Re: Temporal Hours
I think this is a really important thread ! My interest in this whole subject is the various client populations (whose who needed to tell the time) and what technologies they employed and what accuracies they achieved I think one can easily see five (sometimes overlapping) populations… The astronomers and astrologers who undoubtedly used and understood mean hours (one only has to read Ptolemy’s 150AD ‘Almagest' to understand the depth of understanding of the ancient astronomers. This class of person had the capabilities to make the Antikythera mechanism and would have had the wit to try polar dials. It’s my guess that all those exceptional examples of early non-scaphe/hemispherium/etc dials could be attributed to this client population. (And one needs to remember that most astronomers were astrologers (e.g Ptolemy) - there was nothing quaint about that subject from ancient days through to the Enlightenment.) The civic authorities who need to announce the time so that city gates could be opened, markets started etc. These were the people who provided all those beautiful Greek and Roman type dials that sat on pillars or in easily visible public places. To this group, one can perhaps add the very rich - there is a beautiful little personal sundial from Pompei The religious authorities - who generally wanted control - ref Pope Sabianus’ encyclical (606 AD) on mass dials, which was preceded by St Augustine’s 5th C definition of the Christian prayer times (which was derived from ideas from some earlier saint - whose name I can’t remember - who was the first to declare that prayers should be said on time). All of the 8 prayer times - except Vigil in the middle of the night - was defined by the Sun (dawn, sun-rise etc). Then along came Islam and their 5 prayer times initially mirrored those of the Christians (Fajr = Lauds, Zuhr = Sext, Asr = Nones, Maghreb = Vespers, Isha = Compline). This client population used... Christians - Mass dials were used in the countryside by the church until the Enlightenment. In towns, they would used mass dials until clocks came along for the cathedrals and rich monasteries/churches. Beda tables were also used by the church Muslims - personal shadow length (until the introduction of normal common hours dials - starting with the Ibn el Shatir dial). Of interest is the fact that Muslim purists still refer to variants of the original personal shadow length rules to dictate their prayer times. Ordinary people who used their personal shadow length to tell the time using Beda tables - what were available across Europe for various latitudes until medieval times. Thereafter they would use publicly visible sundials or clocks. There was not much change in this until clocks became available to the middle classes in 17/18th C and to the poor in the 19th/20th C. Rich people - always ahead of the game. They would use the handsome and beautiful miniature dials of the late medieval and renaissance times, until clocks and eventually watches (both of which were expensive) began to be more widely made. And then there was the Clepsydra… The simple ones were good for telling “How Long” and were very commonly used. The complex ones which told “When” were developed by the Greeks (e.g. Ctesibius in 245 BC) and made glorious by the Chinese (Su Sung 1088), the Arabs (al Sa’ati 11xx) and Persians (Al Jazari 1206). But these were the domain of the city fathers or the very, very wealthy/powerful. As far as I know, the first sophisticated water clock to reach Europe was a gift from the King of Persia to Charlemagne ca 900AD. Ctesibus’ clock had gearing to allow it to tell the time in unequal hours. As far as I can see, Su Sung’s al Saati's and Al Jazari's clock told the time in Common Hours (but I would need to research further to be sure of this). I found a quote that Ctesibus was more accurate than any clock until the arrival of the pendulum (I wonder if this a really true!) And what about accuracy of the “When in the day. Until the arrival of the Huygens’ pendulum clock (1656), one would be lucky to tell the time from a clock to better than +/-15 mins - sundials perhaps doing rather better. Serious time telling by clocks with minute or second accuracy was only really required to meet demands of navigators and then the growth of science and industry leading to the industrial revolution. And always bear in mind that until the arrival of the telegraph and railways, no one in the countryside could set a clock with anything other than a sundial (except perhaps unless they were an astronomer). Does anyone know of an authoritative and available source on water clocks? Kevin On 3 Aug 2015, at 02:55, Jack Aubert j...@chezaubert.net wrote: I assume that you are referring to the Arachne of the Amphiareion. I have a photocopy of your article on that dial, which was reconstructed from fragments, describing a (very old) horizontal dial with equal
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---BeginMessage--- -Ursprüngliche Mitteilung- Von: Karlheinz Schaldach lt;karlheinz_schald...@t-online.degt; An: schaldachk lt;schalda...@aol.comgt; Verschickt: Mo, 3 Aug 2015 6:19 pm Betreff: Fw: Temporal Hours Dear Jack, the Arachne of the Amphiareion is no horizontal dial, but equatorial. In the meanwhile there are at least 6 equatorial dials known from antiquity, some were made for temporal hours, some for equinoctial hours. You may have look at the not yet completed digital archive of Greco-Roman sundials http://repository.edition-topoi.org/projektinfo.php?project=BSDP K. Von: Jack Aubert lt;j...@chezaubert.netgt; An: schaldachk lt;schalda...@aol.comgt;; rtbailey lt;rtbai...@telus.netgt;; email9648742 lt;email9648...@gmail.comgt;; sundial lt;sundial@uni-koeln.degt; Verschickt: Mo, 3 Aug 2015 3:55 am Betreff: RE: Temporal Hours I assume that you are referring to the Arachne of the Amphiareion. I have a photocopy of your article on that dial, which was reconstructed from fragments, describing a (very old) horizontal dial with equal hours. Another atypical dial: The Ai Khanum dial found in the ruins of Alexandria on the Oxus (in modern Afghanistan) that dates from approximately 145 BC is an example of a polar-oriented gnomon with unequal hours. This dial is interesting for several reasons, in particular the fact that while it “naturally” told equal hours using the line-shadow of the gnomon, the constructor carefully incised lines to read unequal hours using the gnomon tip. (It was done incorrectly for its latitude, but that’s another story.) However, both these dials are quite exceptional. My general impression from what I have been able to read is that equal hours were used by astronomers and astrologers. While there is at least one example of a horizontal dial that uses equal hours and at least one example of a polar gnomon using temporal hours, people generally wanted their time in temporal hours so the vast majority of surviving dials prior to the Ibn al-Shatir dial used temporal hours. Jack Aubert From: schalda...@aol.com [mailto:schalda...@aol.com?] Sent: Thursday, July 30, 2015 1:55 AM To: rtbai...@telus.net; email9648...@gmail.com; sundial@uni-koeln.de Subject: Re: Temporal Hours Greek and Roman dials were not horizontal or vertical flat planar dials, but hemispheres, scafes or other projections of the sky onto a spherical or conical surface. Planar dials came with the Islamic dials. Only a short note:This is not true. The first Greek dials were plane equatorial dials with equal hours. Karlheinz The first planar dial with a polar gnomon was by Ibn al-Shatir in Damascus in 1371. This dial had temporal hours, equal hours based on noon, sunrise and sunset, and Islamic prayer times, including reference lines to prayer times when the sun was well below the horizon. For me this dial is the epitome of sundials. It includes all the time systems in vogue at that time and for hundreds of years before and after. They all existed and were in common usage suited for different purposes. The question remains Who is bringing the duck for dinner. Time is important. Don't overcook it. Regards, Roger Bailey Michael Ossipoff Sent: Wednesday, July 29, 2015 11:57 AM To: Roger Bailey ; sundial list Subject: Re: Temporal Hours Roger, thanks for the answer. Ok, I shouldn't say that as a fact without having more information than I do. This is what I was implying or saying, without really having much support for it: In Europe and the fertile-crescent region, in ancient, classical and medieval times, before mechanical clocks (starting with Folliet-balance clocks) came into wide use, Equal Hours were of interest, for the most part, only to astronomers and astrologers. For ordinary civil timekeeping, for arranging meetings, keeping schedules or other civil/social purposes, Temporary Hours were preferred by pretty much everyone. Were a fair percentage of people making their appointments and schedules by Equal Hours in the times and places named in the above paragraph? I'm not being argumentative--I really don't know. -- Thanks for reminding me about Temporary Hours lines on Flat Dials being satisfactorily approximated by straight lines. I'd temporarily (no pun intended) forgotten that. It was a question that I'd asked, and received an answer to, when I first wrote to NASS. Were Flat-Dials (for Temporary or Equal Hours) in use before mechanical clocks were getting popular? What about _wide_ use? How early? - Can anyone explain why the early, inaccurate inertia-controlled Folliet-Balance clocks replaced the cheaper, more easily-made water-clocks? Were those
Re: Temporal Hours
Hi Jack, While following a lead based on Sasch Stevens display at the conference, I came across an interesting article on the Al Khanum dial by Googling Alexander the Great sundial. This search found this article: A Unique Greek Sundial Recently Discovered in Central Asia by Rene Rohr in 1980 in the JRASC. The article describes the work at Al Khanum by Paul Bernard. See http://adsabs.harvard.edu/full/1980JRASC..74..271R Their conclusion is the same as yours, the dial is a an equatorial with a polar gnomon but the lines show temporal hours rather that straightforward equal hours. Regards, Roger From: Jack Aubert Sent: Sunday, August 02, 2015 6:55 PM To: schalda...@aol.com ; rtbai...@telus.net ; email9648...@gmail.com ; sundial@uni-koeln.de Subject: RE: Temporal Hours I assume that you are referring to the Arachne of the Amphiareion. I have a photocopy of your article on that dial, which was reconstructed from fragments, describing a (very old) horizontal dial with equal hours. Another atypical dial: The Ai Khanum dial found in the ruins of Alexandria on the Oxus (in modern Afghanistan) that dates from approximately 145 BC is an example of a polar-oriented gnomon with unequal hours. This dial is interesting for several reasons, in particular the fact that while it “naturally” told equal hours using the line-shadow of the gnomon, the constructor carefully incised lines to read unequal hours using the gnomon tip. (It was done incorrectly for its latitude, but that’s another story.) However, both these dials are quite exceptional. My general impression from what I have been able to read is that equal hours were used by astronomers and astrologers. While there is at least one example of a horizontal dial that uses equal hours and at least one example of a polar gnomon using temporal hours, people generally wanted their time in temporal hours so the vast majority of surviving dials prior to the Ibn al-Shatir dial used temporal hours. Jack Aubert --- https://lists.uni-koeln.de/mailman/listinfo/sundial
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---BeginMessage--- Dear Jack, the Arachne of the Amphiareion is no horizontal dial, but equatorial. In the meanwhile there are at least 6 equatorial dials known from antiquity, some were made for temporal hours, some for equinoctial hours. You may have look at the not yet completed digital archive of Greco-Roman sundials http://repository.edition-topoi.org/projektinfo.php?project=BSDP K. Sorry for double-posting. ? ---End Message--- --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Temporal Hours
Interesting riff Kevin. It reminds me of an old B.C. cartoon where one caveman is showing the other the sundial he has made and asks, Guess what I have invented here? Then the other answers, A race of neurotics. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
