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--- Begin Message ---To make my little contribution to the solution of the problem, I think, that Sara Schechner, as always, has pointed the best solution. At that time it was no difference between Astrology and Astronomy, and all the Astronomical_Astrological events were calculated with the help of astrolabes, which they take in account the "Dusk", because they have the "Crepuscular Line" 18° below the horizon line. If it could be of some help, here is a link to Academia, where is my work about the construction of the astrolabes in the time of Alfonso X of Castille, (The same of the Alfonsine Tables), and also according to some other Spanish manuscripts. I hope this will help to understand about the capability of Astrolabes to measure minutes (of arc) after the Sunrise, and how the Sky was at this time. Here is the link to my papers. https://independent.academia.edu/PastorAlfonso Sincerely yours. Stanislav Putowsky putow...@yahoo.com > On 1 Jul 2020, at 18:23, Ross Sinclair Caldwell <belmu...@hotmail.com> wrote: > > > 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 <gian.casale...@gmail.com> > Envoyé : mercredi 1 juillet 2020 18:13 > À : Ross Sinclair Caldwell <belmu...@hotmail.com> > Cc : sundial list sundials <sundial@uni-koeln.de> > 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 > <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 <sundial-boun...@uni-koeln.de> de la part de Ross Sinclair > Caldwell <belmu...@hotmail.com> > Envoyé : mercredi 1 juillet 2020 16:41 > À : John Davis <john.davi...@btopenworld.com>; Schechner, Sara > <sche...@fas.harvard.edu> > Cc : 'sundial list sundials' <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 <john.davi...@btopenworld.com> > Envoyé : mercredi 1 juillet 2020 10:10 > À : Ross Sinclair Caldwell <belmu...@hotmail.com>; Schechner, Sara > <sche...@fas.harvard.edu> > Cc : 'sundial list sundials' <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" <sche...@fas.harvard.edu> > > To: "Ross Sinclair Caldwell" <belmu...@hotmail.com> > > Cc: "'sundial list sundials'" <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 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 | @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/ > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial >
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