Hi Peter,If we set a horizontal stereographic dial at 55deg N and move it to 35deg S, not changing its position in space, it becomes a vertical there.What changes is the position of the observer on the globe - not the sundial.The difference is that in a vertical position at 35deg S the upper halve of the original dial is useless, as Sun rays are cut by the horizon in Adelaide.But you can make the upper halve usefull in a simple way, by folding the sundial along the horizon line !By doing it, you get a second (south-oriented) face for your dial and preserve the all year functionality of the original 55deg location !But you must remember to extend the gnomon rod to the south side !The co-latitude similarity brought me an idea of establishing gnomonic twin cities, for which one sundial would work !As a resident of the latitude of 51deg North I'm looking for offers from lat. 39deg South !As the winter is coming in North hemisphere, I will kindly accept offers for a courtsey visit to 39deg South with a stereographic sundial at hand ready for experiments !Regards,Maciej LoseOd: "Peter Mayer" <a1000...@adelaide.edu.au>Do: ml...@interia.pl; peter.ma...@adelaide.edu.au; Wysłane: 2:12 Piątek 2022-11-04Temat: Re: Vertical stereographic sundial
Hi Maciej, Here's a puzzle for you and others on the list. Does the usual 'co-latitude' rule for other plane sundials hold for Oughtred/stereograph dials? I've tried a quick empirical experiment using Orologi Solari creating a vertical stereograph for my latitude (35S) and a horizontal for the co-latitude (55N). The two seem identical (except for the numbering of hours). It's not a 'geometric proof' but it seems entirely reasonable. I had meant to add in my earlier post that a few years ago I, too, wrote a DeltaCad macro for an Oughtred dial. Unlike the elegant trigonometry used by Valentin, I tried to replicate the protractor, compass and straightedge methods in a traditional construction. Once it worked for my Southern Hemisphere location, I stopped working on it, so it is really a beta version, but I'm happy to forward it to anyone who is interested. best wishes, Peter On 2/11/2022 5:25:29, ml...@interia.pl wrote: CAUTION: External email. Only click on links or open attachments from trusted senders. Hi Peter, Thank You for the links. My plea concerned vertical stereographic sundials - not the horizontal ones. I'm aware that there are a number of programs to construct horizontal sterographic dials. Helmut Sonderegger kindly proposed to include vertical ones in Sonne, when he finds a time for it, and the info form Valentin was that for the vertical plane he actually worked on a spider dial, which is most interesting but of different type than stereographic. But I must admit that I was unaware of construction possibilty of vertical stereographic dials (under the name "vertical astrolabe") in Oroligi Solari. Though, the program doesn't give any limits for the gnomon - which in this type of instruments is no longer that 1/2 the dial's radius, as discussed in my paper, irrespective of walls' declination, latitude and sundial's plane inclination. It doesn't also give options for inclining dials. So there is some space for it to be upgraded making this very nice typology more approachable for sundial makers. Also, derivatives like the four-sided, "gnomon-less" stereographic vertical sundial could be included. Drawing by hand (with CAD) is obviously time consuming, but it allows for understanding of geometrical relations behind and allows for inclusion of elements not available in the custom software. So not being a skilful programmer, I will rather stay with that ! But for the sundial makers it is obviously easier to use a software. Regards, Maciej Od: "Peter Mayer" <a1000...@adelaide.edu.au> Do: sundial@uni-koeln.de; ml...@interia.pl; Wysłane: 5:58 Poniedziałek 2022-10-31 Temat: Re: Vertical stereographic sundial Hi Maciej, Thanks for your recent post. Since no one seems to have replied to your plea in the final paragraph for software to draw a stereographic/Oughtred dial, here are some existing open software options: * Gian Casalegna's Orologi Solari will draw one: azimuth: horizontal/vertical: astrolabe *Helmut Sondereggers' Sonne will draw at least a horizontal stereograph: Azimuthal: Sun Altitude * Valentin Hristov has written some elegant code for DeltaCad :www.math.bas.bg/complan/valhrist/az-ht.bas [When I tried to re-run it a few minutes ago, it now seems to be stuck in a loop which I haven't had time to debug. I've attached an example which I created about 4 years ago]. So: no need to create a stereograph by hand! best wishes, Peter On 27/10/2022 4:02:34, ml...@interia.pl wrote: CAUTION: External email. Only click on links or open attachments from trusted senders. Dear All, As proven in a separate tread on "Sun elevation tool/ horizontoscope", stereographic projection is a fascinating geometric construction with great potential in gnomonics. During last year I explored the idea of vertical stereographic sundial and it resulted in a paper describing several stereographic sundial types: - vertical stereographic sundial, for walls of any declination and for any latitude, - four-sided stereographic vertical sundial, attractive for its “gnomon-less” form, - double – stereographic & polar – vertical sundial for walls of any declination, a vertical reference to Oughtred’s horizontal design, - folded pocket, double stereographic & polar – vertical sundial - inclined, proclined and polyhedral stereographic sundials The paper can be downloaded free of charge from Cursiva publishers website: http://cursiva.pl/e-ksiegarnia/vertical-stereographic-sundial-properties-construction-and-related-instruments/ or from Academia.edu website: https://www.academia.edu/88820719/Vertical_stereographic_sundial_Properties_construction_and_related_instruments Have fun with it ! Vertical stereographic sundials offer plenty of possibilities for sundial makers and I believe might be a very interesting addition to existing sundial types. As the geometric construction of vertical stereographic sundials with CAD software is time-consuming, it would be great to include it in existing sundial design software. I kindly ask sundial list members running such software, please consider it ! Regards, Maciej Lose --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial -- ----------- 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://www.adelaide.edu.au/study/ -- ----------- 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. 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