Fer's legacy - diptych
Hello Frans Your link to all the articles of Fer’s Legacy is wonderful. Thank you very much for telling us about it. I had already seen a copy of his article "Construction of hemispherium", showing how to generate Babylonian and Italian hour lines in a hemisphere bowl. Do you know if he described a method for doing the same lines in a spherical concave saucer, not a bowl, like the diptych dials by Reinman of Nuremberg and others? There must have been a method that worked, or was it custom and practice perhaps. Good wishes Alastair Hunter __ Macmillan Hunter Sundials, 3 Peel Terrace, Edinburgh EH9 2AY, Scotland, UK Telephone: 44 0 131 468 2616 Email: <mailto:sundi...@macmillanhunter.co.uk> sundi...@macmillanhunter.co.uk Website: <https://www.macmillanhunter.co.uk/> https://www.macmillanhunter.co.uk/ __ From: sundial On Behalf Of Maes, F.W. Sent: 03 September 2020 13:49 To: siegfried.netzb...@t-online.de Cc: sundial@uni-koeln.de Subject: Re: Fake "trifilar" Sun Dial? Dear Siegfried, Bernard Rouxel of France designed this original sundial. It got him second prize in the Italian "Le ombre del Tempo” contest of 2008. It was discussed by the late Fer de Vries in one of his online articles. That website does not exist anymore, but you can find his articles in "Fer's legacy": - Go to www.zonnewijzerkring.nl <http://www.zonnewijzerkring.nl> - Click the English flag - Click "Downloads" - At the bottom of the page, download the zip-file and unzip - Open "FersLegacy.html" The article is in the section "Article of the Month", November 2009. Enjoy! Best regards, Frans Maes On Thu, Sep 3, 2020 at 10:34 AM Siegfried Netzband mailto:siegfried.netzb...@t-online.de> > wrote: Dear sundialists, found the attached picture in an old archive and do not have any details about it. The dial shown seems to be somethig like a "bifilar sundial with three straight wires". The wires obviously do not touch one another. The picture was taken at the moment when all wire shadows cross in one point on the dial face suggesting that the sundial shows the time at that moment (and any other?). There is no dial face visible. What kind of sun dial is that - what could be the idea behind it and it´s purpose? Is there anyboddy out threre who could answer the following questions and can help me to solve my problem, i.e. clarify that sun dial: - Has any one seen that picture before? If so, do you have any details about it? Please let me know. - The originator of that sun dial must have had some very special ideas when constructing that sun dial. To the best of my knowledge a picture like that where the shadows of three wires which do not touch one another, mounted at different heights and angles across the face of the dial, cross in one point on the face of the dial, can only be taken at at most 2 times a year, each time at exactly the same solar time. Am I right or does there realy exist something like a "trifilar sundial" as shown in the picture idicating time over the year? - Taking the sun dial shown to a singular, simplistic extreme: At whatever angles or hights multiple wires might run across a dial and touch each other at their crrossing point, the dial would simply work and could be calculated taking the crossing / touching point as the tip of the gnomon, the node of the dial. Correct? - Does any one know wether H. Michnik, the inventor of the bifilar sun dial and its theory in 1923, has made any mathematical statement about "multifilar sundails"? Thank you for your help and Kind Regards Siegfried Siegfried Netzband Hebelstr. 12 75233 Tiefenbronn Tel: 07234 2802 Fax: 07234 942909 Mob: 0151 53083636 / 0160 1531634 E-Post: siegfried.netzb...@epost.de <mailto:siegfried.netzb...@epost.de> Skype: siegfried75233 www.ferienhaus-frieseneck.de <http://www.ferienhaus-frieseneck.de> --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Fer's legacy - diptych
Dear Frans Thank you very much for your reply. I can only imagine the time and effort all of you have put into making Fer’s legacy available in data form and in English. It is terrific! The diptych concave is, I think, not a simple mathematical problem. I have done it by 3D drawing but it needs great care to avoid errors. I suspect the Nuremberg makers had their own tried and tested methods. Best wishes Alastair __ Macmillan Hunter Sundials, 3 Peel Terrace, Edinburgh EH9 2AY, Scotland, UK Telephone: 44 0 131 468 2616 Email: <mailto:sundi...@macmillanhunter.co.uk> sundi...@macmillanhunter.co.uk Website: <https://www.macmillanhunter.co.uk/> https://www.macmillanhunter.co.uk/ __ From: Maes, F.W. Sent: 07 September 2020 16:52 To: Alastair & Sheila Cc: Sundial Mailing List Subject: Re: Fer's legacy - diptych Dear Alistair, I am glad you appreciate the effort we invested in saving the English version of Fer's legacy. Transmitting the original 360 Dutch articles from Fer's html-version into the CMS of our present website was quite a job. Repeating that for the 360 English articles (skillfully translated by our secretary Ruud Hooijenga) was beyond our stamina. The present solution, keeping the English html-files and linking to the database for the figures, appears to be a workable compromise. It might be interesting for the list members that the English summaries of the articles in our Bulletin from 1998 onward and its successor Zon & Tijd, are also available from the English section of our website, www.zonnewijzerkring.nl <http://www.zonnewijzerkring.nl> , via the link Journal Contents. As far as I know, Fer has not dealt with the construction of Bab. & Ital. hour lines in a concave saucer. Best regards, Frans Maes <http://www.avg.com/email-signature?utm_medium=email_source=link_campaign=sig-email_content=webmail> Virusvrij. <http://www.avg.com/email-signature?utm_medium=email_source=link_campaign=sig-email_content=webmail> www.avg.com On Mon, Sep 7, 2020 at 3:44 PM Alastair & Sheila mailto:a...@3peel.co.uk> > wrote: Hello Frans Your link to all the articles of Fer’s Legacy is wonderful. Thank you very much for telling us about it. I had already seen a copy of his article "Construction of hemispherium", showing how to generate Babylonian and Italian hour lines in a hemisphere bowl. Do you know if he described a method for doing the same lines in a spherical concave saucer, not a bowl, like the diptych dials by Reinman of Nuremberg and others? There must have been a method that worked, or was it custom and practice perhaps. Good wishes Alastair Hunter __ Macmillan Hunter Sundials, 3 Peel Terrace, Edinburgh EH9 2AY, Scotland, UK Telephone: 44 0 131 468 2616 Email: <mailto:sundi...@macmillanhunter.co.uk> sundi...@macmillanhunter.co.uk Website: <https://www.macmillanhunter.co.uk/> https://www.macmillanhunter.co.uk/ __ From: sundial mailto:sundial-boun...@uni-koeln.de> > On Behalf Of Maes, F.W. Sent: 03 September 2020 13:49 To: siegfried.netzb...@t-online.de <mailto:siegfried.netzb...@t-online.de> Cc: sundial@uni-koeln.de <mailto:sundial@uni-koeln.de> Subject: Re: Fake "trifilar" Sun Dial? Dear Siegfried, Bernard Rouxel of France designed this original sundial. It got him second prize in the Italian "Le ombre del Tempo” contest of 2008. It was discussed by the late Fer de Vries in one of his online articles. That website does not exist anymore, but you can find his articles in "Fer's legacy": - Go to www.zonnewijzerkring.nl <http://www.zonnewijzerkring.nl> - Click the English flag - Click "Downloads" - At the bottom of the page, download the zip-file and unzip - Open "FersLegacy.html" The article is in the section "Article of the Month", November 2009. Enjoy! Best regards, Frans Maes On Thu, Sep 3, 2020 at 10:34 AM Siegfried Netzband mailto:siegfried.netzb...@t-online.de> > wrote: Dear sundialists, found the attached picture in an old archive and do not have any details about it. The dial shown seems to be somethig like a "bifilar sundial with three straight wires". The wires obviously do not touch one another. The picture was taken at the moment when all wire shadows cross in one point on the dial face suggesting that the sundial shows the time at that moment (and any other?). There is no dial face visible. What kind of sun dial is that - what could be the idea behind it and it´s purpose? Is there anyboddy out threre who could answer the follow
Sundial - accurate
Hello Steve An accurate sundial has many faces! The theory goes hand in hand with the practical problems. In my experience accuracy in the end result depends very much on the particular path you decide to follow. Each case is its own problem and I am sure there are no perfect solutions. I have done a number of wall sundials and many gnomons for declining and inclining dials on faceted sundial stones. The starting point has to be measurement of the declination of the wall. You calculate the gnomon and the hour lines from there, as I am sure you already know. But if your wall measurement is in error, it is the first of the errors in building your sundial. As you point out there are other parts of the sundial you can control like precision machining. Wall declination may be contributing your greatest error, it is not easy to measure. I can send you pictures if you like to show you what I mean. And I have a device you can use to help with accurate measurement of declination, if this interests you. Your other question about penumbra is really a separate matter. It is more to do with resolution or discrimination you can observe on the time graduations of your dial rather than the accuracy of the sundial itself. In other words the sundial can be quite inaccurate, for example badly made or not well aligned with true north, but you are still able to observe changes in shadow position that apparently are 1 minute apart or less. You might describe this as bad at absolute time but good at incremental time, or not so good as a watch but quite good as a stopwatch! Depending on your ideas for your design of sundial any penumbra effect may not be the most important. Let me know if you want to follow up with any of this. Kindest wishes Alastair Hunter, Macmillan Hunter Sundials, Edinburgh, Scotland = What accuracy to aim for with a carefully made sundial? Steve Lelievre steve.lelievre.can...@gmail.com via uni-koeln.de Jul 30, 2019, 6:37 PM (2 days ago) to Sundial Hello everyone, I'm planning to make a small vertical west dial, about 1m for the width of the dial face, at my latitude of 49N. It will not use a nodus. The angular width of the sun makes it hard to get a really accurate time reading, but there will also be small errors from mis-positioning of the dial plate when installing (declination and inclination), imprecise positioning of the gnomon or the hour lines, and perhaps other causes too. First, questions directed at those of you who have practical experience of creating vertical sundials: If I'm careful and have a well-machined gnomon, what level of accuracy might be achievable in practice? I assume +/- 5 minutes throughout the day and year is fairly easy to achieve, but what about +/- 2 minutes, or even +/- 1 minute? How well did you do? How did you measure your wall's declination? Second, have there been any studies of how well dial users compensate for a penumbra - by which I mean gathering data from volunteers, studying the spread of errors in time readings taken from a dial versus a reference time source? (without employing a shadow sharpener) Thanks, Steve --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Stone Discs on the South Wall of Salamanca Cathedral? - thoughts
Hello Azucena A couple of thought for you, see below. I copied your email to one or two people and this is far as we have got. Hope this helps. Kind wishes Alastair Edinburgh, UK = Dear all You sometimes see columns recycled from classical sites re-used as structural ties running through walls for additional strength. Zooming in on these photographs it looks like one or two of the projecting stones display moulded detail – possibly capitals or bases. Also these projecting stones don’t seem to relate to the stonework of the surrounding walling – i.e. they are individual stones that run into the wall (they cross the joints of the coursing of the surrounding masonry). So my thought is probably a structural device rather than anything more profound. However happy to be wrong if evidence to the contrary emerges. Tom Tom Addyman For Addyman Archaeology Hello James Happy New Year. Here is an architectural puzzle for you, maybe you will know the answer? Through our sundial circulation list, an enquiry has come up about the ancient cathedral of Salamanca. There are four circular stones projecting on the south wall of the south transept, the email below explains. They do seem to be placed in a hanging circular pattern but no one seems to know why they are there. The idea of them being related to sundials does not seem to fit, but conceivably they have another astronomical connection. My guess is they have something to do with the interior of the building, could they be end-caps for some structural support or reinforcement. They do look like later fittings into or through the stonework. Any ideas? This is purely a brain-teaser but I am sure Azucena who sent the enquiry will be delighted to know what you think. Kind wishes Alastair __ Dear all, My apologies. The dropbox link I sent in my previous message seems not to work. I also apologize for those who dislike having to enter in a website to have a look to some photographs which may interest them very little. I do not know other alternative way to send 10 photographs to a huge mailing list. I copy my previous message again: The reason of this message is to ask you about the four stone circles attached to the upper part of the South wall of the South Transept of the Salamanca Old Cathedral (12th century). Detailed photographs taken from the roof of the cathedral are available in: http://www.mediafire.com/folder/gh4z23vpm0lmfxr,86of1051tl9968q,i9870jqzdijcvcl,5oea9916tg6q5zv,nne0cyej0k5qq0l,yayoddwvjexgla3,44i1zzbdif6i2ne,4zczcfx97be25f4,shmellrfjt82sm4,q32d936j8up9rxf/shared The stone circles seem to have been located there in purpose and possible reasons like holding coat of arms or any other kind of sculpture have been discharged for various reasons. This South wall is only visible from the cloister. Our first idea was to be a kind of sundial but completely different from the many medieval sundials engraved in south walls of cathedrals or other buildings in Spain with their well known layout of engraved hour lines. Have you seen anything similar? Any idea from your side will be more than welcomed. Best regards and again my apologies, Azucena Dra. Azucena Hernández Pérez Universidad Complutense de Madrid https://www.ucm.es/historiadelarte/azucena-hernandez-perez https://ucm.academia.edu/AzucenaHernandez --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Azimuth circles - definition
Hello Fritz No responses so far, but maybe there are few people who can cast their mind back to sundial terminology from the 16th century (at least not from lifetime experience)! The earlier response I received, from Frank King, is delightful but really a misunderstanding. This was my fault because I didn't phrase my question very well. Alastair -Original Message- From: fritzstump...@gmail.com [mailto:fritzstump...@gmail.com] Sent: Thursday, 10 January, 2019 2:39 PM To: a...@3peel.co.uk Subject: RE: Azimuth circles - definition Did you get any responses? I'm curious because I didn't fully understand the previous discussion of them either. Fritz -Original Message- From: sundial On Behalf Of Alastair Hunter Sent: Tuesday, January 8, 2019 12:26 AM To: sundial@uni-koeln.de Subject: Azimuth circles - definition Good wishes to all in 2019 Has anyone come across the term 'azimuth or azimuthal circles' in the context of sundials in the 16th or 17th centuries? It would be useful to know for some work I am doing and to have a definition of what this term means. I don't think it relates to altitude and azimuth in our familiar horizon coordinate system. In which case does it relate to another coordinate system and if so which one? Or is it something else relating to sundials? Very grateful for help that anyone can offer Alastair Hunter Edinburgh, UK -Original Message- From: Frank King [mailto:f...@cl.cam.ac.uk] Sent: Thursday, 3 January, 2019 3:07 PM To: a...@3peel.co.uk Cc: sundial@uni-koeln.de; Frank King Subject: Re: Gnomon Gap Puzzle - wonderful Dear Alastair, Many thanks for your kind words... > Your design is wonderful... I hope you enjoy the book. You ask... > ... have you come across the term 'azimuth circles', how would you > define this term? I have heard this term in several contexts. In an astronomical context, any great circle that runs from your local zenith via the horizon down to the out-of-sight nadir is sometimes called an azimuth circle. As it happens, I call this a vertical circle; that's just habit but see later. In another context, I actually OWN an azimuth circle... I have an army marching compass (magnetic) which has an annular ring supporting the glass cover. The instructions call this the "azimuth circle". There is a radial line on the glass marked in luminous paint! The idea is that if you want to march towards some distant point, you aim the body of the compass at that point and then twiddle the azimuth circle so that the radial line covers the large N for north on the compass card. This N is also in luminous paint. I expect the whole thing is radio-active! You then walk along (er, MARCH along) keeping the line on top of the N. A more common azimuth circle is the horizontal graduated ring on a theodolite which enables you to determine the difference in bearing between two terrestrial objects. More generically, an azimuth circle seems to be any ring which is mounted in a horizontal plane and which can either be twiddled round itself or it is fixed and something else rotates round within it. In my opening example this means the entire horizon is an azimuth circle; it runs round all the vertical circles. That's one reason I call them vertical circles rather than azimuth circles! Some technical terms can be confusing :-) I expect Mr Google can give you more examples. Very best wishes Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Azimuth circles - definition
Good wishes to all in 2019 Has anyone come across the term 'azimuth or azimuthal circles' in the context of sundials in the 16th or 17th centuries? It would be useful to know for some work I am doing and to have a definition of what this term means. I don't think it relates to altitude and azimuth in our familiar horizon coordinate system. In which case does it relate to another coordinate system and if so which one? Or is it something else relating to sundials? Very grateful for help that anyone can offer Alastair Hunter Edinburgh, UK -Original Message- From: Frank King [mailto:f...@cl.cam.ac.uk] Sent: Thursday, 3 January, 2019 3:07 PM To: a...@3peel.co.uk Cc: sundial@uni-koeln.de; Frank King Subject: Re: Gnomon Gap Puzzle - wonderful Dear Alastair, Many thanks for your kind words... > Your design is wonderful... I hope you enjoy the book. You ask... > ... have you come across the term 'azimuth > circles', how would you define this term? I have heard this term in several contexts. In an astronomical context, any great circle that runs from your local zenith via the horizon down to the out-of-sight nadir is sometimes called an azimuth circle. As it happens, I call this a vertical circle; that's just habit but see later. In another context, I actually OWN an azimuth circle... I have an army marching compass (magnetic) which has an annular ring supporting the glass cover. The instructions call this the "azimuth circle". There is a radial line on the glass marked in luminous paint! The idea is that if you want to march towards some distant point, you aim the body of the compass at that point and then twiddle the azimuth circle so that the radial line covers the large N for north on the compass card. This N is also in luminous paint. I expect the whole thing is radio-active! You then walk along (er, MARCH along) keeping the line on top of the N. A more common azimuth circle is the horizontal graduated ring on a theodolite which enables you to determine the difference in bearing between two terrestrial objects. More generically, an azimuth circle seems to be any ring which is mounted in a horizontal plane and which can either be twiddled round itself or it is fixed and something else rotates round within it. In my opening example this means the entire horizon is an azimuth circle; it runs round all the vertical circles. That's one reason I call them vertical circles rather than azimuth circles! Some technical terms can be confusing :-) I expect Mr Google can give you more examples. Very best wishes Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Gnomon Gap Puzzle - wonderful
Hello Frank Your design is wonderful, I would not have guessed it exactly, specifically that it was an azimuth dial. I did imagine it was a dial with a double (or split) style. I will buy the book! A question for you and others, have you come across the term 'azimuth circles', how would you define this term? I will be grateful for information. Many thanks and very best wishes for 2019 Alastair Hunter Edinburgh, UK -Original Message- From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Frank King Sent: Thursday, 3 January, 2019 12:49 PM To: Sundial List Subject: Re: Gnomon Gap Puzzle Dear All, I have a simple rule with my puzzles: wait for a reply from Geoff Thurston and then reveal all. The time has come! In the recent spate of messages, both Bill Gottesman and Steve Lelievre were very close. Bill is the only person to suggest an azimuthal dial with vertical styles (which describes my design) but Steve's drawing (despite the polar styles) is remarkably close to my design too. The 'unusual space' is "The End-Flap of a Book" - not easy to guess! By arranging for the top and bottom edges of the front cover to serve as vertical gnomons, you can mark out an azimuthal dial on the end-flap. This way the user doesn't need to supply a gnomon, nor is there any need for any kind of pop-out gnomon. The sundial is shown in operation outdoors in the real sun at: http://www.cl.cam.ac.uk/users/fhk1/Sundials/GnomonGapDial.jpg This shows what the design looks like. There are many forms of azimuthal dial but, as one who enjoys astrolabes, I like stereographic projections. [OK, I do realise that my design uses the zenith as the centre of the projection and not the NCP!] In terms of 'looking good', this design hardly competes with the Nuremburg or Harvard dials or the dials in the stunning images that Sara has just sent us. We can all look forward to the Adler catalogue. Sadly, those dials look a bit expensive. The link above shows the upmarket version of my design and this costs 15 GBP but you do get a book bundled in at no extra charge! There are lots of pretty pictures of sundials inside. What about implementing the design for less than a dime? Well, a dime is about what it costs me to print out a sheet of paper, and all you have to do is to print out the following: http://www.cl.cam.ac.uk/users/fhk1/Sundials/DoubleGapDial.jpg This is intended for A4-paper. You may have to trim the edges if you use LETTER size. This shows what is hidden on the inside back cover of the book. That is where the early morning and late evening summer-time hours are found. All you have to do is to fold along the black straight line (a valley fold not a ridge fold), place the S-part flat on a horizontal table, and point the S to SOUTH [some users find this a bit surprising!]. You must arrange for the larger part to be perpendicular to the S-part. In summer, in the early morning and late afternoon, you have to place the larger part flat on the table; the edges of the S-part then serve as gnomons. This really is a working diptych sundial and they don't come any cheaper! Sadly it is designed for my latitude +52d 12m but anyone who has read this far is likely to be well equipped to adapt the design for another latitude. Adventurous readers can add the appropriate wiggles to the hour lines to deal with longitude offset and EoT. Maybe it would be best to design two such dials (one on each side of the paper), with December to June hour lines on one side and June to December hour lines on the other. In the unlikely event that you might want the up-market version (with book attached) please contact: Hallam Kindersley Very best wishes Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
App for iPad - Phaeton
Tony Amazing, can't believe my eyes with Phaeton, admire! Alastair --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Sundial related links - add
Daniel Thank you very much for adding me to your sundial mailing list. I have already enjoyed reading your list of sundial related links. As a sundial maker, may I add my own one, please - Macmillan Hunter Sundials, website www.macmillanhunter.co.uk . With kind regards Alastair Hunter __ Alastair Hunter, 3 Peel Terrace, Edinburgh EH9 2AY Email: a...@3peel.co.uk Telephone: 0131 468 2616 __ --- https://lists.uni-koeln.de/mailman/listinfo/sundial
