RE: Time problem

[Ross Sinclair Caldwell]

Thank you, Gian!

So it was in the "second part" of Maria Arnaldi's paper, that I stupidly did 
not read.

Perfect. I am very grateful.

Best regards,

Ross
43.349399 3.22422981
Béziers, France


De : Gian Casalegno 
Envoyé : mercredi 1 juillet 2020 18:13
À : Ross Sinclair Caldwell 
Cc : sundial list sundials 
Objet : Re: Time problem

You can find an explanation of the meaning of the hours "da campanile" i.e. "a 
half hour after" in :
https://www.academia.edu/2021256/Le_ore_italiane._Origine_e_declino_di_uno_dei_piu_importanti_sistemi_orari_del_passato_seconda_parte_
Regards,
Gian


Il giorno mer 1 lug 2020 alle ore 17:04 Ross Sinclair Caldwell 
mailto:belmu...@hotmail.com>> ha scritto:

To find some authority for the understanding that the Italian hours begin at 
the end of dusk, or about half an hour after sunset, I note that in the BBS 
Sundial Glossary under “hour plane” - “Italian” it says -


“there is some evidence in older works that Italian hours were counted from 30 
minutes after sunset.”

http://sundialsoc.org.uk/discussions/glossary-a-z/8/


Does anyone know what this evidence in older works is?


A few other places I've looked -


Wikipedia says “end of dusk, i.e. half an hour after sunset.”

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


This looked promising - Mario Arnaldi, Le ore italiane. Origine e declino di 
uno dei più importanti sistemi orari del passato (prima parte).

https://www.academia.edu/2021250/Le_ore_italiane._Origine_e_declino_di_uno_dei_piu_importanti_sistemi_orari_del_passato_prima_parte_


But he does not mention the notion of "a half hour after" (mezz'ora dopo) 
sunset  (tramonto del sole).


Ross Caldwell
43.349399 3.22422981
Béziers, France



De : sundial 
mailto:sundial-boun...@uni-koeln.de>> de la part 
de Ross Sinclair Caldwell mailto:belmu...@hotmail.com>>
Envoyé : mercredi 1 juillet 2020 16:41
À : John Davis 
mailto:john.davi...@btopenworld.com>>; Schechner, 
Sara mailto:sche...@fas.harvard.edu>>
Cc : 'sundial list sundials' mailto:sundial@uni-koeln.de>>
Objet : RE: Time problem

Hi John, Sara et al.,
My understanding is that a seasonal (or unequal) hour is a period of time ('in 
the first hour' etc) and not an instant. It is never divided up into minutes 
and so the time of 6 minutes after dawn must be referring to a time in equal 
hours, most probably measured with an astrolabe as you suggest.
I agree. All that remains unknowable is the visibilty at the time. If it were 
overcast at dawn, they must have calculated rather than observed. But I tend to 
think it was observed, and determined with an astrolabe.

Ross

De : John Davis 
mailto:john.davi...@btopenworld.com>>
Envoyé : mercredi 1 juillet 2020 10:10
À : Ross Sinclair Caldwell mailto:belmu...@hotmail.com>>; 
Schechner, Sara mailto:sche...@fas.harvard.edu>>
Cc : 'sundial list sundials' mailto:sundial@uni-koeln.de>>
Objet : RE: Time problem

Hi Sara, Ross et al,


My understanding is that a seasonal (or unequal) hour is a period of time ('in 
the first hour' etc) and not an instant. It is never divided up into minutes 
and so the time of 6 minutes after dawn must be referring to a time in equal 
hours, most probably measured with an astrolabe as you suggest.


Regards,


John

---



-- Original Message --
From: "Schechner, Sara" 
mailto:sche...@fas.harvard.edu>>
To: "Ross Sinclair Caldwell" mailto:belmu...@hotmail.com>>
Cc: "'sundial list sundials'" 
mailto:sundial@uni-koeln.de>>
Sent: Tuesday, 30 Jun, 20 At 21:20
Subject: RE: Time problem


>>> In short, I am researching the biography of Filippo Maria Visconti 
>>> (1392-1447), duke of Milan, and you probably know that these Italian 
>>> princes relied heavily on astrology. So, Visconti's time of birth is known 
>>> precisely - "six minutes after sunrise," Monday, 23 September, 1392. His 
>>> natal chart was of course produced and interpreted, but it has been lost. I 
>>> am trying to recreate it as it might have been done by a court astrologer 
>>> of the time.<<<

I have some thoughts about ascertaining the time of “6 minutes after sunrise” 
in 1392 in Milan.

First of all, Milan is one of the earliest towns to have a public tower clock 
in the 14th century, but it would only strike and show hours according to local 
solar time. It would not be divided into minutes. It was not reliable enough 
for such a horological chart.

Sundials would be the more commonly used timepiece, but the six-minutes is an 
unusual amount of precision. My guess is that the court astronomer was using an 
astrolabe, which can be divided into units in the range of 4-6 minutes. Many 
also had arcs for the astrological houses and for both 

RE: Time problem

[Ross Sinclair Caldwell]

Hi Sara,

There will be local customs but the technical time, taken from the Latin 
description of the hours is that Italian hours were counted from sunset and 
Babylonian hours from sunrise.  There is no mention of dusk.

Indeed, I find that technical definition with no mention of dusk, but I also 
keep coming across the “half hour after” description as well, not only in the 
BBS glossary. This is the assertion of Dohrn-van Rossum that I am trying to 
find authority for, since he cites none (it is not in Galvano Fiamma, who only 
describes the clock in Milan in 1336).


In what is presumably the oldest Italian form of hour-reckoning, unequivocally 
attested for the first time by Galvano Fiamma, the twenty-four hours were 
counted through from one evening – more precisely: one half-hour after sundown 
– to the evening of the following day. The twenty-fourth hour was the last hour 
of daytime. The only linkage to daylight has to do with timing the point at 
which the counting begins in the evening.

(Gerhard Dohrn-van Rossum, History of the Hour: Clocks and Modern Temporal 
Orders (UChicago Press, 1996 (translation of Die Geschichte der Stunde: Uhren 
und moderne Zeitordnungen. München-Wien, Carl Hansen Verlag, 1992, p. 114))


So Riccardo Anselmi, in the “Piccolo glossario” to his sundial page ( 
http://sundials.anselmi.vda.it/ ) says, with you, “in some cases” it is half an 
hour after sunset -


Ore Italiche, sistema di suddivisione del tempo che viene misurato dal tramonto 
del sole o, in taluni casi, mezz’ora dopo il tramonto.


http://sundials.anselmi.vda.it/MyPage_GenericPage2_Italiano.htm


In the Italian wikipedia page for Ora italica, 
https://it.wikipedia.org/wiki/Ora_italica , they define Italian hours as the 
method by which


...la giornata era divisa in 24 ore della stessa durata, che venivano numerate 
a partire da mezz'ora dopo il tramonto (quando le campane suonavano l'Ave 
Maria).
So here it is connected to the bell ringing the Ave Maria prayer time (I have 
read elsewhere it was for the Angelus, or maybe they were synonymous, since the 
Angelus consists of three statements about the Annunciation each followed by an 
Ave Maria).

In the last paragraph of the page, they cite an episode in Alessandro Manzoni's 
1827 novel I promessi sposi, set in 1628, in which the character Renzo 
describes being awakened when the clock rang eleven times. The wikipedia 
editors calculate from his description that it was on 13 November, and go on to 
say that the sun set at 16:55 CET, or at 16:32 local time. A half-hour after 
this, around 17:00 local time, the bell would have rung the Ave Maria. 
Therefore “eleven strikes” means four in the morning our time.


So it would seem that Milan was one of those “sometimes,” or local places that 
used the half-hour after sunset, or end of dusk, rule.


Best regards,


Ross

43.349399 3.22422981
Béziers, France



De : Schechner, Sara 
Envoyé : mercredi 1 juillet 2020 17:41
À : Ross Sinclair Caldwell 
Cc : 'sundial list sundials' 
Objet : RE: Time problem


There will be local customs but the technical time, taken from the Latin 
description of the hours is that Italian hours were counted from sunset and 
Babylonian hours from sunrise.  There is no mention of dusk.



Sara Schechner

Author of Time of Our Lives: Sundials at the Adler Planetarium



From: sundial  On Behalf Of Ross Sinclair Caldwell
Sent: Wednesday, July 01, 2020 11:04 AM
Cc: 'sundial list sundials' 
Subject: RE: Time problem



To find some authority for the understanding that the Italian hours begin at 
the end of dusk, or about half an hour after sunset, I note that in the BBS 
Sundial Glossary under “hour plane” - “Italian” it says -



“there is some evidence in older works that Italian hours were counted from 30 
minutes after sunset.”

http://sundialsoc.org.uk/discussions/glossary-a-z/8/<https://urldefense.proofpoint.com/v2/url?u=http-3A__sundialsoc.org.uk_discussions_glossary-2Da-2Dz_8_=DwMF-g=WO-RGvefibhHBZq3fL85hQ=7ZsgDX5inZSMERqhZEQacOtdADP0iy6-YB7dx6Z_mVo=UVmfG-Lwit5L4Etra9dngAhE7-_MBgKCK6nhJjl2zNk=Otrt5JkuLSHGmLmV5ku8B4qjZc9bNH8XXWwN7M-P4s4=>



Does anyone know what this evidence in older works is?



A few other places I've looked -



Wikipedia says “end of dusk, i.e. half an hour after sunset.”

https://en.wikipedia.org/wiki/Hour<https://urldefense.proofpoint.com/v2/url?u=https-3A__en.wikipedia.org_wiki_Hour=DwMF-g=WO-RGvefibhHBZq3fL85hQ=7ZsgDX5inZSMERqhZEQacOtdADP0iy6-YB7dx6Z_mVo=UVmfG-Lwit5L4Etra9dngAhE7-_MBgKCK6nhJjl2zNk=e9M1Wr7ky9nfDOfVM5T1hGV6XkG6oMzk2v92ms6AwfQ=>



This looked promising - Mario Arnaldi, Le ore italiane. Origine e declino di 
uno dei più importanti sistemi orari del passato (prima parte).

https://www.academia.edu/2021250/Le_ore_italiane._Origine_e_declino_di_uno_dei_piu_importanti_sistemi_orari_del_passato_prima_parte_<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.academia.edu_2021250_Le-5Fore-5Fital

RE: Time problem

[Ross Sinclair Caldwell]

To find some authority for the understanding that the Italian hours begin at 
the end of dusk, or about half an hour after sunset, I note that in the BBS 
Sundial Glossary under “hour plane” - “Italian” it says -


“there is some evidence in older works that Italian hours were counted from 30 
minutes after sunset.”

http://sundialsoc.org.uk/discussions/glossary-a-z/8/


Does anyone know what this evidence in older works is?


A few other places I've looked -


Wikipedia says “end of dusk, i.e. half an hour after sunset.”

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


This looked promising - Mario Arnaldi, Le ore italiane. Origine e declino di 
uno dei più importanti sistemi orari del passato (prima parte).

https://www.academia.edu/2021250/Le_ore_italiane._Origine_e_declino_di_uno_dei_piu_importanti_sistemi_orari_del_passato_prima_parte_


But he does not mention the notion of "a half hour after" (mezz'ora dopo) 
sunset  (tramonto del sole).


Ross Caldwell
43.349399 3.22422981
Béziers, France



De : sundial  de la part de Ross Sinclair 
Caldwell 
Envoyé : mercredi 1 juillet 2020 16:41
À : John Davis ; Schechner, Sara 

Cc : 'sundial list sundials' 
Objet : RE: Time problem

Hi John, Sara et al.,
My understanding is that a seasonal (or unequal) hour is a period of time ('in 
the first hour' etc) and not an instant. It is never divided up into minutes 
and so the time of 6 minutes after dawn must be referring to a time in equal 
hours, most probably measured with an astrolabe as you suggest.
I agree. All that remains unknowable is the visibilty at the time. If it were 
overcast at dawn, they must have calculated rather than observed. But I tend to 
think it was observed, and determined with an astrolabe.

Ross

De : John Davis 
Envoyé : mercredi 1 juillet 2020 10:10
À : Ross Sinclair Caldwell ; Schechner, Sara 

Cc : 'sundial list sundials' 
Objet : RE: Time problem

Hi Sara, Ross et al,


My understanding is that a seasonal (or unequal) hour is a period of time ('in 
the first hour' etc) and not an instant. It is never divided up into minutes 
and so the time of 6 minutes after dawn must be referring to a time in equal 
hours, most probably measured with an astrolabe as you suggest.


Regards,


John

---



-- Original Message --
From: "Schechner, Sara" 
To: "Ross Sinclair Caldwell" 
Cc: "'sundial list sundials'" 
Sent: Tuesday, 30 Jun, 20 At 21:20
Subject: RE: Time problem


>>> In short, I am researching the biography of Filippo Maria Visconti 
>>> (1392-1447), duke of Milan, and you probably know that these Italian 
>>> princes relied heavily on astrology. So, Visconti's time of birth is known 
>>> precisely - "six minutes after sunrise," Monday, 23 September, 1392. His 
>>> natal chart was of course produced and interpreted, but it has been lost. I 
>>> am trying to recreate it as it might have been done by a court astrologer 
>>> of the time.<<<

I have some thoughts about ascertaining the time of “6 minutes after sunrise” 
in 1392 in Milan.

First of all, Milan is one of the earliest towns to have a public tower clock 
in the 14th century, but it would only strike and show hours according to local 
solar time. It would not be divided into minutes. It was not reliable enough 
for such a horological chart.

Sundials would be the more commonly used timepiece, but the six-minutes is an 
unusual amount of precision. My guess is that the court astronomer was using an 
astrolabe, which can be divided into units in the range of 4-6 minutes. Many 
also had arcs for the astrological houses and for both equal and unequal hours. 
The actual time might have been taken from a bright star still visible in the 
dawn.

It is also worth considering what this 6-minutes after dawn really means. Is 
the astrologer using unequal hours which were still more common in these early 
days of clocks? If so, then six minutes would be equal to 1/10 of the first 
hour on that day of the year—i.e., 1/10 of 1/12 of the length of daylight.

Lastly, in reconstructing a horoscope, one needs to know the position of the 
planets to place them on the chart. Some might be observed, but mostly they are 
taken from a table. These varied in different manuscript traditions. Do we have 
a clue what table the astrologer was using?

Good luck with your project.

Sara

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: 617-495-3344

sche...@fas.harvard.edu<mailto:sche...@fas.harvard.edu> | @SaraSchechner

http://scholar.harvard.edu/saraschechner

http://chsi.harvard.edu/

__

RE: Time problem

[Ross Sinclair Caldwell]

Hi John, Sara et al.,
My understanding is that a seasonal (or unequal) hour is a period of time ('in 
the first hour' etc) and not an instant. It is never divided up into minutes 
and so the time of 6 minutes after dawn must be referring to a time in equal 
hours, most probably measured with an astrolabe as you suggest.
I agree. All that remains unknowable is the visibilty at the time. If it were 
overcast at dawn, they must have calculated rather than observed. But I tend to 
think it was observed, and determined with an astrolabe.

Ross

De : John Davis 
Envoyé : mercredi 1 juillet 2020 10:10
À : Ross Sinclair Caldwell ; Schechner, Sara 

Cc : 'sundial list sundials' 
Objet : RE: Time problem

Hi Sara, Ross et al,


My understanding is that a seasonal (or unequal) hour is a period of time ('in 
the first hour' etc) and not an instant. It is never divided up into minutes 
and so the time of 6 minutes after dawn must be referring to a time in equal 
hours, most probably measured with an astrolabe as you suggest.


Regards,


John

---



-- Original Message --
From: "Schechner, Sara" 
To: "Ross Sinclair Caldwell" 
Cc: "'sundial list sundials'" 
Sent: Tuesday, 30 Jun, 20 At 21:20
Subject: RE: Time problem


>>> In short, I am researching the biography of Filippo Maria Visconti 
>>> (1392-1447), duke of Milan, and you probably know that these Italian 
>>> princes relied heavily on astrology. So, Visconti's time of birth is known 
>>> precisely - "six minutes after sunrise," Monday, 23 September, 1392. His 
>>> natal chart was of course produced and interpreted, but it has been lost. I 
>>> am trying to recreate it as it might have been done by a court astrologer 
>>> of the time.<<<

I have some thoughts about ascertaining the time of “6 minutes after sunrise” 
in 1392 in Milan.

First of all, Milan is one of the earliest towns to have a public tower clock 
in the 14th century, but it would only strike and show hours according to local 
solar time. It would not be divided into minutes. It was not reliable enough 
for such a horological chart.

Sundials would be the more commonly used timepiece, but the six-minutes is an 
unusual amount of precision. My guess is that the court astronomer was using an 
astrolabe, which can be divided into units in the range of 4-6 minutes. Many 
also had arcs for the astrological houses and for both equal and unequal hours. 
The actual time might have been taken from a bright star still visible in the 
dawn.

It is also worth considering what this 6-minutes after dawn really means. Is 
the astrologer using unequal hours which were still more common in these early 
days of clocks? If so, then six minutes would be equal to 1/10 of the first 
hour on that day of the year—i.e., 1/10 of 1/12 of the length of daylight.

Lastly, in reconstructing a horoscope, one needs to know the position of the 
planets to place them on the chart. Some might be observed, but mostly they are 
taken from a table. These varied in different manuscript traditions. Do we have 
a clue what table the astrologer was using?

Good luck with your project.

Sara

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: 617-495-3344

sche...@fas.harvard.edu<mailto:sche...@fas.harvard.edu> | @SaraSchechner

http://scholar.harvard.edu/saraschechner

http://chsi.harvard.edu/


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



Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor 
http://sundialsoc.org.uk/publications/the-bss-bulletin/<http://www.sundialsoc.org.uk/bulletin.php>

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

RE: Time problem

[Ross Sinclair Caldwell]

Hi Sara, thank you for your comments.

First of all, Milan is one of the earliest towns to have a public tower clock 
in the 14th century, but it would only strike and show hours according to local 
solar time.  It would not be divided into minutes.  It was not reliable enough 
for such a horological chart. ... My guess is that the court astronomer was 
using an astrolabe, which can be divided into units in the range of 4-6 
minutes.  Many also had arcs for the astrological houses and for both equal and 
unequal hours.  The actual time might have been taken from a bright star still 
visible in the dawn.
I agree that his astrologers would not have counted minutes by the clock. Venus 
was indeed far enough from the Sun to be clear at dawn, presuming it were a 
clear day.

Is the astrologer using unequal hours which were still more common in these 
early days of clocks?

I can't answer that with certainty. My guess would be equal hours, since 
astronomers had no practical use to distinguish between daylight and nighttime 
hours, but would want a consistent system throughout for their calculations.

I am sure I can find the answer, though.

Do we have a clue what table the astrologer was using?

We know the textbooks used at Pavia, where the first Lectureship of Astrology 
was established, so it should be easy to find out. Monica Azzolini, who has 
written on astrology in the time of Visconti and Sforza rule of Milan, compares 
modern values to the Alfonsine Tables when she discusses Galeazzo Maria 
Sforza's chart, so I assume that those tables were standard, and I won't go 
wrong using them. A Swedish physicist, Lars Gislén, has produced spreadsheets 
to calculate various pre-modern astronomical data, including by the Alfonsine 
Tables . His homepage http://home.thep.lu.se/~larsg/Site/Welcome.html
At "Download my applications," http://home.thep.lu.se/~larsg/Site/download.html 
, scroll down to "Astromodels" to get all of the Excel spreadsheets if you want 
to try them out. He has Ptolemy Almagest, two Arab astronomers, Toledan, and 
Alfsono.

Thanks for your interest. I'll share my final result with you before daring to 
publish it. I would be interested to know more about the methods of astrologers 
in the 14th-15th centuries in Milan, including astrolabes, which is John Davis' 
specialty.

Best regards,

Ross Caldwell
43.349399 3.22422981
Béziers, France

De : Schechner, Sara 
Envoyé : mardi 30 juin 2020 22:20
À : Ross Sinclair Caldwell 
Cc : 'sundial list sundials' 
Objet : RE: Time problem


>>> In short, I am researching the biography of Filippo Maria Visconti 
>>> (1392-1447), duke of Milan, and you probably know that these Italian 
>>> princes relied heavily on astrology. So, Visconti's time of birth is known 
>>> precisely - "six minutes after sunrise," Monday, 23 September, 1392. His 
>>> natal chart was of course produced and interpreted, but it has been lost. I 
>>> am trying to recreate it as it might have been done by a court astrologer 
>>> of the time.<<<



I have some thoughts about ascertaining the time of “6 minutes after sunrise” 
in 1392 in Milan.



First of all, Milan is one of the earliest towns to have a public tower clock 
in the 14th century, but it would only strike and show hours according to local 
solar time.  It would not be divided into minutes.  It was not reliable enough 
for such a horological chart.



Sundials would be the more commonly used timepiece, but the six-minutes is an 
unusual amount of precision.  My guess is that the court astronomer was using 
an astrolabe, which can be divided into units in the range of 4-6 minutes.  
Many also had arcs for the astrological houses and for both equal and unequal 
hours.  The actual time might have been taken from a bright star still visible 
in the dawn.



It is also worth considering what this 6-minutes after dawn really means.  Is 
the astrologer using unequal hours which were still more common in these early 
days of clocks?  If so, then six minutes would be equal to 1/10 of the first 
hour on that day of the year—i.e., 1/10 of 1/12 of the length of daylight.



Lastly, in reconstructing a horoscope, one needs to know the position of the 
planets to place them on the chart.  Some might be observed, but mostly they 
are taken from a table.  These varied in different manuscript traditions.  Do 
we have a clue what table the astrologer was using?



Good luck with your project.



Sara



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: 617-495-3344

sche...@fas.harvard.edu<mailto:sche...@fas.harvard.edu>  | @SaraSchechner

http://scholar.harvard

RE: Time problem

[Ross Sinclair Caldwell]

Hi Jack,

Thanks for thinking about this problem.

It isn't the clock time, in any system, that matters here. The biographer - 
Pier Candido Decembrio - reports only that it was six minutes after sunrise. So 
all that matters is to determine when sunrise was, by any system we can, in 
order to be able to put the data into an astronomy program or a helpful 
spreadsheet using medieval values, like Lars Gislén's "Astromodels" for the 
Alfonsine Tables, which those astrologers probably used. 
http://home.thep.lu.se/~larsg/Site/download.html

The problem I encounter is that two very apparently reliable sources give 
different times for the sunrise from Milan on that day, once the date is 
corrected to Gregorian and given a Julian day.

The NOAA site gives 06:22 CET, the program Stellarium gives 06:00. On 
Stellarium, today I went back year by year, and noticed that they not only 
automatically switch to Julian calendar before 15 October 1582, but also make a 
change in  times in the year 1847. In both Béziers, where I live, and Milan, 
sunrise for 1 October is 07:22 (what is the historical basis for this 
additional hour?) in 1848, but goes to 06:00 in 1847 and all the years thence 
back to 1583 (within a minute or so, for the quarter days leading to a leap 
year). In 1582, 1 October sunrise in Milan is 06:12, so you have to know to 
change to the Julian calendar date of 23 September to get the right sunrise, 
which is 06:01.

Hank showed from the "old" NOAA Earth System Research Lab page 
https://www.esrl.noaa.gov/gmd/grad/solcalc/sunrise.html that putting in the 
data with the UTC offset at +0.61 for Milan (-0.61 for American users) at that 
longitude produced the "correct" time at 05:58, so with a few more decimals it 
would be within a minute of the Stellarium and YourSky programs (which 
rigorously uses Meeus, I believe).

I am leaning to a 06:00 as the consensus.

Ross



De : Jack Aubert 
Envoyé : mardi 30 juin 2020 15:31
À : 'Ross Sinclair Caldwell' ; 'Michael Ossipoff' 

Cc : 'sundial list sundials' 
Objet : RE: Time problem


I have been thinking about this problem but I may not be understanding it 
correctly.  I think you want to find out what time sunrise was on September 23 
in 1392.  Because of the change from Julian to Gregorian dates, this 
corresponds to our October 1.  On October 1, a real clock in Milan this year 
would not tell quite the same time as a municipal clock in 1392, though.



We can easily correct for daylight saving time.  The second thing to consider 
would be the equation of time.  But it has changed very little between 1329 and 
now, so sunrise on October 1 1329 in Milan should be almost the same time as it 
is now, so if you could transport a modern clock to Milan in 1329, it would 
show sunrise at very close to the same time as it does now.  But this would not 
necessarily be the case in 1392.  At that time, clocks would normally not take 
the equation of time into account at all.  Since they were not very accurate 
over an extended period, they would have had to be adjusted frequently using a 
sundial.  So the municipal clock would probably have shown noon at what we 
would call 12:11.  It is possible that a clock used by an astronomer might make 
the adjustment using a contemporaneous equation of time table (which would have 
been less accurate than our calculation) but this seems unlikely.



The other thing to take into account is Milan's longitude.  At 9.11 degrees 
East, Milan is six degrees from the 15 degree time zone center, for a clock 
offset of 24 minutes.   So a calculation for modern civil time at that location 
should include both the longitude and equation of time.  A calculation of 
contemporary civil time would obviously not have included a time zone offset, I 
think, should not have included the equation of time either.



It sounds to me as if the programs may be handling the longitude offset, and 
possibly the equation of time differently.



Does this make sense?



Jack Aubert



From: sundial  On Behalf Of Ross Sinclair Caldwell
Sent: Monday, June 29, 2020 2:06 PM
To: Michael Ossipoff 
Cc: sundial list sundials 
Subject: RE: Time problem



Yes, but I don't know if any estimation of refraction or diameter would account 
for 20 minutes!



In any case, the real time is scarcely relevant - they only wanted to say that 
it was shortly after sunrise, sufficiently so that the Sun  was estimated to be 
clear of the horizon.



The clock they used only matters for the calculation of minutes, which with a 
24-hour clock, however calibrated, would be the same as ours for all practical 
purposes.



The biographer doesn't give the time in clock time, only minutes after sunrise. 
This is why I want to know what that is. The true time of his birth is 
absolutely irrelevant; we only need to know what they believed, and interpreted 
from that belief.



Ross



De : Mic

RE: Time problem

[Ross Sinclair Caldwell]

Yes, but I don't know if any estimation of refraction or diameter would account 
for 20 minutes!

In any case, the real time is scarcely relevant - they only wanted to say that 
it was shortly after sunrise, sufficiently so that the Sun  was estimated to be 
clear of the horizon.

The clock they used only matters for the calculation of minutes, which with a 
24-hour clock, however calibrated, would be the same as ours for all practical 
purposes.

The biographer doesn't give the time in clock time, only minutes after sunrise. 
This is why I want to know what that is. The true time of his birth is 
absolutely irrelevant; we only need to know what they believed, and interpreted 
from that belief.

Ross

De : Michael Ossipoff 
Envoyé : lundi 29 juin 2020 19:31
À : Ross Sinclair Caldwell 
Cc : sundial list sundials 
Objet : Re: Time problem

Okay, but there's the inaccuracy of the clocks in those days, and the 
importance of that would depend on how they determined Sunrise. I guess they 
set the clocks by sundial or noon-mark, but, as you said, it depends on how 
often they set them.

Anyway, the difference between the NOAA Sunrise-time, and the one calculated by 
the planetarium-programs could result from the planetarium-programs not taking 
into account the changes in orbit or obliquity.  I'd expect that the NOAA 
figure would be more reliable.

Sunrise & Sunset times are usually calculated using a standard value for 
atmospheric refraction at the horizon. The usual assumption is that the 
refraction is 34 minutes and that the Sun's apparent semi-diameter is 16 
minutes. Maybe NOAA used a calculated semi-diameter instead of the standard 16 
minutes.

You don't have sufficiently reliably accurate information for a horoscope 
accurate to the minute, and another reason for that is that unusual atmospheric 
refractivity could change Sunrise-time by minutes.

Michael



On Mon, Jun 29, 2020 at 1:09 PM Ross Sinclair Caldwell 
mailto:belmu...@hotmail.com>> wrote:

Hi Michael,

Also, when they said that he was born a certain number of minutes after 
Sunrise, how did they determine that? By judging when it seemed to be Sunrise, 
when the Sun appeared over the trees, mountains or buildings, or by calculating 
Sunrise-time based on a 14th century estimate of Milan's longiitude?  And were 
they minutes of equal-hours time, or of temporary-hours time?
I can answer some of those questions with reasonable certainty.

For minutes, they used an equal-hour 24 hour clock, beginning a half-hour after 
sunset the previous day. That is, the clock would strike "1" at, say, at our 
20:45 on that particular day (30 September Gregorian). Of course it was 
constantly adjusted, with what frequency I don't know. Obviously it depended on 
the season, but there must have also been a regular schedule of maintenance for 
the mechanism. I don't know if an example of such a schedule survives from any 
of these early clocks, since Europe generally moved to the equal-hour 24-hour 
day starting at midnight in the sixteenth century.

For sunrise, it is a flat view east of Milan, and the part of the castle where 
he is reported to have been born was one of the highest places in the city. 
From the top of one of the four corner towers, you would see clear to the 
eastern horizon. But it is possible they made a calculation rather than an 
observation, and so perhaps it was theoretical rather than observed, even if 
they used an hourglass with minutes we would recognize. Even if it were a 
cloudy morning, they knew what time the sun rose.

For what value it had, the propaganda, since he was the second son, he was not 
expected to inherit the throne, so there was less reason to fudge the data to 
make him appear better than he was. The day of birth was a public announcement; 
the time was apparently a closely guarded secret, since astrology could be a 
political weapon.

Ross

De : Michael Ossipoff mailto:email9648...@gmail.com>>
Envoyé : lundi 29 juin 2020 18:39
À : Ross Sinclair Caldwell mailto:belmu...@hotmail.com>>
Cc : sundial list sundials mailto:sundial@uni-koeln.de>>
Objet : Re: Time problem

Of course, even if the Earth's orbit didn't change, no civil calendar keeps a 
constant relation between date and ecliptic-longitude.  So you'd have to 
determine the calendar's date-ecliptic-longitude displacement for the date of 
interest.
.
But the Earth's orbit does change. Our orbit's eccentricity, and the relation 
between the apsides and the equinoxes have been steadily changing since the 
14th century. ...as has the obliquity of the ecliptic.
.
Might some of the commercially-available planetarium-programs disregard that? 
Sure. At least some of those programs ignore changes in the precessional-rate, 
so why expect them to take into account the changing eccentricity, 
apsides/equinoxes relation, and obliquity of the ecliptic?
.
Also, when they 

RE: Time problem

[Ross Sinclair Caldwell]

Hi Michael,

Also, when they said that he was born a certain number of minutes after 
Sunrise, how did they determine that? By judging when it seemed to be Sunrise, 
when the Sun appeared over the trees, mountains or buildings, or by calculating 
Sunrise-time based on a 14th century estimate of Milan's longiitude?  And were 
they minutes of equal-hours time, or of temporary-hours time?
I can answer some of those questions with reasonable certainty.

For minutes, they used an equal-hour 24 hour clock, beginning a half-hour after 
sunset the previous day. That is, the clock would strike "1" at, say, at our 
20:45 on that particular day (30 September Gregorian). Of course it was 
constantly adjusted, with what frequency I don't know. Obviously it depended on 
the season, but there must have also been a regular schedule of maintenance for 
the mechanism. I don't know if an example of such a schedule survives from any 
of these early clocks, since Europe generally moved to the equal-hour 24-hour 
day starting at midnight in the sixteenth century.

For sunrise, it is a flat view east of Milan, and the part of the castle where 
he is reported to have been born was one of the highest places in the city. 
From the top of one of the four corner towers, you would see clear to the 
eastern horizon. But it is possible they made a calculation rather than an 
observation, and so perhaps it was theoretical rather than observed, even if 
they used an hourglass with minutes we would recognize. Even if it were a 
cloudy morning, they knew what time the sun rose.

For what value it had, the propaganda, since he was the second son, he was not 
expected to inherit the throne, so there was less reason to fudge the data to 
make him appear better than he was. The day of birth was a public announcement; 
the time was apparently a closely guarded secret, since astrology could be a 
political weapon.

Ross

De : Michael Ossipoff 
Envoyé : lundi 29 juin 2020 18:39
À : Ross Sinclair Caldwell 
Cc : sundial list sundials 
Objet : Re: Time problem

Of course, even if the Earth's orbit didn't change, no civil calendar keeps a 
constant relation between date and ecliptic-longitude.  So you'd have to 
determine the calendar's date-ecliptic-longitude displacement for the date of 
interest.
.
But the Earth's orbit does change. Our orbit's eccentricity, and the relation 
between the apsides and the equinoxes have been steadily changing since the 
14th century. ...as has the obliquity of the ecliptic.
.
Might some of the commercially-available planetarium-programs disregard that? 
Sure. At least some of those programs ignore changes in the precessional-rate, 
so why expect them to take into account the changing eccentricity, 
apsides/equinoxes relation, and obliquity of the ecliptic?
.
Also, when they said that he was born a certain number of minutes after 
Sunrise, how did they determine that? By judging when it seemed to be Sunrise, 
when the Sun appeared over the trees, mountains or buildings, or by calculating 
Sunrise-time based on a 14th century estimate of Milan's longiitude?  And were 
they minutes of equal-hours time, or of temporary-hours time?
.
Michael Ossipoff





On Mon, Jun 29, 2020 at 5:23 AM Ross Sinclair Caldwell 
mailto:belmu...@hotmail.com>> wrote:
Hi diallists,

This is not a sundial problem, but a time discrepancy I don't understand 
between NOAA sunrise calculations and the results of two reliable planetarium 
programs, Stellarium and YourSky (part of HomePlanet). http://stellarium.org/  
https://www.fourmilab.ch/yoursky/ https://www.fourmilab.ch/homeplanet/

In short, I am researching the biography of Filippo Maria Visconti (1392-1447), 
duke of Milan, and you probably know that these Italian princes relied heavily 
on astrology. So, Visconti's time of birth is known precisely - "six minutes 
after sunrise," Monday, 23 September, 1392. His natal chart was of course 
produced and interpreted, but it has been lost. I am trying to recreate it as 
it might have been done by a court astrologer of the time.

First step - get the Gregorian equivalent, and the Julian day. This is 1 
October 1392 Gregorian, which is Julian day 2229751.5 (".5" because Julian days 
start on noon, and the .5 represents midnight, the beginning of 23 September 
Julian/1 October Gregorian).

Now, both Stellarium and YourSky automatically correct for the change from 
Julian calendar to Gregorian. That is, if you look at the sky for 15 October 
1582, and then go back one day, the calendar reads 4 October 1582. This was the 
change mandated by Pope Gregory, that Thursday 4 October 1582 would be followed 
Friday 15 October 1582.

So, there is no need to use 1 October 1392 for my purposes - both programs read 
23 September as Julian day 2229751.5(etc).

These programs give the sunrise in Milan on that date at 06:00 and 05:59 
respectively. Obviously they use an ideal horizon, but t

Time problem

[Ross Sinclair Caldwell]

Hi diallists,

This is not a sundial problem, but a time discrepancy I don't understand 
between NOAA sunrise calculations and the results of two reliable planetarium 
programs, Stellarium and YourSky (part of HomePlanet). http://stellarium.org/  
https://www.fourmilab.ch/yoursky/ https://www.fourmilab.ch/homeplanet/

In short, I am researching the biography of Filippo Maria Visconti (1392-1447), 
duke of Milan, and you probably know that these Italian princes relied heavily 
on astrology. So, Visconti's time of birth is known precisely - "six minutes 
after sunrise," Monday, 23 September, 1392. His natal chart was of course 
produced and interpreted, but it has been lost. I am trying to recreate it as 
it might have been done by a court astrologer of the time.

First step - get the Gregorian equivalent, and the Julian day. This is 1 
October 1392 Gregorian, which is Julian day 2229751.5 (".5" because Julian days 
start on noon, and the .5 represents midnight, the beginning of 23 September 
Julian/1 October Gregorian).

Now, both Stellarium and YourSky automatically correct for the change from 
Julian calendar to Gregorian. That is, if you look at the sky for 15 October 
1582, and then go back one day, the calendar reads 4 October 1582. This was the 
change mandated by Pope Gregory, that Thursday 4 October 1582 would be followed 
Friday 15 October 1582.

So, there is no need to use 1 October 1392 for my purposes - both programs read 
23 September as Julian day 2229751.5(etc).

These programs give the sunrise in Milan on that date at 06:00 and 05:59 
respectively. Obviously they use an ideal horizon, but the view east from Milan 
is flat, so there is nothing delaying the appearance of the sun.

Now,, when you go to NOAA's Solar Calculator, they use straight Gregorian 
dates. That is, you can get sunrise times for 5, 6, 7, etc. up to 14 October, 
1582. So you have to use the Gregorian equivalent of 23 September 1392, which 
is 1 October. https://www.esrl.noaa.gov/gmd/grad/solcalc/

They give the sunrise time as 06:22 on 1 October 1392. If you are in doubt 
about the Gregorian/Julian switch, they give the time on 23 September as 06:12. 
Neither is in agreement, in any case, with the astronomy programs.

Now, the difference between 1392 and today should be negligible in any case. We 
can just as well use this year's 1 October for the time of sunrise. Of course, 
it is 06:22 (or 07:22 since in 2020 Italy uses daylight saving time).

In order to get a sunrise time of 06:22 on Stellarium, I have to push the date 
to 11 October.

The problem is that both NOAA and the astronomy programs are right for me for 
sunrise and sunset in Béziers today (within a minute).

So, the astronomy programs are apparently wrong for the 1392 date. This is not 
really ancient, so I wonder if anyone could suggest to me why it might be that 
there is 22 minutes' difference between these programs and the NOAA data for 
the same date?

Thank you for any thoughts that anyone might have.

Ross Caldwell
43.349399 3.22422981
Béziers
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RE: A Happy Leap Year Day to everyone

[Ross Sinclair Caldwell]

Thank you for that reminder, Frank!

I will be the first to say that it made me learn something. 

I live in France, but I can tell you that no one, in a quick survey of a half 
dozen people, could explain what, literally, "bissextile" actually refers to in 
the calendar, except that it is the leap year.

How is it abbreviated differently, then, from "a. d. VI Kal Mar"? Perhaps with 
a "bis" added after the VI, or "diem"? (i.e. "a. d. VI bis Kal Mar", or "a. d. 
bis VI Kal Mar")

I will henceforth adopt your erudite custom on the 24th of February of leap 
years, in order to stimulate conversation and love of learning.

Ross Caldwell
Béziers, France 


De : sundial  de la part de Frank King 

Envoyé : mercredi 24 février 2016 09:11
À : Sundial Mailing List
Objet : A Happy Leap Year Day to everyone

Dear All,

As is my four-yearly custom, I wish readers of
this list a Happy Leap Year Day.

I was delighted, in 2012, when I sent out a
similar greeting, that not a single reader
queried why I had sent out the message on
24 February.

I will add my four-yearly lament that the
perfectly good English term "bissextile year"
seems to be almost obsolete.  Around 100 years
ago it was in fairly common use.

I continue to applaud the French, the Italians
and the Portuguese (just to give three examples)
who still use année bissextile, anno bisestile
and ano bissexto.

Let us hope that they do not indulge in the
dumbing-down from which we in the U.K. seem
to suffer.

Frank King
Cambridge, U.K.




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3500 year old Egyptian sundial uncovered (with photo)

[Ross Sinclair Caldwell]

From the Egyptologist's Electronic Forum 
-http://www.egyptologyforum.org/EEFCharter.html* Press report: One of the 
world's oldest sun dials dug up
in Valley of the Kings (with photo)

http://www.heritagedaily.com/2013/03/one-of-the-worlds-oldest-sun-dial-dug-up-in-kings-valley/

During archaeological excavations in the Kings' Valley in Upper Egypt
a team of researchers from the University of Basel found one of the
world's oldest ancient Egyptian sun dials. The team of the Egyptological
Seminar under the direction of Prof. Susanne Bickel made the significant
discovery while clearing the entrance to one of the tombs. During this
year's excavations the researchers found a flattened piece of limestone
(so-called Ostracon) on which a semicircle in black color had been
drawn. The semicircle is divided into twelve sections of about 15 degrees
each. A dent in the middle of the approximately 16 centimeter
long horizontal baseline served to insert a wooden or metal bolt that
would cast a shadow to show the hours of the day. Small dots in the
middle of each section were used for even more detailed time measuring.
The sun dial was found in an area of stone huts that were used in the 13th
century BC to house the men working at the construction of the graves.
The sun dial was possibly used to measure their work hours. (..)

* German press release:

http://www.unibas.ch/index.cfm?uuid=6314229FE0430B8C588204CE905F183Atype=searchshow_long=1

Ross Caldwell43°20'N 3°12'E   ---
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RE: Why are schools, across the world, 'banning' analemmatic sundials ?

[Ross Sinclair Caldwell]

I remember this discussion a year or so ago (maybe more?)
A dialist in Australia explained that the school argued that the children would 
be tempted to spend too much time in the sun because of the dial.
In another part of this discussion, perhaps in the UK, someone mentioned that 
the school worried the dial would provoke fights over using it, or just because 
it was there. 
These sorts of things.
Ross Caldwell43° 20' N3° 13' E


 Date: Tue, 15 May 2012 16:46:18 +0200
 To: sundial@uni-koeln.de
 From: tcha...@dds.nl
 Subject: Re: Why are schools, across the world, 'banning' analemmatic 
 sundials ?
 
 Did any of the schools ever mention what the danger is of an 
 analemmatic sundial?
 Thibaud
 
 At 16:19 15-5-2012, Martina Addiscott wrote:
 
 Roughly one year ago, I had mentioned on this 'Mailing List' that
 our local Educational Authority would not permit us to install an
 interactive 'analemmatic' sundial on our school playground - since
 their opinion was that it was simply too dangerous, for children !
 
 It now seems that other countries are 'banning' these, for similar
 Health and Safety reasons - which I think is totally ridiculous,
 and suggest that the general Sundial community should 'protest' to
 the people concerned, as otherwise we are in danger of losing the
 opportunity to have these interesting outdoor educational projects.
 
 
 I know that they are generally 'frowned-upon', by schools here in
 Britain - but it appears that Canadian and Australian schools have
 also decided, that these 'Human Sundials' cause too much trouble !
 
 See the page at:  www.sunclocks.com/pics/fs-007.htm#reconstituted
 
 
 If anyone might like to join me in a 'campaign', to stop sundials
 being discouraged by schools - then please get in touch with me by
 E-mail, or you could also contact me on my mobile: +44 7769561152.
 
 Should anyone have comments on this deplorable situation - then I
 would also appreciate your thoughts, direct to the 'Mailing List'.
 
 
 Sincerely,
 
 Martina Addiscott.
 
 
 --
 
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RE: BBC bans The B.C. and A.D.

[Ross Sinclair Caldwell]

Hi Roger,

I completely agree with you. I want to correct something though.

At least 
in French, Friday is Vendredi, a shopping day. In our non secular world 
Vendredi should be Sunday. 

Actually that's a false (but perfectly understandable) etymology. There is a 
town called Vendres near where I live (Béziers). Both vendredi and Vendres 
have the same etymology from veneris, of Venus. Vendredi is the modern French 
of vendresdi, itself not far different from its Latin origin, veneris dies - 
the day of Venus (Venus = Freya/Frigga, so Friday and Vendredi mean the same 
thing). Compare the Italian venerdi.

The town of Vendres is so named because in Roman times there was an important 
temple of Venus in the town (and she was perhaps the patron of the town, it 
being at the time an important port). 

Best regards,

Ross


From: rtbai...@telus.net
To: jlcarmich...@comcast.net; sundial@uni-koeln.de
Subject: Re: BBC bans The B.C. and A.D. 
Date: Wed, 28 Sep 2011 20:41:59 -0700










Hi John,
 
Unfortunately the nanny state rules. Political 
correctness, we must not offend rules. I am offended by this neutering of our 
common background. We are what our cultural progenitors were in this 
multicultural background. Get over it!
 
What is next? What about the days of the week. 
First the big ones, sun day, moon day followed by a series of Norse 
Gods, Tuesday for Tiw, a Teutonic deity, Wednesday from Woden the chief god 
of the Norsemen. Thursday is from their Thor's day, Thor being the god of war. 
Friday from Freya, the goddess wife of Oldin, another big cheese in Norse 
deities With Saturday we are back to the planets for Saturn's day. These are 
our 
days of the week. French is even more tuned to the planetary gods, Lundi moon 
day, Mardi, for Mars the Roman god of war. Hence Martial arts. What is 
the art in Martial Arts, the art of beating someone to submission. This is our 
heritage. Mercredi is for the swift god and planet Mercury. On it goes. At 
least 
in French, Friday is Vendredi, a shopping day. In our non secular world 
Vendredi should be Sunday. 
 
BC/AD, CE/BCE, AC/DC, it really does not matter. We 
are who we are and we have a heritage.
 
Regards, Roger Bailey
 


  Solomon Grundy, 
  Born on a Monday, 
  Christened on Tuesday, 
  Married on Wednesday, 
  Took ill on Thursday, 
  Grew worse on Friday, 
  Died on Saturday, 
  Buried on Sunday. 
  This is the end 
  Of Solomon Grundy.




From: John Carmichael 
Sent: Wednesday, September 28, 2011 5:49 PM
To: sundial@uni-koeln.de 
Subject: BBC bans The B.C. and A.D. 



 
Britain’s BBC 
has banned the use of B.C and A.D. when refering to dates!
 
See:
 
http://www.theblaze.com/stories/christians-outraged-after-bbc-bans-network-mentions-of-christ-centric-timestamps/
 
Is this 
happening anywhere else wonder?



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RE: BBC bans The B.C. and A.D.

[Ross Sinclair Caldwell]

Thanks for pointing out the truth, Tony!

I smelled something fishy about the website, given conservative Christians' 
penchant for overreacting to the merest hint of a slight, and I couldn't find 
anything on the BBC website about it.

Thanks for the link. It won't stop the lies being propagated throughout the 
web, however. It will become an urban legend, no doubt. 

Best regards,

Ross

 Date: Thu, 29 Sep 2011 10:43:29 +0100
 From: d...@dotat.at
 To: jlcarmich...@comcast.net
 Subject: Re: BBC bans The B.C. and A.D. 
 CC: sundial@uni-koeln.de
 
 John Carmichael jlcarmich...@comcast.net wrote:
 
  Britain's BBC has banned the use of B.C and A.D. when refering to dates!
 
 Please don't propagate tabloid lies.
 http://www.guardian.co.uk/politics/reality-check-with-polly-curtis/2011/sep/26/1
 
 Tony.
 -- 
 f.anthony.n.finch  d...@dotat.at  http://dotat.at/
 Forties, Cromarty, Forth, Tyne, Dogger: South 4 or 5. Slight or moderate.
 Mainly fair. Good, occasionally poor.
 ---
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RE: Matin Lotto

[Ross Sinclair Caldwell]

Looking
 on Google, it comes from the liturgy for the Easter Vigil, the whole 
phrase being Ipsius sunt tempora et saecula - His are the times and 
the ages.





Ross Caldwell


43°20′51″N 3°13′08″E / 43.347615°N 3.218991°E



 Date: Sat, 13 Aug 2011 15:18:05 +0100
 From: t...@lindisun.demon.co.uk
 To: sundial@uni-koeln.de
 Subject: Matin Lotto
 
 Hi all,
   To limp back on topic, I have been asked to include the motto 
 'IPSIUS SUNT TEMPORA' in the design a dial to be carved in stone - by 
 someone else.
 
 The originator is a real live Franciscan hermit who lives on a hill in 
 the wilds of Northumberland so a direct query to him would involve the 
 Royal Mail and probably Pony Express and I need to know quickly. Can 
 someone satisfy my curiosity with a translation please?
 
 Tony Moss
 
 P.S.  For the curious the Hermitage can be found at
 
 http://www.geograph.org.uk/photo/2043589
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RE: Navicula Sundial

[Ross Sinclair Caldwell]

Dear Jürgen,

Perhaps try asking Trevor Philips and Sons

http://www.trevorphilip.com/

They don't have a complete list of their publications on-line, here are only a 
few -
http://www.trevorphilip.com/Trevor-Philip-Son-Library-DesktopDefault.aspx?tabid=9

- but I'm sure they will respond to a request.

Best regards,

Ross


Date: Mon, 1 Nov 2010 18:07:10 +0100
Subject: Navicula Sundial
From: juergen.hoef...@googlemail.com
To: sund...@rrz.uni-koeln.de


Dear
colleagues,



I
am looking for a copy of „The Late-Medieval Navicula“ which is
cited in various references to be from different authors/publishers.



1.
Nicola Severino: Gnomonics Bibliography:
„PHILIP,
Trevor  Sons Ltd. The Late-Medieval Navicula, see Turner, Gerard
L’E entry.
TURNER,
Professor Gerard L’E. The Late-Medieval Navicula, pp 19, with
illustrations of front and rear of the instrument. circa 1990.
The
account commences with how the dial functions and then moves on to
describe the instrument offered by Trevor Philips and Sons Ltd
in their auction room. It finally ends with the history of the
Navicula and manuscripts describing the navicula. See the Philips
entry.“






2.
Library of the Geneva Musee D' Histoire des Sciences:
1061750709
 Genf  MHS 529.78 WAT Waterman, Trevor. – The late-mediaeval
Navicula,



3.Eagleton,
Catherine: Monks, Manuscripts and Sundials, Brill Leiden 2010:
cited
as: Phillip, Trevor  Sons: The Late-mediaeval navicula
(London, [1993]). Sold at Sotheby's on Feb 25, 1993



Up
to now I have not been able to trace this publication, neither in
public libraries nor in the  internet, nor in antiquarian bookshops.



I
am very much interested in this probably short publication with
illustrations. A pdf would be fine, but I would also purchase a paper
copy at a reasonable price.



Thank
you very much for your consideration.



Yours,

Juergen
Hoefeld



juergen.hoef...@googlemail.com

www.hoefeld.de









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RE: Publication Cultural heritage of astronomical observatories

[Ross Sinclair Caldwell]

There is a copy for sale at AHA-Hon-Buch-Book, Germany, for 19 euros (shipping 
in Europe for 6 euros; 25 to the US)





http://www.choosebooks.com/refreshSearchPreferences.do;jsessionid=5d4bfbd1d9cc41c747455445e82f?itemId=136803294





I use Bookfinder.com for searches like this.





Best regards,





Ross



 Date: Sat, 16 Oct 2010 07:56:19 +0200
 From: wd...@astrohist.org
 Subject: Re: Publication Cultural heritage of astronomical observatories
 To: sund...@rrz.uni-koeln.de
 
 Unfortunately, this book is out of print. In June this year I ordered
 it from the publisher (at a price of about 20 Euro), but I got the
 answer that it is no longer available.
 
 BR, Wolfgang
 
  Original-Nachricht 
 Datum: Sat, 16 Oct 2010 15:41:30 +1100
 Von: John Pickard john.pick...@bigpond.com
 An: Sundial List sund...@rrz.uni-koeln.de
 Betreff: Publication Cultural heritage of astronomical observatories
 
 Good afternoon from a very chilly Sydney (where's Spring when you want it?),
 
 The following book may be of interest to list members:
 
 Wolfschmidt, G. (ed) 2009 Cultural heritage of astronomical observatories: 
 From astronomical observatories to modern astrophysics (Proceedings of the 
 International ICOMOS Symposium in Hamburg, October 14-17, 2008) Monuments and 
 Sites series, No. XVIII. Berlin, ICOMOS-Hendrik Bäßler-Verlag, 2009. 378 pp. 
 ISBN: 978-3-930388-53-0
 
 You can order it from the ICOMOS Documentation Centre: 
 http://www.international.icomos.org/icomos//publications/ms18.htm
 
 However, despite some looking, I could not find a price mentioned anywhere, 
 and it is not a free PDF.
 
 The title page, and table of contents can be seen at 
 http://www.math.uni-hamburg.de/spag/ign/stw/icomos221109-inhalt.pdf (5 MB)
 
 
 Cheers, John
 
 John Pickard
 john.pick...@bigpond.com 
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RE: moon shadows

[Ross Sinclair Caldwell]

Hi Brent,

It is only a coincidence that the full moon/ lunar 
opposition happened so close to the equinox this year, AD 2010. It could
 happen any of the 14.5 days around the equinox, so roughly September 5 
to October 5.

Last year the closest lunar opposition to the equinox was October 2 (or 3 
depending on where you live). 

Ross



 Date: Fri, 24 Sep 2010 11:46:50 -0700
 From: bren...@verizon.net
 To: sundial@uni-koeln.de
 Subject: Re: moon shadows
 
   Hello, I am afraid that if you wanted to make the sort of 
 observations that you suggest to any accuracy then the gnomon set up 
 that you have used is incorrect.  It should be set to point to true 
 north (not
   compass north) and be at an angle to the horizontal which is equal 
 to your latitude.  The sun is due South at solar Noon and is not 
 (generally) at an altitude equal to your latitude at noon during an 
 equinox.
   Regards
   Patrick
 
 
 
 Hi patrick;
 
 I have seen the type of gnomon dial you refer to.
 I think they call it an equatorial dial.
 
 Mine is the opposite, mine points due south since I am in the northern 
 hemisphere. And it does give me an accurate reading of my latitude.
 I don't think it is coincidence.
 When you point a gnomon at the sun at noon on the equinox the gnomon 
 is essentially in the same plane as the equatorial plane as the sun is 
 directly above the equator on equinox days.
 So I think you can determine your latitude anywhere on earth by using 
 the same method.
 
 Correct me if I am wrong.
 
 As far as the moon shadows; I guess now if the moon was in the exact 
 same position as the sun was 12 hours earlier on an equinox that would 
 mean they are in the same plane and we would have had an eclipse.
 However, I still find it fascinating that I had that big bright 
 harvest full moon so closely aligned with my pipe at solar midnight.
 
 brent
 
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RE: Nun Appleton Dial Mystery

[Ross Sinclair Caldwell]

I think the b/w photo has to be reversed.

Here is the photo reversed in Photoshop -
http://www.rosscaldwell.com/images/astronomy/sgsundialrev.jpg

The inscription reads correctly from the inside now. Secondly, the colour photo 
should have been taken from inside, since there is a major light source behind 
it. Therefore the inscription should be read from the inside, just as the time 
on the dial is. So the older photo has been accidentally reversed.

Ross

Ross  Aline's little (French) World
http://www.angelfire.com/space/france

From: [EMAIL PROTECTED]
To: sundial@uni-koeln.de
Subject: Nun Appleton Dial Mystery
Date: Thu, 19 Jun 2008 10:00:16 -0700
















Hi All (esp. John Davis, Mike Cowhan  David Brown):

 

I just noticed something odd about the very famous stained
glass sundial that is known as “The Nun Appleton Dial”. 
I don’t know why I never saw this before.  It slipped by right me. 

 

Take a look at this graphic of two photographs:

 

http://www.advanceassociates.com/Sundials/Stained_Glass/sundials_files/Stained_Glass_Sundial_6.jpg


 

On the left is a close-up color photo of the dial. 
This photo, as with most of our SGS photos, presumably shows the dial as it
would have looked from inside the building.  The inscriptions and numerals
all look corrected and were made to be read from the inside of the building. 
 On the right is old black  white interior photo showing the dial as
it was mounted in the transom above the door.  But look at the dial. 
It is backwards!

 

Why is this?

 

I’m thinking that it was incorrectly mounted in the transom. 
It was mounted in reverse.  But it just might be possible that it was
mounted correctly and that the old black and white photo is reversed!  I
copied that photo from a captured freeze frame still shot from an article by
Hans Behrendt called Alte Englischen Fenstersonnenhren (II) 1990. 
Could it be possible that the printers that Hans used might have accidentally
reversed the photograph?

 

Which leads me to ask if any of you ever saw this dial in
its original location above the door at Nun Appleton Hall, York, England. 
If we could only find another photograph or testimony from somebody who saw
it.  It no longer is there and I don’t know when it was removed. 
It now resides in lightbox for display at entrance to York Art Gallery.  

 

Can anybody help me solve this mystery?

 

Thx

 

John

 

p.s.

 

Here is the information we have on this dial:

 

The Nun Appleton Dial 

Maker: Henry Gyles
(1645-1709)

Date: 1670

Original Location: Nun Appleton Hall,
York, England.

Present Location: in lightbox for
display at entrance to York Art Gallery.

Orientation: south

Size: unknown (large)

Adornment: Cupid holds small sundial.
Small landscapes with The Four Seasons. House rebuilt by Sir William Milner
whose arms are on a corresponding pane of glass.

Mottos: Qui non est Hodie (Who is not
today). Lines from Ovid: Poma dat Autumnus, Formosa est messibus Aestas, Ver
praebet fores, Igne levatur hiems. (Autumn gives fruits, Summer fair with corn
appears, Spring bestows flowers, Winter fire cheers).

Condition: excellent

Comment: From a print by Titian. In
dark corner of gallery and back lit with unmoving electric light.

Article by Christopher Daniel (5 MB):
(Apr
1988) Stained Glass Sundials in England and Wales. Clocks 10, 30-37

Article by Christopher Daniel (2 MB):
(1987)
Shedding a Glorious Light. Country Life 181, 72-75

Original Photos: Here,
Here,
Here

Left Photo: shows dial mounted on
lightbox at the gallery.

Right Photo: shows dial above
entrance door at its original location. This poor quality photo and some of
this information are copied from an article by Hans Behrendt called Alte
Englischen Fenstersonnenhren (II) 1990.

Drawing by Gatty, The Book of
Sun-Dials: Here

Website: York Art Gallery

 

John L. Carmichael

Sundial Sculptures

925 E. Foothills Dr.

Tucson AZ 85718-4716

USA

Tel: 520-6961709

Email: [EMAIL PROTECTED]


 

Websites:

(business) Sundial Sculptures: http://www.sundialsculptures.com


(educational) Chinook Trail Sundial: 
http://advanceassociates.com/Sundials/COSprings/

(educational) Earth  Sky Equatorial
Sundial: http://advanceassociates.com/Sundials/Earth-Sky_Dial/ 


(educational) My Painted Wall Sundial:
http://www.advanceassociates.com/WallDial


(educational) Painted Wall Sundials: 
http://advanceassociates.com/WallDial/PWS_Home.html


(educational) Stained Glass Sundials: http://www.stainedglasssundials.com


(educational) Sundial Cupolas, Towers
 Turrets: http://StainedGlassSundials.com/CupolaSundial/index.html


 







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Re: Sundial mottos for clergy

[Ross Sinclair Caldwell]

The Bible has a miracle-story concerning the reversal of a shadow on a 
sundial, but it doesn't seem to have any suitable quotes (at least in 
Latin).


See Isaiah 38:4-8 and 2 Kings 20:1-11.

The first one, in the King James Version, contains a nice line if you 
truncate the sentence -


Behold, I will bring again the shadow of the degrees (Isa. 38:8) That has 
a nice ring to it, I think.


The full sentence is Behold, I will bring again the shadow of the degrees, 
which is gone down in the sun dial of Ahaz, ten degrees backward (i.e. the 
miracle)


The Vulgate's Latin is really unsuitable - Ecce ego reverti faciam umbram 
linearum per quas descenderat in horologio Ahaz in sole retrorsum decem 
lineis.


Thus the ambiguity of the KJV bring again, obscures that it means 
reverse, and hence produces a really lovely sounding motto for a sundial.


Ross Caldwell
4320 N
312' E
Béziers
France


-

FWDDon Filippo Puccetti

[Ross Sinclair Caldwell]

I am looking for any information about Don Filippo Puccetti, from 16th or 
17th

century Florence.  He apparently wrote a treastise on sundials and possibly
made at least one astrolabe.

Thanks and best regards,

Jim
--
James E. Morrison
[EMAIL PROTECTED]
Astrolabe web pages at
www.astrolabes.org




Ross  Aline's Fantastic French Adventure!
http://www.angelfire.com/space/france

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-

Re: Sundials on the moon

[Ross Sinclair Caldwell]

but they did so in the obviously reduced time associated with a lower
gravity

Oops, my mistake.  In my last message  I meant:  but they did so in the
obviously INCREASED time associated with a lower gravity



You probably thought/meant reduced SPEED but wrote time - funny, but I 
knew what you meant.


I was only 3 years old at the time, but my father sat me in front of the 
television and made a great point of making me watch and explaining to me 
the profound importance of this event. Since then, the images have become 
such a part of humanity's collective memory that I can't tell which parts I 
remember personally ... I do know I have never had much patience with talk 
of a moon-landing hoax.


Ross Caldwell
3'21E 43'35N
Béziers, France



Ross  Aline's Fantastic French Adventure!
http://www.angelfire.com/space/france


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-

Sundials on other planets

[Ross Sinclair Caldwell]

Combining an astronomy hobby with sundials, I wonder if anyone has thought 
of how a sundial on Mars or Venus might look (ignoring the thick venusian 
clouds for the experiment), or one on the Moon?


And what about designing dials for Earth that keep the different planetary 
times? So that one could set up a line of dials each keeping time on the 
different planets of the solar system.


This just popped into my head just now, so I haven't worked out any of the 
details, but I look forward to the response of anyone else who's willing to 
spend some time thinking about it.


Ross Caldwell
43.3166N
-3.4667E


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