Re: A question abou scaphes
On Tue, Apr 7, 2020 at 12:24 PM Michael Ossipoff wrote: > ...and of course the surrounding flat-dials could, instead, be > Reclining-Declining Dials facing in the cardinal-directions. > > But the sphere-segment indentation surface gives a better continuous > system of dial-lines. > > On Tue, Apr 7, 2020 at 12:18 PM Michael Ossipoff > wrote: > >> If the indentation were a shallow rectangular hollow instead of a segment >> of a sphere, it would of course amount to several adjoined flat dials--a >> horizontal-dial surrounded by vertical-dials. >> >> Michael Ossipoff >> 16 Tu >> Aries 19th >> Aprilis 7th >> >> On Tue, Apr 7, 2020 at 7:07 AM Peter Mayer >> wrote: >> >>> Hi, >>> Dan-George Uza's recent post reminded me of a question I have. I was >>> looking at Mark Lennox-Boyd's lovely *Sundials* the other day, >>> especially photos of some of the beautiful Renaissance ivory diptychs, and >>> realised that I didn't understand the principles behind the small scaphes >>> on many dials. (Here's a Wikicommons photo of a Leonhard Miller dial). >>> The Greek and Roman scaphes, like the one in Dan-George's photo, were >>> hollow sections of either spheres or cones, with a gnomon at their centre. >>> Their mode of operation seems quite straight-forward. >>> But the scaphes in diptyches weren't like that. They appear to be tiny >>> slices of much larger spheres. And the gnomons are, of course, far from the >>> centre. The 'furniture' on several of them seems similar to stereographic >>> projections. But, since instrument-makers then were well able to make >>> astrolabes with stereographs, perhaps not. >>> So: can someone point me to an article which discusses these small >>> scaphes? Or, in the meantime, help me understand how and why they were >>> used? Why don't we make them any more? Or: are there any contemporary >>> examples, using, say, bowls, or bird-baths or skateboard parks? >>> best wishes, >>> >>> Peter >>> >>> --- >>> Peter Mayer >>> Department of Politics & International Relations (POLIR) >>> School of Social Scienceshttp://www.arts.adelaide.edu.au/polis/ >>> 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 attachment >>> are free of viruses. Virus scanning is recommended and is the >>> responsibility of the recipient. >>> -- >>> >>> --- >>> https://lists.uni-koeln.de/mailman/listinfo/sundial >>> >>> --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: A question abou scaphes
If the indentation were a shallow rectangular hollow instead of a segment of a sphere, it would of course amount to several adjoined flat dials--a horizontal-dial surrounded by vertical-dials. Michael Ossipoff 16 Tu Aries 19th Aprilis 7th On Tue, Apr 7, 2020 at 7:07 AM Peter Mayer wrote: > Hi, > Dan-George Uza's recent post reminded me of a question I have. I was > looking at Mark Lennox-Boyd's lovely *Sundials* the other day, especially > photos of some of the beautiful Renaissance ivory diptychs, and realised > that I didn't understand the principles behind the small scaphes on many > dials. (Here's a Wikicommons photo of a Leonhard Miller dial). > The Greek and Roman scaphes, like the one in Dan-George's photo, were > hollow sections of either spheres or cones, with a gnomon at their centre. > Their mode of operation seems quite straight-forward. > But the scaphes in diptyches weren't like that. They appear to be tiny > slices of much larger spheres. And the gnomons are, of course, far from the > centre. The 'furniture' on several of them seems similar to stereographic > projections. But, since instrument-makers then were well able to make > astrolabes with stereographs, perhaps not. > So: can someone point me to an article which discusses these small > scaphes? Or, in the meantime, help me understand how and why they were > used? Why don't we make them any more? Or: are there any contemporary > examples, using, say, bowls, or bird-baths or skateboard parks? > best wishes, > > Peter > > --- > Peter Mayer > Department of Politics & International Relations (POLIR) > School of Social Scienceshttp://www.arts.adelaide.edu.au/polis/ > 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 attachment > are free of viruses. Virus scanning is recommended and is the > responsibility of the recipient. > -- > > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: A question abou scaphes
It seems to me that the indented dial-surface could serve a useful purpose, by ensuring that the nodus's shadow falls on that dial-surface whenever the Dyptich's flat horizontal surface has sunlight. . Maybe it's desired to make the indented dial-surface much larger than the hemispherical indentation that could be accomodated by the thickness of the horizontal plate of the Dyptich. . Of course not having the nodus at the center of the sphere would complicate the marking of the lines on the indented spherical surface, explaining why that isn't encountered more often. . It's related to stereographic lines, by having a projection-point not at the center of the sphere. It sounds like a great idea for a birdbath or bowl, but it might be too distracting for a skateboard-park. . Michael Ossipoff Aprilis 7th, 2020 16 Tu Aries 19th On Tue, Apr 7, 2020 at 7:07 AM Peter Mayer wrote: > Hi, > Dan-George Uza's recent post reminded me of a question I have. I was > looking at Mark Lennox-Boyd's lovely *Sundials* the other day, especially > photos of some of the beautiful Renaissance ivory diptychs, and realised > that I didn't understand the principles behind the small scaphes on many > dials. (Here's a Wikicommons photo of a Leonhard Miller dial). > The Greek and Roman scaphes, like the one in Dan-George's photo, were > hollow sections of either spheres or cones, with a gnomon at their centre. > Their mode of operation seems quite straight-forward. > But the scaphes in diptyches weren't like that. They appear to be tiny > slices of much larger spheres. And the gnomons are, of course, far from the > centre. The 'furniture' on several of them seems similar to stereographic > projections. But, since instrument-makers then were well able to make > astrolabes with stereographs, perhaps not. > So: can someone point me to an article which discusses these small > scaphes? Or, in the meantime, help me understand how and why they were > used? Why don't we make them any more? Or: are there any contemporary > examples, using, say, bowls, or bird-baths or skateboard parks? > best wishes, > > Peter > > --- > Peter Mayer > Department of Politics & International Relations (POLIR) > School of Social Scienceshttp://www.arts.adelaide.edu.au/polis/ > 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 attachment > are free of viruses. Virus scanning is recommended and is the > responsibility of the recipient. > -- > > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
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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.--- Begin Message --- Hi Peter, For a mathematical and practical analysis, see Ortwin Feustel, 'Ivory Sundials of Nuremberg Incorporating a Scaphe Sundial' BSS Bulletin 24(ii) 36-42. Regards, John Dr J Davis Flowton Dials http://www.flowton-dials.co.uk/ BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/ On Tuesday, 7 April 2020, 12:07:28 BST, Peter Mayer wrote: Hi, Dan-George Uza's recent post reminded me of a question I have. I was looking at Mark Lennox-Boyd's lovely Sundials the other day, especially photos of some of the beautiful Renaissance ivory diptychs, and realised that I didn't understand the principles behind the small scaphes on many dials. (Here's a Wikicommons photo of a Leonhard Miller dial). The Greek and Roman scaphes, like the one in Dan-George's photo, were hollow sections of either spheres or cones, with a gnomon at their centre. Their mode of operation seems quite straight-forward. But the scaphes in diptyches weren't like that. They appear to be tiny slices of much larger spheres. And the gnomons are, of course, far from the centre. The 'furniture' on several of them seems similar to stereographic projections. But, since instrument-makers then were well able to make astrolabes with stereographs, perhaps not. So: can someone point me to an article which discusses these small scaphes? Or, in the meantime, help me understand how and why they were used? Why don't we make them any more? Or: are there any contemporary examples, using, say, bowls, or bird-baths or skateboard parks? best wishes, Peter --- Peter Mayer Department of Politics & International Relations (POLIR) School of Social Sciences http://www.arts.adelaide.edu.au/polis/ 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 attachment are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. -- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- End Message --- --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Denizli sundial
Thank you, it looks great! Roser Raluy Missatge de Dan-George Uza del dia dt., 7 d’abr. 2020 a les 10:12: > Hello, I've just read about the discovery of an antique sundial in Turkey. > > > https://www.dailysabah.com/life/history/2000-year-old-sundial-unearthed-in-southern-turkeys-denizli > > Best regards, > > -- > Dan-George Uza > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Denizli sundial
Hello, I've just read about the discovery of an antique sundial in Turkey. https://www.dailysabah.com/life/history/2000-year-old-sundial-unearthed-in-southern-turkeys-denizli Best regards, -- Dan-George Uza --- https://lists.uni-koeln.de/mailman/listinfo/sundial
