Apologies if this has been linked to before.

https://www.scientificamerican.com/article/an-ancient-greek-astronomical-calculation-machine-reveals-new-secrets/

Scientific American