Copernicus reflecting dial
Hello, As of reflecting dials, a Copernican one must be recalled. On the wall of the gallery of Olsztyn castle, there are remnants of the reflecting dial made by Copernicus during his stay in the castle in years 1516-21, from where he administered diocese of Warmia. Actually this is the only extant Copernican instrument. It is thought that the original reflective surface was a liquid - mercury or wine (!), put in the bowl on the sill of one of the arched openings of the gothic gallery. Here is a link to a short movie presenting the dial, its spatial context and how it operated: http://copernicus.torun.pl/nauka/astronomia/5/?view=filmfile=4 And below are links to papers or web pages were more information on this dial can be found: http://ptfit.sgp.geodezja.org.pl/wydawnictwa/miedzyzdroje/calosc_18b_1.pdf (pp. 387-395.) http://dydaktyka.fizyka.umk.pl/hipst/pliki/1/Artyk_o_kalendarzu_cz_1.pdf http://gnomonika.pl/news.php?id=33 Similar reflecting dials were constructed in Rome in mid 17th century by Maignan, but I don't know if any is preserved to our times. Our Italian diallists will surely know it ! Regards, Maciej Lose Od: Claude Hartman sunlightdesi...@earthlink.net Do: sundial@uni-koeln.de; Wysłane: 20:18 Wtorek 2015-03-31 Temat: Reflecting Dials I am looking for photographs of reflecting dials other than ceiling dials.The recent note about the village of Aiello del Friuli has shown several. What other locations are there? Contact off list if you wish. I hope to make a list of all known examples and types. Many thanks, Claude Hartman 35N 120W --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Making Dials with plane mirrors
Some readers have asked How can you make such a dial? I would love to hear from an author of such dials to hear how it is done in less than a year of marking points. How did they do it? Computer software certainly makes it easier. The popular Zonwvlak, ZW2000, has long had a reflection function and one could play with choosing distance and angles until satisfied. I have managed to find that more recently three programs have been modified or specifically written to aid in design and construction of reflected dials. On the web site of Riccardo Anselmi you can find Cartesius Mirror, see: http://sundials.anselmi.vda.it/AWA_2_GenericDocumentDynamic.aspx?p1=Softwarep2=Software%20realizzatip3=Software I have not tried it but it seems very numeric. As mentioned previously, Gianni Ferrari's program, Reflsun, can be found in the Compendium, March 2004. It also is seems very numeric although special diagrams are employed. My favorite is the new edition of Gian Casalegno’s freeware, Orologi Solari. It was part of the digital bonus of the Compendium, December 2014. It is available on line at http://www.sundials.eu/indexENU.htm Here is the note sent by the author, The main new feature is the addition of reflection sundials to the hour angle family of dials. As usual all the features of OS are now available for this new type of dial: all types of hour lines, simulation, lighting conditions computation, true horizon computation and use etc. Moreover to facilitate the placement of the mirror, tools similar to those already provided by Gianni Ferrari software (thanks Gianni) have been added: calculation of the position of the light spot at desired time instants, calculation of the orientation of the mirror from one or more measurements of the coordinates of the light spot. An original feature that I think can be very useful is to change the orientation of the mirror with the mouse (left button + shift key pressed) and to see in real time on the screen the changes in the hour lines pattern. When combined with the ability to insert a correctly sized photo of the wall behind the dial, this tool allows you to easily find the optimum orientation of the mirror. A tutorial specifically dedicated to the design and construction of reflection sundials is available at the address (http://www.sundials.eu/download/riflessioneENU.pdf)(See digital bonus.) I hope it can be helpful in order to learn all the new features of the program. This new release also includes the new tables by Gianni Ferrari (thanks again Gianni) containing the mean values of the Equation of Time and of the Sun Declination for years from 2014 to 2061. Thank you Gian! --- https://lists.uni-koeln.de/mailman/listinfo/sundial
The other Mayall Mayall formula (in the wikipedi article notes) likewise gives the correct answer.
The other of the 2 Reclining-Declining formulas listed in the notes, at the bottom of the wikipedia Sundial article, likewise gives correct answers. Again, using: Lat = 51.5 Incline = 45 Decline direction = 45 degrees left of south ...The Mayall Mayall formula, in the article's notes, for Hrd--gives the correct answer for the angle between the 8:00 a.m. line and the noon line on the dial. If the line for a particular hour is counterclockwise from the noon line, then that answer is given as negative, (or maybe under some circumstances, as the positive number consisting ofthe sum of that negative + 360). Let me repeat some things about the use of those formulas: Where Hrd1 and Hrd2 appear at the left side of the two equations, Hrd1 should be replaced by tan Hrd1, and Hrd2 should be replaced by tan Hrd2. The equation Hrd = Hrd1 + Hrd2 is correct as shown. D, the decline direction, is measured from north. It's the azimuth that the dial is facing. R, the recline, is measured from the horizontal. (Nowadays that's probably more often called incline and represented by I). So, both of the Mayall Mayall Reclining-Declining formulas in the notes at the bottom of the wikipedia Sundial article are correct, and give the correct answer. MichaelOssipoff --- https://lists.uni-koeln.de/mailman/listinfo/sundial
