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. - "The personal computer and contemporary gnomonics" by Riccardo Anselmi The author presents an overview of gnomonics over the last 50 years, revolutionized by the advent of the personal computer, and recalls the contributions of several gnomonist friends. 2. - "Notes on the ASR curve and twilight curves (part 3 of 3)" by Dominique Collin The 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 third of three parts of the study in which the author addresses the construction of such curves with a mathematical approach of advanced gnomonics. 3. - "Projective” sundials laboratory (part 4)" by Francesc Clarà The author continues the description of "projective" sundials. The sundials considered this time are again those with the direction of projection along the bisector between the equatorial plane and the dial plane, which this time is vertical. These instruments belong to the Foster-Lambert category and have the advantage of featuring a time scale with uniform spacing of 15°. 4. - "The Sun's position on the Ecliptic" by Alessandro Gunella The author, commenting on an essay by M. Hosseinzadeh of the University of Tehran, proposes a personal graphic solution to the problem of the position of the Sun on the Ecliptic in a given moment of a given day knowing the location's latitude, azimuth and solar altitude and using the methods proposed by the sixteenth-century translators of Vitruvius and Ptolemy. 5. - "How to create an astronomical nomogram" by Alberto Nicelli The author describes the creation and use of a simple nomogram to solve basic problems in positional astronomy, even if approximately, without using spherical trigonometry formulas. 6. - "Temporary hours and Federico Commandino's mistake" by Alberto Nicelli In his "Liber De Horologiorum Descriptione", Federico Commandino (1509-1575) demonstrated, by a mistaken deduction, that temporary time lines are straight lines. Was it really a mistake, or was it a deliberate and tacit simplification to improve readers' understanding? The author reports and comments on the passage in question and, as a didactic exercise, demonstrates, using analytical geometry, why this deduction is erroneous. 7. - "The celestial parable" by Alberto Nicelli An original representation of the celestial sphere on the parabola is described. It allows us to graphically and very simply obtain the hour angle of sunrise and sunset of any star at any latitude. 8. - "Formulas from Analemma" by Elsa Stocco Using plane trigonometry and the analemma, the three fundamental formulas of gnomonics are derived. Two other frequently used formulas are added: one for calculating the semidiurnal arc, and the other for calculating the ecliptic longitude of the Sun. 9. - "Saint Pio X, Pope, Saint, sundials maker" by Elsa Stocco The figure of Giuseppe Sarto is remembered. Born in Riese (Treviso), he became Pope Pio X and was canonized forty years after his death. As a young country chaplain, he dedicated himself to the study and construction of various sundials, inheriting the tradition of a lively and active "school of gnomonics" at the Episcopal Seminary of Padova. 10. - Useful information for restorers (Short contribution)" by Alessandro Gunella The author indicates how to find the fundamental parameters of a sundial: latitude of the place and declination of the wall. These are useful for its restoration. 11. - "De horologiis describendis libellus -Translation and commentary of Daniele Barbaro's book (Short contribution)" by Alessandro Gunella The author translates and comments a book of notes on sundials, “De horologiis describendi libellus” by Daniele Barbaro. Hope you will enjoy the reading, although in Italian only. Regards. Gian
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