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. - "Notes on Asr Curves and Twilight Curves – Part 1 of 3” by Dominique Collin This study focuses on the curves indicating the Asr prayer that can be indicated on Arabic sundials, both horizontal and vertical. The analysis is extended to the curves of astronomical twilight, used to announce the Ishā’ prayer. This issue presents the first of three parts of the study in which the author addresses the construction of such curves with a mathematical approach of advanced gnomonics. 2. - "The old sundials of Colle Santa Lucia" by Giuseppe De Donà Researches are proposed on two ancient sundials in Colle Santa Lucia (BL), currently among the oldest known in Veneto. The checks, made with modern instruments, show that the unknown gnomonist of the 17th century who made them was a competent person. 3. - "More sundials by Fra Felice from Val di Biadene?" by Giuseppe Flora Three sundials on the facades of the eighteenth-century villa Gera-Bellati, have some graphic characteristics that, supported by recent historical information, suggest their execution can be attributed to “Fra Felice da Val di Biadene”, the friar of the Capuchin Order who in the first half of the 18th century drew numerous sundials in Veneto and Friuli regions. Fra Felice was talked about in issue 32 of Orologi Solari – December 2023. 4. - "A variant of an azimuthal sundial" by Alessandro Gunella A variant of an azimuthal sundial is proposed, obtained by repeatedly reporting, at appropriate distances from a fixed-position style, the elliptical figure of the analemmatic sundial. The layout is then appropriately modified to make it more readable and pleasant. 5. - "The projection of the equinoctial sundial" by Alessandro Gunella The equinoctial sundial is projected according to different directions, always along the meridian line, and the same number of sundial schemes are obtained on different planes. The author also suggests, without the projective modality, but with an alternative method, the construction of a horizontal sundial. 6. - "The historical development of Geometry" by Michele T. Mazzuccato A brief historical excursus is proposed on the development of geometry from Euclid to the present day. In particular, the birth of analytical geometry, descriptive geometry and projective geometry, of fundamental importance also for Gnomonics, are highlighted. 7. - "Cylindrical astrolabe with the projection of Marinus of Tyre" by Alberto Nicelli and Nicolò Nicelli The design and construction of a cylindrical astrolabe, based on the equidistant projection, invented by the ancient cartographer Marinus of Tyre (1st-2nd century AD), is described. The astrolabe is made up of two coaxial and tangent cylinders: the external one, on which the celestial sphere is projected, can rotate around the internal one, on which the altazimuth system for a given latitude is projected. The prototype described in this article is also the only example of a cylindrical astrolabe known to the authors. 8. - "The time of Asr prayer from the analemma" by Elsa Stocco The construction of the Asr prayer curves, which we find in many Islamic sundials, is proposed in two different horizontal sundials made with graphical methods starting from the analemma and with the use of Geogebra. The Asr curves are inserted into a sundial with modern hours, the first at hour angle, the second an altitude sundial. A possible analytical definition is also suggested for the latter. 9. - "Finding the distance between two points on Earth: graphical solution with spherical triangles" by Alessandro Gunella (Short contribution) Old and new graphical methods are proposed to find the distance between two points on the Earth's surface. Hope you will enjoy the reading, although in Italian only. Best wishes for a Happy Easter from the editorial staff of Orologi Solari ! Gian
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