Antikythera Mechanism

[Pete RimmerParticipant @peterimmer30576]

Posted by Hopper on 26/11/2022 11:58:02:

Perhaps they could have made a really basic rotary table by mounting say a 150mm diameter disc to be drilled in the middle of a say 10 meter diameter turntable, or even just had a 10 metre long beam of wood pivoted in the middle and the far end free to describe a large circle. So the number of holes to be drilled could be stepped out with dividers etc on the large 10 metre radius circle within say 1mm easily enough. So a 1mm error at the end of the 10m radius beam or turntable would be a tiny fraction of that.

An idea utilised by SF writer E.E. 'Doc' Smith in one of his Skylark series trilogy if I recall. Could be 'Skylark three'?

The beam would not even need to describe a full circle merely swing through several divisions or perhaps even just a single division..

[egaParticipant @ega]

Thanks for these interesting comments.

I look forward to MichaelG's reality check.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 26/11/2022 08:30:50:

[…]

Whilst those Euclidean techniques are ‘philosophically’ entirely valid … the practical difficulty of physically doing it for a large number of holes would be immense [i.e. nearing impossible]

A couple of pages back [16-Nov-2021] I mentioned that I had been doing an exercise in QCAD

… I will, later today, post what I think is a convincing ‘reality check’ on the practicality of that approach to the dividing.

MichaelG.

 

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As promised …

 

I prepared this little sketch when we were attempting to ‘reverse engineer’ the number of holes in the full circle, from the segment remaining.

It was sufficient to convince me that it is impossible to do that with confidence.

With a starting point of Hole_0 … at which the first hole for every circle would be co-located

… this is a screenshot of the Hole_7 cluster, showing the position of the seventh hole on each circle.

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It also illustrates the difficulty that would be faced when setting-out the holes ‘by chords’ or even by the use of Hopper’s long arm … the positional tolerance at the hole is tiny.

Simple in CAD … Difficult to execute by marking-out and drilling.

MichaelG.

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Edit: __ Nice to see that S.O.D. linked the conveniently readable version of the Elements 

The first two of Euclid’s Definitions say it all, really :

1. A point is that of which there is no part.
2. And a line is a length without breadth.

Edited By Michael Gilligan on 26/11/2022 15:46:59

[david bennett 8Participant @davidbennett8]

Why not simply use a " geared pointer " to indicate the holes positions?

dave8

[Ian PParticipant @ianp]

Posted by david bennett 8 on 26/11/2022 16:40:34:

Why not simply use a " geared pointer " to indicate the holes positions?

dave8

Is this a commercially available device? it sounds really useful

Ian P

[Michael GilliganParticipant @michaelgilligan61133]

Posted by david bennett 8 on 26/11/2022 16:40:34:

Why not simply use a " geared pointer " to indicate the holes positions?

dave8

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Sorry, Dave … I’m confused

Was that a response to my post or a general comment ?

MichaelG.

[david bennett 8Participant @davidbennett8]

Posted by Ian P on 26/11/2022 16:47:27:

Posted by david bennett 8 on 26/11/2022 16:40:34:

Why not simply use a " geared pointer " to indicate the holes positions?

dave8

Is this a commercially available device? it sounds really useful

Ian P

Not commercially available (except on rotary tables etc ), but would have to be made for this mechanism. (it uses many) My point is , if this has to be made anyway, why not use it for marking out ?

dave8

Edited By david bennett 8 on 26/11/2022 17:08:40

[david bennett 8Participant @davidbennett8]

Posted by Michael Gilligan on 26/11/2022 16:57:49:

Posted by david bennett 8 on 26/11/2022 16:40:34:

Why not simply use a " geared pointer " to indicate the holes positions?

dave8

.

Sorry, Dave … I’m confused

Was that a response to my post or a general comment ?

MichaelG.

General comment. I was just musing on how I might have done it. Cheers.

dave8

[Michael GilliganParticipant @michaelgilligan61133]

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 26/11/2022 15:33:41:

[…]

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I forgot to explicitly mention [although there is a scale visible]

Those holes are 0.4mm diameter

MichaelG.

[Mick B1Participant @mickb1]

I think if future archaeologists find examples of our current instruments with mechanical/geometric components like, say, telescopes, theodolites or 20th C warship gunnery dumaresqs, it will be in a well-populated context of contemporary supporting technology like machine tools and measuring devices.

Where's the circumstantial context for the AK mech?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Mick B1 on 26/11/2022 18:43:08:

[…]

Where's the circumstantial context for the AK mech?

 

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Presumably spread about the sea-bed

MichaelG.

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https://en.wikipedia.org/wiki/Antikythera

Edited By Michael Gilligan on 26/11/2022 19:15:41

[david bennett 8Participant @davidbennett8]

Here is a very simple example of using a geared pointer for positioning. The enamel paint markings were indicated on stained glass by simply winding round the minute hand after putting on the 12 o'clock dot with a paint brush. (sorry its sideways)

dave8

[Mick B1Participant @mickb1]

Posted by Michael Gilligan on 26/11/2022 19:14:01:

Posted by Mick B1 on 26/11/2022 18:43:08:

[…]

Where's the circumstantial context for the AK mech?

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Presumably spread about the sea-bed

MichaelG.

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**LINK**

Edited By Michael Gilligan on 26/11/2022 19:15:41

But I meant elsewhere in the context of the civilisation involved – just as in the case of the modern instruments I suggested, you'd find remains of the supporting machine tool technology etc. anywhere technical goods are manufactured.

I'm just saying that products don't exist in isolation – their supporting technology is spread throughout the culture's area of influence.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Mick B1 on 26/11/2022 20:28:24:

[…]

But I meant elsewhere in the context of the civilisation involved – just as in the case of the modern instruments I suggested, you'd find remains of the supporting machine tool technology etc. anywhere technical goods are manufactured.

I'm just saying that products don't exist in isolation – their supporting technology is spread throughout the culture's area of influence.

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If you follow a chain of links from that Wikipedia page, Mick … you will eventually get to this one:

**LINK**

https://en.wikipedia.org/wiki/Out-of-place_artifact

… from which I deduce that informed opinion says this product does currently "exist in isolation"

MichaelG.

[Mick B1Participant @mickb1]

Posted by Michael Gilligan on 26/11/2022 21:03:40:

Posted by Mick B1 on 26/11/2022 20:28:24:

[…]

But I meant elsewhere in the context of the civilisation involved – just as in the case of the modern instruments I suggested, you'd find remains of the supporting machine tool technology etc. anywhere technical goods are manufactured.

I'm just saying that products don't exist in isolation – their supporting technology is spread throughout the culture's area of influence.

.

If you follow a chain of links from that Wikipedia page, Mick … you will eventually get to this one:

**LINK**

https://en.wikipedia.org/wiki/Out-of-place_artifact

… from which I deduce that informed opinion says this product does currently "exist in isolation"

MichaelG.

Thanks for that, Michael. I hadn't known of the OOPArt acronym. I'll have a read of that.

[egaParticipant @ega]

Posted by Michael Gilligan on 26/11/2022 17:57:15:

Posted by Michael Gilligan on 26/11/2022 15:33:41:

[…]

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…

Those holes are 0.4mm diameter

MichaelG.

The division plate on GHT's Lorch watchmaker's lathe seems worth a mention; he says (page 119 of Workshop Techniques):

"This plate, together with the lathe and its accessories was obtained from Germany in 1939 and I never use it without thinking of the person who drilled all those 2209 holes which are mostly 1mm dia. but the two outer rows, comprising 660 holes, are only 0.8mm dia". (I think the relevant hole counts were 360 and 300).

Looking at the photo of this plate, I would doubt that the holes were stepped out. Being intended for direct indexing, they would need to be accurate.

[HowiParticipant @howi]

Posted by Mick B1 on 26/11/2022 20:28:24:

Posted by Michael Gilligan on 26/11/2022 19:14:01:

Posted by Mick B1 on 26/11/2022 18:43:08:

[…]

Where's the circumstantial context for the AK mech?

 

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Presumably spread about the sea-bed

MichaelG.

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**LINK**

Edited By Michael Gilligan on 26/11/2022 19:15:41

But I meant elsewhere in the context of the civilisation involved – just as in the case of the modern instruments I suggested, you'd find remains of the supporting machine tool technology etc. anywhere technical goods are manufactured.

I'm just saying that products don't exist in isolation – their supporting technology is spread throughout the culture's area of influence.

I do not think your hypothesis is valid unless there were thousands of such mechanisms made, rather than the only one so far found.

If they had the wherewithall to design such a mechanism, someone would have the skill to make it.

We can speculate all we want, made all the more intreaging due to only a small part of the mechanism surviving after centuries under water, but will we ever know what it was for, how it did it and how it was made, probably not fully unless another mechanism was to surface in a slightly better condition.

The ancients knew a lot more than we give them credit for………

Edited By Howi on 27/11/2022 10:05:10

[SillyOldDufferModerator @sillyoldduffer]

Posted by Mick B1 on 26/11/2022 20:28:24:

Posted by Michael Gilligan on 26/11/2022 19:14:01:

Posted by Mick B1 on 26/11/2022 18:43:08:

[…]

Where's the circumstantial context for the AK mech?

.

Presumably spread about the sea-bed

MichaelG.

.

**LINK**

Edited By Michael Gilligan on 26/11/2022 19:15:41

…

I'm just saying that products don't exist in isolation – their supporting technology is spread throughout the culture's area of influence.

That's my view as well, except our modern understanding is biased by whatever happens to have survived, which may not be much.

Not far from where I was brought up in Bath lie some remains of the Wansdyke. The remains suggest it's a 30 mile long fortified border about built about AD500 by southerners to keep northerners out. Although a substantial earthwork, it's not known who built it, who the enemy was, or why it was needed. It seems to mark a border between two substantial power groups unknown to history. Around AD500 there existed a power able to organise a huge civic engineering project, probably requiring most fit males in the region to report for duty with a spade, and presumably able to fund a fighting force large enough to man it. There's no evidence it was ever attacked, and hints it was soon abandoned.

A little further south can be found the remains of the GHQ Stop Line. Built in a hurry in 1940 by General Ironside in expectation that the Germans would invade after Dunkirk, what's left is a scattered smear of pillboxes, dragons teeth, and demolition arrangements. Had the line been put to use, depth and strength would gave been added with trenches, barbed wire, mines, and artillery support, but none of this evident. To make sense of it, you have to know who the invader was, and what constraints both sides were operating under. A pillbox on it's own makes little sense; they were always part of a larger defensive arrangement, most of which was very temporary. Worse, some of the clues left to future archaeologists are positively misleading! Although the GHQ line was carefully laid out by Royal Engineers to maximise protection and establish interlocking killing zones, the pillboxes were installed in a hurry by civilian contractors. The build-quality is often poor, and some of them were installed back to front. Thus a future archaeologist might conclude the whole thing was for show, never intended to be used. The written record says otherwise, but archaeologists rarely see those!

Perhaps the GHQ line and Wansdyke were both built to deal with temporary emergencies, and the need for them soon passed, leaving them behind as inconclusive evidence that something big was going on.

On the subject of the Antikythara Mechanism, it is known that other mechanical devices existed at the time because Cicero mentions them. But he doesn't explain how many, how complicated, or how they were used. The evidence is incomplete, leaving us to make educated guesses as best we can.

The study of archaeologists is quite interesting, because looking at their early work often reveals biased conclusions, caused by overlaying cultural prejudices on partial clues left by ancient peoples. Time-Team often got unprofessionally excited about finding 'high-status' buildings, the problem being Blenheim Palace does not represent how most of us live. When joining the dots, be careful not to draw a rude donkey!

Dave

[Michael GilliganParticipant @michaelgilligan61133]

For what it’s worth [i.e. something closely approximating the diameter of Euclid’s point]

My working hypothesis is that the ‘lone genius’ Inventor of the mechanism was on his way to the Ancient Greek Patent Office … when the ship sank.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

< duplicate >

Edited By Michael Gilligan on 27/11/2022 12:56:55

[Michael GilliganParticipant @michaelgilligan61133]

< triplicate >

Edited By Michael Gilligan on 27/11/2022 12:56:26

[John HaineParticipant @johnhaine32865]

As I've said before, I think it's accidentally left behind from a visiting time machine. Or they were poking some gentle fun at humanity…

[Mick B1Participant @mickb1]

Posted by John Haine on 27/11/2022 14:04:21:

As I've said before, I think it's accidentally left behind from a visiting time machine. Or they were poking some gentle fun at humanity…

Yes, and why not do that? We think we're dead clever, but we messed about with lenses for more'n a thousand years before somebody thought to put a couple of 'em together and make a telescope…

[david bennett 8Participant @davidbennett8]

If the original AM did indeed use its own geared pointer to indicate holes and divisions, it could explain some of the obvious spacing errors. We could not expect these relatively crude hand cut gears to be error-free. It could also go some way to answering Neil's original post.

dave8

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