Orologi Solari n. 30, abril 2023

Gràcies a la gentilesa dels nostres col·legues italians, ja ens podem descarregar de la xarxa el n. 30 de la revista Orologi Solari. Recordeu també descarregar, en el mateix enllaç, el "bonus" que conté molt material complementari.

Here is the list of articles together with a short abstract:

1. - "The obelisk of Augustus. A detail so far ignored: deductions and updates" by Paolo Albéri Auber
The research on the Obelisk of Augustus requires some insights that the author tries to clarify here. First of all, the question of the 100 Roman feet (present in the calculation) confirmed by an abnormal and hitherto ignored diurnal sign. It is demonstrated here that the “observatio umbrarum” connected to the Julian calendar badly applied for 36 years (see table at the end of the article) can be done even if the gnomonic height of the center of the summit sphere is not exactly 100 Roman feet, as practically perfect in the layout. A re-reading of Pliny the Elder's text confirms this. If the level of the meridian line was, since the initial project, higher (and not moved higher in a second phase as unfortunately sometimes asserted) it corresponds to the level of trampling of the people present within the ARA PACIS, also designed higher than the “Augustien” level to avoid flooding.

2. - "Suggestions for the elementary teaching of Gnomonics" by Alessandro Gunella
The author proposes some useful suggestions for beginners or for willing teachers who want to tackle the creation of a sundial. The graphic methods proposed, designed for junior high school students, can be effectively used to broaden and consolidate the mathematical and scientific knowledge expected for the age.

3. - "Orontius Fineus of Dauphiné's Astrolabe Dial" by Alessandro Gunella
The author presents the translation of a 1534 treaty by Orontius Fineus on the Astrolabe Dial, an instrument that “offers the same and even greater comfort than the vulgar Planisphere, and is useful for all the Regions of Europe”. Since the graphic tables attached to the text have been lost, in the reconstruction of the instrument the translator uses a fourteenth-century manuscript by the “Maestro Profacio”.

4. - "The equinoctial curve in the bifilar sundials with a polar wire" by Fabio Savian
The author returns to a study relating to bifilar sundials, where an equinoctial line of any shape can be obtained with a properly shaped wire. Already dealt with in 2007, the topic is presented here in a more complete way, both for the new explanatory images and for the mathematical description of the declination curves.

5. - "Rapturous Glimpse of Antique Hous Sublime" by Fred Sawyer
This is an exploration of a millennium of history, misconceptions, false statements, and general lack of clarity concerning antique hour lines.

6. - "Ring sundials with fixed hole: the calculation with Geogebra and Excel" by Elsa Stocco
We propose a study on the determination of the “correct” hour layout in a ring clock with a fixed hole. The problem has already been dealt with in an article in the previous issue of this journal and solved there by exploiting the potential of Geogebra in 3D “graphic” construction, with the simple use of geometric objects such as cylinders, cones, etc. Here it is once again tackled in an analytical way, through calculation, by Geogebra and by Excel, investigating the problem of the maximum width allowed for the ring and of the appropriate flaring of the light entry hole, in order to have a complete reading of the hours.

7. - "Sundials of Egypt in Villette" (Short contribution) - by Giacomo (Gim) Bonzani
In the context of the “liberi di imparare” (Free to learn) exhibition on ancient Egypt, set up in 2022 in Villette (VB, Italy), two portable sundials calculated with the parameters of Giza, in Egypt, were created. These are two small sundials for true local time, at modern hours: one on the polar plane and one horizontal, the latter with unique characteristics for a longterm chronological function.

8. - "Scalar : a horizontal sundial" (Short contribution) - by Mauro Giongo
In the Trentino dialect, the flatbed, usually made of wood, which is located on top of the cart to be able to transport logs, hay, etc., is called ”scalar”. The sundial described here takes its name from this object, made precisely on the old flatbed of a wagon. Unlike a common sundial that indicates the current time, this dial shows the position of the Sun in the sky, expressed as azimuth and altitude.

9. - "The Quadrant of Israel by Jacob Ben Machir Ben Tibbon (Magister Profacius)" (Short contribution) - by Alessandro Gunella
The Quadrant of Israel, attributed to Profacius, is a sort of astrolabe dating back to the end of the 13th century, probable result of elaborations by jewish Astronomers/ Astrologers of Arab cultural sources. The author presents his annotated translation of the text describing the instrument, based on the Latin text published by Boffito in 1922.

10. "Pierre de Flovtrieres' Treatise on “horlogeographie” of 1619, translated and commented" (Short contribution) - by Alessandro Gunella
The author presents his annotated translation (from seventeenth-century French) of a treatise by Flovtrieres. Consisting of a few pages, the treatise intends to be an introduction to the subject and limits itself to listing the operations for drawing sundials, not always simple ones, according to an original sequence which is not found in other texts and which the author does not justify with theoretical considerations.

11. - "An ancient sundial in the Treviso area has been restored" (Short contribution) - by Enio Vanzin
The conservative restoration of the large sundial (about 3 x 2 m) on the parish church of S.S. Peter and Paul of Mareno di Piave (TV, Italy) is described. The sundial indicates the true local time and is presumably from the 19th century. The restoration was carried out by the author and Mosè Pavanello, with the sponsorship of the cultural association "L'Albero blu" of Mareno di Piave.

Hope you will enjoy the reading, although in Italian only.