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The Equation of Time(keeping)



 
 
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  #31  
Old December 8th 17, 07:28 PM posted to sci.astro.amateur
Gerald Kelleher
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Posts: 1,295
Default The Equation of Time(keeping)

On Friday, December 8, 2017 at 4:30:33 PM UTC, Mikko wrote:
In article ,
Gerald Kelleher wrote:

For those who want to understand history it is important to know that a clock
is a device with one job - to maintain a constant or average pace.


You then ask what is the constant pace and how is it derived using the Sun
crossing the meridian each day/night cycle while knowing that each cycle is
different.


No, I don't. Instead I ask whether and how well the clock will do what
it is made to do.


Nearly impossible to find men of stature who have enough engineering sense along with basic astronomical principles to discern clocks are essentially constructed on the 24 hour cycle and equable hours, minutes and seconds are derivative of that core principle. The fact that a star returns to the foreground reference requiring two stick can't displace a meridian line which determines noon with sunrise and sunset representing a location exiting and entering the circle of illumination each day.

Clocks follow from the 24 hour day and not the other way around so learning how the timekeeping AM/PM cycle is created first becomes the key to understanding what is right from what isn't.





In order to understand history, the point is that until
recently clocks were not very accurate (nor common). Astronomers
who wanted to study the equation of the time could only compare the
(apparent) motions of Sun and fixed stars. Even that was not easy as
Sun and stars are not visible at the same time.

Mikko


You are like the brexiteers who make things up as they go along hence the actual structure of timekeeping and the role of the Equation of Time(keeping) would only really appeal to those who have a combined interest in the subtleties of clocks development in tandem with the subtleties of planetary motions.

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  #32  
Old December 9th 17, 07:01 AM posted to sci.astro.amateur
Chris.B[_3_]
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Default The Equation of Time(keeping)

On Friday, 8 December 2017 17:30:33 UTC+1, Mikko wrote:
In article ,
Gerald Kelleher wrote:

For those who want to understand history it is important to know that a clock
is a device with one job - to maintain a constant or average pace.


You then ask what is the constant pace and how is it derived using the Sun
crossing the meridian each day/night cycle while knowing that each cycle is
different.


No, I don't. Instead I ask whether and how well the clock will do what
it is made to do. In order to understand history, the point is that until
recently clocks were not very accurate (nor common). Astronomers
who wanted to study the equation of the time could only compare the
(apparent) motions of Sun and fixed stars. Even that was not easy as
Sun and stars are not visible at the same time.

Mikko


Accurate clocks have been running to sidereal time for far longer than you seem to realise.
[Search for observatory regulators and be re-educated]

The high quality, observatory regulators of old [well before 1800] were constantly checked against costly and highly accurate transit instruments.
Many observatories had both and it was usually their prime purpose.
Then there were the later Shortt Synchronome Free Pendulums [and others] of the Early 20th Century.

Mankind was well aware of the rotation of the earth and the effects of the Moon via tidal drag well before the beginning of the *last* century.
Though it took the Shortt FP to provide the final proof of lunar tidal effects on the Earth.

The lapreclown merely continues to display its raving ignorance.
Another Strumpet doll, surfing the modern wave of screeching delight in personal ignorance, in a desperate bid to inflate its own flaccid ego.
  #33  
Old December 9th 17, 02:53 PM posted to sci.astro.amateur
Mikko
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Posts: 15
Default The Equation of Time(keeping)

In article ,
"Chris.B" wrote:

Accurate clocks have been running to sidereal time for far longer than you
seem to realise.


Have you got any evidence?

The accuracy of the best clocks before pendulum clocks was abut 15
minutes per day. Before about 1650 the best pendulum clocks'
accuracy was about 10 seconds per day. In order to determine the
equation of time with a clock even one second per day, achieved by
Harrison in about 1760, is very little. Only in 1870 was accuracy of
0.1 seconds per day achieved, and equation of time determined with
a clock.

Mikko
  #34  
Old December 9th 17, 03:47 PM posted to sci.astro.amateur
Gerald Kelleher
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Posts: 1,295
Default The Equation of Time(keeping)

On Saturday, December 9, 2017 at 2:53:41 PM UTC, Mikko wrote:



The accuracy of the best clocks before pendulum clocks was abut 15
minutes per day. Before about 1650 the best pendulum clocks'
accuracy was about 10 seconds per day. In order to determine the
equation of time with a clock even one second per day, achieved by
Harrison in about 1760, is very little. Only in 1870 was accuracy of
0.1 seconds per day achieved, and equation of time determined with
a clock.

Mikko


The Equation of Time(keeping) determines 12 noon as a function of the 24 hour day when two shadows line up exactly as the Sun crosses a longitude meridian -

"Draw a Meridian line upon a floor and then hang two plummets, each by a small thread or wire, directly over the said Meridian, at the distance of some 2. feet or more one from the other, as the smallness of the thread will admit. When the middle of the Sun (the Eye being placed so, as to bring both the threads into one line) appears to be in the same line exactly you are then immediately to set the Watch, not precisely to the hour of 12. but by so much less, as is the Aequation of the day by the Table."

https://adcs.home.xs4all.nl/Huygens/06/kort-E.html

They later discovered an easier method and a shortcut to check the accuracy of a watch once they had the average 24 hour day by using two foreground references and the return of a star to the same position each 24 hour day. The Equation of Timekeeping refers the 24 hour day to the Latitude/Longitude system an therefore a rotational rate of 15 degrees per hour.

Assigning significance to circumpolar motion and using a watch is a different matter altogether and that is where everyone went astray. It takes people with a dual interest in astronomy and engineering to look at how the average 24 hour day substitutes for constant rotation at 15 degrees per hour insofar as the neat transformation of 'average' into 'constant' is at the heart of the Lat/Long system, planetary geometry and planetary rotation.

  #35  
Old December 11th 17, 08:56 PM posted to sci.astro.amateur
Gerald Kelleher
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Posts: 1,295
Default The Equation of Time(keeping)

A tour of London's museums is an eye-opener and especially the development of watches/clocks in the British Museum and the Science Museum. They were not just engineers, they were artists so seeing how they went from sundials/ water clocks through the golden era of horology in the 18th century is truly a journey of genuine achievement. I sometimes understand why the clockwork solar system colors so much of astronomy and how the engineering expertise was solely directed to creating clocks with a constant pace however the expertise to know the limits of timekeeping is simply not present to expand on topics that cannot wait for those chained to the clockwork solar system to die out.

I am correct in the matter of two distinct types of surface rotationS to the Sun creating both the seasons and the variations in the natural noon cycle with each surface rotation having their own distinct traits. It simply means that if daily rotation is subtracted, the entire surface of the Earth will still turn parallel to the orbital plane and once over the course of an orbit. It is also central to the Equation of Time which extracts daily rotation as a constant motion in context of the average 24 hour day and the Lat/Long system.

I also went to Westminster Abbey and saw the enormous memorial to Newton and that is dismaying given the influence he holds in Britain and elsewhere. It doesn't matter, although nobody I know could untangle the clockwork solar system from the antecedent astronomical methods and insights, I can - it is a God given gift. In that gift is a life that lives for others .









  #36  
Old December 12th 17, 08:01 AM posted to sci.astro.amateur
Martin Brown[_3_]
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Default The Equation of Time(keeping)

On 09/12/2017 14:53, Mikko wrote:
In article ,
"Chris.B" wrote:

Accurate clocks have been running to sidereal time for far longer than you
seem to realise.


Have you got any evidence?


Ptolemy's Almagest Volume III shows conclusively that the variable speed
of the sun across the heavens was well known to the educated ancients.
Although he explained it with circular epicycles rather than an
elliptical orbit he had computed pretty good tables for correcting solar
time. Epicycles were a crude predecessor of Fourier analysis.

https://en.wikipedia.org/wiki/Equati...on_and_E gypt

I can't find anywhere online with free access though. Closest is:

https://www.sciencedirect.com/scienc...15086013000530

Full article is behind a paywall.

The accuracy of the best clocks before pendulum clocks was abut 15
minutes per day. Before about 1650 the best pendulum clocks'
accuracy was about 10 seconds per day. In order to determine the
equation of time with a clock even one second per day, achieved by
Harrison in about 1760, is very little. Only in 1870 was accuracy of
0.1 seconds per day achieved, and equation of time determined with
a clock.


To measure the day to day variation directly you need this sort of
precision and a transit instrument to go with it. But to notice the
variation of the suns motion against the constellations at different
times of the year he could watch the movement of the sun against the
fixed stars. The suns motion was known to be uneven from the first
development of water clocks and calendars by the Babylonians.

The Chinese even had a mercury based liquid clock that was not subject
to the same viscosity problems as water. It kept better time year round.

--
Regards,
Martin Brown
  #37  
Old December 12th 17, 08:55 AM posted to sci.astro.amateur
Gerald Kelleher
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Posts: 1,295
Default The Equation of Time(keeping)

Too many dunces trying to talk past the components of the Equation of Time and specifically the distinct rotations that comprise the return of the Sun to a meridian and the varying surface rotation in response to the variable orbital speed of the Earth.

The human mind cannot handle two simultaneous rotations in combination however what the mind can do is isolate each rotation by their traits and infer the combination by their effects whether it is the cause of the seasons or the variations in the total length of each noon cycle.

https://www.usap.gov/videoclipsandmaps/spWebCam.cfm

It is approaching Polar noon at the South pole as the forward motion of the planet turns the surface midway to the circle of illumination on the Solstice. This is how to isolate the orbital surface rotation insofar as its existence visually is swamped by daily rotation.

https://epic.gsfc.nasa.gov/


I was thrilled to see timekeeping evolve through the centuries while visiting the London museums over the weekend and the stature of men who tried their best to work with the observed cycles. This integrity and sense of accomplishment is missing from this era as the mismatch between timekeeping and the planetary cycles have not been dealt with properly before but they have now.
  #38  
Old December 12th 17, 10:26 AM posted to sci.astro.amateur
Mikko
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Posts: 15
Default The Equation of Time(keeping)

In article ,
Martin Brown wrote:

On 09/12/2017 14:53, Mikko wrote:
In article ,
"Chris.B" wrote:

Accurate clocks have been running to sidereal time for far longer than you
seem to realise.


Have you got any evidence?


Ptolemy's Almagest Volume III shows conclusively that the variable speed
of the sun across the heavens was well known to the educated ancients.


It was well known that the number from equinox to solstice or solstice
to equinox was not the same for all seasons. No clocks were needed to
observe that. Whether lengths of days or lengths of seasons were
unequal could not be directly determined.

Although he explained it with circular epicycles rather than an
elliptical orbit he had computed pretty good tables for correcting solar
time. Epicycles were a crude predecessor of Fourier analysis.


Ptolemy did not use epicycles to explain the motion of Sun although he
did use them for planets. He explained the motion of Sun as uneven
motion along an eccentric circle.

https://en.wikipedia.org/wiki/Equati..._Babylon_and_E
gypt

I can't find anywhere online with free access though. Closest is:

https://www.sciencedirect.com/scienc...15086013000530

Full article is behind a paywall.

The accuracy of the best clocks before pendulum clocks was abut 15
minutes per day. Before about 1650 the best pendulum clocks'
accuracy was about 10 seconds per day. In order to determine the
equation of time with a clock even one second per day, achieved by
Harrison in about 1760, is very little. Only in 1870 was accuracy of
0.1 seconds per day achieved, and equation of time determined with
a clock.


To measure the day to day variation directly you need this sort of
precision and a transit instrument to go with it. But to notice the
variation of the suns motion against the constellations at different
times of the year he could watch the movement of the sun against the
fixed stars.


Comparison of motions of fixed stars and Sun shows that at least one of
them is not uniform.

At the time and until Huygen's pendulum clock the most accurate clocks
were water clocks. They were not sufficiently accurate to determine
whether Sun or fixed stars or both moved unevenly.

The suns motion was known to be uneven from the first
development of water clocks and calendars by the Babylonians.


Water clocks were not useful for the purpose but a calendar was.

The Chinese even had a mercury based liquid clock that was not subject
to the same viscosity problems as water. It kept better time year round.


But was it ever used to check uniformity of any celestial motion?

Mikko
  #39  
Old December 13th 17, 06:09 AM posted to sci.astro.amateur
Gerald Kelleher
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Posts: 1,295
Default The Equation of Time(keeping)

The Equation of Time is the bridge between planetary motions/cycles and timekeeping but only as a close proximity rather than an exact relationship. It is not the core principle as it all depends on the greater relationship which formats the 1461 rotations for 4 orbital circuits into 3 cycles of 365 rotations and 1 cycle of 366 rotations rather than the pure proportion of 365 1/4 rotations for 1 orbital circuit.

The precise engineering that makes watches possible is matched by the exquisite principles which mirror the motions of the Earth however the external references for timekeeping develop in sequence and few if anyone has the discipline to consider where it all began ,at least in written form -

"On account of the precession of the rising of Sirius by one day in the course of 4 years therefore it shall be, that the year of 360 days and the 5 days added to their end, so one day shall be from this day after every 4 years added to the 5 epagomenae before the New Year" Canopus Decree, 236 BC

 




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