Sundials

The structure and operating principles of a solar compass conceived and realised at the ENEA Laboratories in Frascati are presented. The optical design, the underlying software and the calibration procedure make this instrument a reliable, stand-alone tool with an unprecedented combination of accuracy and cost-effectiveness. In-field operation gives evidence of azimuth determination capability with an accuracy of 0.01°. Exploitation of built-in sensors of smartphones (e.g. GPS, camera, accelerometer) allowed us to move this technology to popular level, providing everybody with a cheap tool of orienteering, far superior to any magnetic compass, despite a reduced accuracy with respect to the original instrument.

Exactly 500 years ago, Nicolaus Copernicus drew a lattice of lines on a panel above the doorway to his rooms at Olsztyn Castle, then in the Bishopric of Warmia. Although its design has long been regarded as some kind of reflecting vertical sundial, the exact astronomical designation of the lines and related measuring techniques remained unknown. Surprisingly, Copernicus did not refer to his new observational methods in his principal work, De Revolutionibus. A data analysis of a 3D model of the panel has, at last, solved the mystery: Copernicus created a new type of measuring device – a heliograph with a non-local reference meridian – to precisely measure ecliptic longitudes of the Sun around the time of the equinoxes. The data, 3D model and modeling results of our analysis are open access and available in the form of digital (Jupyter) notebooks. Copernicus | heliograph | scientific revolution | astronomical measurement |

Over 940 Latin sundial inscriptions with translations, most re-translated and some corrected, from Margaret Gatty's collection. Available as an ebook. Thoroughly corrected for the 2018 edition. Available at https://www.amazon.com/Sundial-Latin-Thoughts-Light-Dark-ebook/dp/B00WTF4D6Q .

Today's 3D modeling programs offer methods for representing gnomonic geometry, the apparent astronomical geometry used in dialing, such that this geometry can be directly applied to modeled objects to quickly create unique dial designs. This paper offers methods for creating a 3D geometric structure, representative of a shadow plane model, which can serve to apply hour lines and day lines to almost any modeled object. The author presents the application of this "dialing scaffold" to the creation and presentation of digital models of object sundials, a chalice dial and a spoon dial.

2011 Axis Mundi belongs to a category of sun dials known as scaphes. Scaphe dials take their name from the Greek word for ship-scaphos. Typically these dials are shallow bowls, unlike hemispheriums, which possess the full depth of a half sphere. The scaphe dial functions much like a cross between a horizontal dial and a hemispherium. Like the hemispherium its bowl shape reflects the arc of the heavens and like the horizontal dial its lines take the form of elegant curves. Cast in the image of a vessel, the scaphe dial suggests a receptacle for catching and gathering the light.

The desire to orient human civilization within the universe is evident in the most ancient structures of the world, including Stonehenge, the Pyramids of Giza and the Pantheon. The baroque architect, priest and polymath, Guarino Guarini (1624–1683), designed seventeen architectural works and wrote ten treatises on a multitude of subjects, including architecture, mathematics and astronomy. Guarini presents three principles in his treatise on architecture, which connects the art of building (edificare) to the sun (orologia, gnomonica) and to solar mechanics (macchinaria). The Church of San Lorenzo in Turin (1668–1687) is an elegant example of these principles created as built form, with a dome resembling the celestial sphere, aligning the church to God and to the cosmos. The vertical alignment of the dome represents the celestial pole, a cosmological center point that is also known as the axis mundi. The interlocked system of stone arcs that comprise the structure of the dome, repre-sents the rings of an ancient model of the celestial sphere known as an armillary that dates as far back as Eratosthenes (276–194 BC). The following dissertation creates an unprece-dented connection between Guarini’s knowledge as an architect, mathematician, astronomer and philosopher, to the Church of San Lorenzo. While a previous theory on Guarini by Marcello Fagiolo briefly established the possibility of a system unifying Guarini’s architec-ture and academic knowledge, I greatly expand this possibility and argue that Guarini is a heliocentric astronomer, not a geocentrist. San Lorenzo was built at the end of the Baroque period and at the beginning of the Enlightenment, representing the bridge between the clas-sical past and the dawn of the age of modern science. By demonstrating that Guarini
believed in a sun-centered solar system, I will argue that for Guarini, the light of the sun was architecturally, theologically and cosmologically of the utmost importance.

In medieval Hungary surely many different sundials were in use to indicate the passing time, but for today only a few
remained which can be still studied. There are especially not many of them which came to the light from archaeological
excavations. Therefore, the analysis and the presentation of the fragments of a sundial that was unearthed in the
church of the Benedictine monastery at Kaposszentjakab is, among other reasons, very important. In addition to the
description of this fragmented sundial from Kaposszentjakab, in the article the author also summarizes the knowledge
about sundials in general as well as he presents those wall clocks and pocket watches that were until now revealed
in Hungary. To do so was an essential task, since from the archaeological point of view no one ever provided such a
summary before. Until now mainly the astronomers were interested in sundials, and not so much the historians and/
or the archaeologists.

Hors Collection 16 x 24 cm ; 448 pages Index ; bibliographie 110 illustrations 978-2-251-44509-0 35 € Diffusion -Distribution : BLDD L'Antiquité est rarement regardée comme une période d'utilisation massive des instruments de mesure du temps. Ces derniers sont même souvent considérés comme sommaires, peu inventifs voire inexistants. Cet ouvrage fait, pour la première fois, la synthèse des données sur le sujet et remet en cause les idées reçues. Les instruments de mesure du temps faisaient partie intégrante des habitudes antiques : l'heure régissait de nombreux aspects de la vie quotidienne, tant privée que publique. L'épigraphie comme l'archéologie attestent de ce besoin particulier. Toute cité se devait de posséder plusieurs instruments publics, rudimentaires ou complexes et monumentaux. Tout propriétaire un tant soit peu fortuné devait disposer d'un cadran solaire dans son jardin. Ces instruments, plus que les horloges hydrauliques, constituaient la base de « l'horlogerie » antique. Avec de nombreuses typologies, le cadran solaire pouvait présenter des informations complexes. Outil astronomique, pédagogique à l'origine, il est rapidement devenu un simple outil d'usage quotidien, perdant peu à peu ses spécificités scientifiques. En contrepartie, le cadran solaire s'est cependant chargé d'une dimension symbolique forte et encore ancrée dans nos mentalités modernes. Ce que nous devons à l'Antiquité en matière de mesure du temps dépasse peut-être les simples questions technologiques habituelles.

Reloj de sol polar. Puerto de Bueu. Detalle del cuadrante del reloj de sol polar. También se llama en "escocia", que es el nombre del arco. Sobre el cuadrante se extienden las horas distribuidas entre horas de la mañana a la izquierda o poniente y de la tarde a la derecha u oriente.

Αρχαία ελληνικά ηλιακά ρολόγια από τη ρωμαϊκή, την ελληνιστική εποχή, καθώς και την περίοδο της ύστερης αρχαιότητας φυλάσσονται στο Αρχαιολογικό Μουσείο Αθηνών. Από τα επτά συνολικά ηλιακά ρολόγια, τα έξι φυλάσσονται στην Αποθήκη της Συλλογής Γλυπτών του Μουσείου ενώ το άλλο, αρκετά βαρύτερο, βρίσκεται στον εκθεσιακό χώρο στου κήπου του Μουσείου. Είναι καταχωρημένα στο ευρετήριο του Μουσείου με αριθμούς: 3156, 3157, 3158, 3159, 3220, 13365 και 13366. Τα ηλιακά ρολόγια με αριθμούς ευρετηρίου 3156, 3157, 3158 και 3159 βρέθηκαν στα ερείπια του θεάτρου του Διονύσου στους πρόποδες της Ακρόπολης, ενώ για τα ηλιακά ρολόγια με αριθμούς ευρετηρίου 3220, 13365 και 13366 δεν είναι γνωστό το μέρος που βρέθηκαν.
Από μετρήσεις των γεωμετρικών τους διαστάσεων, υπολογίζονται χαρακτηριστικές παράμετροι του ηλιακού ρολογιού, όπως η γωνία που σχηματίζεται μεταξύ του άξονα του κώνου και του γεννήτορα, το γεωγραφικό πλάτος του τόπου και το μήκος του γνώμονα.

Questo breve articolo ha lo scopo di presentare e divulgare il contenuto dell'opera "Perspectiva Horaria" di Emanuele Maignan, pubblicata nel 1648 in seguito alla realizzazione di alcune tra le più celebri meridiane a riflessione di tutti i tempi. Un'opera che è integrata in una gnomonica complessiva del XVII secolo, particolarmente intenta all'elaborazione di nuove metodologie derivanti dagli ultimi sviluppi della matematica (trigonometria e geometria) ma rivolte essenzialmente alla realizzazione di quadranti solari classici. Poco o nulla si era fatto fino ad

El arte público es aquel que sale al encuentro de los ciudadanos en las calles, plazas y parques de nuestras ciudades o en otros lugares públicos. Su presencia allí sirve de referente visual de ese entorno, de todo un barrio, y en algunos casos llega a asociarse mentalmente por propios y foráneos con la imagen emblemática de toda la ciudad. Este catálogo ofrece los monumentos, esculturas y vestigios históricos monumentalizados que se elevan exentos en los espacios zaragozanos al aire libre de acceso público, así como una amplia selección de ejemplos escultóricos, pictóricos o cerámicos adosados a muros u otros soportes visibles desde el espacio público. Este catálogo, realizado por un largo elenco de especialistas bajo la coordinación de los profesores Manuel García Guatas y Jesús Pedro Lorente, es el resultado de un convenio entre el Ayuntamiento de Zaragoza y la Universidad de Zaragoza.

Public art is art that meets citizens in the streets, squares and parks of our cities or in other public places. Its presence there serves as a visual reference for that environment, for an entire neighborhood, and in some cases it becomes mentally associated by its own and by outsiders with the emblematic image of the entire city. This catalog offers monuments, sculptures and monumentalized historical vestiges that rise free in the open public spaces of Zaragoza, as well as a wide selection of sculptural, pictorial or ceramic examples attached to walls or other supports visible from public space. This catalog, carried out by a long list of specialists under the coordination of professors Manuel García Guatas and Jesús Pedro Lorente, is the result of an agreement between the Zaragoza City Council and the University of Zaragoza.

ON THE ACCURACY OF WRISTWATCH DETERMINATION OF CARDINAL POINTS

The well-known method for finding cardinal directions with an analogue watch implies holding the timepiece horizontally and pointing the hour hand towards the projection of the Sun on the horizon. Then, it is said that halving the resulting angle to the 12 o‘clock hour mark should give you the South direction. However, precision varies wildly depending on season and location. There are two main reasons for this. Firstly, the method wrongly assumes the Sun‘s azimuth varies at a uniform rate during the day. By projecting the Sun‘s path onto the horizon we show that this is not the case. Secondly, the method wrongly assumes that the Sun‘s southern culmination occurs at 12 o‘ clock standard time. We note that because of the longitude factor, solar noon can occur as late as 12:40 EET in Romania‘s most western parts. Then there is the equation of time, which speeds up or slows down the Sun resulting in an additional error of up to 4° depending on the season. Another complication is the switch to Daylight Saving Time, but in this case the resulting error can be easily avoided by turning the watch back one hour before using the method. Our analysis shows that because of all these factors the worst expected accuracy of the Sun-watch method as applied near Cluj-Napoca occurs near summer solstice (errors of up to 35° in azimuth), while the best accuracy is attained in the weeks around November 1st, with a maximum error in azimuth of 6-8° and an average error of just 3°.

Researher of the University of Warsaw spotted eight previously unknown depictions of sundials in ancient mosaics, bringing the total number of such images up to 15.
Sundials on mosaics known before the last identifications: Torre Anunzaiata (Italy), Sarsina (Italy), Trier (Germany), Saint-Romain-en-Gal (France), Antioch (1a-b, 2, Turkey) and Brading (England).
Sundials previously unknown: Grand (France), Tarsus (Mersin, Turkey), Tayibat al-Imam (Syria), Jerusalem (Israel), Umm al-Rasas - Jordan (Sebastis), Madaba - Jordan (Jerusalem), Umm al-Rasas - Jordan (Kastron Mefaa) and Rome (Jerusalem).

Sundials in Roman and Byzantine Mosaics (1st – 9th Century AD). A scientific monograph. The sundials on ancient mosaics have not been the subject of scientific studies so far. The author has gathered together  in this  publication  the sundials  already known (Torre Anunzaiata, Sarsina, Trier, Saint-Romain-en-Gal, Antioch and Brading; Figs. 1, 2, 4, 5, 7, 9) and those which have  not  previously  been  identified.  Thanks  to  the author’s  new  identifcations,  the  catalogue  has  been enlarged  by  six  new  sundials (Grand,Tarsus, Antiochia – interpreted by H. Pamir; Figs.  3, 6,  8, and 10. Tayibat al-Imam, Jerusalem and Umm al-Rasas (Sebastis); Figs. 10, 11, 12) and three monumental gnomes-columns with multiple functions that were used as monumental sundials [Madaba (Jerusalem), Umm al-Rasas (Kastron Mefaa) and Rome (Jerusalem); Figs. 13–15]. In addition, recognizing fully John H. Humphrey’s  interpretations,  the  author  enriches  the catalogue  by  eight  ancient  mosaic  representations  of obelisks in  circuses (Lyon, Barcelona, Volubilis, Piazza Armerina - two mosaics, Girona, Carthage and Gafsa; Figs.  16–23).  They  performed the roles of monumental sundials. In this way, the catalogue includes  twenty-three  mosaics with  the representations of sundials. They come from the Western and Eastern Provinces of the Roman Empire. The first mosaic is dated to the beginning of the 1st century AD and the last dates to the 9th century AD. The author, after  a  short  description  of each monument,  summarizes the issue discussing the role of sundials in Roman and Byzantine society, their complex signifcance and symbolic dificult linked with the progress of time on which nature and human life are dependent. See Pdf : https://www.academia.edu/22653583/

"This paper proposes three new (and tentatively, another two) identifications of sundials in Middle Eastern mosaics of the 5th – 8th century. The author discusses a vignette from the Holy Martyrs’ Church at Tayibat al-Imâm, central Syria, a mosaic panel from the tomb of Georgia and Theodosia in Jerusalem, two
vignettes of Sebastis and Kastron Mefaa from the St. Stephan’s Church at Umm al-Rasas, and a vignette of Jerusalem from the St. George’s Church at Madaba. These mosaics date, respectively, to 442, to the reign of Justinian (527 –565), and to the Byzantine Umayyad era (718). According to the author, these are probably the latest representations of sundials known to date from the Late Antiquity. Until this study, only six representations of sundials on mosaics from the Roman period were known. This paper adds three new items and two hypothetical ones from Byzantine times. It also offers an interpretation of the function of the famous column in Jerusalem, shown on the map of Madaba and the mega-vignette of the Holy City.
Key words: Sundials, Sonnenhuhren, Meridiane, Cadrans solaires, Relojes de sol."

Among the sporadic Old Syriac inscriptions, some including dates are even fewer. An unpublished inscription will be presented in this paper. Although inscriptions from Hatra have been lost, some of them were recorded during the excavations at Assur in 1989, four of them only as photographs. An unpublished tessera sheds light on the reading of the personal name of a Palmyrenian Bel priest.

The spear established itself as a unit of time measurement in Romania, becoming a synonym for the temporary hours used in antiquity. Thus, a spear would refer to one twelfth of the Sun’s solar arc while having a variable duration according to the season. In the absence of written evidence on the method used, we believe that the time of day was measured in spears either by sundials with equidistant divisions, or by equating the length of the shadows to temporary hours. Holding a spear the size of a person at one arm’s length away from the body and aiming the solar disk, although a seemingly more straightforward procedure, presents many practical problems.

Premessa 4
Il globo andante 7
L’orologio solare di Glauco de Mottoni 13
Il tracciato della linea meridiana in un documento
Di Silvestro II Papa 17
In ricordo di uno gnomonista: Giusto Bellavitis 27
Modo di fare con facilità grandissima gl’Orologi
a sole nelli muri… 35
Un orologio universale indipendente dalla
Meridiana 37
Storia degli orologi solari portatili e sulla
successione cronologica degli orologi rettilinei 39
Il fascino degli orologi equinoziali 69
L’orologio del Re Achaz e il miracolo di Isaia 77
L’orologio solare ad ore Italiche e Babiloniche
di Valentino Pini 91
L’orologio Meridiano 97
Curiosità gnomoniche dei Lumi: orologi portatili 101
Frammenti di orologi solari greco-romani
negli scavi archeologici 117
L’orologio sullo Zoccolo di Oddi Muzio 135
L’orologio orizzontale italico per via di numeri 139
Ampliamento al libro Storia della Gnomonica 143
Orologi solari greco-romani 145
Il solarium di Palestrina 159
Sciatericum Telescopicum 175
L’orologio astronomico di Lorentz-Grassi 178
L’orologio solare floreale 181

Roccasecca, febbraio 2016 La misura del tempo nella Praeneste romana, raccontata attraverso il mito dell'Horologium di Varrone e le meridiane di epoca romana di grande importanza tra le quali due recentemente ritrovate in scavi archeologici.

INDICE
La storia della gnomonica di Montucla 7
Gli strumenti orari di Giulio Capilupi 19
Vincent e John Wing, The art of surveyiing 34
Edmund Gunter, la gnomonica inglese nel XVII secolo 56
Gaspar Schott, erede di Kircher 91
Thaumalemma Cherubicum di Sandolino Cherubino 121
William Leybourn, the art of dialling 139
La gnomonica di Pierre Herigone 207
Athanasius Kircher ela gnomonica magnetica 219
Samuel Foster, l’horologiographia in tutte le salse 253
Fale Thomas, il primo libro di gnomonica inglese 285
William Oughtred, master of arts 293
Jacques Ozanam, un nome una gnomonica 325
Emanuele Maignan e la gnomonica catottrica 369

It is demonstrated that the Greco-Roman zodiac sundials that flourished in Greece and Italy from about the early second century BCE to the second century CE were related to the zodiac calendar in the Dead Sea Scrolls, in the Aramaic Astronomical Book (4Q208-4Q209).
Mediterraneann Archaeology and Archeometry 14.3 (2014): 68-81

Like a number of other prologues of the early modern period, the prologue to Romeo and Juliet is clear about the length of time its play will take in performance. Two hours. But how literal is that claim? A tendency to take the prologue at face value has resulted in the assumption that Shakespeare’s plays, most of which take longer than two hours to perform, have not survived in their stage form. Instead, goes the argument, we have them in a totally different version: as they were rewritten, at length, for the page.
This article will question whether plays ever habitually took two hours to perform. It will look at the lengths of playtexts and will ask when and why the ‘two hour’ claim was made. But it will also investigate a bigger question. What did ‘two hours’ mean in the early modern period? Exploring, in succession, hourglasses, sundials and mechanical clocks, it will consider which chronological gauges were visible or audible in the early modern playhouse, and what hours, minutes and seconds might have meant to an early modern playwright who lacked trustworthy access to any of them. What, it will ask, was time, literally and figuratively, for Shakespeare—and how did chronographia, the rhetorical art of describing time, shape his writing?

Sowohl die Gewichts- als auch die Zeitmessung erlangten im Laufe des Mittelalters dank Effizienzsteigerung und Internationalisierung in Handel und Handwerk zunehmende Bedeutung. Aus archäologischer Sicht lässt sich dieser Prozess allerdings kaum nachvollziehen. Funde von Waagen und Gewichten sind im Mittelalter äußerst rar, und selbst in der Neuzeit bessert sich diese Situation nur marginal. Auch auf dem Gebiet der Zeitmessung sind die Aussagemöglichkeiten der Archäologie begrenzt. Die Funde von Bestandteilen eines mechanischen Uhrwerks im Schlossberg bei Seefeld (Tirol) sowie einer Reisesonnenuhr in der Burg Grafendorf (NÖ) stehen exemplarisch für – an sich bereits durch archivalische, ikonographische und museale Quellen dokumentierte  Innovationsschübe des 14. und 15. Jahrhunderts. Durch den Fundkontext in Burgen kann hier jedoch der Adel als Trägerschicht solcher Innovationen identifiziert werden.

Sundials in Roman and Byzantine Mosaics (1st – 9th Century AD). A scientific monograph. The sundials on ancient mosaics have not been the subject of scientific studies so far. The author has gathered together  in this  publication  the sundials  already known (Torre Anunzaiata, Sarsina, Trier, Saint-Romain-en-Gal, Antiochia and Brading; Figs. 1, 2, 4, 5, 7, 9) and those which have  not  previously  been  identified.  Thanks  to  the author’s  new  identifcations,  the  catalogue  has  been enlarged  by  six  new  sundials (Grand,Tarsus, Antioch – interpreted by H. Pamir; Figs.  3, 6,  8, and 10. Tayibat al-Imam, Jerusalem and Umm al-Rasas (Sebastis); Figs. 10, 11, 12) and three monumental gnomes-columns with multiple functions that were used as monumental sundials [Madaba (Jerusalem), Umm al-Rasas (Kastron Mefaa) and Rome (Jerusalem); Figs. 13–15]. In addition, recognizing fully John H. Humphrey’s  interpretations,  the  author  enriches  the catalogue  by  eight  ancient  mosaic  representations  of obelisks in  circuses (Lyon, Barcelona, Volubilis, Piazza Armerina - two mosaics, Girona, Carthage and Gafsa; Figs.  16–23).  They  performed the roles of monumental sundials. In this way, the catalogue includes  twenty-three  mosaics with  the representations of sundials. They come from the Western and Eastern Provinces of the Roman Empire. The first mosaic is dated to the beginning of the 1st century AD and the last dates to the 9th century AD. The author, after  a  short  description  of each monument,  summarizes the issue discussing the role of sundials in Roman and Byzantine society, their complex signifcance and symbolic difficult linked with the progress of time on which nature and human life are dependent.

Something new under the sun. A 15th-century time keeping device of European significance

This paper presents a handy universal device of the following
makeup: a closable box containing a compass, a retractable
equatorial sundial and a nocturnal. This three-in-one
pocket sundial was ideal for travels thanks to its small size
and compact design. In an era when most people still relied
on more-or-less exact church clocks, this watch offered
precise time measurement to its users from mobile
and educated strata not only from the urban bourgeoisie
but also of the nobility – whether at home or abroad, by
day and night, 365 days a year. While iconographic analogies
of this compendium can already be traced in northern
France around 1450 as well as in Switzerland in 1505/08,
archaeological sources are primarily based on finds by detectorists
in England but also include a sundial from the
second half of the 15th century, found in the Lower Austrian
Castle of Grafendorf. Furthermore, several objects of
central and western European origin have been preserved
in museums – among them the ones recently discovered
on the two ceremonial maces, dated to around 1474/75,
of Emperor Frederick III and Maximilian I at the collection
of the Imperial Armoury in Vienna. In light of the
fact that the centrepiece of this device, the equatorial sundial,
was only invented around 1431, this evidence suggests
an astoundingly swift and wide dissemination of a hitherto little-studied clock type in the 15th and early 16th century.
Although due to the current state of research the archaeological
finds and extant museum objects so far show a clear
geographical bias towards England, this time-measuring instrument
was spread throughout Europe and presumably
produced in multiple yet unidentified manufacturing centres
according to a largely uniform international design.

Keywords: time measurement, equatorial sundial, compass,
nocturnal, 15th century

Zusammenfassung

Dieser Aufsatz beschäftigt sich mit einem handlichen Universalgerät
in Gestalt einer verschließbaren Büchse, bestehend
aus einem Kompass, einer ausklappbaren Äquatorialsonnenuhr
und einem Nokturnal. Dieses dreiteilige
Instrumentenset war aufgrund seiner geringen Größe und
Kompaktheit als Reisesonnenuhr prädestiniert und ermöglichte
in einer Zeit, als die Masse der Bevölkerung immer
noch von mäßig genauen Kirchturmuhren abhängig war,
seinen Benutzern aus mobilen und gebildeten Schichten
nicht nur des Bürgertums, sondern auch des Adels ein präzises
Ablesen der Uhrzeit – egal, ob zuhause oder unterwegs,
sowohl bei Tag als auch bei Nacht, und das 365 Tage
im Jahr! Während dieser Uhrentyp durch ikonographische
Analogien bereits um 1450 in Nordfrankreich und
1505/08 in der Schweiz in Erscheinung tritt, ist er archäologisch
hauptsächlich in Form von Sondengeherfunden aus
England, aber auch anhand einer in der Burg Grafendorf in
Niederösterreich gefundenen Sonnenuhr aus der zweiten
Hälfte des 15. Jahrhunderts dokumentiert. Dazu kommen
noch einige wenige museal überlieferte Stücke mittel- und
westeuropäischer Herkunft – darunter diejenigen, die erst
jüngst an zwei in die Jahre um 1474/75 datierten Prunkstreitkolben
Kaiser Friedrichs III. bzw. Maximilians I. in
der Wiener Hofjagd- und Rüstkammer entdeckt wurden.
Angesichts der Tatsache, dass das Herzstück des Geräts, die
Äquatorialsonnenuhr, erst um 1431 erfunden wurde, sprechen
diese Belege für eine erstaunlich rasche und überraschend
weite Verbreitung eines bisher kaum erforschten
Uhrentyps im 15. und frühen 16. Jahrhundert. Wenngleich
der geographische Schwerpunkt an archäologischen Funden
und erhaltenen Museumsexemplaren forschungsbedingt
bislang eindeutig in England liegt, war dieses Zeitmessinstrument
europaweit verbreitet und dürfte wohl in
verschiedenen, bis jetzt unidentifizierten Zentren nach
einem weitgehend einheitlichen, internationalen Design
hergestellt worden sein.

Schlagworte: Zeitmessung, Äquatorialsonnenuhr, Kompass,
Nokturnal, 15. Jahrhundert.

ABSTRACT: The Tall Gnomon at Gaocheng, Dengfeng Township, Henan Province, China (34°24’8.73”N, 113°8’26.23”E) is described in scholarly literature as tracking changes in the gnomon’s shadow at noon (meridian transit) between midsummer and midwinter.  For example, the Yuan History (Yuan Shih) records that the sun’s shadow cast near the winter solstice on 14 December 1278 CE measured 76.7400 Chinese feet (chi).  However, the 128chi horizontal graduated template scale (kuei piao) of the Tall Gnomon is 40% longer than what is required to measure the sun’s longest shadow at winter solstice. Using GIS and astro-archaeological computer modeling, nocturnal astronomical targets (i.e., midsummer full moon, Venus and bright stars) are investigated to account for the construction of the extra 51chi in length of the Tall Gnomon’s template scale.  Evidence is also presented confirming that the Tall Gnomon solstice observations in the Yuan History were made at Beijing, rather than Gaocheng.
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摘要：在已有學術文獻的描述中，位於河南登封藁城（34°24'8.73“N，113°8'26.23”E）的圭表是用來追蹤表柱從夏至到冬至之間每天正午時分陰影長度的儀器。例如，據《元史》記載，1278年12月14日臨近冬至時，表柱影子長度為76.7400尺。然而，圭表的水平刻度總長128尺，比表柱在冬至時最長的影子多出40％。GIS和天文考古計算機建模表明，圭表水平刻度多出來的51尺與其它天象的觀測有關，如太陽以外的其它天體、仲夏夜滿月、金星以及其它明亮的恆星。同時，還有證據證明《元史》中夏至和冬至表柱陰影長度的觀測地點是北京，並非藁城。

Premessa Quando devo scrivere un articolo su un argomento che mi sembra piuttosto nuovo, almeno nel senso di poco approfondito nella letteratura gnomonica, cerco di attingere informazioni innanzitutto da ciò che sembra essere considerata la "bibbia" o "vademecum" dello gnomonista. Sto parlando del libro di René J-R-Rohr, Die Sonnenuhr, pubblicato a Monaco nel 1982, tradotto in varie lingue tra cui in francese nel 1986 e in italiano nel 1988 da Ulisse Edizioni con il titolo Meridiane. La traduzione italiana vu revisionata dall'astronomo Walter Ferreri dell'Oss. Astr. di Torino, quindi più attendibile che mai. Anche se un pò datato, questo volume costituisce una fonte preziosa per ogni tipo di informazione relativa agli orologi solari, sia storica che tecnica. Devo però evidenziare che se da punto di vista tecnico il testo è impeccabile, dal punto di vista storico, invece, molte cose date per scontate, insieme a diverse affermazioni, hanno lasciato dubbi e perplessità, come vedremo anche in questo breve scritto. Partendo proprio da questo testo di Rohr per la mia ricerca nel voler scrivere una riassuntiva storia degli eliocronometri, mi sono reso conto che le informazioni in merito sono quasi inesistenti. Nel senso che non ho mai trovato un'altra "storia" degli eliocronometri cui fare riferimento, ma solo brevi descrizioni di alcuni strumenti, peraltro trovati in altri testi. Con delusione ho quindi constatato che Rohr nel suo pregevole volume cita a malapena questi strumenti presentandone solo una piccola immagine che è uno schizzo a matita di un orologio equatoriale con gnomone a filo. Ma per essere più precisi ecco quanto riporta testualmente [01]: "La nascita dell'orologio meccanico avrebbe dovuto segnare la fine dell'orologio solare. Ma così non fu, a causa dell'imperfezione cronica dell'orologio. Il suo uso ha comunque accelerato il progresso della divisione del tempo nella vita pratica, e la necessità frequente di regolazione che esso richiedeva. Questa necessità ha anche contribuito, più tardi, al suo perfezionamento in una forma più moderna, quella dell'eliocronometro. Si tratta di una specie di orologio equatoriale, finemente graduato e dotato di uno stilo formato da un filo teso parallelamente all'asse del mondo. Oggi ben pochi sono a conoscenza del fatto che fin verso il 1900 alcune reti ferroviarie

This is a scientific monograph. The sundials on ancient mosaics have not been the subject of scientific studies so far. The author has gathered together  in this  publication  the sundials  already known (Torre Anunzaiata, Sarsina, Trier, Saint-Romain-en-Gal, Antiochia and Brading; Figs. 1, 2, 4, 5, 7, 9) and those which have  not  previously  been  identified.  Thanks  to  the author’s  new  identifcations,  the  catalogue  has  been enlarged  by  six  new  sundials (Grand,Tarsus, Antioch – interpreted by H. Pamir; Figs.  3, 6,  8, and 10. Tayibat al-Imam, Jerusalem and Umm al-Rasas (Sebastis); Figs. 10, 11, 12) and three monumental gnomes-columns with multiple functions that were used as monumental sundials [Madaba (Jerusalem), Umm al-Rasas (Kastron Mefaa) and Rome (Jerusalem); Figs. 13–15]. In addition, recognizing fully John H. Humphrey’s  interpretations,  the  author  enriches  the catalogue  by  eight  ancient  mosaic  representations  of obelisks in  circuses (Lyon, Barcelona, Volubilis, Piazza Armerina - two mosaics, Girona, Carthage and Gafsa; Figs.  16–23).  They  performed the roles of monumental sundials. In this way, the catalogue includes  twenty-three  mosaics with  the representations of sundials. They come from the Western and Eastern Provinces of the Roman Empire. The first mosaic is dated to the beginning of the 1st century AD and the last dates to the 9th century AD. The author, after  a  short  description  of each monument,  summarizes the issue discussing the role of sundials in Roman and Byzantine society, their complex signifcance and symbolic dificult linked with the progress of time on which nature and human life are dependent.

INDICE DEGLI ARTICOLI
-Che ore sono sulla tua mano? 
-Cinque meridiane all’eremo di Montevirginio
-Due misteriose lastre marmoree nel convento dei Cappuccini
Di Bracciano
-Dal tuscolo la prima pietra del tempo
-Importanti scoperte di N. Severino sulle Ore Planetarie
-Le prime immagini delle Ore Planetarie di Sacrobosco
-Il cilindro con gnomone a cappello filtrante
-L’ultimo Decempedalis
-Gli Ambasciatori di Holbein: un nuovo contributo
Il mandolino gnomonica
-La meridiana canonica dell’abbazia dell’Acquafredda
-La linea meridiana nella camera di San Luigi al Collegio Romano
-Storia delle osservazioni gnomoniche solstiziali
-Eliocronometri: una prima storia
-L’orologio analemmatico di Cipriani
-L’orologio multiplo della Certosa di San Martino a Napoli
-La meridiana di Castel Sant’Angelo a Roma
-La pratica della sfera di Galileo edita da Buonardo Savi

The Rotonda is a small circular chapel in Geoagiu (central Romania) which appears to be the oldest of its kind in the country (11th-12th centuries AD). Some say it was built by the Templars, others that it was erected by a local nobleman named Akos. According to legend, on a particular day of the year, the Sun shines through two opposing windows and where the spot of light falls outside on the ground a treasure is said to be buried. The chapel is composed of a circular nave and a half-round apse measuring about 9 meters across. Upstairs there are 6 windows of which two are almost perfectly east-west aligned (with a declination of just 1-2°). The other four windows have no discernable astronomical significance. There is, however, a peculiarity: viewed from the center of the circular nave, the ends of the apse’s half-circle point to sunrise on both solstices. We signal some possible solar alignments in the case of following window combinations: north west and east; west and east, west and south east. North west and east windows produce a visible light spot outside and we hypothesize that this occurs in the evening for almost two months during summer (19 May – 23 July). This is because solar declination changes slowly around summer solstice. The second alignment, involving west and east windows, has been confirmed in 2020 to happen between 6 April – 20 April and 21 August – 4 September. We have thus established that this alignment occurs when the sun is at an average of 268.8° azimuth and 14.21° above the horizon, with a margin of about +/- 2° in both cases. The effect is visually similar to the first type. The last alignment, although not so spectacular, probably occurs between 23 May - 19 July near sunset, but we have not been able to visually verify it. Moon and bright star alignments (at least for Betelgeuse and Altair) should also be possible on some or all of these directions. We offer a computed table for the next two years when the Moon will be visible through the west circular window. Archaeological digs show that the chapel was built even before the Templars. No treasure has ever been found, so the legend of the buried gold should be taken with a grain of salt.

Sundials were the first instruments constructed by the ancient Greek astronomers for the measurement of time. The two ancient sundials described in this work are marble ones of the cylindrical type; they are currently kept in the sculpture storage room of the National Archaeological Museum of Athens (index catalog numbers 3159 and 3220). Their gnomons have been lost. Characteristic parameters of these sundials, such as the angle formed between the cone’s axis and the generatrix, the geographical latitude of operation and the gnomon’s length, are calculated from measurements of their geometrical dimensions.

I give notice of the finding of a new sundial at the site of the greek-roman city of Kale Akte - Calacte, on the hill of Caronia (Sicily, province of Messina). It is in limestone, hemicycle-type, dating to Late Hellenistic period, probably II century B.C. It adds to the few sundials published for Sicily. We cannot know if it is from a domestic or public context, being found reused in a rural wall on the slopes below the modern city.

The linear astrolabe was invented by Sharaf al-Dīn al-Ṭūsī (fl. c. 1180) and although several Arabic monographs on the subject have reached us, none have received sufficient scholarly attention. As a result, one of the most important features of Ṭūsī's invention, the gnomonic application, remains unknown. Based on an analysis of all known monographs on the linear astrolabe, this paper will discuss the gnomonic application of the linear astrolabe, which is an alternative to the azimuth lines typical of the plane astrolabe. We will also consider the potential role of Ṭūsī's pupil, Kamāl al-Dīn ibn Yūnus (d. 1242), in the improvement of this instrument. Finally, after surveying the available manuscript copies of the above-mentioned monographs, we present a full edition and translation of one such text and an edition and translation of one chapter, on the gnomonic application, from another text.

Fragmented copy of a sundial diptych in the form of an oval ivory platen comes from the castle of the Khotyn Fortress. The inner plane of the upper sheet of the appliance is marked with a vertical sundial for 51° northern latitude. The morphological and stylistic features and the adduced analogies (Svodin, Wachtebeke, Iassy, Lüneburg, Eger and National Maritime Museum in Greenwich) make it possible to date a clock within the end of the ХVІ – the middle of the ХVІІ centuries and associate with products (type II) of the Nuremberg masters of the Miller family, probably Hans or Leonard. A diptych clock was discovered among the remains of a small object in the northern part of the Khotyn Castle. The collected material dates back the complex to the late 60s – the last third of the ХVІІ century. Comparison of archaeological data with the event history indicates that there are good reasons to associate the investigated object with the stay in the Khotyn Castle of the Polish-Lithuanian garrison under the command of Jan Ochab. He controlled the fort after the victory of Jan Sobieski’s troops over the Turks since November 13, 1673 and until the surrender on August 4, 1674. Obviously, some of the garrison owned a portable sundial, useful primarily for sentinel service.
Khotyn’s discovery, cartographic material, reports of written sources leads to the opinion that under the device used by the Zaporozhian Cossacks at sea and the Crimean Tatars in the open steppe and known, according to G. L. de Beauplan, as the «Nuremberg Quadrant» (quadran de Nurambert; quadran au Soleil, according to P. Chevalier), should be understood the portable sundial diptych with a compass and characteristic layout of the dial.