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Douglas442
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Re: Grandfather Clocks
Douglas442   3/6/2014 5:53:44 AM
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Max,

Given the nature of your project, it would not be unreasonable to widen the range of applied technologies. If you have FPGA's, microcontrollers, and vacuum tubes, then why not relays and gears as well?

Anyway, clever methods for constructing astronomical clocks, orrery mechanisms, and such like have been around for awhile. Classic examples, that include Moon dials, include the 1500's era Astrarium of Giovanni de Dondi:

http://www.clockmaker.it/ingle37astrario.htm

All the way back to the Antikythera Mechanism, which may owe at least part of it's design to Archimedes. Some beautiful amateur build sites, heavy with technical details, can be found at:

http://www.cnccookbook.com/CCOrreryNotes.html

http://www.tatjavanvark.nl/antikythera/antikythera.html

And a more modern example would be the utterly awesome and astonishingly magnificent design of The 10,000 Year Clock, with funding and preparations currently underway by The Long Now Foundation:

http://www.longnow.org/

There are many horological sites dedicated to detailed examining of such builds, both amateur and professional. Fortunately, one site rounds many of these up for you:

http://www.astroclocks.nl/html/Astroclocks10.htm

---------------------------------------------------

Speaking of things that are reliable... has there been a temporary suspension or reorganization of the designlines newsletters? Mine had suddenly stopped arriving... about one month ago. ALL of them. At the same time. 

Max The Magnificent
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Re: Grandfather Clocks
Max The Magnificent   2/26/2014 4:48:22 PM
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@Bellhop: It's common for Grandfather Clocks to have a "Moon Dial" that shows the phases of the moon.

Ah Ha! Now I see what you mean -- I tell you, they were amazingly clever in ye olden times -- now you have me wondering -- did you see the comment earlier about the Hebrew lunar calander that was calculated using only integers -- this would easily map onto using clockwork gears/cogs.

betajet
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Re: Grandfather Clocks
betajet   2/26/2014 4:41:49 PM
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I suspect clockmaker John Harrison played football in his spare time.  Why else would he have named his temperature-compensated device the Gridiron Pendulum?

Bellhop
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Re: Grandfather Clocks
Bellhop   2/26/2014 3:04:00 PM
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It's common for Grandfather Clocks to have a "Moon Dial" that shows the phases of the moon. I remember that the actual dial looks like a sawblade with two stylized "Moons" painted on the face. The dial was held steady by friction and a pawl poke up from the clock mechanism (from a cam?) to push the dial a notch each day.

Max The Magnificent
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Re: Grandfather Clocks
Max The Magnificent   2/26/2014 2:56:09 PM
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@Bellhop: Does anyone know what the makers of Grandfather Clocks did?

What? In their spare time?

Bellhop
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Grandfather Clocks
Bellhop   2/26/2014 2:51:22 PM
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Does anyone know what the makers of Grandfather Clocks did? My dad had one, but since he was always tinkering with it, I'm not sure what it was capable of.

Max The Magnificent
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Re: Take a walk on the wild side...
Max The Magnificent   2/26/2014 1:30:53 PM
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@Rick: It occurs to me that the Prognosticator should have a knob labeled "Gibbous Compensation"

I like it -- I certainly thing we need to have a "Gibbous Compensation Function" -- just remember that anny annotations will be in Elven script LOL

bkeller137
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Re: Take a walk on the wild side...
bkeller137   2/24/2014 7:24:41 PM
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I agree in that my guess is the same as Elizabeth's. Since you can see the full moon dates are more than 28 days apart from the table, the period has to adjust to the approx 1/12 arc movement around the sun and so the moon has further to travel to get back to where the sun is iluminating the face of the moon that is facing the earth (approx 27.3/12 or 2.2 days). Also, you need to start with a fractional day (not Feb 14, but Feb 14.7 approx). This should explain the 3 days difference you were seeing.

Rcurl
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Re: Take a walk on the wild side...
Rcurl   2/24/2014 5:41:38 PM
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It occurs to me that the Prognosticator should have a knob labeled "Gibbous Compensation". The scale should be zero center with the extremes labeled "Wax" and "Wane" 

mhrackin
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Re: Take a walk on the wild side...
mhrackin   2/24/2014 2:50:51 PM
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Or you could follow the current model and use a 19-year look-up table....  according to Wikipedia, it does lag the Gergorian by a day every 224 years, but then again, the Gregorian is gaining time on the "sol" part, with the equinox dates coming earlier.  Even the recent addition of the 400-year "leap skip" doesn't fix that completely.

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