Dear friends, a new issue of the Italian magazine Orologi Solari is available for download from the usual site http://www.orologisolari.eu/.
Here is the list of articles together with a short abstract: 1. - "Calculation of the limits of the presence of the Sun on a vertical declining wall starting from a singular triestine sundial" by Paolo Alberi Auber A vertical sundial installed on the terrace of a building in Trieste shows two particular hour lines: the author in this article explains their meaning and illustrates their calculation method. 2. - "The name of hours. For a more correct gnomonic lexicon - second part" by Mario Arnaldi In this second part of the article the author continues his considerations on unequal hours, focusing exclusively on the perception of time in the Middle Ages. Although the ancient geometric and astronomical concept was well known since the early Hellenistic times, in the practice during late-ancient and then medieval ages this began to get out of hands even to scholars. 3. - "The sustainable lightness of <Ravenna’s Rule>" by Mario Arnaldi and Fabio Savian Even before the transition from unequal to equal hours, it was realized that a classic medieval sundial could not function properly at latitudes above 25 degrees. Without sufficient knowledge to trace the correct sundials to show the temporary hours, practical methods to limit the error were tested. The article proposes an easy and universal rule, so far little investigated, to read the true temporary hours on medieval sundials. 4. - "Realization of a sundial on an inclined plane" by Gian Casalegno It is explained how, by means of the Orologi Solari program, it was possible to easily design a sundial positioned on an inclined declining plane located on the hill behind the author's house. The problems that came up due to an incorrect choice of materials are then described. 5. - "Letter to a colleague: a lunar dial..." by Alessandro Gunella The author answers to a colleague who asked him about the possibility of using the Vitruvian Analemma for the Moon, and shares with us the reflections he has collected about. 6. - "PRIMITIÆ GNOMONICÆ CATOPTRICÆ...” by Athanasius Kircher" by Alessandro Gunella The author presents one of his latest and precious translations, about one of the first gnomonic texts published by Kircher when he was still living in Avignon: a real novelty on the catottric gnomonics. 7. - "The French hours without their knowledge" by Fabio Savian The author analyzes the terminology used in the classification of sundials, to bring it to attention of experts and submit it to criticism, hoping that more and more the 'gnomonic description' of a sundial can become shared and coherent. 8. - "The Eng. Fadini’s nomograms" by Elsa Stocco The nomograms, that Eng. Fadini in the 90s proposed to calculate the data of a vertical sundial, given latitude and declination of the wall, are remembered. Even then made obsolete by the use of the pocket calculator, today they represent an “Historical” curiosity... Hope you will enjoy the reading, although in Italian only. Ciao and... Happy Christmas ! Gian
--------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
