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. "An ‘almost’ ancient sundial from roman Altino" by Paolo Albéri Auber, Renis Ridolfo The authors describe the only conical sundial found in the territories of northern Italy, analyze its structure and demonstrate how it was made without following any correct gnomonic principle. 2. "Reflection sundial: an update" by Gian Casalegno The author comes back to reflection sundials to improve the tools introduced in his software. The simulations carried out on two different sundials show that the results can be useful for a project if measurements are taken with the utmost care. 3. "A reflection sundial" by Francesco Ferro Milone Proposal and construction of a reflection sundial on the north facade of a farm in Bollettina, Caselle (TO), together with the restorer / painter Valentina Mauro: detailed description of the work. 4. "The ‘camera obscura’ reflection sundial at the Baita delle Meridiane" by Mauro Giongo A hut in Trentino houses, together with many other sundials of all kinds, a reflection sundial called Punto Gamma. In this article the author describes the construction details, tells about the realization and explains what checks he subsequently carried out. 5. "The vertical dial described by Andrea Schoener" by Alessandro Gunella The author analyzes the concise passage from the book "Gnomonice" by Andrea Schoener relating to the construction of an altitude dial at equal hours: dismantles and reconstructs the various parts of the text to interpret the phases of geometric construction and give a plausible justification for all the operations that are superimposed in the original figure. The complete translation of text is shown in the Appendix. 6. "From Margarita Philosophica, Quadrans Vetus and Astronomy" by Alessandro Gunella The author presents us with the translation, included in Bonuses, of two texts extracted from the “Margarita Philosophica” encyclopedic book in a 1508 edition: the first is the one that describes the construction of the "Quadrans Vetus", the second is the chapter dedicated to the Astronomy. 7. "Eng. Garnier makes us experience the shadow retrogradation" by Redazione An article by Enrico Garnier is reproduced from the number 83 (June 1938) of the magazine "Sapere" which describes a simple device for observing the "shadow retrogradation" mentioned in the well-known biblical passage. The introduction mentions the figure of Enrico Garnier and the magazine “Sapere”, and some of the studies made to explain the phenomenon of retrogradation beyond the divine miracle are recalled. Mathematical simulations of the phenomenon are presented in an Appendix. 8. "‘Triptych’ sundial" by Pietro Sangiuseppe A mean time sundial is presented, composed by two vertical sundials one facing 45 ° East and one facing 45° West, and by a third panel with support function. To facilitate reading, the hours are arranged on six circles of different colors and marked with a symbol representing the reference period of the year. 9. "Solar decliners" by Fred Sawyer The author tells how, from a classic 'flag' altitude sundial, he came to design an original declining (i.e. not facing the Sun) altitude sundial, and how from this, with successive reworking, he came to different similar designs, including a dial that faithfully follows a model from 1600. (originally published on The Compendium, March 2020, 27) 10. "Comparison between time systems" by Elsa Stocco The comparison between the modern time system with those of the past (Italic, Babylonian and Temporary) is made for educational purposes with the Geogebra dynamic geometry software. By working on the sphere, or on the plane with Vitruvius' Analemma, it’s possible to vary the latitude and declination of the Sun, and dynamically observe their effect on different kinds of hours. The comparison is then also carried out with mathematical formulas, using Geogebra or an Excel spreadsheet. A digital bonus can also be downloaded for additional reference material. Hope you will enjoy the reading, although in Italian only. Ciao. Gian
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