how did they do it?

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I heard a talk some months back, from one of  
the investigators of the Antikythera mechanism.  
Really fascinating.  Discovered over 100 years ago,  
it's just recently that they finally reverse engineered  
it, completely.  Or so the speaker claimed.

Apparently it was a long development, lasting almost  
a century, ~ 200 B.C.  There's a suspicion that  
Archimedes had a hand in, but no smoking gun.

It's an astronomical calendar, an astonishing  
achievement.  It could predict solar and lunar  
eclipses decades ahead!

An interesting point:  we have no user manual which  
specifies the device as a celestial calendar.  But  
the fact is, it makes an amazingly good calendar!  
Hence, Sherlock, it must be such a device.

In other words, if an unknown object serves a particular  
function, one may assume it was designed to that purpose,  
and a designer behind it.  With obvious implications for the creation/evolution debate -

Now the technical bit - it consists of a complex  
interplay of cogwheels; calculators.  I recall one  
had 53 teeth, another 127.  How the heck did they  
construct those?  How did they even DRAW them?

Today, with AutoCad, it's a piece of cake.  But in  
the days of Euclid?  So, the challenge:  armed with  
only your powerful 21st century brain and education,  
but B.C. era technology, how would you go about designing  
and cutting those wheels?

--
Rich



Re: how did they do it?
fredag den 10. august 2018 kl. 00.32.24 UTC+2 skrev RichD:
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a guy on youtube is making a replica mostly using tools and layout that  
would have available at the time

wheels laid out with dividers and made with files https://youtu.be/BIUAdINXZmQ


his channel is worth a look, he did a clock before



https://www.youtube.com/channel/UCworsKCR-Sx6R6-BnIjS2MA/videos


Re: how did they do it?
snipped-for-privacy@fonz.dk says...
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https://youtu.be/BIUAdINXZmQ

And of course: first make your file! ...

Mike.

Re: how did they do it?
fredag den 10. august 2018 kl. 08.44.32 UTC+2 skrev Mike Coon:
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https://youtu.be/SOw9WqMOHjA


Re: how did they do it?
On Thursday, August 9, 2018 at 6:47:59 PM UTC-4, Lasse Langwadt Christensen wrote:
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Nice, thanks.  
GH
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https://www.youtube.com/channel/UCworsKCR-Sx6R6-BnIjS2MA/videos



Re: how did they do it?
On Thursday, August 9, 2018 at 6:32:24 PM UTC-4, RichD wrote:
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The man who replicated it was on a Nova show about the Antikythera mechanism on PBS a few years ago. It explained how he determined it was 53 teeth and all...

Re: how did they do it?
On Friday, August 10, 2018 at 8:32:24 AM UTC+10, RichD wrote:
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lution debate -

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

Once Darwin had proposed evolution by selective adaption, that argument was
 dead. The Antikythera mechanism isn't all that close to anything it might  
have "descended" from.
  
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Cast them? Filed them out of circular blanks?

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Euclid (323?283 BC) preceeds the Antikythera mechanism by about a c
entury.
  
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Carefully. A 53 tooth wheel would be a bit of a challenge, but Archimedes h
ad worked out an algorithm for calculating pi in 250BC, so it would be poss
ible to work out how long each of the 53 segments around the rim of the whe
el would have to be. Messy arithmetic, but even using 22/7 as an approximat
ion for pi would get you quite close enough.

--  
Bill Sloman, Sydney

Re: how did they do it?
On 10/08/18 02:25, snipped-for-privacy@ieee.org wrote:
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If you are careful about your choice of units, you can get very
accurate.  Draw your circle 135 units, and your 53 teeth will be 8.002
units around the circumference.

Re: how did they do it?
On Thursday, August 9, 2018 at 3:32:24 PM UTC-7, RichD wrote:
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Compass and straightedge, classically.   If you can get
a flat surface to mark on (stretched parchment?) and
inscribe a circle, you can subdivide it.  Powers of two are easy,
so you could use a binary fraction rendition of 1/53, 2/53, etc.
to get to any degree of accuracy you want.

That's why 'trisecting the angle' is an old well-studied problem.

Lens design used large sheets of vellum, H6 (very hard) sharp pencils,
and ratio-of-sines graphic calculation, up 'til the 1970s.
And a gizmo called a 'polar planimeter' integrated areas,
and an exceptionally clever device existed to do harmonic analysis
(for tide calculations, largely); it computed a Fourier transform,
mechanically.

I'm more impressed with the ability to produce flat bronze stock; someone
with a hammer is no match for centerless-ground rollers.

Re: how did they do it?
On 10/08/2018 01:34, whit3rd wrote:

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They probably did that by old mirror grinding techniques to get the  
final truly flat material by working three pieces against each other the  
same way optical flats and snooker tables are still made today. On the  
plus side they wouldn't need to polish it as carefully as for a mirror.

As Bill said they knew pi well enough to compute the right length for a  
known diameter of wheel and would doubtless have made a jig to allow  
precise construction of the gear wheels.

They could also have done it by successive approximation given enough  
time and patience. Prime numbers of teeth are more tedious to do.

53 & 127 are both inaccessible to the Neusis construction known to the  
ancient Greeks so they would have had to do a bit of a fiddle.

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

Engineers of the day would have been more likely to use this sort of  
method to get practical results for N-gons - straight edge and compasses  
geometrical purism came a bit later.

--  
Regards,
Martin Brown

Re: how did they do it?
On Thu, 09 Aug 2018 17:34:32 -0700, whit3rd wrote:

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Loads of really ingenious methods are outlined in this book:

https://tinyurl.com/yc4sr2dl

You can make a *perfectly* flat surface (terribly important to have one  
of these in every serious engineering shop) by placing two slabs of  
granite on top of one another, separated only by grinding paste and  
agitating one against the other. Eventually they rub off each other's  
imperfections and you get two perfect surfaces for reference purposes  
from which you can then make other highly accurate tools and so on.  
Clever stuff!



--  
This message may be freely reproduced without limit or charge only via  
the Usenet protocol. Reproduction in whole or part through other  
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Re: how did they do it?
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Three.  Two will give equal positive and negative spherical sections (or  
paraboloids if you grind them right).  Only in the case when three faces are  
ground against each other, will that spherical section have zero curvature,  
a plane.

Tim

--  
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
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Re: how did they do it?
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Unfortunately perfectly spehrical. you need three to get planar
surfaces.

--  
     ?

Re: how did they do it?
On Fri, 10 Aug 2018 20:53:18 +0000, Jasen Betts wrote:

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OK, well it was a long time ago I read this and it's not my field anyway.




--  
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Re: how did they do it?
wrote:

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Same way they made suits of armor.  Cold beat it flat with a hammer.
Then make it reasonably smooth and flat by grinding between two flat
stones with some sand as an abrasive.  It takes a long time to do it
this way, but in 250BC, the time clock hadn't been invented yet.

Drivel:  My litmus test for reverse engineering technology is to check
what method was used preceding it.  If there's no technology preceding
the idea, it's probably wrong.  The problem with the Antikythera
mechanism is that much of the technology doesn't fit the time
estimates.  For example, everyone seems to assume that steel files
were used to shape the gears.  Yet, the ability to make such fine and
precise files is far into the future.  However, what did proceed gear
the cutting technology of 250BC was knife, weapon, and agricultural
technology.  Much of this was based on the use of abrasives instead of
cutting tools.  The teeth could have been made by notching a knife
blade, and using it like a chisel to notch the teeth.  Or, the knife
blade could have been ground flat on a stone, and the teeth ground
using sand as an abrasive.  It didn't even need a knife as a piece of
hard wood with abrasive grit pounded into the surface would have acted
as a tolerable file.  Etc...

Of course, it could have been made by aliens from outer space.

--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: how did they do it?
On 10/08/2018 18:53, Jeff Liebermann wrote:
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Point of order - the earliest water clock was dated to around 1500BC

https://www.ancient-origins.net/ancient-technology/ancient-invention-water-clock-001818

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It is a fair point that they almost certainly used some slow and very  
tedious method of cutting the teeth into the gear.

But they had geometrical constructions that have now largely been  
forgotten. Their brightest people were probably as clever as they are  
today but less was known. They did have time on their side though.

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Odd choice of technology for a space faring civilisation.

--  
Regards,
Martin Brown

Re: how did they do it?
'''newspam'''@nezumi.demon.co.uk says...
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Yes, go to any sailing forum and observe the interminable discussion  
about sextant vs. GPS...

Mike.

Re: how did they do it?
On Fri, 10 Aug 2018 19:57:36 +0100, Martin Brown

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That's not a "time clock".  On this side of the pond, a "time clock"
looks like this:
<https://www.staples.com/Time-Clocks/cat_CL163590
<https://en.wikipedia.org/wiki/Time_clock
The first patent for a time clock was in 1890.
<https://patents.google.com/patent/US452894
As far as I can tell, no water was used or was necessary.  With a
water clock, I suppose Archimedes and Associates could have "punched
the clock", but then, punched cards also hadn't been invented.

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Slow, tedious, monotonous, boring, and dangerous were not considered a
problem in an age when slaves were cheap and did all that.  It was
also considered a social disgrace for a member of the upper classes to
get their hands dirty.  I suspect that some of the slaves may have
been better educated and more clever than their upper class masters.
The masters had no reason to learn to read, write, or operate the
machinery.  I think it's conceivable that some of the more amazing
inventions of the distant past, were actually contrived and built by
slaves, rather than their masters with their clean hands.

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True, but not totally forgotten:  
<https://en.wikipedia.org/wiki/Archimedes_Palimpsest
There's a Nova video on the topic (in 3 parts):
<
https://www.youtube.com/watch?v=_rHv3OiaVC8

Archimedes got very close to inventing calculus.

No doubt that some people in 250BC were clever and very bright.
However, was it the upper classes, who dabbled in politics, society,
abstractions, royal succession, and religion, or was it the ordinary
slaves who were relegated to the mundane tasks of building
astronomical appliances?

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Well, I meant that as a bad joke, but it's not so difficult to
believe.  A visitor from a space faring civilization arriving on earth
would most likely be greeted in the traditional human manner of "kill
them and eat them".  Under such circumstances, offering something
useful to the natives might dissuaded them from having their visitors
for dinner.  Anything more sophisticated than a mechanical calculator
would probably have been considered magic or the "work of the devil"
resulting in exactly what the alien visitors were trying to avoid.
That's unfortunate as we may have missed our chance at getting a
scientific computer 2200 years early.  Instead, we had to settle for a
crude wind-up toy version.


--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: how did they do it?

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Umm. A Starship in the Iron Age? Methinks that dissuasion involves at least a  
laser blaster. Even a Colt 45 would suffice.

Joe Gwinn


Re: how did they do it?
On Sat, 11 Aug 2018 11:08:03 -0400, Joseph Gwinn

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Nothing happens without proper motivation(s).  What would motivate an
alien race to give the backwards planet Earth a visit?  Forget about
Star Trek and "go to where no man has gone before".  The explorers
probably took one look at Earth, and just kept going.  Think about
what motivated the European explorers and immigrants that followed
Columbus.  Motives vary, but a good percentage were looking for
trading partners and were out to make money for themselves or for
their backers.  Same with the alien visitors.  They land on Earth and
realize that the residents have little or nothing to offer.  However,
if human science and technology could be accelerated, they could
return in a thousand solar rotations and perhaps the humans might have
evolved into better and more profitable customers.  

So, what gifts would an alien race leave behind to accelerate
progress?  It's not going to be a better weapon as they would most
likely exterminate themselves.  It's not going to be an encyclopedia
because no human of the day would understand it.  It has to be
something that would help humans do something that they already are
doing, but better.  Something that humans can understand and
appreciate.  Reading the stars to predict the future has been around
for a long time and shows little indication of disappearing.  So, the
alien visitors left humans with a better way to read the stars and
predict the future.  Eventually, humans will find better uses for the
device, and progress will lurch forward.

Incidentally, the ideal gift problem is the same for giving presents
to worthless slacker teenagers.



--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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