Fwd: equation of time on Earth

[Michael Ossipoff]

-- Forwarded message -
From: Michael Ossipoff 
Date: Thu, Feb 16, 2023 at 14:12
Subject: Re: equation of time on Earth
To: Kevin Karney 


Yes, French hours (Local True Solar Time), Babylonian hours, Italian hours
& can be gotten from a sundial directly, without referring to an EoT table,
& unaffected by precession of the equinoxes.

I claim that nowadays sundials are of interest for Local True Solar Time
anyway. EoT is more likely to be used (along with longitude-correction) to
get Local True Solar Time from a clock or watch.

The obliquity is constantly changing, & that will eventually put some kinds
of sundials off, & those will have to be remade.  Altitude Dials, & Azimuth
Dials, such as the Analemmatic-Dial, use Solar-declination, which will vary
with obliquely.

But sundials that directly measure Solar hour-angle won’t be affected.
Those include the flat-dials, including the Horizontal-Dial.  …& the
Equatorial-Dial, & the dials whose measuring-scale is along a band, ring or
cylinder that measures around a line parallel to the Earth’s axis (I
believe that those are all often called Equatorial-Dials).

On Wed, Feb 15, 2023 at 15:48 Kevin Karney via sundial 
wrote:

> Diese Nachricht wurde eingewickelt um DMARC-kompatibel zu sein. Die
> eigentliche Nachricht steht dadurch in einem Anhang.
>
> This message was wrapped to be DMARC compliant. The actual message
> text is therefore in an attachment.
>
>
> -- Forwarded message --
> From: Kevin Karney 
> To: Sundial 
> Cc:
> Bcc:
> Date: Wed, 15 Feb 2023 23:47:58 +
> Subject: Re: equation of time on Earth
> Hi Fabio,
>
> I found interesting how the eot changes over the millennia and I concluded
> that not all sundial time systems will survive.
>
> See below...
>
> And of course sundials will survive - just differently. The 'Clock of the
> Long Now’ (which is designed to last 10,000 years) has a 3-D cam encoding
> the EoT. When the sun is shining at noon, the clock will read the Sun’s
> presence through an aperture, this connects thermally to the 3-D cam (see
> below), which will re-set the clock to mean time. Mind-blowing project! See
> https://longnow.org/clock/
>
> Best wishes
> Kevin
> Kevin Karney
> Freedom Cottage, Llandogo,
> Monmouth, NP25 4TP, Wales, UK
> 51°44’44” N 2°41’5” W
>
>
>
> On 14 Feb 2023, at 17:12, Fabio Savian 
> wrote:
>
> Hi all
>
> a couple of weeks ago I sent you news about a new app (on Sundial Atlas,
> app 53) to get the equation of time of Mars.
> I haven't heard of any spaceships leaving so I thought you might be
> interested in the one for terrestrial resident as well :-)
>
> There is no shortage of software to draw eot but this new app (app 29,
> www.sundialatlas.net/atlas.php?ori=29) can draw the analemma starting
> from the orbital parameters of the Earth:
> - eccentricity of the orbit
> - inclination of the ecliptic
> - longitude of the perihelion
>
> The app doesn't calculate these parameters but you can digit any values to
> get the resulting analemma.
> I found a web page of NASA (Goddard Institute for Space Studies) where you
> can get the Earth's orbital parameters for the past or for the future:
> https://data.giss.nasa.gov/modelE/ar5plots/srorbpar.html
>
> I found interesting how the eot changes over the millennia and I concluded
> that not all sundial time systems will survive.
> Some sundials could become archaeological finds in a few centuries just as
> we look at those of centuries, or millennia ago and the understandable time
> systems in the future are: temporary, Babylonians, Italians and local Sun
> time.
> Not the analemma because eot changes over the millennia.
> Not time-zone Sun time because the conventions change over the centuries.
> Not mean time because leap seconds may be not updated over the decades.
>
> Watching your wrist watch could become a goofy experience, one hopes to be
> able to look at a sundial and know the local Sun time.
> Also a Martian.
>
> ciao Fabio
>
> PS in the app 29 you can also enter parameters of other planets.
> Remember that the longitude of the perihelion is a local reference, ie it
> is measured from the vernal point of the planet's orbit.
>
>
>
>
> ---
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>
>
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>
>
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equation of time on Earth

[Fabio Savian]

Hi all

a couple of weeks ago I sent you news about a new app (on Sundial Atlas, 
app 53) to get the equation of time of Mars.
I haven't heard of any spaceships leaving so I thought you might be 
interested in the one for terrestrial resident as well :-)


There is no shortage of software to draw eot but this new app (app 29, 
www.sundialatlas.net/atlas.php?ori=29) can draw the analemma starting 
from the orbital parameters of the Earth:

- eccentricity of the orbit
- inclination of the ecliptic
- longitude of the perihelion

The app doesn't calculate these parameters but you can digit any values 
to get the resulting analemma.
I found a web page of NASA (Goddard Institute for Space Studies) where 
you can get the Earth's orbital parameters for the past or for the future:

https://data.giss.nasa.gov/modelE/ar5plots/srorbpar.html

I found interesting how the eot changes over the millennia and I 
concluded that not all sundial time systems will survive.
Some sundials could become archaeological finds in a few centuries just 
as we look at those of centuries, or millennia ago and the 
understandable time systems in the future are: temporary, Babylonians, 
Italians and local Sun time.

Not the analemma because eot changes over the millennia.
Not time-zone Sun time because the conventions change over the centuries.
Not mean time because leap seconds may be not updated over the decades.

Watching your wrist watch could become a goofy experience, one hopes to 
be able to look at a sundial and know the local Sun time.

Also a Martian.

ciao Fabio

PS in the app 29 you can also enter parameters of other planets.
Remember that the longitude of the perihelion is a local reference, ie 
it is measured from the vernal point of the planet's orbit.





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Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Gian Casalegno]

When looking for  astronomical data such as the Equation of Time, it is
important to choose a data source with an adequate level of accuracy.

It can be worthwhile to have a look at the article "Sun Ephemeris
Comparison" published on "Orologi Solari" n. 11 and available in English at
the following link:
http://www.sundials.eu/download/Comparison%20of%20sun%20ephemeris.pdf
This paper shows that one of the best available sources is the Android app
"Sol Et Umbra" that can be downloaded for free from the Google Play Store.

The same level of accuracy is obtained by the freeware Windows program "Sun
Ephemeris" http://www.sundials.eu/download/SunEphemeris_enu.html
It can also create a table including the daily EoT values for whichever
desired year.

It has been correctly underlined that the EoT changes year to year,
therefore the above mentioned data cannot be used outside of the year for
which they have been computed.
When EoT values are required for multi-year use then averaged values should
be used.
In "Orologi Solari" n. 5 a table has been published by Gianni Ferrari
including the averaged EoT values for the years 2014-2061.
It is included in the associated digital bonus.

Ciao.
Gian



2017-04-30 19:46 GMT+02:00 Beverly Stimpson <beverly.stimp...@gmail.com>:

>
> In message <82d3e73456.us...@interwebs.com>
>   Beverly Stimpson <beverly.stimp...@gmail.com> wrote:
>
> >
> > If you need accurate solar 'transit times' (when the sun is exactly
> south),
> > for any geographic locations (showing CLOCK time corrected for Longitude
> in
> > a time-zone) for each day of the year, then you could contact Paul Ratto
> at
> > "SunClocks North America" - E-mail: sunclock...@icloud.com - who can
> supply
> > these details in the 'PDF' format, (if an Excel spreadsheet in
> unsuitable).
> >
> > Sincerely,
> >
> > Bev Stimpson.
> >
>
>
> In reply to an 'off-list' message I received, (plus to avoid discriminating
> against any list-members in the Southern hemisphere) - I have been asked to
> mention that a quite similar service (also giving details in PDF format) is
> available, showing times when the sun is due NORTH.  You can contact George
> Marshall, via his website - which is at URL:
> www.interactivesundials.com.au
>
> Sincerely,
>
> Bev Stimpson.
>
>
> --
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
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Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Beverly Stimpson]

In message <82d3e73456.us...@interwebs.com>
  Beverly Stimpson  wrote:

> 
> If you need accurate solar 'transit times' (when the sun is exactly south),
> for any geographic locations (showing CLOCK time corrected for Longitude in
> a time-zone) for each day of the year, then you could contact Paul Ratto at
> "SunClocks North America" - E-mail: sunclock...@icloud.com - who can supply
> these details in the 'PDF' format, (if an Excel spreadsheet in unsuitable).
> 
> Sincerely,
> 
> Bev Stimpson.
> 


In reply to an 'off-list' message I received, (plus to avoid discriminating
against any list-members in the Southern hemisphere) - I have been asked to
mention that a quite similar service (also giving details in PDF format) is
available, showing times when the sun is due NORTH.  You can contact George
Marshall, via his website - which is at URL: www.interactivesundials.com.au

Sincerely,

Bev Stimpson.


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Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[J. Tallman]

I use the Android app "Solar Coordinates" sometimes, it's worth a look and also 
free.

⁣Best,

Jim Tallman
Artisan Industrials

www.artisanindustrials.com
www.spectrasundial.com
jtall...@artisanindustrials.com
513-253-5497

This message is being sent remotely as I am currently out of the studio. Please 
excuse any further delay in response. ​

On Apr 30, 2017, 11:36 AM, at 11:36 AM, Brooke Clarke  
wrote:
>Hi:
>
>Remember that at that level of precision the value is only good for
>that particular year.  It will change over the 4
>year leap year cycle and keep changing over time.  A more accurate
>method would be to observe star meridian crossings,
>but that to is limited by "seeing".
>http://www.prc68.com/I/StellarTime.shtml
>
>--
>Have Fun,
>
>Brooke Clarke
>http://www.PRC68.com
>http://www.end2partygovernment.com/2012Issues.html
>
> Original Message 
>>
>> Hi Clark,
>>
>> The Solar Info android app provides the EqT value at all times and
>also generates the EqT curve at 12:00 for a date or
>> value of the Sun's declination for one year. It also provides these
>values in an Excel file.
>>
>> César Busto
>>
>>
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>
>
>
>
>
>---
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Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Brooke Clarke]

Hi:

Remember that at that level of precision the value is only good for that particular year.  It will change over the 4 
year leap year cycle and keep changing over time.  A more accurate method would be to observe star meridian crossings, 
but that to is limited by "seeing".

http://www.prc68.com/I/StellarTime.shtml

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

 Original Message 


Hi Clark,

The Solar Info android app provides the EqT value at all times and also generates the EqT curve at 12:00 for a date or 
value of the Sun's declination for one year. It also provides these values in an Excel file.


César Busto



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Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Beverly Stimpson]

In message <8bd92972-2f02-4282-8b7a-dcb0a87a6...@compuserve.com>
  Patrick  wrote:

> You could also try http://ppowers.com/EoT.htm
> Patrick
> 

If you need accurate solar 'transit times' (when the sun is exactly south),
for any geographic locations (showing CLOCK time corrected for Longitude in
a time-zone) for each day of the year, then you could contact Paul Ratto at
"SunClocks North America" - E-mail: sunclock...@icloud.com - who can supply
these details in the 'PDF' format, (if an Excel spreadsheet in unsuitable).

Sincerely,

Bev Stimpson.


-- 

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Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Patrick]

You could also try http://ppowers.com/EoT.htm
Patrick


Sent from my iPhone

> On 30 Apr 2017, at 09:51, César Busto  wrote:
> 
> Hi Clark,
>  
> The Solar Info android app provides the EqT value at all times and also 
> generates the EqT curve at 12:00 for a date or value of the Sun's declination 
> for one year. It also provides these values in an Excel file.
>  
> César Busto
>  
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
---
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Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[César Busto]

Hi Clark,

The Solar Info android app provides the EqT value at all times and also 
generates the EqT curve at 12:00 for a date or value of the Sun's declination 
for one year. It also provides these values in an Excel file.

César Busto

---
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Re: Looking for minutes and seconds correction for whole year, for Equation of Time plaque

[Kenneth R clark]

 Thanks Bob and everyone else for their input.  The EQT really does change 
way into the future.
 
  I am leaning towards Kevin Karney website:  
http://www.precisedirections.co.uk/Sundials/index.html using a “Victorian EOT” 
table adding or subtracting minutes.  I could set it into the future 2050 and 
after that I am sure I will not be around or if the sundial is still standing.

Thanks,

Ken Clark   

Elizabethtown, PA
I tried sending this message by AOL account.  Just not working!


- Original Message -
From: "Robert Kellogg" <rkell...@comcast.net>
To: sundial@uni-koeln.de
Sent: Friday, January 27, 2017 10:39:39 AM
Subject: RE: Looking for minutes and seconds correction for whole year, for 
Equation of Time plaque

I have used Pyephem (a Python programming module) for accurate 
computation of solar transit and have put it to service to compute EOT 
for Ken's latitude and longitude.  However, doing it to the second is 
pure fiction as the tropical year does not precisely repeat after 4 
years cycle ... and any one year in the 4 year cycle is off even more.

Bob


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RE: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Dave Bell]

Thanks for reminding us of your work, Kevin!

That’s a lovely piece of JavaScrpt!

 

Dave

 

From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Kevin Karney
Sent: Friday, January 27, 2017 2:40 AM
To: Kenneth R clark <krcl...@embarqmail.com>
Cc: sundial@uni-koeln.de
Subject: Re: Looking for minutes and seconds correction for whole year for 
Equation of Time plaque

 

Hi Ken

I you want to observe how the Equation of Time varies over the years, go to my 
website

http://www.precisedirections.co.uk/Sundials/index.html

 

The second item may be of interest to you. It gives a table of EoTs (including 
the longitude correction for your time zone). And you can choose either a 
single year or a four year cycle.

For the four-year cycle, the average local noon EoT is calculated for each 
calendar date, except 29 Feb, which stands on its own. If you want the EoT 
without the longitude correction, set your longitude to your time zone 
longitude.

 

The calculations used are far more rigorous than needed for gnomonic purposes. 
They use the complete VSOP theory as described by Meeus and the EoT is 
topographical rather than geocentric (which only makes a marginal difference). 

If you use browser (like Chrome) which allows you to see the web-page source, 
you can see the calculations involved. (In Chrome, select View>Developer>View 
Source)

EoTs calculated have an accuracy of +/- .06 secs of time - using US Naval 
Observatory's MICA program as standard.

I think it is interesting to see how the 4-year table changes as one jumps 4 
years into the future...  

 

See the first item on the original page for comments on the calculations

and consider using a "Victorian EOT" table which gives all the information 
needed but in a tenth of the space

 

The Latitude/Longitude finder - using Google Earth is a bit ratty, but seems to 
work for Elizabethtown.

 

Let me know if you have any problems.

 

Best wishes

Kevin

 

 

On 26 Jan 2017, at 00:21, Kenneth R clark <krcl...@embarqmail.com 
<mailto:krcl...@embarqmail.com> > wrote:

 

I had an error message from AOL Sorry for no subject line and my files were not 
sent.

Let me retry with this account.

 

Hi everyone,

 

     I am working on my Equation of Time plaque for my aluminum cross sundial.  
All the instructions and graphics and EQT will be on an 8 ½” diameter ½” 
aluminum plate.  I do not want to use the standard graph found on many sundials 
but instead a chart for the whole year, mins and secs, to add or subtract total 
correction to get watch time.  I do not have much room for detailed 
instructions.

 

 I looked at difference sources for the chart and would like to verify the 
most accurate times to use the four year leap year cycle for a church at 
40.1526N, 76.6038W.   I have looked at the Solar Noon calculator, Sonne and 
Shadows-(cannot input decimal degrees?)  Are there other sources or spreadsheet 
programs?

 

 I like to convey that sundials are accurate.  I envision that a person 
will wait till the shadow is on a line and the person will know what time it is 
suppose to be even though this type of sundial may not be design for precision.

 

 I made a quick drawing.  There will be some type of sun image at the top 
and a logo at the bottom for the location.  The chart in the center is from 
another project that I did just to see how it would look and if the printing is 
large enough to read.  I would have to change the inputs to standard time for 
the whole year.  I have also attached a picture of the sundial.

 

 I just want to know if I am using the right times and would appreciate any 
comments or suggestions.

 

Thanks very much

 

Ken Clark   

Elizabethtown, 
PA

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https://lists.uni-koeln.de/mailman/listinfo/sundial

 

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Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Thibaud Taudin Chabot]

Some time ago when I was able to use the 
mainframe computer of my employer I made a list 
of declination and time equation for each day for 
the years 2000-2099 and calculated the mean 
values for each date. I found the list again and 
attach it for who is interested.

Thibaud


Hi everyone,


 I am working on my Equation of Time plaque 
for my aluminum cross sundial.  All the 
instructions and graphics and EQT will be on an 
8 ½” diameter ½” aluminum plate.  I do not want 
to use the standard graph found on many 
sundials but instead a chart for the whole 
year, mins and secs, to add or subtract total 
correction to get watch time.  I do not have 
much room for detailed instructions.



 I looked at difference sources for the 
chart and would like to verify the most 
accurate times to use the four year leap year 
cycle for a church at 40.1526N, 76.6038W.   I 
have looked at the Solar Noon calculator, Sonne 
and Shadows-(cannot input decimal 
degrees?)  Are there other sources or spreadsheet programs?



 I like to convey that sundials are 
accurate.  I envision that a person will wait 
till the shadow is on a line and the person 
will know what time it is suppose to be even 
though this type of sundial may not be design for precision.



 I made a quick drawing.  There will be 
some type of sun image at the top and a logo at 
the bottom for the location.  The chart in the 
center is from another project that I did just 
to see how it would look and if the printing is 
large enough to read.  I would have to change 
the inputs to standard time for the whole 
year.  I have also attached a picture of the sundial.



 I just want to know if I am using the 
right times and would appreciate any comments or suggestions.



Thanks very much


Ken 
Clark 
Elizabethtown, PA



<https://lists.uni-koeln.de/mailman/listinfo/sundial>https://lists.uni-koeln.de/mailman/listinfo/sundial
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--
Th. Taudin Chabot, . tcha...@dds.nl



Mean values declination sun and time equation at 12:00 GMT
calculated over the years 2000 - 2099
==
   Day   - Declination sun    -- time equation ---
DatenrDD:MM:SS.ssDD.ddSSS.ssH:MM:SS.ssH.hh
--
01JAN   1-22:58:00.38   -22.966771   -211.953356   -0:03:31.95   -0.058876
02JAN   2-22:52:40.95   -22.878043   -239.917845   -0:03:59.92   -0.066644
03JAN   3-22:46:54.21   -22.781725   -267.534094   -0:04:27.53   -0.074315
04JAN   4-22:40:40.32   -22.677866   -294.772817   -0:04:54.77   -0.081881
05JAN   5-22:33:59.46   -22.566516   -321.605383   -0:05:21.61   -0.089335
06JAN   6-22:26:51.82   -22.447729   -348.003856   -0:05:48.00   -0.096668
07JAN   7-22:19:17.63   -22.321563   -373.941044   -0:06:13.94   -0.103873
08JAN   8-22:11:17.09   -22.188079   -399.390535   -0:06:39.39   -0.110942
09JAN   9-22:02:50.43   -22.047343   -424.326734   -0:07:04.33   -0.117869
10JAN   10   -21:53:57.92   -21.899421   -448.724903   -0:07:28.72   -0.124646
11JAN   11   -21:44:39.79   -21.744385   -472.561195   -0:07:52.56   -0.131267
12JAN   12   -21:34:56.31   -21.582309   -495.812681   -0:08:15.81   -0.137726
13JAN   13   -21:24:47.77   -21.413269   -518.457388   -0:08:38.46   -0.144016
14JAN   14   -21:14:14.45   -21.237347   -540.474318   -0:09:00.47   -0.150132
15JAN   15   -21:03:16.64   -21.054623   -561.843480   -0:09:21.84   -0.156068
16JAN   16   -20:51:54.66   -20.865184   -582.545908   -0:09:42.55   -0.161818
17JAN   17   -20:40:08.82   -20.669116   -602.563685   -0:10:02.56   -0.167379
18JAN   18   -20:27:59.44   -20.466511   -621.879958   -0:10:21.88   -0.172744
19JAN   19   -20:15:26.85   -20.257459   -640.478956   -0:10:40.48   -0.177911
20JAN   20   -20:02:31.40   -20.042056   -658.346003   -0:10:58.35   -0.182874
21JAN   21   -19:49:13.43   -19.820398   -675.467526   -0:11:15.47   -0.187630
22JAN   22   -19:35:33.30   -19.592582   -691.831067   -0:11:31.83   -0.192175
23JAN   23   -19:21:31.36   -19.358710   -707.425286   -0:11:47.43   -0.196507
24JAN   24   -19:07:07.98   -19.118883   -722.239967   -0:12:02.24   -0.200622
25JAN   25   -18:52:23.54   -18.873204   -736.266017   -0:12:16.27   -0.204518
26JAN   26   -18:37:18.40   -18.621779   -749.495468   -0:12:29.50   -0.208193
27JAN   27   -18:21:52.97   -18.364713   -761.921470   -0:12:41.92   -0.211645
28JAN   28   -18:06:07.61   -18.102114   -773.538288   -0:12:53.54   -0.214872
29JAN   29   -17:50:02.72   -17.834090   -784.341294   -0:13:04.34   -0.217873
30JAN   30   -17:33:38.71   -17.560752   -794.326959   -0:13:14.33   -0.220646
31JAN   31   -17:16:55.95   -17.282209   -803.492836   -0:13:23.49   -0.223192
01FEB   32   -16:59:54.87   -16.998574   -811.

RE: Looking for minutes and seconds correction for whole year, for Equation of Time plaque

[Robert Kellogg]

I have used Pyephem (a Python programming module) for accurate 
computation of solar transit and have put it to service to compute EOT 
for Ken's latitude and longitude.  However, doing it to the second is 
pure fiction as the tropical year does not precisely repeat after 4 
years cycle ... and any one year in the 4 year cycle is off even more.


Bob


---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Kevin Karney]

Hi Ken
I you want to observe how the Equation of Time varies over the years, go to my 
website
http://www.precisedirections.co.uk/Sundials/index.html

The second item may be of interest to you. It gives a table of EoTs (including 
the longitude correction for your time zone). And you can choose either a 
single year or a four year cycle.
For the four-year cycle, the average local noon EoT is calculated for each 
calendar date, except 29 Feb, which stands on its own. If you want the EoT 
without the longitude correction, set your longitude to your time zone 
longitude.

The calculations used are far more rigorous than needed for gnomonic purposes. 
They use the complete VSOP theory as described by Meeus and the EoT is 
topographical rather than geocentric (which only makes a marginal difference). 
If you use browser (like Chrome) which allows you to see the web-page source, 
you can see the calculations involved. (In Chrome, select View>Developer>View 
Source)
EoTs calculated have an accuracy of +/- .06 secs of time - using US Naval 
Observatory's MICA program as standard.
I think it is interesting to see how the 4-year table changes as one jumps 4 
years into the future...  

See the first item on the original page for comments on the calculations
and consider using a "Victorian EOT" table which gives all the information 
needed but in a tenth of the space

The Latitude/Longitude finder - using Google Earth is a bit ratty, but seems to 
work for Elizabethtown.

Let me know if you have any problems.

Best wishes
Kevin


> On 26 Jan 2017, at 00:21, Kenneth R clark <krcl...@embarqmail.com> wrote:
> 
> I had an error message from AOL Sorry for no subject line and my files were 
> not sent.
> Let me retry with this account.
> 
> Hi everyone,
> 
>  I am working on my Equation of Time plaque for my aluminum cross 
> sundial.  All the instructions and graphics and EQT will be on an 8 ½” 
> diameter ½” aluminum plate.  I do not want to use the standard graph found on 
> many sundials but instead a chart for the whole year, mins and secs, to add 
> or subtract total correction to get watch time.  I do not have much room for 
> detailed instructions.
> 
>  I looked at difference sources for the chart and would like to verify 
> the most accurate times to use the four year leap year cycle for a church at 
> 40.1526N, 76.6038W.   I have looked at the Solar Noon calculator, Sonne and 
> Shadows-(cannot input decimal degrees?)  Are there other sources or 
> spreadsheet programs?
> 
>  I like to convey that sundials are accurate.  I envision that a person 
> will wait till the shadow is on a line and the person will know what time it 
> is suppose to be even though this type of sundial may not be design for 
> precision.
> 
>  I made a quick drawing.  There will be some type of sun image at the top 
> and a logo at the bottom for the location.  The chart in the center is from 
> another project that I did just to see how it would look and if the printing 
> is large enough to read.  I would have to change the inputs to standard time 
> for the whole year.  I have also attached a picture of the sundial.
> 
>  I just want to know if I am using the right times and would appreciate 
> any comments or suggestions.
> 
> Thanks very much
> 
> Ken Clark 
>   
> 
> Elizabethtown, PA
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial 
> <https://lists.uni-koeln.de/mailman/listinfo/sundial>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

RE: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Jack Aubert]

HI Simon,

 

I like to use the “time of solar transit” version of the EOT from your 
spreadsheet because I can never remember with any confidence if I am correcting 
the watch or the dial.

 

Jack Aubert

 

 

From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Simon Wheaton 
Smith
Sent: Wednesday, January 25, 2017 8:08 PM
To: Kenneth R clark <krcl...@embarqmail.com>
Cc: sundial@uni-koeln.de
Subject: Re: Looking for minutes and seconds correction for whole year for 
Equation of Time plaque

 

Last email from me today...

 

here is the 4 year EOT from my main book

 

Simon

 

On Wed, Jan 25, 2017 at 5:21 PM, Kenneth R clark <krcl...@embarqmail.com 
<mailto:krcl...@embarqmail.com> > wrote:

I had an error message from AOL Sorry for no subject line and my files were not 
sent.

Let me retry with this account.

 

Hi everyone,

 

 I am working on my Equation of Time plaque for my aluminum cross sundial.  
All the instructions and graphics and EQT will be on an 8 ½” diameter ½” 
aluminum plate.  I do not want to use the standard graph found on many sundials 
but instead a chart for the whole year, mins and secs, to add or subtract total 
correction to get watch time.  I do not have much room for detailed 
instructions.

 

 I looked at difference sources for the chart and would like to verify the 
most accurate times to use the four year leap year cycle for a church at 
40.1526N, 76.6038W.   I have looked at the Solar Noon calculator, Sonne and 
Shadows-(cannot input decimal degrees?)  Are there other sources or spreadsheet 
programs?

 

 I like to convey that sundials are accurate.  I envision that a person 
will wait till the shadow is on a line and the person will know what time it is 
suppose to be even though this type of sundial may not be design for precision.

 

 I made a quick drawing.  There will be some type of sun image at the top 
and a logo at the bottom for the location.  The chart in the center is from 
another project that I did just to see how it would look and if the printing is 
large enough to read.  I would have to change the inputs to standard time for 
the whole year.  I have also attached a picture of the sundial.

 

 I just want to know if I am using the right times and would appreciate any 
comments or suggestions.

 

Thanks very much

 

Ken Clark   

Elizabethtown, 
PA


---
https://lists.uni-koeln.de/mailman/listinfo/sundial







 

-- 

Simon Wheaton-Smith

www.illustratingshadows.com <http://www.illustratingshadows.com> 

Phoenix, AZ

W 112.1, N 33.5

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Gian Casalegno]

Sorry for the mail with no subject: it's because it was an answer to Ken's
e-mail.
Here is the text again.

The program "Orologi Solari" can provide a table too (as well as a graph in
several formats) of the Equation of Time, including or not the longitude
difference, as desired.

Values are from Gianni Ferrari study, published on the Italian magazine
"Orologi Solari" n. 5, where he computed the EoT mean value in the years
2014-2061.
>From the same source you can also get an Excel file containing the original
Ferrari's table.
In my opinion this the best choice for a sundial that will be hopefully
used for many years in the future: a 4 years mean value will not give a
correct reading after 30 years (have a look at the article for the
evaluation of the exact resulting errors).

Also note that EoT values are usually computed at 12 AM UTC (this is indeed
the case for Orologi Solari) and you should correct them to move to your
time zone.

Ciao.
Gian Casalegno

2017-01-26 1:21 GMT+01:00 Kenneth R clark <krcl...@embarqmail.com>:

> I had an error message from AOL Sorry for no subject line and my files
> were not sent.
>
> Let me retry with this account.
>
>
> Hi everyone,
>
>
>  I am working on my Equation of Time plaque for my aluminum cross
> sundial.  All the instructions and graphics and EQT will be on an 8 ½”
> diameter ½” aluminum plate.  I do not want to use the standard graph found
> on many sundials but instead a chart for the whole year, mins and secs, to
> add or subtract total correction to get watch time.  I do not have much
> room for detailed instructions.
>
>
>  I looked at difference sources for the chart and would like to verify
> the most accurate times to use the four year leap year cycle for a church
> at 40.1526N, 76.6038W.   I have looked at the Solar Noon calculator, Sonne
> and Shadows-(cannot input decimal degrees?)  Are there other sources or
> spreadsheet programs?
>
>
>  I like to convey that sundials are accurate.  I envision that a
> person will wait till the shadow is on a line and the person will know what
> time it is suppose to be even though this type of sundial may not be design
> for precision.
>
>
>  I made a quick drawing.  There will be some type of sun image at the
> top and a logo at the bottom for the location.  The chart in the center is
> from another project that I did just to see how it would look and if the
> printing is large enough to read.  I would have to change the inputs to
> standard time for the whole year.  I have also attached a picture of the
> sundial.
>
>
>  I just want to know if I am using the right times and would
> appreciate any comments or suggestions.
>
>
> Thanks very much
>
>
> Ken Clark
>
>
> Elizabethtown, PA
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[J. Tallman]

Hi Ken,

I use the 4 year average values from Waugh. When I originally designed the 
Spectra in 2001 that was the best resource available to me, but there are many 
applications now that you can use to check the values. Orologi Solari is very 
good for lots of reasons, and I use Shadows as well.

There are several Android apps that give EOT too...I like Sol et Umbra, but 
most if not all the apps I have seen give EOT on a daily basis, I don't think 
any of them give the whole year at once like you showed.

When I made my EOT chart for the Spectra which is common to every dial that I 
make (longitude correction is added to the hour lines) Tony Moss advised me to 
create the chart and plot the line myself, and in my case I used Adobe 
Illustrator to do that. I'm glad I did, as it seemed like a suitable rite of 
passage for a professional dial maker. I believe you can also use Excel to do 
it, if a chart is what you need.

Hope this helps. I'll bet you could find something on the NASS Repository disk 
as well.

⁣Best, 

Jim Tallman
www.artisanindustrials.com 
www.spectrasundial.com 
jtall...@artisanindustrials.com 
513-253-5497 

This message is being sent remotely as I am currently out of the studio. Please 
excuse any further delay in response. ​


On Jan 25, 2017, at 7:21 PM, Kenneth R clark <krcl...@embarqmail.com> wrote:

I had an error message from AOL Sorry for no subject line and my files were not 
sent.

Let me retry with this account.


Hi everyone,


 I am working on my Equation of Time plaque for my aluminum cross sundial.  
All the instructions and graphics and EQT will be on an 8 ½” diameter ½” 
aluminum plate.  I do not want to use the standard graph found on many sundials 
but instead a chart for the whole year, mins and secs, to add or subtract total 
correction to get watch time.  I do not have much room for detailed 
instructions.


 I looked at difference sources for the chart and would like to verify the 
most accurate times to use the four year leap year cycle for a church at 
40.1526N, 76.6038W.   I have looked at the Solar Noon calculator, Sonne and 
Shadows-(cannot input decimal degrees?)  Are there other sources or spreadsheet 
programs?


 I like to convey that sundials are accurate.  I envision that a person 
will wait till the shadow is on a line and the person will know what time it is 
suppose to be even though this type of sundial may not be design for precision.


 I made a quick drawing.  There will be some type of sun image at the top 
and a logo at the bottom for the location.  The chart in the center is from 
another project that I did just to see how it would look and if the printing is 
large enough to read.  I would have to change the inputs to standard time for 
the whole year.  I have also attached a picture of the sundial.


 I just want to know if I am using the right times and would appreciate any 
comments or suggestions.


Thanks very much


Ken Clark                                                                       
                                                                                
                                                                Elizabethtown, 
PA


https://lists.uni-koeln.de/mailman/listinfo/sundial

On Jan 25, 2017, 7:21 PM, at 7:21 PM, Kenneth R clark  <krcl...@embarqmail.com> 
wrote:
>
>I had an error message from AOL Sorry for no subject line and my files
>were not sent. 
>Let me retry with this account. 
>
>
>Hi everyone, 
>
>
>I am working on my Equation of Time plaque for my aluminum cross
>sundial. All the instructions and graphics and EQT will be on an 8 ½”
>diameter ½” aluminum plate. I do not want to use the standard graph
>found on many sundials but instead a chart for the whole year, mins and
>secs, to add or subtract total correction to get watch time. I do not
>have much room for detailed instructions. 
>
>
>I looked at difference sources for the chart and would like to verify
>the most accurate times to use the four year leap year cycle for a
>church at 40.1526N, 76.6038W. I have looked at the Solar Noon
>calculator, Sonne and Shadows-(cannot input decimal degrees?) Are there
>other sources or spreadsheet programs? 
>
>
>I like to convey that sundials are accurate. I envision that a person
>will wait till the shadow is on a line and the person will know what
>time it is suppose to be even though this type of sundial may not be
>design for precision. 
>
>
>I made a quick drawing. There will be some type of sun image at the top
>and a logo at the bottom for the location. The chart in the center is
>from another project that I did just to see how it would look and if
>the printing is large enough to read. I would have to change the inputs
>to standard time for the whole year. I have also attached a picture of
>the sundial. 
>
>
>I just want to know if I am 

Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[Simon Wheaton Smith]

Last email from me today...

here is the 4 year EOT from my main book

Simon

On Wed, Jan 25, 2017 at 5:21 PM, Kenneth R clark <krcl...@embarqmail.com>
wrote:

> I had an error message from AOL Sorry for no subject line and my files
> were not sent.
>
> Let me retry with this account.
>
>
> Hi everyone,
>
>
>  I am working on my Equation of Time plaque for my aluminum cross
> sundial.  All the instructions and graphics and EQT will be on an 8 ½”
> diameter ½” aluminum plate.  I do not want to use the standard graph found
> on many sundials but instead a chart for the whole year, mins and secs, to
> add or subtract total correction to get watch time.  I do not have much
> room for detailed instructions.
>
>
>  I looked at difference sources for the chart and would like to verify
> the most accurate times to use the four year leap year cycle for a church
> at 40.1526N, 76.6038W.   I have looked at the Solar Noon calculator, Sonne
> and Shadows-(cannot input decimal degrees?)  Are there other sources or
> spreadsheet programs?
>
>
>  I like to convey that sundials are accurate.  I envision that a
> person will wait till the shadow is on a line and the person will know what
> time it is suppose to be even though this type of sundial may not be design
> for precision.
>
>
>  I made a quick drawing.  There will be some type of sun image at the
> top and a logo at the bottom for the location.  The chart in the center is
> from another project that I did just to see how it would look and if the
> printing is large enough to read.  I would have to change the inputs to
> standard time for the whole year.  I have also attached a picture of the
> sundial.
>
>
>  I just want to know if I am using the right times and would
> appreciate any comments or suggestions.
>
>
> Thanks very much
>
>
> Ken Clark
>
>
> Elizabethtown, PA
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>


-- 
Simon Wheaton-Smith
www.illustratingshadows.com
Phoenix, AZ
W 112.1, N 33.5


4yearEOT.pdf
Description: Adobe PDF document
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: PS: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[illustratingshad...@gmail.com]

when I said supplementalShadows.pdf I meant to type 
appendix-main-appendices.pdf
sorry. However my averaging fir 4 years is avtually, now I look at it, in the 
Excel sheet 
illustratingshadows.xls
specifically the "astroEOT" sheet, however I did the averaging for mid month so 
as a turnkey it may not help. But do look at that sheet as it is easy to 
modify. The sheet is orotected, so do ALT-T  then P  then  P  again to 
unprotected it.
simon  

Sent from Yahoo Mail on Android 
 
  On Wed, Jan 25, 2017 at 17:21, Kenneth R clark<krcl...@embarqmail.com> wrote: 
  
I had an error message from AOL Sorry for no subject line and my files were not 
sent.

Let me retry with this account.




Hi everyone,




 I am working onmy Equation of Time plaque for my aluminum cross sundial.  
All the instructions and graphics and EQT willbe on an 8 ½” diameter ½” 
aluminum plate. I do not want to use the standard graph found on many sundials 
butinstead a chart for the whole year, mins and secs, to add or subtract 
totalcorrection to get watch time.  I do nothave much room for detailed 
instructions.




 I looked atdifference sources for the chart and would like to verify the 
most accurate timesto use the four year leap year cycle for a church at 
40.1526N, 76.6038W.   I have looked at the Solar Noon calculator,Sonne and 
Shadows-(cannot input decimal degrees?)  Are there other sources or spreadsheet 
programs?




 I like to conveythat sundials are accurate.  I envisionthat a person will 
wait till the shadow is on a line and the person will knowwhat time it is 
suppose to be even though this type of sundial may not be designfor precision.




 I made a quickdrawing.  There will be some type of sunimage at the top and 
a logo at the bottom for the location.  The chart in the center is from 
anotherproject that I did just to see how it would look and if the printing is 
large enoughto read.  I would have to change theinputs to standard time for the 
whole year. I have also attached a picture of the sundial.




 I just want toknow if I am using the right times and would appreciate any 
comments orsuggestions.




Thanks very much




Ken Clark                                                                       
                                                                                
                                                                Elizabethtown,PA
  
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Looking for minutes and seconds correction for whole year for Equation of Time plaque

[illustratingshad...@gmail.com]

there are many excellent sources for that which you seek.
my own offering would be my 
illustratingshadows.xls
on my Web site which has an astronomically appropriate worksheet, decimal lat 
and long are used, not minutes and seconds.
And I have also averaged 4 years of them in
supplemental Shadows.pdf
also on my Web site:-
www.illustratingshadows.com   

Simon


Sent from Yahoo Mail on Android 
 
  On Wed, Jan 25, 2017 at 17:21, Kenneth R clark<krcl...@embarqmail.com> wrote: 
  
I had an error message from AOL Sorry for no subject line and my files were not 
sent.

Let me retry with this account.




Hi everyone,




 I am working onmy Equation of Time plaque for my aluminum cross sundial.  
All the instructions and graphics and EQT willbe on an 8 ½” diameter ½” 
aluminum plate. I do not want to use the standard graph found on many sundials 
butinstead a chart for the whole year, mins and secs, to add or subtract 
totalcorrection to get watch time.  I do nothave much room for detailed 
instructions.




 I looked atdifference sources for the chart and would like to verify the 
most accurate timesto use the four year leap year cycle for a church at 
40.1526N, 76.6038W.   I have looked at the Solar Noon calculator,Sonne and 
Shadows-(cannot input decimal degrees?)  Are there other sources or spreadsheet 
programs?




 I like to conveythat sundials are accurate.  I envisionthat a person will 
wait till the shadow is on a line and the person will knowwhat time it is 
suppose to be even though this type of sundial may not be designfor precision.




 I made a quickdrawing.  There will be some type of sunimage at the top and 
a logo at the bottom for the location.  The chart in the center is from 
anotherproject that I did just to see how it would look and if the printing is 
large enoughto read.  I would have to change theinputs to standard time for the 
whole year. I have also attached a picture of the sundial.




 I just want toknow if I am using the right times and would appreciate any 
comments orsuggestions.




Thanks very much




Ken Clark                                                                       
                                                                                
                                                                Elizabethtown,PA
  
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Equation of time on a Android Smart Watch

[Gian Casalegno]

No answers from the Equation of Time Smartwatch face developers, however
after some days and several attempts I could finalize my purchase (maybe
thanks to a new s/w version installed on my smartwatch, maybe because of
other obscure reasons).
Now I have it installed and I can tell you about it.

The appearance is exactly what you can see on the Play Store (see the
attached image).
The astronomical information that you can get are the following:
- sunrise time
- sunset time
- EoT value
- moon phase
Each of them can be selectively enabled or disabled from your smartphone.

As far as I can say after a few hours test, all data look almost correct.

Today values (compared to SolEtUmbra) for my location and my time zone are:
  sunrise 8:06 (geometric 8:11:47 - apparent 8:00:32)
  sunset 16:49 (geometric 16:43:16 - apparent 16:54:44)
  EoT 2:00 (1:40)

Sunrise and sunset times seem to be the apparent ones, maybe corrected for
refraction but not for the horizon dip (I'm just guessing as I could not
find any explanation anywhere).

EoT is about 20 seconds wrong, but it is shown on a small dial where
resolution is one minute only: it's therefore very difficult to get a more
precise reading.

Moon phase is shown by means of a partially obscured moon figure: it's a
qualitative representation and I cannot say how it is correct or not.

All in all, in my opinion this is a pleasant watch face that can be well
appreciated by gnomonic people.
However the lack in precision in the EoT value does not permit to use it
for accurate verifications (f.i. when checking a big darkroom sundial).

It would have been much better to include an additional hand to show the
EoT on the main dial and even better to add one more hand showing local
time (i.e. including longitude difference).
Finally I would appreciate an option to show all the astronomical data on a
digital watch face when a higher precision is needed.

As a conclusion I think that there is space for my future smartwatch app
development :-)

Ciao.
Gian


2016-12-17 21:11 GMT+01:00 rodwall1...@gmail.com <rodwall1...@gmail.com>:

> Hi Gian,
>
> Thanks for trying and testing the Equation of Time face for Smart Watches.
> Will be interesting to see how it goes.
>
> Even though you have been beaten in producing a watch face. Do still push
> ahead with your own version. As there is enough room for another maybe more
> interesting  Equation of Time face. The market is worldwide.
>
> Thanks,
>
> Regards,
>
> Roderick Wall.
>
> - Reply message -
> From: "Gian Casalegno" <gian.casale...@gmail.com>
> To: "sundial" <sundial@uni-koeln.de>
> Subject: Equation of time on a Android Smart Watch
> Date: Sun, Dec 18, 2016 1:58 AM
>
> Hi,
> I have recently purchased a smartwatch with the idea of developing some
> gnomonic features for Android Wear.
> Now I see that I have been beaten :-(
>
> Anyway I have just tried to download this "Equation of Time" app but
> unfortunately it failed.
> I have tried several times with no success, even if my Moto 360 smartwatch
> is said to be fully compatible.
>
> I have then sent an email to the app developers and I am now waiting for
> some help.
> I will keep you informed.
>
> Ciao.
> Gian
>
>
> 2016-12-17 1:34 GMT+01:00 rodwall1...@gmail.com <rodwall1...@gmail.com>:
>
> > Hi all,
> >
> > Some time ago there was some discussion on Equation of time watches that
> > cost $60,000 plus. Much too much for my pocket.
> >
> > Someone I can't remembered who. Indicated that it would be possible to
> > have The Equation of time on a Android Smart Watch. But they couldn't find
> > one.
> >
> > I thought that if there was a Equation of time for a Android Smart Watch.
> > I would consider purchasing a Smart Watch. So I went to Google play and
> > found what I thought was a nice watch face. And sent them a email
> > suggesting that they might like to produce one for the Equation of time.
> >
> > They thought that it was a good idea and produced one as in the link below.
> >
> > The problem is I don't have a Android Smart Watch to see if it works.
> >
> > Maybe someone with a Android Smart Watch may like to try it and report
> > back to the group as to how good it is. Cost is $1.39.
> >
> > https://play.google.com/store/apps/details?id=com.cga.time.equation
> >
> > Hoping that it works,
> >
> > Roderick Wall.
> >
> >
> > ---
> > https://lists.uni-koeln.de/mailman/listinfo/sundial
> >
> >
> >
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Equation of time on a Android Smart Watch

[rodwall1...@gmail.com]

Hi Gian,
Thanks for trying and testing the Equation of Time face for Smart Watches. Will 
be interesting to see how it goes.

Even though you have been beaten in producing a watch face. Do still push ahead 
with your own version. As there is enough room for another maybe more 
interesting  Equation of Time face. The market is worldwide.

Thanks,

Regards,

Roderick Wall.

- Reply message -
From: "Gian Casalegno" <gian.casale...@gmail.com>
To: "sundial" <sundial@uni-koeln.de>
Subject: Equation of time on a Android Smart Watch
Date: Sun, Dec 18, 2016 1:58 AM

Hi,
I have recently purchased a smartwatch with the idea of developing some
gnomonic features for Android Wear.
Now I see that I have been beaten :-(

Anyway I have just tried to download this "Equation of Time" app but
unfortunately it failed.
I have tried several times with no success, even if my Moto 360 smartwatch
is said to be fully compatible.

I have then sent an email to the app developers and I am now waiting for
some help.
I will keep you informed.

Ciao.
Gian


2016-12-17 1:34 GMT+01:00 rodwall1...@gmail.com <rodwall1...@gmail.com>:

> Hi all,
>
> Some time ago there was some discussion on Equation of time watches that
> cost $60,000 plus. Much too much for my pocket.
>
> Someone I can't remembered who. Indicated that it would be possible to
> have The Equation of time on a Android Smart Watch. But they couldn't find
> one.
>
> I thought that if there was a Equation of time for a Android Smart Watch.
> I would consider purchasing a Smart Watch. So I went to Google play and
> found what I thought was a nice watch face. And sent them a email
> suggesting that they might like to produce one for the Equation of time.
>
> They thought that it was a good idea and produced one as in the link below.
>
> The problem is I don't have a Android Smart Watch to see if it works.
>
> Maybe someone with a Android Smart Watch may like to try it and report
> back to the group as to how good it is. Cost is $1.39.
>
> https://play.google.com/store/apps/details?id=com.cga.time.equation
>
> Hoping that it works,
>
> Roderick Wall.
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Equation of time on a Android Smart Watch

[Gian Casalegno]

Hi,
I have recently purchased a smartwatch with the idea of developing some
gnomonic features for Android Wear.
Now I see that I have been beaten :-(

Anyway I have just tried to download this "Equation of Time" app but
unfortunately it failed.
I have tried several times with no success, even if my Moto 360 smartwatch
is said to be fully compatible.

I have then sent an email to the app developers and I am now waiting for
some help.
I will keep you informed.

Ciao.
Gian


2016-12-17 1:34 GMT+01:00 rodwall1...@gmail.com <rodwall1...@gmail.com>:

> Hi all,
>
> Some time ago there was some discussion on Equation of time watches that
> cost $60,000 plus. Much too much for my pocket.
>
> Someone I can't remembered who. Indicated that it would be possible to
> have The Equation of time on a Android Smart Watch. But they couldn't find
> one.
>
> I thought that if there was a Equation of time for a Android Smart Watch.
> I would consider purchasing a Smart Watch. So I went to Google play and
> found what I thought was a nice watch face. And sent them a email
> suggesting that they might like to produce one for the Equation of time.
>
> They thought that it was a good idea and produced one as in the link below.
>
> The problem is I don't have a Android Smart Watch to see if it works.
>
> Maybe someone with a Android Smart Watch may like to try it and report
> back to the group as to how good it is. Cost is $1.39.
>
> https://play.google.com/store/apps/details?id=com.cga.time.equation
>
> Hoping that it works,
>
> Roderick Wall.
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Equation of time on a Android Smart Watch

[rodwall1...@gmail.com]

Hi all,
Some time ago there was some discussion on Equation of time watches that cost 
$60,000 plus. Much too much for my pocket.

Someone I can't remembered who. Indicated that it would be possible to have The 
Equation of time on a Android Smart Watch. But they couldn't find one.

I thought that if there was a Equation of time for a Android Smart Watch. I 
would consider purchasing a Smart Watch. So I went to Google play and found 
what I thought was a nice watch face. And sent them a email suggesting that 
they might like to produce one for the Equation of time.

They thought that it was a good idea and produced one as in the link below.

The problem is I don't have a Android Smart Watch to see if it works.

Maybe someone with a Android Smart Watch may like to try it and report back to 
the group as to how good it is. Cost is $1.39.

https://play.google.com/store/apps/details?id=com.cga.time.equation

Hoping that it works,

Roderick Wall.

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Longcase Clock with Equation of TIme

[Miguel A. Garcia]

Hi All

How about this watch.

http://www.yeswatch.com/wrist-watch/timekeeper/zulu.html

Miguel A. G. Arrando





---
El software de antivirus Avast ha analizado este correo electrónico en busca de 
virus.
https://www.avast.com/antivirus
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Longcase Clock with Equation of TIme

[rodwall1...@gmail.com]

Hi Ian,
Thanks, never thought about smartwatch applications. Looks like I'll have to 
purchase a smartwatch for me to have a watch with the equation of time. But 
I'll have to wait until someone produces a application with a dial that has the 
EOT.

I notice that one of the android smartwatch application producers will add your 
watch if you tell them what it is. Maybe we should ask them to do one of the 
$30,000 EOT watches. That would be a lot cheaper.

Thanks,

Regards,

Roderick Wall.

- Reply message -
From: "Ian Maddocks" <ian_maddo...@hotmail.com>
To: "Willy Leenders" <willy.leend...@telenet.be>, "Sundial list" 
<sundial@uni-koeln.de>
Subject: Longcase Clock with Equation of TIme
Date: Sun, Oct 9, 2016 7:40 AM

hi Willy


As is the answer to so many things these days...  There's an app for that

If you have a smart watch you can create your own watch face as you like it 
with underlying code

For example

https://play.google.com/store/search?q=watchmaker=apps=en

shows all the watch-face making apps for android smart watches

I only found one reference to EoT in the G+ forum for the first (WatchMaker) app
(The e-watch was a recreation of a two sided real watch with EoT but they 
didnt' seem to have replicated the second side that had the EoT)
so there's a gap in the market to be plugged!


And in case anyone is interested .  If you want a mechanical watch with EoT 
here's a watch selling site with a search included
http://www.chrono24.co.uk/search/index.htm?query=equation+of+time=true=1
But expect to be paying at least one kidney



Ian Maddocks
Chester, UK
53°11'50"N  2°52'41"W
frog.happy.froze




From: sundial <sundial-boun...@uni-koeln.de> on behalf of Willy Leenders 
<willy.leend...@telenet.be>
Sent: 08 October 2016 18:15
To: rodwall1...@gmail.com
Cc: Kevin Karney; Sundial list
Subject: Re: Longcase Clock with Equation of TIme


More interesting is to know whether there exist modern timepieces which 
indicate the solar time.
With the possibilities of electronics and a built-in GPS system it can not be 
so difficult.


Willy Leenders
Hasselt in Flanders (Belgium)

Visit my website about the sundials in the province of Limburg (Flanders) with 
a section 'worth knowing about sundials' (mostly in Dutch): 
http://www.wijzerweb.be



Op 8-okt-2016, om 19:32 heeft 
rodwall1...@gmail.com<mailto:rodwall1...@gmail.com> het volgende geschreven:

Hi all,

This is an interesting website on equation clocks.

https://en.m.wikipedia.org/wiki/Equation_clock

Regards,

Roderick Wall.

- Reply message -
From: "Kevin Karney" <kar...@me.com<mailto:kar...@me.com>>
To: "rodwall1...@gmail.com<mailto:rodwall1...@gmail.com>" 
<rodwall1...@gmail.com<mailto:rodwall1...@gmail.com>>
Cc: "Sundial list" <sundial@uni-koeln.de<mailto:sundial@uni-koeln.de>>
Subject: Longcase Clock with Equation of TIme
Date: Sat, Oct 8, 2016 4:28 AM


As explained by Fred Sawyer in a recent lecture to the British Sundial Society, 
if often worked the other way around... people had an equation table and all 
kinds of rules so that they could adjust their clock so that it matched dial 
time for as long as possible.

Dial time was (and still is for some) 'true' time. The acceptance of local mean 
time was a slow process. Likewise the acceptance of national mean time met with 
a great deal of resistance. In Dorchester in 1858, in the UK, a judge in a 
court case found in favour of the plaintiff, since the defendant was not 
present at 10:00 o'clock when the case was scheduled. The court was using GMT. 
The defendant arrived at 10:00 local mean time - a few minutes late. He 
appealed and the appeal judge ruled...
"Ten o’clock is 10 o’clock according to the Time of the Place and the Town 
Council cannot say that it is not, 
but that it is 10 o’clock by Greenwich 
time. Nor can the time be altered by a railway company.… Nor by any person who 
regulates the clock on the Town-Hall."

Unless you lived in a (maritime) city, or had an astronomer on hand, or a local 
rich man who went up to the city and owned a chronometer, there was NO way to 
set a clock without a Sundial. It all changed with the the arrival of the 
telegraph   I have found that this is something that watch and clock 
enthusiasts sometimes forget!

Kevin

Sent from my iPad

> On 7 Oct 2016, at 11:07, rodwall1...@gmail.com<mailto:rodwall1...@gmail.com> 
> <rodwall1...@gmail.com<mailto:rodwall1...@gmail.com>> wrote:
>
> Hi all,
>
> In 1730. I think I heard somewhere that. Clock manufacturers also sometimes 
> gave a small window sundial to allow you to set your clock. With a equation 
> of time table. Is that correct?
>
> Roderick Wall..
>
>
> - Reply message -
> From: "Robert Terwilliger" <

Re: Longcase Clock with Equation of TIme

[Ian Maddocks]

hi Willy


As is the answer to so many things these days...  There's an app for that

If you have a smart watch you can create your own watch face as you like it 
with underlying code

For example

https://play.google.com/store/search?q=watchmaker=apps=en

shows all the watch-face making apps for android smart watches

I only found one reference to EoT in the G+ forum for the first (WatchMaker) app
(The e-watch was a recreation of a two sided real watch with EoT but they 
didnt' seem to have replicated the second side that had the EoT)
so there's a gap in the market to be plugged!


And in case anyone is interested .  If you want a mechanical watch with EoT 
here's a watch selling site with a search included
http://www.chrono24.co.uk/search/index.htm?query=equation+of+time=true=1
But expect to be paying at least one kidney



Ian Maddocks
Chester, UK
53°11'50"N  2°52'41"W
frog.happy.froze




From: sundial <sundial-boun...@uni-koeln.de> on behalf of Willy Leenders 
<willy.leend...@telenet.be>
Sent: 08 October 2016 18:15
To: rodwall1...@gmail.com
Cc: Kevin Karney; Sundial list
Subject: Re: Longcase Clock with Equation of TIme


More interesting is to know whether there exist modern timepieces which 
indicate the solar time.
With the possibilities of electronics and a built-in GPS system it can not be 
so difficult.


Willy Leenders
Hasselt in Flanders (Belgium)

Visit my website about the sundials in the province of Limburg (Flanders) with 
a section 'worth knowing about sundials' (mostly in Dutch): 
http://www.wijzerweb.be



Op 8-okt-2016, om 19:32 heeft 
rodwall1...@gmail.com<mailto:rodwall1...@gmail.com> het volgende geschreven:

Hi all,

This is an interesting website on equation clocks.

https://en.m.wikipedia.org/wiki/Equation_clock

Regards,

Roderick Wall.

- Reply message -
From: "Kevin Karney" <kar...@me.com<mailto:kar...@me.com>>
To: "rodwall1...@gmail.com<mailto:rodwall1...@gmail.com>" 
<rodwall1...@gmail.com<mailto:rodwall1...@gmail.com>>
Cc: "Sundial list" <sundial@uni-koeln.de<mailto:sundial@uni-koeln.de>>
Subject: Longcase Clock with Equation of TIme
Date: Sat, Oct 8, 2016 4:28 AM


As explained by Fred Sawyer in a recent lecture to the British Sundial Society, 
if often worked the other way around... people had an equation table and all 
kinds of rules so that they could adjust their clock so that it matched dial 
time for as long as possible.

Dial time was (and still is for some) 'true' time. The acceptance of local mean 
time was a slow process. Likewise the acceptance of national mean time met with 
a great deal of resistance. In Dorchester in 1858, in the UK, a judge in a 
court case found in favour of the plaintiff, since the defendant was not 
present at 10:00 o'clock when the case was scheduled. The court was using GMT. 
The defendant arrived at 10:00 local mean time - a few minutes late. He 
appealed and the appeal judge ruled...
"Ten o’clock is 10 o’clock according to the Time of the Place and the Town 
Council cannot say that it is not, 
but that it is 10 o’clock by Greenwich 
time. Nor can the time be altered by a railway company.… Nor by any person who 
regulates the clock on the Town-Hall."

Unless you lived in a (maritime) city, or had an astronomer on hand, or a local 
rich man who went up to the city and owned a chronometer, there was NO way to 
set a clock without a Sundial. It all changed with the the arrival of the 
telegraph   I have found that this is something that watch and clock 
enthusiasts sometimes forget!

Kevin

Sent from my iPad

> On 7 Oct 2016, at 11:07, rodwall1...@gmail.com<mailto:rodwall1...@gmail.com> 
> <rodwall1...@gmail.com<mailto:rodwall1...@gmail.com>> wrote:
>
> Hi all,
>
> In 1730. I think I heard somewhere that. Clock manufacturers also sometimes 
> gave a small window sundial to allow you to set your clock. With a equation 
> of time table. Is that correct?
>
> Roderick Wall..
>
>
> - Reply message -
> From: "Robert Terwilliger" <b...@twigsdigs.com<mailto:b...@twigsdigs.com>>
> To: "'Ian Maddocks'" 
> <ian_maddo...@hotmail.com<mailto:ian_maddo...@hotmail.com>>, "'Sundial list'" 
> <sundial@uni-koeln.de<mailto:sundial@uni-koeln.de>>
> Subject: Longcase Clock with Equation of TIme
> Date: Fri, Oct 7, 2016 1:00 PM
>
> If you had a similar clock in 1730 - located where you didn't have access to
> another accurate clock, a sundial would be the only way you could set it -
> and to do so you would need to know the equation for the date.
>
>
>
> Bob
>
>
>
>   _
>
> From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Ian
> Maddocks
> Sent: Wednesday, October 5, 2016 12:29 PM
> 

Re: Longcase Clock with Equation of TIme

[rodwall1...@gmail.com]

Hi all,
This is an interesting website on equation clocks.

https://en.m.wikipedia.org/wiki/Equation_clock

Regards,

Roderick Wall.

- Reply message -
From: "Kevin Karney" <kar...@me.com>
To: "rodwall1...@gmail.com" <rodwall1...@gmail.com>
Cc: "Sundial list" <sundial@uni-koeln.de>
Subject: Longcase Clock with Equation of TIme
Date: Sat, Oct 8, 2016 4:28 AM

As explained by Fred Sawyer in a recent lecture to the British Sundial Society, 
if often worked the other way around... people had an equation table and all 
kinds of rules so that they could adjust their clock so that it matched dial 
time for as long as possible. 

Dial time was (and still is for some) 'true' time. The acceptance of local mean 
time was a slow process. Likewise the acceptance of national mean time met with 
a great deal of resistance. In Dorchester in 1858, in the UK, a judge in a 
court case found in favour of the plaintiff, since the defendant was not 
present at 10:00 o'clock when the case was scheduled. The court was using GMT. 
The defendant arrived at 10:00 local mean time - a few minutes late. He 
appealed and the appeal judge ruled...
"Ten o’clock is 10 o’clock according to the Time of the Place and the Town 
Council cannot say that it is not, 
but that it is 10 o’clock by Greenwich 
time. Nor can the time be altered by a railway company.… Nor by any person who 
regulates the clock on the Town-Hall."

Unless you lived in a (maritime) city, or had an astronomer on hand, or a local 
rich man who went up to the city and owned a chronometer, there was NO way to 
set a clock without a Sundial. It all changed with the the arrival of the 
telegraph   I have found that this is something that watch and clock 
enthusiasts sometimes forget!

Kevin

Sent from my iPad

> On 7 Oct 2016, at 11:07, rodwall1...@gmail.com <rodwall1...@gmail.com> wrote:
> 
> Hi all,
> 
> In 1730. I think I heard somewhere that. Clock manufacturers also sometimes 
> gave a small window sundial to allow you to set your clock. With a equation 
> of time table. Is that correct?
> 
> Roderick Wall..
> 
> 
> - Reply message -
> From: "Robert Terwilliger" <b...@twigsdigs.com>
> To: "'Ian Maddocks'" <ian_maddo...@hotmail.com>, "'Sundial list'" 
> <sundial@uni-koeln.de>
> Subject: Longcase Clock with Equation of TIme
> Date: Fri, Oct 7, 2016 1:00 PM
> 
> If you had a similar clock in 1730 - located where you didn't have access to
> another accurate clock, a sundial would be the only way you could set it -
> and to do so you would need to know the equation for the date. 
> 
>  
> 
> Bob
> 
>  
> 
>   _  
> 
> From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Ian
> Maddocks
> Sent: Wednesday, October 5, 2016 12:29 PM
> To: Sundial list
> Subject: Longcase Clock with Equation of TIme
> 
>  
> 
> hi folks
> 
>  
> 
> I was just blundering around the internet when I came across the following
> that may be of interest..
> 
>  
> 
> A long case clock from 1730 London that has an annual dial for displaying
> the date and the equation of time
> 
> http://www.raffetyclocks.com/antique-clocks/d/antique-month-equation-and-yea
> r-calendar-longcase-clock-by-john-topping-london/170271
> 
> It's a premade disk with EoT table that rotates in a year, not a P type
> kidney cam, but was new clock complication to me
> 
>  
> 
> greetings from 
> 
>  
> 
> Ian Maddocks
> Chester, UK
> 53°11'50"N  2°52'41"W
> frog.happy.froze
> 
>  
> 
>  
> 
>  
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Longcase Clock with Equation of TIme

[rodwall1...@gmail.com]

Hi all,
And thanks to all who commented on clocks that have the equation of time on the 
dial. So many of you had something interesting from court cases, bath clocks, 
watches with equation dials etc. 

I did not know that there were clocks that had equation of time dials. I always 
thought that a equation of time table was use to set the clocks from sundials.

I would love to have a watch or pocket watch or even a clock that has a 
equation of time dial. But not at the $30,000 prices that they are asking.
Is there any reasonably priced modern clocks or watches today that have the 
equation of time dials?

Thanks all for such a interesting subject. So many of you have so much 
interesting knowledge thanks.

Regards,

Roderick Wall.

- Reply message -
From: "Kevin Karney" <kar...@me.com>
To: "rodwall1...@gmail.com" <rodwall1...@gmail.com>
Cc: "Sundial list" <sundial@uni-koeln.de>
Subject: Longcase Clock with Equation of TIme
Date: Sat, Oct 8, 2016 4:28 AM

As explained by Fred Sawyer in a recent lecture to the British Sundial Society, 
if often worked the other way around... people had an equation table and all 
kinds of rules so that they could adjust their clock so that it matched dial 
time for as long as possible. 

Dial time was (and still is for some) 'true' time. The acceptance of local mean 
time was a slow process. Likewise the acceptance of national mean time met with 
a great deal of resistance. In Dorchester in 1858, in the UK, a judge in a 
court case found in favour of the plaintiff, since the defendant was not 
present at 10:00 o'clock when the case was scheduled. The court was using GMT. 
The defendant arrived at 10:00 local mean time - a few minutes late. He 
appealed and the appeal judge ruled...
"Ten o’clock is 10 o’clock according to the Time of the Place and the Town 
Council cannot say that it is not, 
but that it is 10 o’clock by Greenwich 
time. Nor can the time be altered by a railway company.… Nor by any person who 
regulates the clock on the Town-Hall."

Unless you lived in a (maritime) city, or had an astronomer on hand, or a local 
rich man who went up to the city and owned a chronometer, there was NO way to 
set a clock without a Sundial. It all changed with the the arrival of the 
telegraph   I have found that this is something that watch and clock 
enthusiasts sometimes forget!

Kevin

Sent from my iPad

> On 7 Oct 2016, at 11:07, rodwall1...@gmail.com <rodwall1...@gmail.com> wrote:
> 
> Hi all,
> 
> In 1730. I think I heard somewhere that. Clock manufacturers also sometimes 
> gave a small window sundial to allow you to set your clock. With a equation 
> of time table. Is that correct?
> 
> Roderick Wall..
> 
> 
> - Reply message -
> From: "Robert Terwilliger" <b...@twigsdigs.com>
> To: "'Ian Maddocks'" <ian_maddo...@hotmail.com>, "'Sundial list'" 
> <sundial@uni-koeln.de>
> Subject: Longcase Clock with Equation of TIme
> Date: Fri, Oct 7, 2016 1:00 PM
> 
> If you had a similar clock in 1730 - located where you didn't have access to
> another accurate clock, a sundial would be the only way you could set it -
> and to do so you would need to know the equation for the date. 
> 
>  
> 
> Bob
> 
>  
> 
>   _  
> 
> From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Ian
> Maddocks
> Sent: Wednesday, October 5, 2016 12:29 PM
> To: Sundial list
> Subject: Longcase Clock with Equation of TIme
> 
>  
> 
> hi folks
> 
>  
> 
> I was just blundering around the internet when I came across the following
> that may be of interest..
> 
>  
> 
> A long case clock from 1730 London that has an annual dial for displaying
> the date and the equation of time
> 
> http://www.raffetyclocks.com/antique-clocks/d/antique-month-equation-and-yea
> r-calendar-longcase-clock-by-john-topping-london/170271
> 
> It's a premade disk with EoT table that rotates in a year, not a P type
> kidney cam, but was new clock complication to me
> 
>  
> 
> greetings from 
> 
>  
> 
> Ian Maddocks
> Chester, UK
> 53°11'50"N  2°52'41"W
> frog.happy.froze
> 
>  
> 
>  
> 
>  
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Longcase Clock with Equation of TIme

[Kevin Karney]

As explained by Fred Sawyer in a recent lecture to the British Sundial Society, 
if often worked the other way around... people had an equation table and all 
kinds of rules so that they could adjust their clock so that it matched dial 
time for as long as possible. 

Dial time was (and still is for some) 'true' time. The acceptance of local mean 
time was a slow process. Likewise the acceptance of national mean time met with 
a great deal of resistance. In Dorchester in 1858, in the UK, a judge in a 
court case found in favour of the plaintiff, since the defendant was not 
present at 10:00 o'clock when the case was scheduled. The court was using GMT. 
The defendant arrived at 10:00 local mean time - a few minutes late. He 
appealed and the appeal judge ruled...
"Ten o’clock is 10 o’clock according to the Time of the Place and the Town 
Council cannot say that it is not, 
but that it is 10 o’clock by Greenwich 
time. Nor can the time be altered by a railway company.… Nor by any person who 
regulates the clock on the Town-Hall."

Unless you lived in a (maritime) city, or had an astronomer on hand, or a local 
rich man who went up to the city and owned a chronometer, there was NO way to 
set a clock without a Sundial. It all changed with the the arrival of the 
telegraph   I have found that this is something that watch and clock 
enthusiasts sometimes forget!

Kevin

Sent from my iPad

> On 7 Oct 2016, at 11:07, rodwall1...@gmail.com <rodwall1...@gmail.com> wrote:
> 
> Hi all,
> 
> In 1730. I think I heard somewhere that. Clock manufacturers also sometimes 
> gave a small window sundial to allow you to set your clock. With a equation 
> of time table. Is that correct?
> 
> Roderick Wall..
> 
> 
> - Reply message -
> From: "Robert Terwilliger" <b...@twigsdigs.com>
> To: "'Ian Maddocks'" <ian_maddo...@hotmail.com>, "'Sundial list'" 
> <sundial@uni-koeln.de>
> Subject: Longcase Clock with Equation of TIme
> Date: Fri, Oct 7, 2016 1:00 PM
> 
> If you had a similar clock in 1730 - located where you didn't have access to
> another accurate clock, a sundial would be the only way you could set it -
> and to do so you would need to know the equation for the date. 
> 
>  
> 
> Bob
> 
>  
> 
>   _  
> 
> From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Ian
> Maddocks
> Sent: Wednesday, October 5, 2016 12:29 PM
> To: Sundial list
> Subject: Longcase Clock with Equation of TIme
> 
>  
> 
> hi folks
> 
>  
> 
> I was just blundering around the internet when I came across the following
> that may be of interest..
> 
>  
> 
> A long case clock from 1730 London that has an annual dial for displaying
> the date and the equation of time
> 
> http://www.raffetyclocks.com/antique-clocks/d/antique-month-equation-and-yea
> r-calendar-longcase-clock-by-john-topping-london/170271
> 
> It's a premade disk with EoT table that rotates in a year, not a P type
> kidney cam, but was new clock complication to me
> 
>  
> 
> greetings from 
> 
>  
> 
> Ian Maddocks
> Chester, UK
> 53°11'50"N  2°52'41"W
> frog.happy.froze
> 
>  
> 
>  
> 
>  
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

RE: Longcase Clock with Equation of TIme

[Schechner, Sara]

All good clocks were set by sundial or observation of the sun’s transit or 
stars until the mid-19th century and the use of time signals sent along 
telegraph lines.  Some people then set their personal clocks or watches to 
these observatory or town clocks (often set up by jewelers or clock shops—you 
still see these “street clocks”), but many preferred to use their own sundials 
or dipleidoscopes  to set their clocks or watches.  Pocket watches had “watch 
papers” in the case that  gave the equation of time and advertised the 
watchmaker who last cleaned the watch.

Cheers,
Sara

Sara J. Schechner
Altazimuth Arts
42°36'N   71° 22'W
West Newton, MA 02465
http://www.altazimutharts.com/

Sara J. Schechner, Ph.D.
David P. Wheatland Curator of the Collection of Historical Scientific 
Instruments
Lecturer on the History of Science
Department of the History of Science, Harvard University
Science Center 251c, 1 Oxford Street, Cambridge, MA 02138
Tel: 617-496-9542   |   Fax: 617-496-5932   |   
sche...@fas.harvard.edu<mailto:sche...@fas.harvard.edu>  | @SaraSchechner
http://scholar.harvard.edu/saraschechner
http://chsi.harvard.edu/




From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of 
rodwall1...@gmail.com
Sent: Friday, October 07, 2016 6:07 AM
To: 'Sundial list'
Subject: Re: Longcase Clock with Equation of TIme

Hi all,

In 1730. I think I heard somewhere that. Clock manufacturers also sometimes 
gave a small window sundial to allow you to set your clock. With a equation of 
time table. Is that correct?

Roderick Wall..
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Longcase Clock with Equation of TIme

[rodwall1...@gmail.com]

Hi all,
In 1730. I think I heard somewhere that. Clock manufacturers also sometimes 
gave a small window sundial to allow you to set your clock. With a equation of 
time table. Is that correct?

Roderick Wall..

- Reply message -
From: "Robert Terwilliger" <b...@twigsdigs.com>
To: "'Ian Maddocks'" <ian_maddo...@hotmail.com>, "'Sundial list'" 
<sundial@uni-koeln.de>
Subject: Longcase Clock with Equation of TIme
Date: Fri, Oct 7, 2016 1:00 PM

If you had a similar clock in 1730 - located where you didn't have access to
another accurate clock, a sundial would be the only way you could set it -
and to do so you would need to know the equation for the date. 



Bob



_  

From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Ian
Maddocks
Sent: Wednesday, October 5, 2016 12:29 PM
To: Sundial list
Subject: Longcase Clock with Equation of TIme



hi folks



I was just blundering around the internet when I came across the following
that may be of interest..



A long case clock from 1730 London that has an annual dial for displaying
the date and the equation of time

http://www.raffetyclocks.com/antique-clocks/d/antique-month-equation-and-yea
r-calendar-longcase-clock-by-john-topping-london/170271

It's a premade disk with EoT table that rotates in a year, not a P type
kidney cam, but was new clock complication to me



greetings from 



Ian Maddocks
Chester, UK
53°11'50"N  2°52'41"W
frog.happy.froze---
https://lists.uni-koeln.de/mailman/listinfo/sundial

RE: Longcase Clock with Equation of TIme

[Robert Terwilliger]

If you had a similar clock in 1730 - located where you didn't have access to
another accurate clock, a sundial would be the only way you could set it -
and to do so you would need to know the equation for the date. 

 

Bob

 

  _  

From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Ian
Maddocks
Sent: Wednesday, October 5, 2016 12:29 PM
To: Sundial list
Subject: Longcase Clock with Equation of TIme

 

hi folks

 

I was just blundering around the internet when I came across the following
that may be of interest..

 

A long case clock from 1730 London that has an annual dial for displaying
the date and the equation of time

http://www.raffetyclocks.com/antique-clocks/d/antique-month-equation-and-yea
r-calendar-longcase-clock-by-john-topping-london/170271

It's a premade disk with EoT table that rotates in a year, not a P type
kidney cam, but was new clock complication to me

 

greetings from 

 

Ian Maddocks
Chester, UK
53°11'50"N  2°52'41"W
frog.happy.froze

 

 

 

---
https://lists.uni-koeln.de/mailman/listinfo/sundial

RE: Longcase Clock with Equation of TIme

[Schechner, Sara]

Let us not forget the famous long-case clock by Thomas Tompion in 1709 for the 
Pump Room in Bath, England.  It is an “equation clock” showing the difference 
between solar and mean time.   Here is a link to an image of the dial:
https://www.duetimeblog.com/wp-content/uploads/2009/09/img_2007.jpg

Tompion also placed a sundial outside of the Pump Room.   See 
http://bathsbloggers.blogspot.com/2016/03/the-tompion-clock.html for a photo 
along with the clock.

Cheers,
Sara

Sara J. Schechner
Altazimuth Arts
42°36'N   71° 22'W
West Newton, MA 02465
http://www.altazimutharts.com/

Sara J. Schechner, Ph.D.
David P. Wheatland Curator of the Collection of Historical Scientific 
Instruments
Lecturer on the History of Science
Department of the History of Science, Harvard University
Science Center 251c, 1 Oxford Street, Cambridge, MA 02138
Tel: 617-496-9542   |   Fax: 617-496-5932
sche...@fas.harvard.edu |@SaraSchechner
http://scholar.harvard.edu/saraschechner
http://chsi.harvard.edu/



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Longcase Clock with Equation of TIme

[rodwall1...@gmail.com]

Hi Ian,
Thanks for this link. Very interesting I've never see this before.

I wonder if there are any other clocks with the equation of time on the dial.

And in what form is the equation of time shown on the clock dial.

Regards,

Roderick Wall.

- Reply message -
From: "Ian Maddocks" <ian_maddo...@hotmail.com>
To: "Sundial list" <sundial@uni-koeln.de>
Subject: Longcase Clock with Equation of TIme
Date: Thu, Oct 6, 2016 3:28 AM

hi folks


I was just blundering around the internet when I came across the following that 
may be of interest..


A long case clock from 1730 London that has an annual dial for displaying the 
date and the equation of time

http://www.raffetyclocks.com/antique-clocks/d/antique-month-equation-and-year-calendar-longcase-clock-by-john-topping-london/170271
It's a premade disk with EoT table that rotates in a year, not a P type 
kidney cam, but was new clock complication to me

greetings from

Ian Maddocks
Chester, UK
53°11'50"N  2°52'41"W
frog.happy.froze---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Longcase Clock with Equation of TIme

[Ian Maddocks]

hi folks


I was just blundering around the internet when I came across the following that 
may be of interest..


A long case clock from 1730 London that has an annual dial for displaying the 
date and the equation of time

http://www.raffetyclocks.com/antique-clocks/d/antique-month-equation-and-year-calendar-longcase-clock-by-john-topping-london/170271
It's a premade disk with EoT table that rotates in a year, not a P type 
kidney cam, but was new clock complication to me

greetings from

Ian Maddocks
Chester, UK
53°11'50"N  2°52'41"W
frog.happy.froze



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Calculating the Equation of Time ..

[Kevin Karney]

Bob

Many thanks

The amazement produced by the method I used was the accuracy obtained by JUST 
SIX parameters. That came from an old-fashioned single body Keplerian approach 
that just requires the longitude at perihelion + eccentricity to get the Sun’s 
longitude. Add to that the obliquity to to give RA  Declination. Add to that 
RA at Epoch + length of tropical year + one precessional constant to find the 
connection between UT and GMST.

In truth, if you look at the code in detail - you will see that I had to 
incorporate three simple linear expressions to account for the time variation 
of obliquity, eccentricity and perihelion to get my target accuracy over a 50 
year period (the limit imposed by my use of MICA as ‘accuracy referee’). So 
sensu stricto, you are probably right that I have used more parameters.

Best wishes
Kevin


On 24 Feb 2014, at 02:03, Robert Kellogg rkell...@comcast.net wrote:

 Kevin,
 
 Welcome the the wonderful world of celestial mechanics ... you need to have 
 only six orbital parameters plus time epoch plus earth inclination and 
 sidereal spin, so total of 8 parameters are required 
 
 Bob
 
 On 2/23/2014 6:49 PM, sundial-requ...@uni-koeln.de wrote:
 Send sundial mailing list submissions to
  sundial@uni-koeln.de
 
 To subscribe or unsubscribe via the World Wide Web, visit
  https://lists.uni-koeln.de/mailman/listinfo/sundial
 or, via email, send a message with subject or body 'help' to
  sundial-requ...@uni-koeln.de
 
 You can reach the person managing the list at
  sundial-ow...@uni-koeln.de
 
 When replying, please edit your Subject line so it is more specific
 than Re: Contents of sundial digest...
 
 
 Today's Topics:
 
1. Calculating the Equation of Time and other Solar Parameters
   (Kevin Karney)
2. CORRECTION Calculating the Equation of Time and other Solar
   Parameters (Kevin Karney)
3. Re: Calculating the Equation of Time and other Solar
   Parameters (Bill Gottesman)
4. online manuscript by Mayall and Mayall (Schechner, Sara)
5. Re: Calculating the Equation of Time and other Solar
   Parameters (Roger Bailey)
 
 
 --
 
 Message: 1
 Date: Sun, 23 Feb 2014 19:32:37 +
 From: Kevin Karney kar...@me.com
 To: sundial@uni-koeln.de List sundial@uni-koeln.de
 Subject: Calculating the Equation of Time and other Solar Parameters
 Message-ID: d9c80f35-d4a1-4414-bac3-d1074c51c...@me.com
 Content-Type: text/plain; charset=windows-1252
 
 Dear Friends
 
 I have spend many happy hours during this wet, wet winter investigating and 
 learning how to calculate all the solar parameters that a gnomonist might 
 possibly need  - Equation of Time, Declination, RA, Altitude, Azimuth, Time 
 of Sunset/Rise, etc, etc.
 
 I have been surprised to find that - with traditional calculation methods 
 and an absolute minimum of astronomical information -  it is possible to 
 calculate everything from first principles to a surprising degree of 
 accuracy.
 
 Other than location and local time, only six pieces of astronomical 
 information are required - obliquity, eccentricity, Sun?s GHA at 1/1/2000, 
 longitude of perihelion, a single precessional constant and the length of 
 the tropical year. Accuracies for the EOT are +/- 2 seconds of time For 
 altitudes/azimuths, less than 1 minute of arc - much better than needed by 
 most gnomonic problems.
 
 If any of you are interested in such calculations, I have loaded a document 
 with all the astronomical theory and background plus the code onto my website
 www.precisedirections.co.uk/sundials
 The code is written in Python, a language available on every type of 
 computer, which is very easily understood, quite easily learnt and very 
 easily translated into any other coding language you might like.
 
 If you own an iPad or iPhone, and are prepared to buy a cheap little app 
 called Pythonista, the code will extract locational  time information from 
 your phone - so you do not even have to input this to get your calculations 
 done
 
 You might also like to see a graphic of a civil mean time horizontal dial, 
 which I think is called a hectomoros dial,  that is destined for my garden. 
 This is also on the website.
 
 Enjoy
 Kevin
 -- next part --
 An HTML attachment was scrubbed...
 URL: 
 https://lists.uni-koeln.de/mailman/private/sundial/attachments/20140223/b50a01bb/attachment-0001.html
 
 --
 
 Message: 2
 Date: Sun, 23 Feb 2014 20:06:51 +
 From: Kevin Karney kar...@me.com
 To: sundial@uni-koeln.de List sundial@uni-koeln.de
 Subject: CORRECTION Calculating the Equation of Time and other Solar
  Parameters
 Message-ID: dc4a7b4d-7d8f-4a83-97b9-c2ed7732c...@me.com
 Content-Type: text/plain; charset=windows-1252
 
 My website is ?
 http://www.precisedirections.co.uk/Sundials
 with a capital S for Sundial
 
 Sorry
 K
 -- next part

Calculating the Equation of Time and other Solar Parameters

[Kevin Karney]

Dear Friends

I have spend many happy hours during this wet, wet winter investigating and 
learning how to calculate all the solar parameters that a gnomonist might 
possibly need  - Equation of Time, Declination, RA, Altitude, Azimuth, Time of 
Sunset/Rise, etc, etc.

I have been surprised to find that - with traditional calculation methods and 
an absolute minimum of astronomical information -  it is possible to calculate 
everything from first principles to a surprising degree of accuracy. 

Other than location and local time, only six pieces of astronomical information 
are required - obliquity, eccentricity, Sun’s GHA at 1/1/2000, longitude of 
perihelion, a single precessional constant and the length of the tropical year. 
Accuracies for the EOT are +/- 2 seconds of time For altitudes/azimuths, less 
than 1 minute of arc - much better than needed by most gnomonic problems.

If any of you are interested in such calculations, I have loaded a document 
with all the astronomical theory and background plus the code onto my website
www.precisedirections.co.uk/sundials
The code is written in Python, a language available on every type of computer, 
which is very easily understood, quite easily learnt and very easily translated 
into any other coding language you might like.

If you own an iPad or iPhone, and are prepared to buy a cheap little app called 
Pythonista, the code will extract locational  time information from your phone 
- so you do not even have to input this to get your calculations done

You might also like to see a graphic of a civil mean time horizontal dial, 
which I think is called a hectomoros dial,  that is destined for my garden. 
This is also on the website.

Enjoy
Kevin---
https://lists.uni-koeln.de/mailman/listinfo/sundial

CORRECTION Calculating the Equation of Time and other Solar Parameters

[Kevin Karney]

My website is …
http://www.precisedirections.co.uk/Sundials
with a capital S for Sundial

Sorry
K---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Calculating the Equation of Time and other Solar Parameters

[Bill Gottesman]

Kevin,

I am excited about your article Basic Astronomy for the Gnomonist.  It
will take some time to digest, but it seems to have a very nice graphic
analysis for the many formulas and solar positioning we deal with.  I
appreciate you making this reference available.

I think what you call a Hectoromos dial is what I have heard described as a
Singleton dial.  Here is a link to a similar (vertical) dial at the
University of Vermont.  Fred Sawyer wrote about the Hectoromos dial in an
early NASS compendium.  I think Plato might have had something to do with
it.

-Bill


On Sun, Feb 23, 2014 at 2:32 PM, Kevin Karney kar...@me.com wrote:

 Dear Friends

 I have spend many happy hours during this wet, wet winter investigating
 and learning how to calculate all the solar parameters that a
 gnomonist might possibly need  - Equation of Time, Declination, RA,
 Altitude, Azimuth, Time of Sunset/Rise, etc, etc.

 I have been surprised to find that - with traditional calculation methods
 and an absolute minimum of astronomical information -  it is possible to
 calculate everything from first principles to a surprising degree of
 accuracy.

 Other than location and local time, only six pieces of astronomical
 information are required - obliquity, eccentricity, Sun's GHA at 1/1/2000,
 longitude of perihelion, a single precessional constant and the length of
 the tropical year. Accuracies for the EOT are +/- 2 seconds of time For
 altitudes/azimuths, less than 1 minute of arc - much better than needed by
 most gnomonic problems.

 If any of you are interested in such calculations, I have loaded a
 document with all the astronomical theory and background plus the code onto
 my website
 *www.precisedirections.co.uk/sundials
 http://www.precisedirections.co.uk/sundials*
 The code is written in Python, a language available on every type of
 computer, which is very easily understood, quite easily learnt and very
 easily translated into any other coding language you might like.

 If you own an iPad or iPhone, and are prepared to buy a cheap little app
 called Pythonista, the code will extract locational  time information from
 your phone - so you do not even have to input this to get your calculations
 done

 You might also like to see a graphic of a civil mean time horizontal dial,
 which *I think* is called a hectomoros dial,  that is destined for my
 garden. This is also on the website.

 Enjoy
 Kevin

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Calculating the Equation of Time and other Solar Parameters

[Roger Bailey]

Thanks Kevin,

A quick review demonstrated how useful your work can be for folk like us. Here 
is a specific example. I have been working with solar and lunar ephemerides 
date from the JPL Horizons website. http://ssd.jpl.nasa.gov/horizons.cgi#top 
This site provides a wealth of data that the user can customize for their own 
purposes. The problem is the user does not know how the data was calculated nor 
how it is to be used  The Explanatory Supplement helps but it is difficult to 
understand.  One simple example is understanding a solar data compilation that 
provided among other things Right Ascension and Declination. But I really 
wanted the EQT. Your formula 9 in Part 1 gave me the simple relationship, 
obvious in hindsight that I was looking for, the conversion of RA to EQT.

I look forward making good use of your work. Thank you for making it available.

Thanks again,
Roger Bailey
Walking Shadow Designs




From: Kevin Karney
Sent: Sunday, February 23, 2014 11:32 AM
To: sundial@uni-koeln.de List
Subject: Calculating the Equation of Time and other Solar Parameters


Dear Friends


I have spend many happy hours during this wet, wet winter investigating and 
learning how to calculate all the solar parameters that a gnomonist might 
possibly need  - Equation of Time, Declination, RA, Altitude, Azimuth, Time of 
Sunset/Rise, etc, etc.


I have been surprised to find that - with traditional calculation methods and 
an absolute minimum of astronomical information -  it is possible to calculate 
everything from first principles to a surprising degree of accuracy.


Other than location and local time, only six pieces of astronomical information 
are required - obliquity, eccentricity, Sun’s GHA at 1/1/2000, longitude of 
perihelion, a single precessional constant and the length of the tropical year. 
Accuracies for the EOT are +/- 2 seconds of time For altitudes/azimuths, less 
than 1 minute of arc - much better than needed by most gnomonic problems.


If any of you are interested in such calculations, I have loaded a document 
with all the astronomical theory and background plus the code onto my website
www.precisedirections.co.uk/sundials
The code is written in Python, a language available on every type of computer, 
which is very easily understood, quite easily learnt and very easily translated 
into any other coding language you might like.


If you own an iPad or iPhone, and are prepared to buy a cheap little app called 
Pythonista, the code will extract locational  time information from your phone 
- so you do not even have to input this to get your calculations done


You might also like to see a graphic of a civil mean time horizontal dial, 
which I think is called a hectomoros dial,  that is destined for my garden. 
This is also on the website.


Enjoy
Kevin





---
https://lists.uni-koeln.de/mailman/listinfo/sundial







No virus found in this message.
Checked by AVG - www.avg.com
Version: 2014.0.4335 / Virus Database: 3705/7118 - Release Date: 02/23/14



-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2014.0.4335 / Virus Database: 3705/7118 - Release Date: 02/23/14
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Calculating the Equation of Time ..

[Robert Kellogg]

Kevin,

Welcome the the wonderful world of celestial mechanics ... you need to 
have only six orbital parameters plus time epoch plus earth inclination 
and sidereal spin, so total of 8 parameters are required 


Bob

On 2/23/2014 6:49 PM, sundial-requ...@uni-koeln.de wrote:

Send sundial mailing list submissions to
sundial@uni-koeln.de

To subscribe or unsubscribe via the World Wide Web, visit
https://lists.uni-koeln.de/mailman/listinfo/sundial
or, via email, send a message with subject or body 'help' to
sundial-requ...@uni-koeln.de

You can reach the person managing the list at
sundial-ow...@uni-koeln.de

When replying, please edit your Subject line so it is more specific
than Re: Contents of sundial digest...


Today's Topics:

1. Calculating the Equation of Time and other Solar Parameters
   (Kevin Karney)
2. CORRECTION Calculating the Equation of Time and other Solar
   Parameters (Kevin Karney)
3. Re: Calculating the Equation of Time and other Solar
   Parameters (Bill Gottesman)
4. online manuscript by Mayall and Mayall (Schechner, Sara)
5. Re: Calculating the Equation of Time and other Solar
   Parameters (Roger Bailey)


--

Message: 1
Date: Sun, 23 Feb 2014 19:32:37 +
From: Kevin Karney kar...@me.com
To: sundial@uni-koeln.de List sundial@uni-koeln.de
Subject: Calculating the Equation of Time and other Solar Parameters
Message-ID: d9c80f35-d4a1-4414-bac3-d1074c51c...@me.com
Content-Type: text/plain; charset=windows-1252

Dear Friends

I have spend many happy hours during this wet, wet winter investigating and 
learning how to calculate all the solar parameters that a gnomonist might 
possibly need  - Equation of Time, Declination, RA, Altitude, Azimuth, Time of 
Sunset/Rise, etc, etc.

I have been surprised to find that - with traditional calculation methods and 
an absolute minimum of astronomical information -  it is possible to calculate 
everything from first principles to a surprising degree of accuracy.

Other than location and local time, only six pieces of astronomical information 
are required - obliquity, eccentricity, Sun?s GHA at 1/1/2000, longitude of 
perihelion, a single precessional constant and the length of the tropical year. 
Accuracies for the EOT are +/- 2 seconds of time For altitudes/azimuths, less 
than 1 minute of arc - much better than needed by most gnomonic problems.

If any of you are interested in such calculations, I have loaded a document 
with all the astronomical theory and background plus the code onto my website
www.precisedirections.co.uk/sundials
The code is written in Python, a language available on every type of computer, 
which is very easily understood, quite easily learnt and very easily translated 
into any other coding language you might like.

If you own an iPad or iPhone, and are prepared to buy a cheap little app called 
Pythonista, the code will extract locational  time information from your phone 
- so you do not even have to input this to get your calculations done

You might also like to see a graphic of a civil mean time horizontal dial, 
which I think is called a hectomoros dial,  that is destined for my garden. 
This is also on the website.

Enjoy
Kevin
-- next part --
An HTML attachment was scrubbed...
URL: 
https://lists.uni-koeln.de/mailman/private/sundial/attachments/20140223/b50a01bb/attachment-0001.html

--

Message: 2
Date: Sun, 23 Feb 2014 20:06:51 +
From: Kevin Karney kar...@me.com
To: sundial@uni-koeln.de List sundial@uni-koeln.de
Subject: CORRECTION Calculating the Equation of Time and other Solar
Parameters
Message-ID: dc4a7b4d-7d8f-4a83-97b9-c2ed7732c...@me.com
Content-Type: text/plain; charset=windows-1252

My website is ?
http://www.precisedirections.co.uk/Sundials
with a capital S for Sundial

Sorry
K
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--

Message: 3
Date: Sun, 23 Feb 2014 15:52:57 -0500
From: Bill Gottesman billgottes...@comcast.net
To: Kevin Karney kar...@me.com
Cc: sundial@uni-koeln.de List sundial@uni-koeln.de
Subject: Re: Calculating the Equation of Time and other Solar
Parameters
Message-ID:
CAMDsn==32iapzw47q7zo4-wwyxbcttzcjcjax+y8vvtv_fd...@mail.gmail.com
Content-Type: text/plain; charset=iso-8859-1

Kevin,

I am excited about your article Basic Astronomy for the Gnomonist.  It
will take some time to digest, but it seems to have a very nice graphic
analysis for the many formulas and solar positioning we deal with.  I
appreciate you making this reference available.

I think what you call a Hectoromos dial is what I have heard described as a
Singleton dial.  Here is a link to a similar (vertical) dial at the
University

Re: equation of time sundial

[jmikeshaw]

Ken,

You wrote:
I take it the motor is to keep the hole pointed toward the sun.
It’s to keep the cylinder pointed in the direction that the sun would be if it 
kept standard time.
I should have added that this device includes the longitude correction as well.

I'm unclear though on what's drawn inside. Is it a single curve of EOT as a 
function of declination, or a family of curves?
It’s a very simple straight line grid with the vertical lines showing minutes 
from standard time and the horizontal lines showing the sun’s declination from 
the equinox position.

I hope that’s clearer.

I’ll see if I can find any photos and contact you off list.

Mike Shaw
53º 22' North 03º 02' West
www.wiz.to/sundials






-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2013.0.2897 / Virus Database: 2639/6078 - Release Date: 02/03/13
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Re: equation of time sundial-heliochronometre 2

[Peter Mayer]

Hi,

You can also see a magnificent heliochronometre made by John Carmichael 
at:
http://www.flickr.com/photos/jlcarmichael/3576166915/in/set-72157618973847752/

best wishes,

Peter

On 4/02/2013 3:13 PM, Ken Baldwin wrote:

Thanks, everyone.

I see now how an analemmic gnomon can be used to read the EOT, if the
equatorial band shows both mean and apparent time and you do the
subtraction in your head. I'm most interested, though, in something
which allows a direct reading of EOT...

Mike, your solution sounds very interesting, but I confess I don't
really understand it :-) I take it the motor is to keep the hole pointed
toward the sun. Presumably this could be done manually, as on a
shepard's dial? I'm unclear though on what's drawn inside. Is it a
single curve of EOT as a function of declination, or a family of curves?

Ken



On Sun, Feb 3, 2013 at 12:02 PM, Ken Baldwin kenneth.bald...@gmail.com
mailto:kenneth.bald...@gmail.com wrote:

Hello,

I'm a new list member, and have a beginner question:

Are there examples of sundials whose sole (or primary) purpose is to
compute the Equation of Time for the current date?

- I know that this information is often provided as a graph in the
furniture, but why should I have to know the date and perform the
look-up manually? Can't I use the position of the sun to do the
computation for me?

- I know that the EOT correction can be incorporated into the layout
of (some) hour lines, but I'm more interested in having dials which
show true solar time. I'd like a separate device dedicated to
computing the EOT.

- I know that I can construct an analemmic noon mark to show the EOT
for that day, since it's simply the east-west component of the
analemma, but I'd like a design that can be read at any daylight hour.

It seems to me that it should be possible to build such a dial,
since the EOT is a function of date, and date lines can be read from
many sundials. In principle, I can just re-label the date lines with
corresponding EOT values and interpolate.

I hope that makes sense. But since I haven't seen anything like that
in introductory sundial books, I must be missing something... Is it
that the shadow length can't be read accurately enough to get a
reasonably precise EOT estimate? Or is it just too hard to make a
readable layout, given that solar altitude is ambiguous between two
dates, and that the component of the EOT due to the eccentricity of
the earth's orbit is out of phase with the equinoxes and solstices?

Thanks in advance,
Ken Baldwin
Corvallis, OR USA




---
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--
--
Peter Mayer
Politics Department
The University of Adelaide, AUSTRALIA 5005
Ph : +61 8 8313 5609
Fax : +61 8 8313 3443
e-mail: peter.ma...@adelaide.edu.au
CRICOS Provider Number 00123M
---

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attachment: tn_Mayall-Heliochronometre1.3.jpg---
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Re: equation of time sundial

[jmikeshaw]

Ken,

I’ve found a couple of small photos of my rather crude device.
I’ve posted then in Dropbox at :
https://www.dropbox.com/sh/tkxqw7x5mbr1axd/tYOlNAwT60

By coincidence, the 2nd photo shows the EoT is –7.5 minutes and sun’s 
declination is –7.5 degrees.

I hope that makes things clearer.

Of course, it’s just really a reverse engineered heliochronometer where you 
drive the alidade round using a 24 hour clock mechanism (widely available), to 
keep the spot of light on the analemma.
However, I’ve used a graph of EoT and declination instead so that you can read 
off the two figures directly.
Over the course of a year, the spot of light will trace out the analemma.


Mike Shaw
53º 22' North 03º 02' West
www.wiz.to/sundials





-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2013.0.2897 / Virus Database: 2639/6078 - Release Date: 02/03/13
---
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Re: equation of time sundial

[fer de vries]

Ken,

Your original mail has the sentence:

*
It seems to me (Ken) that it should be possible to build such a dial, since the 
EOT is a function of date, and date lines can be read from many sundials. In 
principle, I can just re-label the date lines with corresponding EOT values and 
interpolate.
*

I agree with this and a sample of a dial that's suitable is in Copenhagen, 
Denmark.

See the website of De Zonnewijzerkring. Address below.
Follow:
Archives 2003 - 2013
Sundial of the month 2006
06-09 Copenhagen.

Lable te datelines for a half year left and the other half year right with the 
appropriate equation of time rounded to e.g. one minute.

The dial in Copenhagen has three scales so it can be used for many hours of the 
day.

Best wishes, Fer.


Fer J. de Vries

De Zonnewijzerkring
http://www.de-zonnewijzerkring.nl

Molens
http://www.collsemolen.dse.nl

Eindhoven, Netherlands
lat.  51:30 N  long.  5:30 E

  - Original Message - 
  From: jmikes...@ntlworld.com 
  To: Ken Baldwin ; sundial@uni-koeln.de 
  Sent: Monday, February 04, 2013 9:59 AM
  Subject: Re: equation of time sundial


  Ken,

  I’ve found a couple of small photos of my rather crude device.
  I’ve posted then in Dropbox at : 
  https://www.dropbox.com/sh/tkxqw7x5mbr1axd/tYOlNAwT60

  By coincidence, the 2nd photo shows the EoT is –7.5 minutes and sun’s 
declination is –7.5 degrees.

  I hope that makes things clearer.

  Of course, it’s just really a reverse engineered heliochronometer where you 
drive the alidade round using a 24 hour clock mechanism (widely available), to 
keep the spot of light on the analemma.
  However, I’ve used a graph of EoT and declination instead so that you can 
read off the two figures directly.
  Over the course of a year, the spot of light will trace out the analemma.


  Mike Shaw
  53º 22' North 03º 02' West
  www.wiz.to/sundials



  No virus found in this message.
  Checked by AVG - www.avg.com
  Version: 2013.0.2897 / Virus Database: 2639/6078 - Release Date: 02/03/13



--


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Re: equation of time sundial

[Simon [illustratingshadows]

A good question, however except for the solstices, there is ambiguity. Each 
declination has two dates. For example March and September equinoxes are 6 
months apart, but same declination. 
 
Simon

Simon Wheaton-Smith
www.illustratingshadows.com
Phoenix, Arizona, W112.1 N33.5

--- On Sun, 2/3/13, Ken Baldwin kenneth.bald...@gmail.com wrote:


From: Ken Baldwin kenneth.bald...@gmail.com
Subject: equation of time sundial
To: sundial@uni-koeln.de
Date: Sunday, February 3, 2013, 1:02 PM




Hello, 


I'm a new list member, and have a beginner question:


Are there examples of sundials whose sole (or primary) purpose is to compute 
the Equation of Time for the current date?


- I know that this information is often provided as a graph in the furniture, 
but why should I have to know the date and perform the look-up manually? Can't 
I use the position of the sun to do the computation for me?


- I know that the EOT correction can be incorporated into the layout of (some) 
hour lines, but I'm more interested in having dials which show true solar time. 
I'd like a separate device dedicated to computing the EOT.


- I know that I can construct an analemmic noon mark to show the EOT for that 
day, since it's simply the east-west component of the analemma, but I'd like a 
design that can be read at any daylight hour.


It seems to me that it should be possible to build such a dial, since the EOT 
is a function of date, and date lines can be read from many sundials. In 
principle, I can just re-label the date lines with corresponding EOT values and 
interpolate.


I hope that makes sense. But since I haven't seen anything like that in 
introductory sundial books, I must be missing something... Is it that the 
shadow length can't be read accurately enough to get a reasonably precise EOT 
estimate? Or is it just too hard to make a readable layout, given that solar 
altitude is ambiguous between two dates, and that the component of the EOT due 
to the eccentricity of the earth's orbit is out of phase with the equinoxes and 
solstices?


Thanks in advance,
Ken Baldwin

Corvallis, OR USA


-Inline Attachment Follows-


---
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---
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Re: equation of time sundial

[Peter Mayer]

Hi Ken,

	One of the most beautiful (IMHO) is the Schmoyer dial which 
incorporates the EOT in the gnomon.  You can see a picture of the dial at:

http://www.precisionsundials.com/schmoyer.htm

best wishes,

Peter

On 4/02/2013 6:32 AM, Ken Baldwin wrote:

Hello,

I'm a new list member, and have a beginner question:

Are there examples of sundials whose sole (or primary) purpose is to
compute the Equation of Time for the current date?

- I know that this information is often provided as a graph in the
furniture, but why should I have to know the date and perform the
look-up manually? Can't I use the position of the sun to do the
computation for me?

- I know that the EOT correction can be incorporated into the layout of
(some) hour lines, but I'm more interested in having dials which show
true solar time. I'd like a separate device dedicated to computing the EOT.

- I know that I can construct an analemmic noon mark to show the EOT for
that day, since it's simply the east-west component of the analemma, but
I'd like a design that can be read at any daylight hour.

It seems to me that it should be possible to build such a dial, since
the EOT is a function of date, and date lines can be read from many
sundials. In principle, I can just re-label the date lines with
corresponding EOT values and interpolate.

I hope that makes sense. But since I haven't seen anything like that in
introductory sundial books, I must be missing something... Is it that
the shadow length can't be read accurately enough to get a reasonably
precise EOT estimate? Or is it just too hard to make a readable layout,
given that solar altitude is ambiguous between two dates, and that the
component of the EOT due to the eccentricity of the earth's orbit is out
of phase with the equinoxes and solstices?

Thanks in advance,
Ken Baldwin
Corvallis, OR USA



---
https://lists.uni-koeln.de/mailman/listinfo/sundial



--
--
Peter Mayer
Politics Department
The University of Adelaide, AUSTRALIA 5005
Ph : +61 8 8313 5609
Fax : +61 8 8313 3443
e-mail: peter.ma...@adelaide.edu.au
CRICOS Provider Number 00123M
---

This email message is intended only for the addressee(s) and contains 
information that may be confidential and/or copyright. If you are not 
the intended recipient please notify the sender by reply email and 
immediately delete this email. Use, disclosure or reproduction of this 
email by anyone other than the intended recipient(s) is strictly 
prohibited. No representation is made that this email or any attachments 
are free of viruses. Virus scanning is recommended and is the 
responsibility of the recipient.

---
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Re: equation of time sundial

[Peter Mayer]

Hi Ken,

	Here's another example of a dial which may interest you.  This is my 
adaptation of a brilliant dial coded by Steve Lelievre.  To fit the size 
limit on this list, I've had to squeeze the image greatly, but you 
should be able to grasp the principle of the dial: each month is a 
separate concentric circle.  Between month lines one must interpolate 
the date to read the civil time.


best wishes,

Peter

On 4/02/2013 6:32 AM, Ken Baldwin wrote:

Hello,

I'm a new list member, and have a beginner question:

Are there examples of sundials whose sole (or primary) purpose is to
compute the Equation of Time for the current date?

- I know that this information is often provided as a graph in the
furniture, but why should I have to know the date and perform the
look-up manually? Can't I use the position of the sun to do the
computation for me?

- I know that the EOT correction can be incorporated into the layout of
(some) hour lines, but I'm more interested in having dials which show
true solar time. I'd like a separate device dedicated to computing the EOT.

- I know that I can construct an analemmic noon mark to show the EOT for
that day, since it's simply the east-west component of the analemma, but
I'd like a design that can be read at any daylight hour.

It seems to me that it should be possible to build such a dial, since
the EOT is a function of date, and date lines can be read from many
sundials. In principle, I can just re-label the date lines with
corresponding EOT values and interpolate.

I hope that makes sense. But since I haven't seen anything like that in
introductory sundial books, I must be missing something... Is it that
the shadow length can't be read accurately enough to get a reasonably
precise EOT estimate? Or is it just too hard to make a readable layout,
given that solar altitude is ambiguous between two dates, and that the
component of the EOT due to the eccentricity of the earth's orbit is out
of phase with the equinoxes and solstices?

Thanks in advance,
Ken Baldwin
Corvallis, OR USA



---
https://lists.uni-koeln.de/mailman/listinfo/sundial



--
--
Peter Mayer
Politics Department
The University of Adelaide, AUSTRALIA 5005
Ph : +61 8 8313 5609
Fax : +61 8 8313 3443
e-mail: peter.ma...@adelaide.edu.au
CRICOS Provider Number 00123M
---

This email message is intended only for the addressee(s) and contains 
information that may be confidential and/or copyright. If you are not 
the intended recipient please notify the sender by reply email and 
immediately delete this email. Use, disclosure or reproduction of this 
email by anyone other than the intended recipient(s) is strictly 
prohibited. No representation is made that this email or any attachments 
are free of viruses. Virus scanning is recommended and is the 
responsibility of the recipient.
attachment: tn_Lelievre Dial.jpg---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: equation of time sundial

[Ken Baldwin]

Hi guys,

Thanks for your responses.

I'm not trying to read the EOT-adjusted time from the device, I want to
read the actual EOT value itself for that date. For example, on Aug 9th, at
any daylight hour, I'd like to be able to read, say, -5.5 min. Maybe I'm
misunderstanding, but do I get that from these analemmic gnomons or hour
lines?

I'm suggesting something like Peter's design, but with the hour lines
removed, and the date lines labelled with the EOT value (-15 min - 15 min).

I understand Simon's point that the altitude of the sun is ambiguous
between two dates, so perhaps it would have to be split into two plates
(like half-analemmas). Of course, this requires the user to know which 6
month period of the year they are in, which partially defeats the purpose
of not needing to know the date :-)

Ken


On Sun, Feb 3, 2013 at 2:14 PM, Peter Mayer peter.ma...@adelaide.edu.auwrote:

 Hi Ken,

 Here's another example of a dial which may interest you.  This is
 my adaptation of a brilliant dial coded by Steve Lelievre.  To fit the size
 limit on this list, I've had to squeeze the image greatly, but you should
 be able to grasp the principle of the dial: each month is a separate
 concentric circle.  Between month lines one must interpolate the date to
 read the civil time.


 best wishes,

 Peter

 On 4/02/2013 6:32 AM, Ken Baldwin wrote:

 Hello,

 I'm a new list member, and have a beginner question:

 Are there examples of sundials whose sole (or primary) purpose is to
 compute the Equation of Time for the current date?

 - I know that this information is often provided as a graph in the
 furniture, but why should I have to know the date and perform the
 look-up manually? Can't I use the position of the sun to do the
 computation for me?

 - I know that the EOT correction can be incorporated into the layout of
 (some) hour lines, but I'm more interested in having dials which show
 true solar time. I'd like a separate device dedicated to computing the
 EOT.

 - I know that I can construct an analemmic noon mark to show the EOT for
 that day, since it's simply the east-west component of the analemma, but
 I'd like a design that can be read at any daylight hour.

 It seems to me that it should be possible to build such a dial, since
 the EOT is a function of date, and date lines can be read from many
 sundials. In principle, I can just re-label the date lines with
 corresponding EOT values and interpolate.

 I hope that makes sense. But since I haven't seen anything like that in
 introductory sundial books, I must be missing something... Is it that
 the shadow length can't be read accurately enough to get a reasonably
 precise EOT estimate? Or is it just too hard to make a readable layout,
 given that solar altitude is ambiguous between two dates, and that the
 component of the EOT due to the eccentricity of the earth's orbit is out
 of phase with the equinoxes and solstices?

 Thanks in advance,
 Ken Baldwin
 Corvallis, OR USA



 --**-
 https://lists.uni-koeln.de/**mailman/listinfo/sundialhttps://lists.uni-koeln.de/mailman/listinfo/sundial


 --
 --
 Peter Mayer
 Politics Department
 The University of Adelaide, AUSTRALIA 5005
 Ph : +61 8 8313 5609
 Fax : +61 8 8313 3443
 e-mail: peter.ma...@adelaide.edu.au
 CRICOS Provider Number 00123M
 --**-

 This email message is intended only for the addressee(s) and contains
 information that may be confidential and/or copyright. If you are not the
 intended recipient please notify the sender by reply email and immediately
 delete this email. Use, disclosure or reproduction of this email by anyone
 other than the intended recipient(s) is strictly prohibited. No
 representation is made that this email or any attachments are free of
 viruses. Virus scanning is recommended and is the responsibility of the
 recipient.

---
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Re: equation of time sundial

[jmikeshaw]

Ken,

I think I made a device some time ago to do what you want .

A cylinder was tilted to the appropriate latitude angle and direction.
There was a small hole on one side of the cylinder which gave a projected a 
spot of light from the sun on the inner opposite surface where there was a 
graph which showed:
left to right – the equation of time
up and down – the sun’s declination.

The cylinder was driven round using a 24 hour clock motor, so the spot of light 
remained apparently stationary except for changes in the EoT and sun’s 
declination that were read directly from the graph.

Sadly, I don’t think I have it any more.

Mike Shaw
53º 22' North 03º 02' West
www.wiz.to/sundials



-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2013.0.2897 / Virus Database: 2639/6076 - Release Date: 02/02/13
---
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Re: equation of time sundial

[Roger Bailey]

Hello Ken,

The examples using an analemma shaped gnomon that project the shadow the 
equatorial line do what you want. An improvement could be a wire stretched 
along the centerline of the gnomon in Willy's Spanish example. This would 
provide solar time. The two values of the EQT at that declination would be the 
shadow line of the aperture. Thus the two possible values of EQT could be read 
directly without knowing the the date. 

Regards, 
Roger Bailey
Walking Shadow designs. 

  


From: Ken Baldwin 
Sent: Sunday, February 03, 2013 2:19 PM
To: peter.ma...@adelaide.edu.au 
Cc: sundial 
Subject: Re: equation of time sundial


Hi guys, 


Thanks for your responses.


I'm not trying to read the EOT-adjusted time from the device, I want to read 
the actual EOT value itself for that date. For example, on Aug 9th, at any 
daylight hour, I'd like to be able to read, say, -5.5 min. Maybe I'm 
misunderstanding, but do I get that from these analemmic gnomons or hour lines? 


I'm suggesting something like Peter's design, but with the hour lines removed, 
and the date lines labelled with the EOT value (-15 min - 15 min).


I understand Simon's point that the altitude of the sun is ambiguous between 
two dates, so perhaps it would have to be split into two plates (like 
half-analemmas). Of course, this requires the user to know which 6 month period 
of the year they are in, which partially defeats the purpose of not needing to 
know the date :-)


Ken



On Sun, Feb 3, 2013 at 2:14 PM, Peter Mayer peter.ma...@adelaide.edu.au wrote:

  Hi Ken,

  Here's another example of a dial which may interest you.  This is my 
adaptation of a brilliant dial coded by Steve Lelievre.  To fit the size limit 
on this list, I've had to squeeze the image greatly, but you should be able to 
grasp the principle of the dial: each month is a separate concentric circle.  
Between month lines one must interpolate the date to read the civil time. 


  best wishes,

  Peter

  On 4/02/2013 6:32 AM, Ken Baldwin wrote:

Hello,

I'm a new list member, and have a beginner question:

Are there examples of sundials whose sole (or primary) purpose is to
compute the Equation of Time for the current date?

- I know that this information is often provided as a graph in the
furniture, but why should I have to know the date and perform the
look-up manually? Can't I use the position of the sun to do the
computation for me?

- I know that the EOT correction can be incorporated into the layout of
(some) hour lines, but I'm more interested in having dials which show
true solar time. I'd like a separate device dedicated to computing the EOT.

- I know that I can construct an analemmic noon mark to show the EOT for
that day, since it's simply the east-west component of the analemma, but
I'd like a design that can be read at any daylight hour.

It seems to me that it should be possible to build such a dial, since
the EOT is a function of date, and date lines can be read from many
sundials. In principle, I can just re-label the date lines with
corresponding EOT values and interpolate.

I hope that makes sense. But since I haven't seen anything like that in
introductory sundial books, I must be missing something... Is it that
the shadow length can't be read accurately enough to get a reasonably
precise EOT estimate? Or is it just too hard to make a readable layout,
given that solar altitude is ambiguous between two dates, and that the
component of the EOT due to the eccentricity of the earth's orbit is out
of phase with the equinoxes and solstices?

Thanks in advance,
Ken Baldwin
Corvallis, OR USA




---
https://lists.uni-koeln.de/mailman/listinfo/sundial



  -- 
  --
  Peter Mayer
  Politics Department
  The University of Adelaide, AUSTRALIA 5005
  Ph : +61 8 8313 5609
  Fax : +61 8 8313 3443
  e-mail: peter.ma...@adelaide.edu.au
  CRICOS Provider Number 00123M
  ---

  This email message is intended only for the addressee(s) and contains 
information that may be confidential and/or copyright. If you are not the 
intended recipient please notify the sender by reply email and immediately 
delete this email. Use, disclosure or reproduction of this email by anyone 
other than the intended recipient(s) is strictly prohibited. No representation 
is made that this email or any attachments are free of viruses. Virus scanning 
is recommended and is the responsibility of the recipient.








---
https://lists.uni-koeln.de/mailman/listinfo/sundial







No virus found in this message.
Checked by AVG

Re: equation of time sundial

[Bill Gottesman]

Hello All,
I think Mike nailed it, as to what Ken is asking.  I know of no sundial,
other than Mike's here, that directly measures the Eot, rather than somehow
incorporate the EoT calculated elsewhere.  I did not think this was
possible until I saw Mike's solution just now, because a sundial has no way
of measuring Mean Solar Time without a previously calculated EoT chart.  In
Tom Hank's movie Cast Away, he records an analemma on a cave wall, but this
is movie fiction.  His watch was broken and he had no way to measure mean
time, only local solar time.
-Bill

On Sun, Feb 3, 2013 at 5:51 PM, jmikes...@ntlworld.com wrote:

   Ken,

 I think I made a device some time ago to do what you want .

 A cylinder was tilted to the appropriate latitude angle and direction.
 There was a small hole on one side of the cylinder which gave a projected
 a spot of light from the sun on the inner opposite surface where there was
 a graph which showed:
 left to right – the equation of time
 up and down – the sun’s declination.

 The cylinder was driven round using a 24 hour clock motor, so the spot of
 light remained apparently stationary except for changes in the EoT and
 sun’s declination that were read directly from the graph.

 Sadly, I don’t think I have it any more.

 Mike Shaw
 53º 22' North 03º 02' West
 www.wiz.to/sundials


 No virus found in this message.
 Checked by AVG - www.avg.com
 Version: 2013.0.2897 / Virus Database: 2639/6076 - Release Date: 02/02/13

 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial



---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: equation of time sundial

[Ken Baldwin]

Thanks, everyone.

I see now how an analemmic gnomon can be used to read the EOT, if the
equatorial band shows both mean and apparent time and you do the
subtraction in your head. I'm most interested, though, in something which
allows a direct reading of EOT...

Mike, your solution sounds very interesting, but I confess I don't really
understand it :-) I take it the motor is to keep the hole pointed toward
the sun. Presumably this could be done manually, as on a shepard's dial?
I'm unclear though on what's drawn inside. Is it a single curve of EOT as a
function of declination, or a family of curves?

Ken



On Sun, Feb 3, 2013 at 12:02 PM, Ken Baldwin kenneth.bald...@gmail.comwrote:

 Hello,

 I'm a new list member, and have a beginner question:

 Are there examples of sundials whose sole (or primary) purpose is to
 compute the Equation of Time for the current date?

 - I know that this information is often provided as a graph in the
 furniture, but why should I have to know the date and perform the look-up
 manually? Can't I use the position of the sun to do the computation for me?

 - I know that the EOT correction can be incorporated into the layout of
 (some) hour lines, but I'm more interested in having dials which show true
 solar time. I'd like a separate device dedicated to computing the EOT.

 - I know that I can construct an analemmic noon mark to show the EOT for
 that day, since it's simply the east-west component of the analemma, but
 I'd like a design that can be read at any daylight hour.

 It seems to me that it should be possible to build such a dial, since the
 EOT is a function of date, and date lines can be read from many sundials.
 In principle, I can just re-label the date lines with corresponding EOT
 values and interpolate.

 I hope that makes sense. But since I haven't seen anything like that in
 introductory sundial books, I must be missing something... Is it that the
 shadow length can't be read accurately enough to get a reasonably precise
 EOT estimate? Or is it just too hard to make a readable layout, given that
 solar altitude is ambiguous between two dates, and that the component of
 the EOT due to the eccentricity of the earth's orbit is out of phase with
 the equinoxes and solstices?

 Thanks in advance,
 Ken Baldwin
 Corvallis, OR USA


---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: equation of time sundial-heliochronometre

[Peter Mayer]

Hi Ken,

	I think it would be straightforward to modify a heliochronometre to 
achieve the same result as Mike's solution.  In addition to the usual 
figure-of-eight analemma, you'd add a centre line for local solar time. 
 After adjusting the dial for local solar time and 'zeroing' the (new) 
minutes scale, you would then rotate it slightly to the EOT curve and 
directly read out the difference between the two in minutes.
	Here are two scanned images from the Mayall's _Sundials: Their 
Construction and Use_ pp. 193ff which illustrate how one is constructed. 
 I'll attach a third image in a separate message.


On 4/02/2013 3:13 PM, Ken Baldwin wrote:

Thanks, everyone.

I see now how an analemmic gnomon can be used to read the EOT, if the
equatorial band shows both mean and apparent time and you do the
subtraction in your head. I'm most interested, though, in something
which allows a direct reading of EOT...

Mike, your solution sounds very interesting, but I confess I don't
really understand it :-) I take it the motor is to keep the hole pointed
toward the sun. Presumably this could be done manually, as on a
shepard's dial? I'm unclear though on what's drawn inside. Is it a
single curve of EOT as a function of declination, or a family of curves?

Ken



On Sun, Feb 3, 2013 at 12:02 PM, Ken Baldwin kenneth.bald...@gmail.com
mailto:kenneth.bald...@gmail.com wrote:

Hello,

I'm a new list member, and have a beginner question:

Are there examples of sundials whose sole (or primary) purpose is to
compute the Equation of Time for the current date?

- I know that this information is often provided as a graph in the
furniture, but why should I have to know the date and perform the
look-up manually? Can't I use the position of the sun to do the
computation for me?

- I know that the EOT correction can be incorporated into the layout
of (some) hour lines, but I'm more interested in having dials which
show true solar time. I'd like a separate device dedicated to
computing the EOT.

- I know that I can construct an analemmic noon mark to show the EOT
for that day, since it's simply the east-west component of the
analemma, but I'd like a design that can be read at any daylight hour.

It seems to me that it should be possible to build such a dial,
since the EOT is a function of date, and date lines can be read from
many sundials. In principle, I can just re-label the date lines with
corresponding EOT values and interpolate.

I hope that makes sense. But since I haven't seen anything like that
in introductory sundial books, I must be missing something... Is it
that the shadow length can't be read accurately enough to get a
reasonably precise EOT estimate? Or is it just too hard to make a
readable layout, given that solar altitude is ambiguous between two
dates, and that the component of the EOT due to the eccentricity of
the earth's orbit is out of phase with the equinoxes and solstices?

Thanks in advance,
Ken Baldwin
Corvallis, OR USA




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--
--
Peter Mayer
Politics Department
The University of Adelaide, AUSTRALIA 5005
Ph : +61 8 8313 5609
Fax : +61 8 8313 3443
e-mail: peter.ma...@adelaide.edu.au
CRICOS Provider Number 00123M
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Need help calculating equation of time

[Dwayne Henderson]

Hello!

At https://gist.github.com/1278755 - is anybody able to tell what's wrong
with my equation of time calculation?

Thank you!

--Dwayne
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The Equation of Time - a simple movie to show its effect

[Kevin Karney]

Dear Friends
I have just put up onto my website
www.precisedirections.co.uk
a little movie made with Google Sketchup (which has quite reasonable algorithms 
for the Sun's position).
It show a horizontal dial at 1.30 pm every day of the year in a wonderful place 
where the sun shines every day in the afternoon.

If you have a copy of Sketchup (which is freely available from Google), I have 
also included the file from which the movie was made. It takes a little time to 
become familiar with Sketchup, but - for seeing how your dial will perform in 
the real world with nearby trees, surrounding buildings, etc. - there is 
nothing better...

Enjoy

Best regards
Kevin Karney
Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales UK
01594 530 595



 



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RE: A new look at the Equation of Time

[Les Lombard]

Hello Kevin,

 

I really believe that this look is not only quite different but rather
attractive as well - I am incorporating it in my current design - thank you

Les lombard

 

From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On
Behalf Of Kevin Karney
Sent: 28 September 2010 03:06 PM
To: sundial
Subject: A new look at the Equation of Time

 

Dear Colleagues


You may be interested in the attached chart of the Equation of Time for
2011. It is of interest for a number of reasons...
-   it is an 'intrinsic' plot - not the familiar cartesian, polar or
analemmatic form. 

An intrinsic plot has equal increments of the independent
variable along the curve of the plot rather than along the x-axis. 

This allows the curve to be folded - making a very compact form.
-   it is much easier to read than a normal plot, because the day
points are all equally spaced along the curve.
-   it looks good !

 

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Re: A new look at the Equation of Time

[Bill Gottesman]

  
  
Very nice Kevin. Thank you sharing this.
-Bill

On 9/28/2010 9:05 AM, Kevin Karney wrote:
Dear Colleagues
  
You may be interested in the attached chart of the Equation of
Time for 2011. It is of interest for a number of reasons...
- it
is an 'intrinsic' plot - not thefamiliar cartesian, polar or
analemmatic form.
 An
  intrinsic plot has equal increments of the
  independentvariable along the curve of the plot rather than
  along the x-axis.
 This
  allows the curveto be folded - making a very compact form.
  - it
  is much easier to read than a normal plot, because the day
  points are all equally spaced along the curve.
  - it
  looks good !


  
  
  
  
  

  

The use of an intrinsic plot for the equation of time was
  first used in the Bury St Edmunds dial in the 1860s. SeeF.
  Sawyer: The Bury St Edmunds
  Curve,NASS Compendium12(3), p.29(Sept 2005)or John
  Davies: 'More on the Equation of Time on Sundials', BSS Bull
  17(ii), p.75 (June 2005).
This particular 'Flame' form is one of many possible
  compact folded forms that can easily be generated with a
  spreadsheet.
  
  For the number-obsessed, the chart is very precise. Though you
  cannot of course read it on the chart, the values of EoT are
  exact to within afraction of a second, since I have used the
  2011 polynomial algorithms issued to surveyors and
  navigatorsby HM Nautical Almanac Office. Thechart is for
  noon UT. If anyone would like a copy - correct for their own
  time zone and longitude - please let me know. Or if you are
  familiar withExcel, you can download the spreadsheet used to
  draw the curve from http://www.precisedirections.co.uk/Sundials/Index.html.
  The file is called "Almanac 2010_2011.xls". This has all the
  polynomial coefficients for the Sun and navigational stars for
  both 2010 and 2011.You can see a number of other intrinsic
  plots of the EoT at the above website. Click on the
  'Grange-over-Sands Conference' link.


For the really observant, you will notice a tiny additional
  gap between 31 Dec and 1st Jan: that is there because there
  are 365 1/4 days in a year not 365...


The zodiac signs on the chart mark the day starting the
  astronomical constellations when the Sun's longitude are
  passes 30, 60, 90 degrees etc. This may not conform with the
  astrological dates.


Best regards
Kevin




  
  

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Equation of time cam

[Frederick Jaggi]

Apparently the long now people sell a copy of the cam. See:

http://www.levenger.com/PAGETEMPLATES/PRODUCT/Product.asp? 
Params=Category=5-23|PageID=4871|Level=2-3

Fred Jaggi
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Equation of Time Booklet and Calendar - 2008 / Re: sundial Digest, Vol 24, Issue 6

[Mashallah Ali-Ahyaie]

*Dear Mr Carl and Mrs Barbara Sabanski,*
**
*Greetings, your work on the calendar of 2008, including EOT and sun's
declination is marvelous.I wonder whether you could help from where one can
get the same data for the exact time of the vernal equinox, in March 2008,
but with the most possible precision; to the fractions of seconds (time and
degree.) This is the exact moment on which the Iranian calendar is based on,
as a starting point, but the timing has to be very precise. For the Iranian
calendar the exact quantity of EOT, to the most possible precision is
required too.*
**
*   Also the Universal Year adopted by the United Nations is  based on the
same, I think.*
**
*Is this the first calendar you have prepared or you have it also for
preceding years?*
**
*Thanks once again for your generous data.*
**
*Best regards,*
**
*Mashallah Ali-Ahyaie*

On Dec 13, 2007 2:30 PM, [EMAIL PROTECTED] wrote:

 Send sundial mailing list submissions to
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 When replying, please edit your Subject line so it is more specific
 than Re: Contents of sundial digest...


 Today's Topics:

   1. Equation of Time Booklet and Calendar - 2008
  (Carl  Barbara Sabanski)
   2. sun dial info (Jim Engleman)
   3. Re: Equation of Time Booklet and Calendar - 2008 (wee-meng lee)
   4. The Sundial Christmas present 2007 ([EMAIL PROTECTED])


 --

 Message: 1
 Date: Wed, 12 Dec 2007 17:44:35 -0600
 From: Carl  Barbara Sabanski [EMAIL PROTECTED]
 Subject: Equation of Time Booklet and Calendar - 2008
 To: Sundial Mailing List \(E-mail\) sundial@uni-koeln.de
 Message-ID: [EMAIL PROTECTED]
 Content-Type: text/plain;   charset=Windows-1252

 Sunny Day!

 I invite you to come and get a copy of a handy Equation of Time booklet
 and/or calendar for 2008.  It's yours for the taking.

 http://www.mysundial.ca/tsp/eot_booklet.html

 Happy Dialling!

 Carl Sabanski
 www.mysundial.ca
 Get Hooked on Gnomonics!


 --

 Message: 2
 Date: Wed, 12 Dec 2007 20:34:55 -0500
 From: Jim Engleman [EMAIL PROTECTED]
 Subject: sun dial info
 To: sundial@uni-koeln.de
 Message-ID: [EMAIL PROTECTED]
 Content-Type: text/plain; charset=iso-8859-1

 have a sundial would like ti know origin and how to set it up.
 thanks
 jim
 -- next part --
 An HTML attachment was scrubbed...
 URL:
 https://lists.uni-koeln.de/mailman/private/sundial/attachments/20071212/3bdbefae/attachment-0001.htm

 --

 Message: 3
 Date: Thu, 13 Dec 2007 14:13:29 +0800
 From: wee-meng lee [EMAIL PROTECTED]
 Subject: Re: Equation of Time Booklet and Calendar - 2008
 To: Sundial Mailing List (E-mail) sundial@uni-koeln.de
 Message-ID: [EMAIL PROTECTED]
 Content-Type: text/plain; charset=iso-8859-1

 hi,

 nice work carl, thk u!

 i've converted it into a small 8 page wallet size reference booklet here
 in 2 paper sizes:
 http://leewm.freeshell.org/pocketmod/eqn-time-2008-ltr.pdf
 http://leewm.freeshell.org/pocketmod/eqn-time-2008-a4.pdf

 http://leewm.freeshell.org/pocketmod/calendar-2008-ltr.pdf
 http://leewm.freeshell.org/pocketmod/calendar-2008-a4.pdf

 Folding instructions are at the centre/bottom of the page.
 Click on the Video instructions button or folding guide button.
 http://www.pocketmod.com/app/

 To aid in deciphering the tiny font, u may need something like this:

 http://www.grannysstore.com/Wilderness_Survival/Fresnel_Lens_Fire_Starter.htm

 rgds
 weemeng

  - Original Message -
  From: Carl  Barbara Sabanski
  To: Sundial Mailing List (E-mail)
  Sent: Thursday, December 13, 2007 7:44 AM
  Subject: Equation of Time Booklet and Calendar - 2008


  Sunny Day!

  I invite you to come and get a copy of a handy Equation of Time booklet
  and/or calendar for 2008.  It's yours for the taking.

  http://www.mysundial.ca/tsp/eot_booklet.html

  Happy Dialling!

  Carl Sabanski
  www.mysundial.ca
  Get Hooked on Gnomonics!
  ---
  https://lists.uni-koeln.de/mailman/listinfo/sundial
 -- next part --
 An HTML attachment was scrubbed...
 URL:
 https://lists.uni-koeln.de/mailman/private/sundial/attachments/20071213/eca2f80b/attachment-0001.htm

 --

 Message: 4
 Date: Thu, 13 Dec 2007 09:23:49 +0100
 From: [EMAIL PROTECTED] [EMAIL PROTECTED]
 Subject: The Sundial Christmas present 2007
 To: sundial sundial@uni-koeln.de
 Message-ID: [EMAIL PROTECTED]
 Content-Type: text/plain; charset=iso-8859-1

  Dear Friends,

 I am glad to announce you a nice and simple Christmas 2007 present on my
 web site
 http://www.nicolaseverino.it

Equation of Time Booklet and Calendar - 2008

[Carl Barbara Sabanski]

Sunny Day!

I invite you to come and get a copy of a handy Equation of Time booklet
and/or calendar for 2008.  It's yours for the taking.

http://www.mysundial.ca/tsp/eot_booklet.html

Happy Dialling!

Carl Sabanski
www.mysundial.ca
Get Hooked on Gnomonics!
---
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Re: Equation of Time Booklet and Calendar - 2008

[wee-meng lee]

hi,

nice work carl, thk u!

i've converted it into a small 8 page wallet size reference booklet here in 2 
paper sizes:
http://leewm.freeshell.org/pocketmod/eqn-time-2008-ltr.pdf
http://leewm.freeshell.org/pocketmod/eqn-time-2008-a4.pdf

http://leewm.freeshell.org/pocketmod/calendar-2008-ltr.pdf
http://leewm.freeshell.org/pocketmod/calendar-2008-a4.pdf

Folding instructions are at the centre/bottom of the page.
Click on the Video instructions button or folding guide button.
http://www.pocketmod.com/app/

To aid in deciphering the tiny font, u may need something like this:
http://www.grannysstore.com/Wilderness_Survival/Fresnel_Lens_Fire_Starter.htm

rgds
weemeng

  - Original Message - 
  From: Carl  Barbara Sabanski 
  To: Sundial Mailing List (E-mail) 
  Sent: Thursday, December 13, 2007 7:44 AM
  Subject: Equation of Time Booklet and Calendar - 2008


  Sunny Day!

  I invite you to come and get a copy of a handy Equation of Time booklet
  and/or calendar for 2008.  It's yours for the taking.

  http://www.mysundial.ca/tsp/eot_booklet.html

  Happy Dialling!

  Carl Sabanski
  www.mysundial.ca
  Get Hooked on Gnomonics!
  ---
  https://lists.uni-koeln.de/mailman/listinfo/sundial
---
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Poncet Platform: was Re: Equation of Time

[Peter Mayer]

Hi,

   I've tried to send a couple of small jpgs of my crude Poncet 
Platform, but they've been blocked by the server, too large.  I may have 
to try in stages.


best wishes,

Peter

--
Peter Mayer
Politics Department
The University of Adelaide, AUSTRALIA 5005
Ph: +61 8 8303 5606
Fax   : +61 8 8303 3443
e-mail: [EMAIL PROTECTED]
CRICOS Provider Number 00123M
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Re: Poncet Platform: was Re: Equation of Time

[Edley McKnight]

Hi Peter,

Your small jpgs came through fine.  There seem to be a number of Poncet 
patents with curved surfaces, to answer other questions.  This embodyment 
seems sturdier and less likely to shift.  It appears to be an indoor dial, 
through a south window, yes.  It looks really good!  I wish I had a south 
window.

Nice to hear from you again.

Edley. 
 Hi,
 
 I've tried to send a couple of small jpgs of my crude Poncet
 Platform, but they've been blocked by the server, too large.  I may
 have to try in stages.
 
 best wishes,
 
 Peter
 
 -- 
 Peter Mayer
 Politics Department
 The University of Adelaide, AUSTRALIA 5005
 Ph: +61 8 8303 5606
 Fax   : +61 8 8303 3443
 e-mail: [EMAIL PROTECTED]
 CRICOS Provider Number 00123M
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 copyright.  If you are not the intended recipient please 
 notify the sender by reply email and immediately delete 
 this email. Use, disclosure or reproduction of this email 
 by anyone other than the intended recipient(s) is strictly 
 prohibited. No representation is made that this email or 
 any attachments are free of viruses. Virus scanning is 
 recommended and is the responsibility of the recipient.
 
 


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Re: Poncet Platform: was Re: Equation of Time

[Peter Mayer]

Dear Edley,
   My version is a Gee platform, named for Alan Gee which uses a 
circular section.  I rested the section in the piece of plywood I'd cut 
it from, resting it, as perhaps you can see, on two little teflon 
furniture glides.
   Oh! And since I'm in Oz, the door (and deck) face north.  (Perhaps 
if you can see the numbers on the dial you'll see they run from right to 
left!).


best wishes,

Peter

Edley McKnight wrote:


Hi Peter,

Your small jpgs came through fine.  There seem to be a number of 
Poncet patents with curved surfaces, to answer other questions.  This 
embodyment seems sturdier and less likely to shift.  It appears to be 
an indoor dial, through a south window, yes.  It looks really good!  I 
wish I had a south window.


Nice to hear from you again.

Edley.

Hi,

I've tried to send a couple of small jpgs of my crude Poncet
Platform, but they've been blocked by the server, too large.  I may
have to try in stages.

best wishes,

Peter

--
Peter Mayer
Politics Department
The University of Adelaide, AUSTRALIA 5005
Ph: +61 8 8303 5606
Fax   : +61 8 8303 3443
e-mail: [EMAIL PROTECTED]
CRICOS Provider Number 00123M
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copyright.  If you are not the intended recipient please
notify the sender by reply email and immediately delete
this email. Use, disclosure or reproduction of this email
by anyone other than the intended recipient(s) is strictly
prohibited. No representation is made that this email or
any attachments are free of viruses. Virus scanning is
recommended and is the responsibility of the recipient.




 



--
Peter Mayer
Politics Department
The University of Adelaide, AUSTRALIA 5005
Ph: +61 8 8303 5606
Fax   : +61 8 8303 3443
e-mail: [EMAIL PROTECTED]
CRICOS Provider Number 00123M
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RE: Equation of Time

[Roger Sinnott]

Mac and others,

Here is a first attempt, using Google Sketchup.

 -- Roger


Hi Roger,

Any chance you could post pictures of your prototype? Maybe even drawings?

Best wishes,

Mac Oglesby


attachment: Poncet1.jpg---
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Re: Equation of Time

[Dave Bell]

Roger Sinnott wrote:
 Mac and others,

 Here is a first attempt, using Google Sketchup.

  -- Roger

 
   
 Nice!! So, you have two matching inclined surfaces, one on the pedestle, and 
 one on the carrier.
   
If you were doing this for a telescope, I guess you'd put two Teflon 
pads on the carrier's surface.
For this application, more friction is actually beneficial, so that's 
not necessary.

I've seen Poncet mounts that use a ball/socket for the pivot point. How 
are you suggesting the pivot be made?
Maybe a rounded pin into a conical hole in a hardwood block? And it 
looks like the pin would lie in an equatorial plane, parallel to the 
polar end plane...

Is there a height alignment requirement for the pivot point, relative to 
the inclined plane?
Horizontally, it should be centered, but I have a feeling it needs to be 
placed at the right height on the meridian end, as well.

Great sketch - I have to get around to learning Sketchup!

Dave
   

 

 

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RE: Equation of Time

[Roger Sinnott]

Dave Bell wrote:

 Nice!! So, you have two matching inclined surfaces, one on the pedestle,
and one on the carrier.

Actually no, there is only one surface (the big one in front) that *has* to be 
inclined.  I gave the rear one a similar tilt to catch the pivot point more 
securely and prevent the upper table from sliding foward under gravity. But its 
angle is not critical.


If you were doing this for a telescope, I guess you'd put two Teflon
pads on the carrier's surface. For this application, more friction is actually
beneficial, so that's not necessary.

Good points.

I've seen Poncet mounts that use a ball/socket for the pivot point. How
are you suggesting the pivot be made? Maybe a rounded pin into a
conical hole in a hardwood block? And it looks like the pin would lie in
an equatorial plane, parallel to the polar end plane...

The pivot can be almost anything -- even a nail through the upper table. Its 
angle is nothing special.

Is there a height alignment requirement for the pivot point, relative to
the inclined plane? Horizontally, it should be centered, but I have a
 feeling it needs to be placed at the right height on the meridian
end, as well.

Nope -- the height is not important, nor does it have to be centered. But you 
are right that the unit will be more stable this way. If the table tilts too 
much, as can happen when star-tracking with a heavy camera or telescope on top, 
things can get out of balance and there is a risk of the upper board toppling 
off.  But this problem shouldn't arise in a sundial with an equation-of-time 
correction, and maybe not with a daylight-saving-time correction either.

Great sketch - I have to get around to learning Sketchup!

I first heard of SketchUp about a year ago, on this list, and I've been having 
a BLAST with it!

 -- Roger



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RE: Equation of Time

[Roger Sinnott]

From Edley McKnight:
Hi Roger and all,

Not ever having seen one, I'd imagined it as a horizontal slice through an 
equatorial
dial, with the pivot on the gnomon and the sliding on the dial face, but this 
looks
easier to adjust.  I would imagine now that so long as the pivot point and the 
inclined
plane contact points all start out in a horizontal triangle that it would 
work.  The inclined
plane appears to be parallel with the equatorial plane, yes?

Hi Edley,

The pivot and contacts on the inclined plane don't *have* to define a 
horizontal plane, but they might as well, since they are being used to carry a 
horizontal sundial.  Also, everything will be more stable that way.

You're right, the inclined plane must be parallel to the plane of the celestial 
equator (and Earth's equator). Therebore, this original form of Poncet table 
works well at high and temperate latitudes. But when you get close to the 
Earth's equator (say, within the latitude band from 15 N to 15 S),  the 
inclined plane would become so steep that it wouldn't support the table 
properly.

   -- Roger



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RE: Equation of Time

[dbell]

 Concerning equatorial tables, people seem to be looking at recent patents
 for ELABORATE designs (conical rollers and such).  But the original Poncet
 table is quite simple. I made my 1977 prototype out of wood, with a piece
 of Formica for the inclined plane on which one end of the table slides.
 My unit has no curved surfaces at all.

I agree - all I see lately are roller bearing designs, not the sliding
plane. Smooth, frictionless motion is NOT needed here!

 I took it to Turkey for the 1999
 eclipse (latitude 39 N)

We went to Romania for 1999... Did you get out before the quake?

Dave

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RE: Equation of Time

[Mac Oglesby]

Hi Roger,

Any chance you could post pictures of your prototype? Maybe even drawings?

Best wishes,

Mac Oglesby





Chris,

Concerning equatorial tables, people seem to be looking at recent 
patents for ELABORATE designs (conical rollers and such).  But the 
original Poncet table is quite simple. I made my 1977 prototype out 
of wood, with a piece of Formica for the inclined plane on which one 
end of the table slides.  My unit has no curved surfaces at all.

I've used mine for astrophotography at latitudes other than 42 N 
(for which it was constructed).  Shoving a small rock under the 
north or south end will tilt the whole unit appropriately.  I made a 
couple of small alignment wedges on which I can place a bubble 
level for setting the proper base tilt when away from home.  I took 
it to Turkey for the 1999 eclipse (latitude 39 N) and to the Winter 
Star Party in Florida (latitude 25 N) a few years later. The only 
restriction is that it won't work too near the Earth's equator.

I think there's definitely a sundial application here, and I hope to 
make one in the coming weeks to show to the list.

 -- Roger


From: [EMAIL PROTECTED] [EMAIL PROTECTED] On 
Behalf Of Chris Lusby Taylor [EMAIL PROTECTED]
Sent: Tuesday, June 05, 2007 5:30 AM

This has been an excellent discussion. As several of my designs 
purport to be readable to a couple of minutes, I, too, had been 
exploring ways to correct for the EoT.

The Poncet platform rotates the entire sundial about a polar axis, 
but has to be made for a specific latitude, so cannot be 
mass-produced. A latitude-independent version is described in US 
patent 09874026 filed just last year (see 
http://www.patentstorm.us/patents/7035005-description.html) Patrick 
is correct in saying that if the gnomon has two edges you must 
rotate it, not just the dial, as the orientation of the edges would 
remain correct, but their position in space would not.

An alternative that I've investigated is to use two wedges, similar 
to those Bill Gottesman uses for the latitude adjustment of his 
sundials (also patented: see
  http://www.precisionsundials.com/equant%20dial.htm).

---
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---
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RE: Equation of Time

[Edley McKnight]

Hi Roger,

Yes, Now that the concept finally comes fully in to mind, this is a great idea! 
 
As you say only about 4 degrees of rotation, a small width of incllined plane 
for the two sliding contacts, would do it for just EOT correction.  Quite 
compactly too.  To handle both Longitude and EOT just about anywhere it 
would be much larger.  3 hours in a time zone plus daylight saving time plus 4 
degrees, What, 65 degrees or so??? total swing.  We would need very strong 
bolts holding the sundial and maybe a mirror to view the dial? G
I guess we could probably handle the 19 degrees or so of Daylight saving time 
and EOT with this inclined plane Poncet mount.  Who knows when Daylight 
saving time will happen in your zone next time? 
Some of the more current designs that have the hour lines spaced evenly 
along a line or circular curve would allow us to just slide a straight or 
curved 
plate to correct for all three corrections.  I think my future designs will 
tend in 
that direction.

Thanks for your persistance, sorry it took so long to soak in!

Edley.

 Chris,
 
 Concerning equatorial tables, people seem to be looking at recent
 patents for ELABORATE designs (conical rollers and such).  But the
 original Poncet table is quite simple. I made my 1977 prototype out of
 wood, with a piece of Formica for the inclined plane on which one end
 of the table slides.  My unit has no curved surfaces at all.
 
 I've used mine for astrophotography at latitudes other than 42 N (for
 which it was constructed).  Shoving a small rock under the north or
 south end will tilt the whole unit appropriately.  I made a couple of
 small alignment wedges on which I can place a bubble level for
 setting the proper base tilt when away from home.  I took it to Turkey
 for the 1999 eclipse (latitude 39 N) and to the Winter Star Party in
 Florida (latitude 25 N) a few years later. The only restriction is
 that it won't work too near the Earth's equator.
 
 I think there's definitely a sundial application here, and I hope to
 make one in the coming weeks to show to the list.
 
 -- Roger
 
 
 From: [EMAIL PROTECTED] [EMAIL PROTECTED] On
 Behalf Of Chris Lusby Taylor [EMAIL PROTECTED] Sent:
 Tuesday, June 05, 2007 5:30 AM
 
 This has been an excellent discussion. As several of my designs
 purport to be readable to a couple of minutes, I, too, had been
 exploring ways to correct for the EoT.
 
 The Poncet platform rotates the entire sundial about a polar axis, but
 has to be made for a specific latitude, so cannot be mass-produced. A
 latitude-independent version is described in US patent 09874026 filed
 just last year (see
 http://www.patentstorm.us/patents/7035005-description.html) Patrick is
 correct in saying that if the gnomon has two edges you must rotate it,
 not just the dial, as the orientation of the edges would remain
 correct, but their position in space would not.
 
 An alternative that I've investigated is to use two wedges, similar to
 those Bill Gottesman uses for the latitude adjustment of his sundials
 (also patented: see
  http://www.precisionsundials.com/equant%20dial.htm).
 
 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial
 


---
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Re: Equation of Time

[Chris Lusby Taylor]

This has been an excellent discussion. As several of my designs purport to be 
readable to a couple of minutes, I, too, had been exploring ways to correct for 
the EoT.

The Poncet platform rotates the entire sundial about a polar axis, but has to 
be made for a specific latitude, so cannot be mass-produced. A 
latitude-independent version is described in US patent 09874026 filed just last 
year (see http://www.patentstorm.us/patents/7035005-description.html) Patrick 
is correct in saying that if the gnomon has two edges you must rotate it, not 
just the dial, as the orientation of the edges would remain correct, but their 
position in space would not.

An alternative that I've investigated is to use two wedges, similar to those 
Bill Gottesman uses for the latitude adjustment of his sundials (also patented: 
see
 http://www.precisionsundials.com/equant%20dial.htm).
The wedge angle can be vey small - just 2 degrees. But having to set three 
alignments seems an unacceptable burden.

My latest approach is to take the Housewife's Trick from AP Herbert: just 
turn the whole horizontal sundial about a vertical axis, so the dial plate 
remains horizontal but the gnomon and the 12 o'clock line are no longer 
North-South. This is very much easier to do than any of the other suggestions. 
But, is it accurate?

Of course not - an article in The Compendium a few years ago analysed it and 
rejected it. But The Compendium is written with a USA perspective. AP Herbert 
was English. The housewives to whom he referred were at 51 or more degrees 
North. Does this make a difference?

Yes, it does. By rotating the sundial appropriately, the maximum time error can 
be made to be less than one minute except in July when it may be as much as 90 
seconds. Well, for my money that's a pretty good result. I'm sorry it doesn't 
work as well in the USA because you're too near the equator. For us in northern 
Europe I suggest it is quite good enough. The further north you are, the less 
the error. Should I patent it, or at least the calculation of the appropriate 
angle? I think I'm too late. It appears that it's common knowledge amongst 
housewives in this country.

Chris Lusby Taylor
51.4N 1.3W

  - Original Message - 
  From: Edley McKnight 
  To: Roger Sinnott ; sundial@uni-koeln.de 
  Sent: Tuesday, June 05, 2007 6:59 AM
  Subject: RE: Equation of Time


  Hi Folks, just a short note on hinging in latitude/EOT corrections. 


  I tend to think of the hinge as one side of a parallelogram with the gnomon 
as the opposite side.  The parallelogram extending down through the dial plate 
and base.  When any set of parallel lines is rotated around one of them, they 
still stay parallel, further, if only a subset of these lines is rotated, all 
of them are still parallel.  So, really, the hinge could be just below an edge 
of the dial plate if the dial plate is allowed to swing to positive and 
negative angles. So long as the hinge is parallel to the gnomon.  A half circle 
with a screw clamp or any number of other ways could be used to set the 
angle/time.  I hope this makes sense.  It is all equivalent to translating the 
dial in Longitude( rotating around the earth's axis as a hinge). 


  Enjoy the Light! 


  Edley. 


--


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RE: Equation of Time

[Edley McKnight]

Hi Simon,

Ahhh!  Thanks much for the information!  So, nearly any sundial, if 
competently made can be used nearly anywhere on earth, if oriented 
properly.  That is good to hear.

Thanks again!

Edley McKnight.

 not only altitude dials, but azimuth dials also. I
 have a chapter in Illustrating More Shadows showing
 the portability and rules for portability of both dial
 types, from the equator to the pole, and the
 correlation with calendar curves on an hour angle
 dial.
 
 The DeltaCAD macros for the Shepherd and the winged
 azimuth dial's both animate over latitude, and it
 interesting to see the evolution fro the equator to
 the pole, and in the case of the azimuth dial, even
 more fun when given a longitude correction.
 
 Simon
 
 
 
 --- Edley McKnight [EMAIL PROTECTED] wrote:
 
  Hi Duane, Roger, and all,
  
  A true equatorial mount is truly fine if you have
  one, A simple hinge mounted 
  in parallel with the earth's axis at some point
  below the horizontal surface, 
  allowing the dial to tip a little one way or the
  other will allow adjusting for both 
  Longitude and the Equation of Time.  One could
  consider the sundial to be a 
  slightly slow or fast clock and set it daily for the
  correct time, like any other 
  clock. (even daylight saving's time if the tilt is
  large enough) Mounting an 
  east west hinge below that would allow adjusting for
  errors in Latitude as 
  well.  Setting up such a table is a fun thing to
  test various designs or sundials 
  found.  I call it an Latitude/Longitude table.
  
  BTW, Even Pillar or Shepherd's dials made for other
  places seem to work 
  just fine locally when rotated on such a table, set
  for the correct Lat/Long 
  rather than dangled by their cords.  Has anyone else
  observed this?
  
  I still like Hendrik Hollander's cone gnomon design
  the best currently.
  
  Enjoy the Light!
  
  Edley McKnight
  
   Duane,
   
   In addition to all the other comments, I'd like to
  mention this
   possibility:
   
   An ordinary garden sundial with triangular gnomon
  is usually mounted
   on a solid pedestal with the horizontal plane
  fixed.  If instead you
   place it on an equatorial table, the sundial can
  wobble about an
   axis through the north and south celestial poles. 
  By controlling this
   wobble with the seasons, you can easily counteract
  the equation of
   time and make the sundial show mean time without
  any mental
   corrections at all.
   
   Equatorial tables, or platforms, have been around
  since they were
   invented by a French genius, Adrien Poncet, and
  described in the
   January 1977 issue of Sky  Telescope, pages
  64-67. The prototype that
   I made then is sitting on the table in front of me
  now, and it seems
   ideal for carrying a horizontal sundial!  This is
  Poncet's concept: 
   If a rigid body (in this case the entire sundial)
  is supported at
   three points, one acting as a fixed pivot and the
  other two
   constrained to slide on a fixed plane (that of the
  celestial equator),
   the body can only rotate around the polar axis
  (defined by the
   gnomon's shadow-casting upper edge).
   
   Since 1977, many versions of the Poncet platform
  have been devised and
   produced commercially. They tend to get more
  complicated when you need
   them to carry heavy telescopes, such as
  Dobsonians, and track smoothly
   enough for time-exposure imaging.  But for a
  sundial Poncet's original
   design seems quite adequate. All you would need is
  a cam of the proper
   shape to raise or lower one end of the table (by
  no more than 4
   degrees) to correct for the equation of time.
   
   Using a knob attached to this cam, you could dial
  in the current month
   and day and that's it! (And if you forget to reset
  the date for a week
   or two, the readings will still be quite close.)
   
  -- Roger
   
   
   Greetings,
   
   I am a new member and have what is probably a very
  simplistic
   question.  My apologies in advance.
   
   When considering a flat, fixed sundial (not an
  equatorial dial) it
   appears that to get the sundial as close as
  possible to watch time you
   set it to the latitude and then adjust it for the
  longitude when
   laying out the hour lines.  Having done all that,
  am I right in
   assuming that you are still at the mercy of the
  Equation of Time and
   will need to add/subtract minutes to the dials
  time to equal watch
   time?  - or is it somehow possible to adjust a
  flat, fixed sundial to
   incorporate the equation of time also?
   
   Thank you for any guidance/help you will tender.
   
   Sincerely,
   
   Duane Thomson
   
   
  
  ---
  
  https://lists.uni-koeln.de/mailman/listinfo/sundial
   
  
  
  
 ---
  https://lists.uni-koeln.de/mailman/listinfo/sundial

RE: Equation of Time

[Edley McKnight]

Hi Roger, Patrick, Dave and all,

My idea was to tilt the whole sundial, gnomon, base and all.  It is as if it 
were remounted at a 
longitude where the local time was the same as the corrected time here.

In light of that, couldn't a wide gnomon standard horizontal dial be considered 
two dials 
mounted close to each other?  In that case the tilt of the dial would still 
keep the two 
gnomons parallel to the earth's axis, thus correcting both.

Well, of course it wouldn't be a horizontal dial anymore, but I wouldn't be 
that picky.

The single rod gnomon that the balance of the dial hangs from would work nicely 
too, thanks 
Dave

Edley.

 Dave, Edley, and others,
 
 Thanks for the excellent suggestions!
 
 Edley's idea is simple and elegant.  The only slight drawback I see is
 that the base of the sundial has to be made thick enough to
 accommodate the hinge.
 
 Dave's idea is also nice, and it avoids the need for a thick base. 
 Adrien Poncet liked to refer to his invention as a no axis telescope
 mount (meaning that the polar axis was not a physical thing but was
 implied by the 3-D geometry and degrees of freedom of the parts). 
 That is helpful in a telescope/camera mount because it means the
 equatorial table can have a very low profile.  But a sundial of this
 type has a solid gnomon anyway, so why not make use of it, as Dave's
 idea does!
 
 In a separate e-mail, Patrick Powers commented that the usual garden
 sundial has a thick gnomon (in which you read the shadow from one edge
 of the gnomon in the morning and the other edge in the afternoon). So
 the gnomon theoretically needs to tilt *with* the base, rather than
 being independently fixed while the base tilts under it.
 
 I'm trying to come up with the mathematical shape of a suitable cam
 for controlling the base tilt in a sundial of this general type,
 during the course of a year. So far, no luck.  It may be easier to go
 ahead and make one empirically.
 
 -- Roger
 
 
 From Edley McKnight:
 
 A true equatorial mount is truly fine if you have one, A simple hinge
 mounted in parallel with the earth's axis at some point below the
 horizontal surface, allowing the dial to tip a little one way or the
 other will allow adjusting for both Longitude and the Equation of
 Time.  One could consider the sundial to be a slightly slow or fast
 clock and set it daily for the correct time, like any other clock.
 (even daylight saving's time if the tilt is large enough) Mounting an
 east west hinge below that would allow adjusting for errors in
 Latitude as well.  Setting up such a table is a fun thing to test
 various designs or sundials found.  I call it an Latitude/Longitude
 table.
 
 BTW, Even Pillar or Shepherd's dials made for other places seem to
 work just fine locally when rotated on such a table, set for the
 correct Lat/Long rather than dangled by their cords.  Has anyone else
 observed this?
 
 I still like Hendrik Hollander's cone gnomon design the best
 currently.
 - From
 Dave Bell:
 
 A variant on that would be to use a long, straight shaft for the polar
 axis and gnomon, letting the horizontal dial hang from the axis. The
 adjustment would be very slight, barely noticeable as off-level...
 -
 
 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial
 


---
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RE: Equation of Time

[Edley McKnight]

Hi Folks, just a short note on hinging in latitude/EOT corrections.

I tend to think of the hinge as one side of a parallelogram with the gnomon as 
the opposite side.  The parallelogram extending down through the dial plate 
and base.  When any set of parallel lines is rotated around one of them, they 
still stay parallel, further, if only a subset of these lines is rotated, all 
of them 
are still parallel.  So, really, the hinge could be just below an edge of the 
dial 
plate if the dial plate is allowed to swing to positive and negative angles. So 
long as the hinge is parallel to the gnomon.  A half circle with a screw clamp 
or any number of other ways could be used to set the angle/time.  I hope this 
makes sense.  It is all equivalent to translating the dial in Longitude( 
rotating 
around the earth's axis as a hinge).

Enjoy the Light!

Edley.
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

RE: Equation of Time

[Roger Sinnott]

Duane,

In addition to all the other comments, I'd like to mention this possibility:

An ordinary garden sundial with triangular gnomon is usually mounted on a solid 
pedestal with the horizontal plane fixed.  If instead you place it on an 
equatorial table, the sundial can wobble about an axis through the north and 
south celestial poles.  By controlling this wobble with the seasons, you can 
easily counteract the equation of time and make the sundial show mean time 
without any mental corrections at all.

Equatorial tables, or platforms, have been around since they were invented by a 
French genius, Adrien Poncet, and described in the January 1977 issue of Sky  
Telescope, pages 64-67. The prototype that I made then is sitting on the table 
in front of me now, and it seems ideal for carrying a horizontal sundial!  This 
is Poncet's concept:  If a rigid body (in this case the entire sundial) is 
supported at three points, one acting as a fixed pivot and the other two 
constrained to slide on a fixed plane (that of the celestial equator), the body 
can only rotate around the polar axis (defined by the gnomon's shadow-casting 
upper edge).

Since 1977, many versions of the Poncet platform have been devised and produced 
commercially. They tend to get more complicated when you need them to carry 
heavy telescopes, such as Dobsonians, and track smoothly enough for 
time-exposure imaging.  But for a sundial Poncet's original design seems quite 
adequate. All you would need is a cam of the proper shape to raise or lower one 
end of the table (by no more than 4 degrees) to correct for the equation of 
time.

Using a knob attached to this cam, you could dial in the current month and day 
and that's it! (And if you forget to reset the date for a week or two, the 
readings will still be quite close.)

   -- Roger


Greetings,

I am a new member and have what is probably a very simplistic question.  My 
apologies in advance.

When considering a flat, fixed sundial (not an equatorial dial) it appears that 
to get the sundial as close as possible to watch time you set it to the 
latitude and then adjust it for the longitude when laying out the hour lines.  
Having done all that, am I right in assuming that you are still at the mercy of 
the Equation of Time and will need to add/subtract minutes to the dials time to 
equal watch time?  - or is it somehow possible to adjust a flat, fixed sundial 
to incorporate the equation of time also?

Thank you for any guidance/help you will tender.

Sincerely,

Duane Thomson


---
https://lists.uni-koeln.de/mailman/listinfo/sundial

RE: Equation of Time

[Edley McKnight]

Hi Duane, Roger, and all,

A true equatorial mount is truly fine if you have one, A simple hinge mounted 
in parallel with the earth's axis at some point below the horizontal surface, 
allowing the dial to tip a little one way or the other will allow adjusting for 
both 
Longitude and the Equation of Time.  One could consider the sundial to be a 
slightly slow or fast clock and set it daily for the correct time, like any 
other 
clock. (even daylight saving's time if the tilt is large enough) Mounting an 
east west hinge below that would allow adjusting for errors in Latitude as 
well.  Setting up such a table is a fun thing to test various designs or 
sundials 
found.  I call it an Latitude/Longitude table.

BTW, Even Pillar or Shepherd's dials made for other places seem to work 
just fine locally when rotated on such a table, set for the correct Lat/Long 
rather than dangled by their cords.  Has anyone else observed this?

I still like Hendrik Hollander's cone gnomon design the best currently.

Enjoy the Light!

Edley McKnight

 Duane,
 
 In addition to all the other comments, I'd like to mention this
 possibility:
 
 An ordinary garden sundial with triangular gnomon is usually mounted
 on a solid pedestal with the horizontal plane fixed.  If instead you
 place it on an equatorial table, the sundial can wobble about an
 axis through the north and south celestial poles.  By controlling this
 wobble with the seasons, you can easily counteract the equation of
 time and make the sundial show mean time without any mental
 corrections at all.
 
 Equatorial tables, or platforms, have been around since they were
 invented by a French genius, Adrien Poncet, and described in the
 January 1977 issue of Sky  Telescope, pages 64-67. The prototype that
 I made then is sitting on the table in front of me now, and it seems
 ideal for carrying a horizontal sundial!  This is Poncet's concept: 
 If a rigid body (in this case the entire sundial) is supported at
 three points, one acting as a fixed pivot and the other two
 constrained to slide on a fixed plane (that of the celestial equator),
 the body can only rotate around the polar axis (defined by the
 gnomon's shadow-casting upper edge).
 
 Since 1977, many versions of the Poncet platform have been devised and
 produced commercially. They tend to get more complicated when you need
 them to carry heavy telescopes, such as Dobsonians, and track smoothly
 enough for time-exposure imaging.  But for a sundial Poncet's original
 design seems quite adequate. All you would need is a cam of the proper
 shape to raise or lower one end of the table (by no more than 4
 degrees) to correct for the equation of time.
 
 Using a knob attached to this cam, you could dial in the current month
 and day and that's it! (And if you forget to reset the date for a week
 or two, the readings will still be quite close.)
 
-- Roger
 
 
 Greetings,
 
 I am a new member and have what is probably a very simplistic
 question.  My apologies in advance.
 
 When considering a flat, fixed sundial (not an equatorial dial) it
 appears that to get the sundial as close as possible to watch time you
 set it to the latitude and then adjust it for the longitude when
 laying out the hour lines.  Having done all that, am I right in
 assuming that you are still at the mercy of the Equation of Time and
 will need to add/subtract minutes to the dials time to equal watch
 time?  - or is it somehow possible to adjust a flat, fixed sundial to
 incorporate the equation of time also?
 
 Thank you for any guidance/help you will tender.
 
 Sincerely,
 
 Duane Thomson
 
 
 ---
 https://lists.uni-koeln.de/mailman/listinfo/sundial
 


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Re: Equation of Time

[Mike Shaw]

Duane,

The easiest way, I think, is to combine the longitude correction and the 
Equation of Time graph.
You can then just apply one correction without the need to calculate in the 
longitude correction into the dial.

See: http://homepage.ntlworld.com/jmikeshaw/page13.html for an adjustable one.

Mike Shaw

53.37N
3.02W

www.wiz.to/sundials

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Equation of Time

[DRTAIA]

Greetings, 
 
I am a new member and have what is probably a very simplistic  question.  My 
apologies in advance.
 
When considering a flat, fixed sundial (not an equatorial dial) it appears  
that to get the sundial as close as possible to watch time you set it to the  
latitude and then adjust it for the longitude when laying out the hour  lines.  
Having done all that, am I right in assuming that you are still at  the mercy 
of the Equation of Time and will need to add/subtract minutes to the  dials 
time to equal watch time?  - or is it somehow possible to adjust a  flat, fixed 
sundial to incorporate the equation of time also?
 
Thank you for any guidance/help you will tender.
 
Sincerely,
 
Duane Thomson



** See what's free at http://www.aol.com.
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RE: Equation of Time

[Carl Barbara Sabanski]

Sunny Day Duane?

As you suggest it is possible to incorporate the Equation of Time into a
garden variety horizontal sundial.  However it must be done to each
individual hour line in the form of an analemma, which is in the shape of an
8.  If used, it is normally done only on the full hours.  I am sure you
have seen this.  I many cases the graph of the Equation of Time is included
in the dial plate.  When reading the sundial the graph is used to estimate
the correction required on a particular day.  You can see this at:

http://www.mysundial.ca/sdu/sdu_correct_a_dial_2.html

There is a more complex horizontal sundial that will indicate standard time.

Happy Dialling!

Carl Sabanski
www.mysundial.ca
Get Hooked on Gnomonics!
  -Original Message-
  From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of [EMAIL PROTECTED]
  Sent: Friday, June 01, 2007 2:57 PM
  To: sundial@uni-koeln.de
  Subject: Equation of Time


  Greetings,

  I am a new member and have what is probably a very simplistic question.
My apologies in advance.

  When considering a flat, fixed sundial (not an equatorial dial) it appears
that to get the sundial as close as possible to watch time you set it to the
latitude and then adjust it for the longitude when laying out the hour
lines.  Having done all that, am I right in assuming that you are still at
the mercy of the Equation of Time and will need to add/subtract minutes to
the dials time to equal watch time?  - or is it somehow possible to adjust a
flat, fixed sundial to incorporate the equation of time also?

  Thank you for any guidance/help you will tender.

  Sincerely,

  Duane Thomson






--
  See what's free at AOL.com.
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Re: Equation of Time

[Roger Bailey]

Hello Duane,

This is a good question, one that has challenged us since the railways forced 
the introduction of standard time. My initial advice is to Get over it!. 
Sundials show solar time, in tune with the rotations and orbits of our 
universe. Clock time is defined by law and international conventions. This is 
fine for catching an airplane but it is a totally  arbitrary system of time. 
There are translations available but the bottom line is the clocks are wrong. 
Go with the sun.

I have mellowed a bit and now accept  that there are good reasons to show clock 
time on a sundial. The advice that you have been getting for slewing for 
longitude and adding an EOT correction is appropriate. This used to be what we 
were stuck with to show mean clock time. But things have changed with the 
wonderful subtle design by Hendrik Hollander, a mean time sundial with conical 
gnomon. This dial looks quite normal, with straight lines and smooth curves but 
it incorporates the equation of time and shows clock time. Hendrik won the 
prestigious Sawyer Dialing Prize last year for this concept and has published 
the details in in the NASS Compendium, Sept 2006. The latest Compendium digital 
edition, June 2007, included software by Brian Albinson to design such a 
Hollander mean time dial for your location. Google Hendrik Hollander sundial 
for more leads. 

My final recommendation is to not construct a sundial based on Hollander's 
concepts until you can explain the hidden subtly to your friends and family. 
Actually this is not a recommendation but a challenge. I am not there yet. 

Welcome to the Sundial Mailing List,

Roger Bailey
Walking Shadow Designs www.walkingshadow.info 
NASS Secretary www.sundials.org 



- Original Message - 
  From: [EMAIL PROTECTED] 
  To: sundial@uni-koeln.de 
  Sent: Friday, June 01, 2007 1:57 PM
  Subject: Equation of Time


  Greetings, 

  I am a new member and have what is probably a very simplistic question.  My 
apologies in advance.

  When considering a flat, fixed sundial (not an equatorial dial) it appears 
that to get the sundial as close as possible to watch time you set it to the 
latitude and then adjust it for the longitude when laying out the hour lines.  
Having done all that, am I right in assuming that you are still at the mercy of 
the Equation of Time and will need to add/subtract minutes to the dials time to 
equal watch time?  - or is it somehow possible to adjust a flat, fixed sundial 
to incorporate the equation of time also?

  Thank you for any guidance/help you will tender.

  Sincerely,

  Duane Thomson





--
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Re: Equation of Time

[Aten Heliochronometers]

Hi Duane:

  Another way to incorporate the equation of time into a sundial is to use the 
analemma - a graphic representation of the EofT - placed on a pivoting 
surface with a gnomon/sight to produce a shadow or solar image on the analemmic 
surface - the pivot is scaled relative to a fixed, marked surface to show the 
time in standard hours/mins. during daylight.  This is generally known as a 
heliochronometer - you can see the ones I make at http://atensundials.com . I 
like this design because it is simple and one design works at any longitude and 
latitudes between 20 and 50 degrees North or South without much loss of 
accuracy at the extreme ranges.  

Cheers!
Dave G.
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Re equation of time

[dougdot]

Hello all,
As a newcomer to dialling, I would like to know 
whether the "fast" or "slow" as shown on the graph is the same for the southern 
hemisphere as for the northern hemisphere.
Doug

Re: Equation of time

[Gianni Ferrari]

Hello all,
on Sat, 4 Jan 1997 I sent a message to this list with the results of a
little research on the definition of the Equation of Time.
I send  it again (only partly) after having revised the results   (extended
to new books..)

I've  searched for EoT on many books on Sundials and on Astronomy and  I've
reached this conclusion : THERE IS E GREAT CONFUSON ON THIS SUBJECT

Let be
AT   the Local Apparent Time (often called True Time or Solar Time) (marked
by  a  Sundial)
MT   the Mean Solar Time (marked by standard clocks)

The results of my search are the following :

BOOKS ON SUNDIALS
n. 2 Italian books on Sundial   EoT=AT-MT  in
some pages and EoT=MT-AT  in others

n. 2 Italian books on Sundial   EoT=AT-MT
n. 4 Italian book  on SundialEoT=MT-AT

Rohr (It. Engl.  Editions)   EoT=MT-AT
is said that in Anglo-Saxon Countries is   EoT=AT-MT

n. 1 English  book  on SundialEoT=MT-AT
n. 1 English  book  on SundialEoT=AT-MT

n. 2 Spanish book  on SundialEoT=AT-MT

n. 3 French book  on SundialEoT=MT-AT
n. 1 French book  on SundialEoT=AT-MT

Mayall-1994 - pag. 86
Waugh -1973 - pag.201
Duffett-Smith-1979 - pag.171EoT=MT-AT

Jhon Davis -The British Sundial Society Glossary  EoT=AT-MT


ASTRONOMY BOOKS
n. 6 handbook on Spherical .Astronomy  EoT=AT-MT

Meeus-Astronomical .Algh. - pag. 171 EoT=AT-MT
In the book is said that in older  and in French texts is EoT=MT-AT

H..Mills-Positional Astronomy  EoT=AT-MT  when
Sun transits  Meridian
(Very good explanations )

Explanatory Sup. Astronomical Almanac (ESAA)  pag. 5 - 74EoT=MT-AT

Total : 30 books or documents

RESULTS:
- in Astronomy handbooks the definition  EoT=AT-MT   wins (8 to 1)
( ALSO IF THIS IS NOT IN   ESAA  !! )
This occurrence probably because in Astronomy EoT was used ( and also now is
used at sea) to determine the True (Apparent)  Time when is known the Mean
Time (from Clock)

- in books on Sundials  (21) , where EoT is used to find the Clock's
Time knowing the Sundial's one (AT), the definition EoT=MT-ATwins ( 13
to 8)

--

For the use of EoT with Sundials I suggest that is preferred the definition
EoT=MT-AT

so EoT is the correction to add to Sundial's time (AT) to obtain the Mean
Time (MT) : MT=AT+EoT
see : Duffett-Smith, ESAA, Ferrari, Mayall, Rohr, Savoie, Waugh

- the values to use for tables or graphs have to be calculated in every day
in the instant of the Meridian transit of the True Sun ( True Noon) ( for
European countries also at 12h UT)
In such a way the values in the same day in different places of the world
are not equal but the differences are small ( max. 20 sec.)  (and therefore
the tables published in the books should not be used all over the world)


Gianni Ferrari

Equation of time

[Yvon Mass]

Dear all,

I would like to know how the equation of time (EoT) is defined according to
country.
For example in France, traditionally: EoT = real time - mean time
while in USA: Eot = mean time - real time.
Could you tell me how you define the Eot in your country ?

Many thanks

Yvon

Yvon MASSE  7, rue des Tilleuls  95300 PONTOISE  FRANCE
Mél:  [EMAIL PROTECTED]

Equation of time

[Yvon Mass]

Hello all,

Ooops!... Of course, I make a mistake:

For example in France, traditionally: EoT = real time - mean time
while in USA: Eot = mean time - real time.

Please read:
For example in France, traditionally: EoT = local mean time - solar time
while in USA: Eot = solar time - local mean time.

Yvon

Re: Solar Noon Equation of Time Calculator

[Sungroup]

Oops!  Sorry about the banal error, and most grateful for all the
comments.  Fortunately nothing was carved in stone, and the sign error
has now been corrected.  

Other points:

1. The incorrect Equation of Time has now been relabelled Standard
Time Correction and it is explained that it is the sum of EOT and the
longitude correction

2.  I have learnt something about astronomy.  However, for the current
purpose we will stick with the +180 to -180 convention

3. Printing.  You have to print it landscape (not portrait) and you may
need to narrow the margins to get December on.  We cant see any way
round this one.  It is explained on the final page.

We have now reposted the pages of www.solar-noon.com, and I have sent a
further message outlining two outstanding matters concerning the
Equation of Time,  on which I would welcome views.

Many thanks to all 

Piers Nicholson

Re: Solar Noon Equation of Time Calculator

[Gianni Ferrari]

Even if, already from two centuries, in all the nations, engineers and
scientists have tried of to reach an unification of the different quantities
that are used in industry and in science and hundreds of International
Conferences have been made for adopting the same definitions all over the
world (and this for the obvious reasons of clarity in transmitting data and
results), in my opinion everyone can do as he please and choose, in his
calculations and jobs, the units that are more congenial to him and that he
prefers for traditional or  personal reasons.
If then the conversion between these personal units and those recognized
(and understood) from others  is not made, there will be some difficulties
inthe communication and in the comprehension:-)

Returning to the Longitude, also I prefer the range from -180 to +180
degrees and I  believe that this is not important because of  the
periodicity of the trigonometric functions that use these values.
For the Longitude's Sign instead, if there is some difficulties in using (in
our
writings) the IAU convention (Long. positive if East), we could not to use
the signs and speak only of  East or West Longitude
Everyone then,  for a East/West Longitude,  will put the necessary sign to
get correct results with the formulas that he uses.

Best wishes

Gianni Ferrari

Re: Solar Noon Equation of Time Calculator

[John Davis]

Hi Gianni et al,

Re. the Longitude convention: note that conventions 
are just that and, by definition, aren't right or wrong but accepted (or 
not). When I wrote the BSS Glossary, I consciously avoided using the IAU 
definition (0-360 degrees, Eastwards positive) in favour of the one almost 
universally used by diallists and navigators for four centuries (-180 to +180 
degrees, Westward positive). The astronomers can use what they like, but 
they don't rule the world and the rest of us (like Steve Lelievre) use what is 
convenient.

For the Second Edition of the Glossary (in preparation), I 
have stuck to my original definition but have added a note that the IAU one is 
different.

The other area where I (and Jean Meeus) are at odds with 
the IAU is the sign of the EoT, but that's another can of 
worms.

The key thing is to be consistent in a document and to 
make sure that the reader is given enough information to get the right 
answer.

It's clear that we could do with a term for (EoT + 
longitude correction). I didn't find a common one in my trawl through the 
literature, though the NASS Dialist's Companion uses "Total Correction" which 
seems reasonable. However, there are still chinks not defined, such as: is 
the atmospheric refraction correction included?

I quite agree that a table of the mean EoT over a long 
period (the lifetime of a sundial) is very useful as an addition to the exact 
EoT for a particular date/time. The new Glossary will include the one 
which you (Gianni) so kindly gave me.

Best regards to all,

John
--
Dr J R DavisFlowton, UK52.08N, 1.043Eemail: [EMAIL PROTECTED]

  - Original Message - 
  From: 
  Gianni 
  Ferrari 
  To: sundial@rrz.uni-koeln.de 
  Sent: 01 May 2001 16:13
  Subject: Solar Noon  Equation of 
  Time Calculator 
  Hi Piers ,I have visited with a lot of interest your Solar 
  Noon Calculator on the webat www.solar-noon.com and I have immediately 
  made some tests to compare yourvalues with those calculated from me and 
  published in an article in theproceedings of our "X Seminario 
  di Gnomonica" ( X Italian Meeting onSundials - 2000)Here are 
  some considerations of mine1)From the comparison I have 
  immediately seen that your results are wrongbecause of a banal error: 
  anywhere the value of the EoT has been or takenwith opposite sign or 
  subtracted instead that added.An example : Long. =12d E and TZ of 
  Central Europe (central Meridian 15 dEast): longitude correction =+3d = 
  +12mAt 1/1/2001 the exact value of the Eot = - 3m41s an so :- 
  Local Apparent Time (apparent solar time) = 12h- Local mean time (local 
  mean solar time) = 12h 3m 41s- Standard Time = 12 15m 41s (NASS Dialist 
  Companion gives the value, lessapproximate, 12h 15m39s )In 
  the Table calculated with the Solar Noon Calculator is written the value= 
  12h08m48s, value that is obtained adding (instead that subtracting ) 
  thevalue of the Eot: 12h+12m+(-3m12s) = 12h08m48s2)The table 
  of the EoT NOT gives the values of the EoT but the Totalcorrection that it 
  is necessary to add to the Local Apparent Time to obtainthe Standard Time 
  : it is therefore the sum of the EoT + longitudecorrection..This value 
  is certainly very useful but, perhaps, it is necessary to givesome 
  explanations and it is opportune not to call it EotMoreover in this 
  way the table with the values of noon is useless becausethese values are 
  equal to those of the EoT + 12hThe definition :"Equation of Time 
  displays the difference between solar time and thestandard times where you 
  are"(note at the foot of the page) it is not correct.Davis' Sundials 
  Glossary gives the following:Equation of Time: the time difference between 
  Local Apparent Time (apparentsolar time) and mean solar time at the same 
  location (NOT Standard Time).Its value varies between extremes of about 
  +14 minutes in February and -16minutes in October.3)Checking 
  only for the date 1/1/2001 I have found that the error between theexact 
  value and the mean value of the EoT = 3m41s -3m12s=29 sec: almost 
  thedouble of the maximum error (in the Note).With NASS Dialist 
  Companion we obtain the less approximate value Eot =3m37s: also with 
  this value the error would be of 25sDoes the greater error depend on the 
  fact that the Eot has been calculatedat 0h (UT) instead that at 12h 
  (UT)In fact the Eot can also change till 20s a day.4)In my 
  opinion it is very useful, for instance in the construction ofsundials 
  with mean time, to have a table of the mean values of the Eot (asof the 
  mean declination of the Sun), while the table that gives the 
  meanlocalnoon (mean on 4 years) can be used in a wrong 
  way.In fact these tables, that should be used only for the search of the 
  meantime from the apparent solar time given by a sundial, could be 
  consideredright also in the search of t

Solar Noon Equation of Time Calculator

[Gianni Ferrari]

Hi Piers ,
I have visited with a lot of interest your Solar Noon Calculator on the web
at www.solar-noon.com and I have immediately made some tests to compare your
values with those calculated from me and published in an article in the
proceedings of our  X Seminario di  Gnomonica ( X Italian Meeting on
Sundials - 2000)
Here are some considerations of mine

1)
From the comparison I have immediately seen that your results are wrong
because of a banal error: anywhere the value of the EoT has been or taken
with opposite sign or subtracted instead that added.
An  example : Long. =12d E and TZ of Central Europe (central Meridian 15 d
East): longitude correction =+3d = +12m
At 1/1/2001  the exact value of the Eot = - 3m41s an so :
- Local Apparent Time (apparent solar time) = 12h
- Local mean time (local mean solar time) = 12h 3m 41s
- Standard Time = 12 15m 41s (NASS Dialist Companion gives  the value, less
approximate, 12h 15m39s  )
In the Table calculated with the Solar Noon Calculator is written the value
= 12h08m48s, value that is obtained  adding (instead that subtracting ) the
value of the Eot: 12h+12m+(-3m12s) = 12h08m48s

2)
The table of the EoT NOT gives the values of the EoT but the Total
correction that it is necessary to add to the Local Apparent Time to obtain
the Standard Time : it is therefore the sum of the EoT + longitude
correction..
This value is certainly very useful but, perhaps, it is necessary to give
some  explanations and it is opportune not to call it Eot

Moreover in this way the table with the values of noon is useless because
these values are equal to those of the  EoT + 12h
The definition :
Equation of Time displays the difference between solar time and the
standard times where you are
(note at the foot of the page) it is not correct.
Davis' Sundials Glossary gives the following:
Equation of Time: the time difference between Local Apparent Time (apparent
solar time) and mean solar time at the same location (NOT Standard Time).
Its value varies between extremes of about +14 minutes in February and -16
minutes in October.

3)
Checking only for the date 1/1/2001 I have found that the error between the
exact value and the mean value of the EoT = 3m41s -3m12s=29 sec: almost the
double of the maximum error (in the Note).
With NASS Dialist Companion we obtain  the less approximate value Eot =
3m37s: also with this value the error would be of 25s
Does the greater error depend on the fact that the Eot has been calculated
at 0h (UT) instead that at 12h (UT)
In fact the Eot can also change till 20s a day.

4)
In my opinion it is very useful, for instance in the construction of
sundials with mean time, to have a table of the mean values of the Eot (as
of the mean declination of the Sun), while the table  that gives the mean
local
noon (mean on 4 years) can be used in a  wrong way.
In fact these tables, that should be used only for the search of the mean
time from  the apparent solar time given by a sundial, could be considered
right also in the search of the declination of the walls.
In this case it is better to use the true value of the EqT calculated with
programs as NASS Diallist Companion
Perhaps a note could clarify the thing.

5)
As in almost all Web sites,  also you take as positive the Longitudes for
places   West of  Greenwich.
Despite the opinion of the known astronomer J. Meeus, with which also Davis
agrees in his Sundial Glossary, even if a secular tradition justifies this
definition, it is NOT correct.
The Explanatory Supplement to the Astronomic Almanac (USNO 1992) at page 203
affirms:
The geocentric longitude is defined by the angle between the reference (or
zero) meridian and the meridian of point p, measured EASTWARD around the
Earth from 0 to 360 deg (IAU, 1983, p.47)   

Perhaps it would be opportune, at least in new programs and in new
Web sites , to use this correct definition

Best wishes

Gianni Ferrari

Re: Solar Noon Equation of Time Calculator

[Steve Lelievre]

Gianni wrote:
 As in almost all Web sites,  also you take as positive the Longitudes for
 places   West of  Greenwich.
 Despite the opinion of the known astronomer J. Meeus, with which also
Davis
 agrees in his Sundial Glossary, even if a secular tradition justifies this
 definition, it is NOT correct.
 The Explanatory Supplement to the Astronomic Almanac (USNO 1992) at page
203
 affirms:
 The geocentric longitude is defined by the angle between the reference
(or
 zero) meridian and the meridian of point p, measured EASTWARD around the
 Earth from 0 to 360 deg (IAU, 1983, p.47)   

 Perhaps it would be opportune, at least in new programs and in new
 Web sites , to use this correct definition

Just because there is a definition which professional astronomers have
adopted for their purposes, I don't see any reason to assume automatically
that it is the correct one for practical sundialling. It seems to me that
for our purposes a range -180 to +180 is more convenient than 0 to 360,
especially when trying to visualise what's going on. For instance, in the
morning the sun has a negative Hour Angle which links conveniently to the
idea that the East has less longitude than Here. Another example is that for
calculating my standard time, I can just add my longitude number and my time
zone meridian to get the adjustment required. That is, I'm at 64.50°W in the
Atlantic time zone which is -4. So I divide +64.5 degrees by 15 to get 4.3
hours and add -4, and I know I'm 0.3 hours from my TZ meridian. I'm to the
West, which is consistent with positive sense of the number I calculated.

If I treat my longitude as 295.5 measured going East, it is a harder sum. I
have to multiply my TZ meridian by 15 and subtract that from 360 to get 300,
then subtract my longitude of 295.5 to get 4.5 and divide that by 15 to get
the 0.3 final result. It is positive which fits with positive now being to
the East, so it is still consistent and the final result is the same, but it
more work mentally and thus I suspect more error prone for those of us who
are still learning or who don't work routinely with these concepts.

I'd like to know what other people think about the right convention to use.

Steve



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Try my UK Tactical Voting Wizard at
http://users.eastlink.ca/~srgl/election2001.htm

Re: Solar Noon Equation of Time Calculator

[Dave Bell]

On Tue, 1 May 2001, Steve Lelievre wrote:

 Gianni wrote:
  As in almost all Web sites,  also you take as positive the Longitudes for
  places   West of  Greenwich.

  The Explanatory Supplement to the Astronomic Almanac (USNO 1992) at page
  203 affirms:
  The geocentric longitude is defined by the angle between the reference
  (or zero) meridian and the meridian of point p, measured EASTWARD
  around the Earth from 0 to 360 deg (IAU, 1983, p.47)   

 for our purposes a range -180 to +180 is more convenient than 0 to 360,
 especially when trying to visualise what's going on. For instance, in the
 
 Steve

Steve, I agree with your point that -180 to +180 is more convenient, and
is also more common usage, I believe. However, if I understood the above
correctly, the more significant difference between your convention and
that espoused by Gianni, is that you are have positive longitude West of
the Prime Meridian, rather than East...

Dave
37.3 N 121.9 W

Re: Solar Noon Equation of Time Calculator

[Patrick Powers]

Message text written by Steve Lelievre

I'd like to know what other people think about the right convention to
use.

I don't think that it matters ONE JOT what convention is actually used so
long as the end result is correct,  explained and understandable to others
of a different persuasion.

The difference in the preferred usage of the sign of the Equation of Time
has been known for so long that we need to be able to accommodate it, not
try to change it.

It is no different to the use of different weights or temperature scales. 
There will always be those strange folk who somehow find an equally 
strange need to seek a common standard be it of units or conventions and
apply it to everyone, but there are those (whom frankly  I applaud) who
seek to solve the problem and not argue about the means by which the answer
has been obtained - even if it means using a 'less approved' system of
units or a 'different' convention.  The logical end argument for all this
is that there should be a common language amongst peoples of the world. 
What an absurd nonesense.  However I do agree that there should be defined
a 'preferred system of units' or a 'preferred convention' and perhaps a
'preferred language' for some purposes, and those who choose to use a
different one should accept that they should always explain their
calculations, views and conventions for the benefit of others.

Perhaps as an Englishman I am an 'Imperial Measures' man after all?  Yes,
for areas where it is sensible - like for much of life for most people -
even youngsters -  in the UK, I suppose I am.

Patrick

Re: Solar Noon Equation of Time Calculator

[John Schilke]

Amen!
John S

- Original Message -
From: Patrick Powers [EMAIL PROTECTED]
 Message text written by Steve Lelievre

 I'd like to know what other people think about the right convention to
 use.

 I don't think that it matters ONE JOT what convention is actually used so
 long as the end result is correct,  explained and understandable to others
 of a different persuasion.

 The difference in the preferred usage of the sign of the Equation of Time
 has been known for so long that we need to be able to accommodate it, not
 try to change it.

 It is no different to the use of different weights or temperature scales.
 There will always be those strange folk who somehow find an equally
 strange need to seek a common standard be it of units or conventions and
 apply it to everyone, but there are those (whom frankly  I applaud) who
 seek to solve the problem and not argue about the means by which the
answer
 has been obtained - even if it means using a 'less approved' system of
 units or a 'different' convention.  The logical end argument for all this
 is that there should be a common language amongst peoples of the world.
 What an absurd nonesense.  However I do agree that there should be defined
 a 'preferred system of units' or a 'preferred convention' and perhaps a
 'preferred language' for some purposes, and those who choose to use a
 different one should accept that they should always explain their
 calculations, views and conventions for the benefit of others.

 Perhaps as an Englishman I am an 'Imperial Measures' man after all?  Yes,
 for areas where it is sensible - like for much of life for most people -
 even youngsters -  in the UK, I suppose I am.

 Patrick

Solar Noon Equation of Time Calculator at www.solar-noon.com

[Sungroup]

We have just posted on the web a new Solar Noon Calculator which prints out a 
table showing the time of solar noon for your longitude for every day of the 
year on one side of a landscape A4 sheet.   It is at www.solar-noon.com.  

Please feel free to use it.  We would welcome links to it - we have a links 
page if you would like a reciprocal link.  

You can also get a printout of the Equation of Time in the same format.  

We hope this will be useful.  We would appreciate your comments.  

The page was developed as part of the Spot-On Sundial project (see 
www.spot-on-sundials.co.uk).  This sundial can be set up precisely knowing 
only the time of solar noon - when the Calculator.

Haopy dialling to all,

Piers Nicholson

 

Needed: history of equation of time

[Gordon Uber]

recommend a reference (preferably in English) on the subject?

I understand that John Flamsteed and Christiaan Huygens published tables of 
it in 1666 and 1662, respectively. If anyone has copies of these tables, 
the tables (or citations to them) would be greatly appreciated.


So far I have located G. Toomer's translation of Ptolemy's Almagest, 
which has a section on it, as does Neugebauer's History of Ancient 
Mathematical Astronomy.


I am following up on some articles in the NAWCC Bulletin.

Any help would be greatly appreciated.

Gordon

Gordon Uber   [EMAIL PROTECTED]  San Diego, California  USA
Webmaster: Clocks and Time: http://www.ubr.com/clocks

Re: Needed: history of equation of time

[John Davis]

Hi Gordon,

According to my research for the Sundial Glossary, Huygens was the first to
publish an accurate EoT table in 1665, and he republished this in his
Horologium Oscillatorium in 1673.

Flamsteed calculated the first accurate English table in 1665, when he was
only 19, but it was not published until 1669, in De Aequatione Dierum.

Unfortunately, I cannot remember easily where I came by this information.
If you get a clearer picture, I would be grateful if you would share it with
the List.

Best regards,

John
--
Dr J R Davis
Flowton, UK
52.08N, 1.043E
email: [EMAIL PROTECTED]

- Original Message -
From: Gordon Uber [EMAIL PROTECTED]
To: sundial sundial@rrz.uni-koeln.de
Sent: 27 November 2000 07:35
Subject: Needed: history of equation of time


 I have become interested in the history of the Equation of Time. Can
anyone
 recommend a reference (preferably in English) on the subject?

 I understand that John Flamsteed and Christiaan Huygens published tables
of
 it in 1666 and 1662, respectively. If anyone has copies of these tables,
 the tables (or citations to them) would be greatly appreciated.

 So far I have located G. Toomer's translation of Ptolemy's Almagest,
 which has a section on it, as does Neugebauer's History of Ancient
 Mathematical Astronomy.

 I am following up on some articles in the NAWCC Bulletin.

 Any help would be greatly appreciated.

 Gordon

 Gordon Uber   [EMAIL PROTECTED]  San Diego, California  USA
 Webmaster: Clocks and Time: http://www.ubr.com/clocks

Re: equation of time

[Arthur Carlson]

Willy Leenders [EMAIL PROTECTED] writes:

 The equation of time has two causes. The first is that the orbit of
 the earth around the sun is an ellipse and not a circle. The second
 is that the plane of the earth's equator is inclined tot the plane
 of the earth's orbit.  Please can anyone explain me the second cause
 so that I can conceive it. I am not a astronomer!

I have given this question a lot of thought, but I realized when I was
asked about it a few days ago that I am still not satisfied with my
answer.  I have tried to explain it in detail on my page
http://www.ipp.mpg.de/~Arthur.Carlson/sundial.html;, but that isn't
the intuitively obvious answer we would all like to have in order to
claim that we understand the effect.  If I had to answer in one
sentence, I might say that the effect arises because the sun moves
against the stars (in the Ptolemaic sense) on a circle (the ecliptic)
that differs from the coordinate system we use to define time (the
equatorial plane).  You can see that it is a mathematical effect, as
opposed to the physical effect of the eccentricity, by considering a
planet that does not rotate, so you can place the poles anywhere you
want.  The hour angle of the sun during the course of the year, except
at the solstices and equinoxes, will depend on your choice.

 You can do it in Dutch (for preference), in French, in German or in English.

I can offer you German, if you have trouble understanding the English.

Art Carlson