Re: The most exact sundial of the world In Samedan!
Dear All, This is a high claim for the accuracy of reading a sundial. I want to add my thoughts about the effect of the EoT to the reading. Near the dial is a table with the daily correction for longitude and EoT. Now the values are given for 2011 and 2012. It looks that every two years this table will be replaced. To me it is strange that this table is rounded to 5 seconds. This introduces a possible error in the reading between + 2.5 and - 2.5 seconds. This error can be reduced to 1 second by a table rounded to 1 second and has nothing to do with the quality of the dial itself. Apart from this the EoT changes daily. In spring and summer this change is maximum around the 1th of September and is about 20 seconds per 24 hours. Look in the table for the given nine days in september. The difference always is 20 seconds. Assuming the change is linear in one day this is 0.8 per hour. The lenght of the day in Samedan on the 1th of September is some more then 12.5 hours. The total change in the Eot then is 10.4 seconds during daylight. This introduces an error between -5.2 and +5.2 seconds in this period. In other periods of the year the error is smaller because the EoT changes less. On the other hand the error increases because the period of daylight is longer. Nevertheless, I would like to play around with the beautiful dial. Fer J. de Vries De Zonnewijzerkring http://www.de-zonnewijzerkring.nl Molens http://www.collsemolen.dse.nl Eindhoven, Netherlands lat. 51:30 N long. 5:30 E - Original Message - From: Bill Gottesman To: sundial@uni-koeln.de Sent: Tuesday, June 26, 2012 3:50 AM Subject: Re: The most exact sundial of the world In Samedan! Hello All, I am a little confused: Who made this dial? I think it is magnificent. The setting is stunning, the rock mounting is dramatic. This is a first-class project. I would be interested in reading (in English) how it was mounted, how it was aligned, how it was engraved, how the discs are mechanically assembled and what kind of bearings are used to minimize play. I hope an article in the NASS Compendium, or the BSS Journal is forthcoming. Although the Renaissance double focusing dial can be read to within 10 seconds, in practice it has mostly only been accurate to within 1 minute, and sometimes worse. This is because the Equation-of time is an average over the current 4 year cycle, and is further due to imperfections in the roundness and concentricity of the helix and imperfections in polar alignment. -Bill Gottesman On 6/25/2012 3:55 PM, Frans W. Maes wrote: Dear Fabio, Roger all, It is always interesting and instructive to consider claims of extraordinary properties; in this case, a temporal accuracy of 10 seconds. The final accuracy of a sundial is the result of several factors, among which the accuracy of orientation and mounting. However, the basic factor here is the accuracy with which a hair line can be placed in the exact center of a strip of light by rotating a disk. The attached photo nr. 7 from the following pdf, taken from Fabio's site: http://www.sundialatlas.eu/photo/CH/156/CH000220_2_A.pdf sets the stage. The slit (the gnomon) is placed at the center of rotation of the disk that carries the hair line. Ten seconds of time corresponds to a rotation of 2.5 minutes of arc around the polar axis. So the question is: can the hair line be placed on the theoretical center line of the light strip with an accuracy of 2.5 arcminutes? I think that only actual experiments can answer this question, but I am doubtful. The edges of the light strip are sharpest close to the gnomon, but the lateral displacement of the hair line due to rotation is small there. Further out (to the right in Fig. 7) the light strip gets wider, with fuzzier edges. What would be the best distance from the gnomon to look for estimating the center? And what accuracy would be feasible? Does anyone know about experimental data on such a task? As far as I know, the only case where a reading accuracy of 10 seconds of time is achieved, is in the double focusing sundial of Bill Gottesman; see: http://www.precisionsundials.com/sundial_list.htm (scroll all the way down). Best regards, Frans Maes On 24-6-2012 20:09, Fabio nonvedolora wrote: On Sundial Atlas there is the card of this sundial with 4 pdf files attached, one of them with technical info. All of them are in german. www.sundialatlas.eu/atlas.php?so=CH220 ciao Fabio Fabio Savian fabio.sav...@nonvedolora.it Paderno Dugnano, Milano, Italy 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2) From: Reinhold Kriegler Sent: Sunday, June 24, 2012 4:39 PM To: Sundial Mailingliste Subject: The most exact sundial of the world In Samedan! Dear friends! Have a look to Switzerland! Genaueste
Re: The most exact sundial of the world In Samedan!
Hello All, I am a little confused: Who made this dial? I think it is magnificent. The setting is stunning, the rock mounting is dramatic. This is a first-class project. I would be interested in reading (in English) how it was mounted, how it was aligned, how it was engraved, how the discs are mechanically assembled and what kind of bearings are used to minimize play. I hope an article in the NASS Compendium, or the BSS Journal is forthcoming. Although the Renaissance double focusing dial can be read to within 10 seconds, in practice it has mostly only been accurate to within 1 minute, and sometimes worse. This is because the Equation-of time is an average over the current 4 year cycle, and is further due to imperfections in the roundness and concentricity of the helix and imperfections in polar alignment. -Bill Gottesman On 6/25/2012 3:55 PM, Frans W. Maes wrote: Dear Fabio, Roger all, It is always interesting and instructive to consider claims of extraordinary properties; in this case, a temporal accuracy of 10 seconds. The final accuracy of a sundial is the result of several factors, among which the accuracy of orientation and mounting. However, the basic factor here is the accuracy with which a hair line can be placed in the exact center of a strip of light by rotating a disk. The attached photo nr. 7 from the following pdf, taken from Fabio's site: http://www.sundialatlas.eu/photo/CH/156/CH000220_2_A.pdf sets the stage. The slit (the gnomon) is placed at the center of rotation of the disk that carries the hair line. Ten seconds of time corresponds to a rotation of 2.5 minutes of arc around the polar axis. So the question is: can the hair line be placed on the theoretical center line of the light strip with an accuracy of 2.5 arcminutes? I think that only actual experiments can answer this question, but I am doubtful. The edges of the light strip are sharpest close to the gnomon, but the lateral displacement of the hair line due to rotation is small there. Further out (to the right in Fig. 7) the light strip gets wider, with fuzzier edges. What would be the best distance from the gnomon to look for estimating the center? And what accuracy would be feasible? Does anyone know about experimental data on such a task? As far as I know, the only case where a reading accuracy of 10 seconds of time is achieved, is in the double focusing sundial of Bill Gottesman; see: http://www.precisionsundials.com/sundial_list.htm (scroll all the way down). Best regards, Frans Maes On 24-6-2012 20:09, Fabio nonvedolora wrote: On Sundial Atlas there is the card of this sundial with 4 pdf files attached, one of them with technical info. All of them are in german. www.sundialatlas.eu/atlas.php?so=CH220 ciao Fabio Fabio Savian fabio.sav...@nonvedolora.it Paderno Dugnano, Milano, Italy 45 34' 10'' N, 9 10' 9'' E, GMT+1 (DST +2) From: Reinhold Kriegler Sent: Sunday, June 24, 2012 4:39 PM To: Sundial Mailingliste Subject: The most exact sundial of the world In Samedan! Dear friends! Have a look to Switzerland! Genaueste Sonnenuhr der Welt steht im Engadin Auf Muottas Muragl auf 2456 Meter ber Meer ist am Donnerstag die genaueste Sonnenuhr der Welt eingeweiht worden. a.. http://www.bote.ch/vermischtes/genaueste-sonnenuhr-der-welt-steht-im-engadin Quelle: suedostschweiz.ch b.. Datum: 22.06.2012, 17:00 Uhr c.. Webcode: 39872 O I love the superlatives in connection with sundials!! :-) So far this one I did not know: The most exact sundial of the world! Best regards Reinhold Kriegler * ** *** * ** *** Reinhold R. Kriegler Lat. 53 6' 52,6" Nord; Long. 8 53' 52,3 Ost; 48 m . N.N. GMT +1 (DST +2) www.ta-dip.de http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html http://www.ta-dip.de/salon-der-astronomen/bewohner-des-salons-der-astronomen.html
RE: The most exact sundial of the world In Samedan!
Its an interesting dial and looks well engineered, but there sure isnt much information around about it. Appears to be an Equatorial dial with rotating outer ring to adjust for EoT and Summer Time, but I dont see how one *reads* it. That tiny axial pin is useless as a gnomon except at the Equinoxes. It seems like the inner disk also rotates and the time could be read from the graduation on the perimeter, but lining up the three little pins shadows still seems impossible. And perhaps the dial was inaugurated at noon on the longest day of the year, but that photo was taken much earlier in the day!! Dave _ From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Reinhold Kriegler Sent: Sunday, June 24, 2012 7:40 AM To: Sundial Mailingliste Subject: The most exact sundial of the world In Samedan! Dear friends! Have a look to Switzerland! Genaueste Sonnenuhr der Welt steht im Engadin Auf Muottas Muragl auf 2456 Meter über Meer ist am Donnerstag die genaueste Sonnenuhr der Welt eingeweiht worden. * http://www.bote.ch/vermischtes/genaueste-sonnenuhr-der-welt-steht-im-engadin Quelle: suedostschweiz.ch * Datum: 22.06.2012, 17:00 Uhr * Webcode: 39872 O I love the superlatives in connection with sundials!! :-) So far this one I did not know: The most exact sundial of the world! Best regards Reinhold Kriegler * ** *** * ** *** Reinhold R. Kriegler Lat. 53° 6' http://www.ta-dip.de/sonnenuhren/meine-sonnenuhren.html 52,6 Nord; Long. 8° 53' 52,3 Ost; 48 m ü. N.N. GMT +1 (DST +2) www.ta-dip.de http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html http://www.ta-dip.de/salon-der-astronomen/bewohner-des-salons-der-astronome n.html http://www.ta-dip.de/salon-der-astronomen/bewohner-des-salons-der-astronomen .html --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: The most exact sundial of the world In Samedan!
On Sundial Atlas there is the card of this sundial with 4 pdf files attached, one of them with technical info. All of them are in german. www.sundialatlas.eu/atlas.php?so=CH220 ciao Fabio Fabio Savian fabio.sav...@nonvedolora.it Paderno Dugnano, Milano, Italy 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2) From: Reinhold Kriegler Sent: Sunday, June 24, 2012 4:39 PM To: Sundial Mailingliste Subject: The most exact sundial of the world In Samedan! Dear friends! Have a look to Switzerland! Genaueste Sonnenuhr der Welt steht im Engadin Auf Muottas Muragl auf 2456 Meter über Meer ist am Donnerstag die genaueste Sonnenuhr der Welt eingeweiht worden. a.. http://www.bote.ch/vermischtes/genaueste-sonnenuhr-der-welt-steht-im-engadin Quelle: suedostschweiz.ch b.. Datum: 22.06.2012, 17:00 Uhr c.. Webcode: 39872 O I “love” the superlatives in connection with sundials!! :-) So far this one I did not know: “The most exact sundial of the world!” Best regards Reinhold Kriegler * ** *** * ** *** Reinhold R. Kriegler Lat. 53° 6' 52,6 Nord; Long. 8° 53' 52,3 Ost; 48 m ü. N.N. GMT +1 (DST +2) www.ta-dip.de http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html http://www.ta-dip.de/salon-der-astronomen/bewohner-des-salons-der-astronomen.html --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: The most exact sundial of the world In Samedan!
Thanks Fabio, The link you provided Sine Sole Sileo has a link to a pdf that gives instructions in several languages including English. Here is a direct link: http://objects.estm.xiag.ch/images/Bergbahnen/Bedienungsanleitung_Sonnenuhr_Balken.pdf Regards, Roger Bailey From: Fabio nonvedolora Sent: Sunday, June 24, 2012 11:09 AM To: Sundial Mailingliste Subject: Re: The most exact sundial of the world In Samedan! On Sundial Atlas there is the card of this sundial with 4 pdf files attached, one of them with technical info. All of them are in german. www.sundialatlas.eu/atlas.php?so=CH220 ciao Fabio Fabio Savian fabio.sav...@nonvedolora.it Paderno Dugnano, Milano, Italy 45° 34' 10'' N, 9° 10' 9'' E, GMT+1 (DST +2) From: Reinhold Kriegler Sent: Sunday, June 24, 2012 4:39 PM To: Sundial Mailingliste Subject: The most exact sundial of the world In Samedan! Dear friends! Have a look to Switzerland! Genaueste Sonnenuhr der Welt steht im Engadin Auf Muottas Muragl auf 2456 Meter über Meer ist am Donnerstag die genaueste Sonnenuhr der Welt eingeweiht worden. a.. http://www.bote.ch/vermischtes/genaueste-sonnenuhr-der-welt-steht-im-engadin Quelle: suedostschweiz.ch b.. Datum: 22.06.2012, 17:00 Uhr c.. Webcode: 39872 O I “love” the superlatives in connection with sundials!! :-) So far this one I did not know: “The most exact sundial of the world!” Best regards Reinhold Kriegler * ** *** * ** *** Reinhold R. Kriegler Lat. 53° 6' 52,6 Nord; Long. 8° 53' 52,3 Ost; 48 m ü. N.N. GMT +1 (DST +2) www.ta-dip.de http://www.ta-dip.de/dies-und-das/r-e-i-n-h-o-l-d.html http://www.ta-dip.de/salon-der-astronomen/bewohner-des-salons-der-astronomen.html --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
