Lizard / Viper Gnomon of Monumental Dial . Museo Galileo . Florence


The Museo Galileo‘s Monumental Sundial was built as a mathematical ornament in 2007. The slender bronze column (stele) is in fact formed from two matching columns closely aligned, symbolising day and night. The (mid)day stele faces south, with a vertical meridian line on which the shadow is cast by a lizard’s tail (actually, an imaginary half-lizard, half-viper). The night stele faces north and signifies the constellations Ursa Major and Ursa Minor that enable the Pole Star to be identified.

Monumental Dial . Museo Galileo . Florence

The encircled quadrant design on the pavement at the base of the bronze columns indicates the geographic orientation. This glass base of the gnomon, and also the Zodiac signs in the meridian line (below), are up-lit after dark.

Orientation dial . Monumental Dial . Museo Galileo . Florence

The Museo explains the meridian line in helpfully simple terms: A travertine and brass meridian line is drawn on the pavement, flanked with glass and marble signs of the Zodiac. The meridian line extends for about 15 metres from the museum entrance, where the winter solstice is marked, to the base of the gnomon, where the summer solstice is marked. The travertine curves crossing the meridian line indicate the date. The brass radial lines forming a grid with the two solstitial curves indicate the hours.

The seasons and the four elements are symbolised by the choice of materials: travertine for the earth and autumn; glass for the water and winter; grey stone for the air and spring; bronze for the fire and summer.


This extraordinary sundial stands by the Arno with the Ponte Vecchio (which itself has a wonderful dial LINK) close by to the west. For anyone with even a minuscule interest in or curiosity about the gradual development of scientific instruments and techniques from medieval times onwards, pay a visit to the excellent online gallery LINK. Look in particular for the two astronomical telescopes made by Galileo himself.

The North American Sundial Society has very good online information about this unique dial. You can watch a short animation of how this gnomonic sundial works here LINK

For those interested in finer details of the way the dial works, the museum’s detailed account is included at the end of this article.

Museo Galileo – Istituto e Museo di Storia della Scienza

Museo Galileo – Monumental Sundial

NASS (North American Sundial Society) Video: Filippo Camerota, Luise Schnabel, Giorgio Strano

How the Sundial works

The shadow cast by the glass polyhedron atop the large bronze gnomon indicates the date and time. The hours from 9:00 AM to 2:00 PM are marked out by radial brass lines. The date is indicated by the travertine traversal lines which mark the Sun’s diurnal course for various periods of the year – precisely when the Star enters the signs of the Zodiac. The shadow cast by the gnomon changes in length during the course of the days and seasons, and indicates true solar time for the place where it is located, which is a different time than that of our wristwatches, known as mean time. In respect to mean timetrue solar time has a periodic variation that can exceed a quarter of an hour.

schema minuti

Moreover, during daylight saving time, the hands of a clock are moved forward one hour. For example, true midday in the month of February would be indicated by the sundial around 12:28 AM while in the month of July it would be indicated around 1:20 PM daylight saving time.

To read the hour and date, you have to identify the hour lines and the calendrical lines closest to the gnomon’s shadow. When the shadow does not fall exactly on a hour line, you can read the half-hours and quarters with close approximation by ideally subdividing the space between two hour lines in two or four parts. The date can also be read by referring to the Zodiac signs and the start of the months marked out along the meridian line.

© 2018 – 2022 Museo Galileo – Istituto e Museo di Storia della Scienza
Piazza dei Giudici 1 · 50122 Firenze · ITALIA
tel. +39 055 265 311 – P.I. 01346820481

LLUC MONASTERY . MALLORCA . COMPLEX MULTI-DIAL: from Canonical to 20th Century

Multiple Vertical Sundial, Lluc Monastery, Mallorca (Keith Salvesen)
Lluc Monastery . Mallorca – Sundial (Keith Salvesen)

The secluded Monastery of Lluc is situated near Escorca in the Tramuntana mountains of Mallorca. It dates from the c13, and is famous for its Black Madonna, the discovery of which is said to have led to the monastery’s foundation . It is a place of pilgrimage. The location is remote and peaceful, though inevitably the monastery has become an essential stop on the tourist and coach party trail. We returned there recently, not having visited Mallorca for more than 20 years. The buildings were much as we remembered, but the parking and visitor arrangements were more regimented and complex. Before, one just drove down the narrow road from the main mountain road and parked in the forecourt area close to the buildings. Now, everything is (unsurprisingly) geared to a daily mass influx of people and their needs for sustenance and souvenirs. We were pleased to see that it is still possible to stay at Lluc in one of small rooms under a long covered walk where the monks once slept. You can even book a room for the night.

Lluc Monastery . Mallorca – Sundial

A short walk from the monastery, there is a path that leads up to a calvary and some great views. Along the way is an amazing multiple vertical sundial. It was designed by Rafael Soler, and carved in 1991. It displays with some style the evolution of sundials from medieval to modern. There are two historical dials, one solar dial, and two seasonal dials.


This dial simply records the 3-hourly canonical divisions of the liturgical day (as with the early medieval mass / scratch dials), starting with midnight (top) and working counterclockwise round a central gnomon. 

Lluc Monastery . Mallorca – Sundial (Canonical)


A more complex dial, starting at noon shown as XXIV (I’m not clear why not XII) through to 21.00. The dial includes months and the signs of the Zodiac.

Lluc Monastery . Mallorca – Sundial – Babylonian / Mallorquines


The centre dial shows true solar time. The polar gnomon (triangular) shows the hours, the pointer shows the date with the declination lines. The inscription MULIER AMICTER SOLE (Woman Clothed by the Sun) references an account in the Book of Revelations. You can find out more HERE

Lluc Monastery . Mallorca – Sundial


The two right-hand sundials are complementary and each covers two seasons. Presumably for a particular month, one dial will be reliable as to time and the ‘off-season’ one will not. The words are Catalan eg Hores Mitjanes = Mean Time; Estiu I Tardor = Summer and Autumn.

Lluc Monastery . Mallorca – Sundial


Lluc Monastery . Mallorca – Sundial
BBS Record

The creation of these dials was obviously a labour of love and skill combined. There’s doubtless plenty more to be said about these sundials and the splendid ensemble but I decided not to get too technical – indeed, as an amateur I don’t understand enough to do so. The rather washed out appearance of the images was operator error – I had the camera on the wrong settings and didn’t realise until too late…

Lluc Monastery . Mallorca

GSS Category: canonical to modern multi-dial; sundial Lluc Mallorca

All photos: Keith Salvesen; snippet from BSS record

Original Credits: ‘Props to arby101ca and lumbricus, members of a geocaching & waymarking website called Groundspeak. They hiked to Lluc (respect!) and wrote informatively about these dials. I found relatively little elsewhere.