Solarium Augusti

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Part of the meridian of the Augusti Solarium (looking south) below the cellar of a building in Via di Campo Marzio in Rome; Photographs of the entire exposed portion without disturbing bars in the foreground are in the publication by Edmund Buchner included

The Solarium Augusti or Horologium Augusti is a large astronomical measuring instrument with a sphere on an obelisk about 30 meters high as a shadow thrower, which was erected on the Field of Mars in Rome under Emperor Augustus .

It is considered to be an incomparably large meridian instrument ( noon wise , annual calendar ), as it was already described by the contemporary witness Pliny . The piece of meridian line uncovered by the German Archaeological Institute is about 1.6 meters above the original level of the Martian field. It is believed that the destroyed Augustan instrument was rebuilt at the time of Emperor Domitian on the now higher Martian field caused by the floods of the Tiber . The complex probably formed a structural unit with the Augustus mausoleum , the associated parks and the Ara Pacis and is interpreted as one of the most important political symbols of the power of the emperor Augustus.

After investigations by the German Archaeological Institute, which took place between 1970 and 1981 and were accompanied by extensive excavations, this complex was interpreted as an extremely large sundial . This interpretation is no longer upheld today.

The meridian instrument of the emperor Augustus

Location of the Augusti solarium in ancient Rome

An obelisk ( Obelisco di Montecitorio ) from Heliopolis in Egypt, built by Augustus in 10 BC. Was erected, served as a gnomon about 30 meters high . However, it has not been proven that it was supplemented with an equally large (at least 200 meters) flat dial to form a sundial. A 6.6 meter long piece of a scaled meridian line was excavated , according to which the Augusti solarium is now regarded as a meridian instrument (annual calendar, noon indicator) that works with the sun. The location is about 1.6 meters above the level of the Mars field at the time of Augustus. It is attributed to a renewal of the original meridian instrument described by Pliny, which took place around the time of Emperor Domitian.

The obelisk, broken into five parts, and its original base were excavated in 1748. About 40 years later it was reassembled, crowned with a new ball and in 1792, including the base, was erected at its current location, about 250 meters to the south in front of the Italian Parliament on the Piazza di Montecitorio . The umbra of an original, similarly large (about 75 cm diameter) and equally high (about 30 meters) placed sphere as a nodus extends about 80 meters. The midday shadow of this sphere, which can be read on the associated meridian line, is about 65 meters from the obelisk at the winter solstice in Rome. The meridian line is laid as a bronze line in the floor slabs and has a length of about 55 meters between the two solstice points. At right angles to the meridian line, longer markings are made of bronze as dividing lines between the signs of the zodiac and shorter ones for the 30-degree division of the signs of the zodiac. So the shadow of the sphere showed the location of the sun in the zodiac. The section of the meridian line uncovered to this day under the property Via del Campo Marzio 48 has a length of 6.60 m, divided by 27 short transverse lines for graduation and 1 long transverse line as a separation between neighboring signs. It is labeled along the meridian line with the Greek names of the signs: On the west side it ranges from 19 ° [KRI] OS (Aries) to 16 ° TAUR [OS] (Taurus), on the east side, symmetrically to it, from 14 ° [ LE] ON (Leo) to 11 ° PARTH [ENOS] (Virgo). The degree distances increase from south to north from 19 cm to 30 cm. From this, M. Schütz calculated in 1990 that the shadow-casting sphere that crowned the obelisk must have been about 17.7 m south of the Leo-Virgo dividing line at a height of about 30 to 31 m. At the long dividing line Leo-Virgo is the Greek inscription ETESIAI PAUONTAI, the Etesien cease. With Etesia winds were referred to, which appeared very regularly every summer (today: Meltemi ). At the 15 ° bull mark there is the inscription THEROUS ARCHE, beginning of summer. According to ancient custom, summer did not begin with the summer solstice, but the middle of summer; the summer went from 15 ° Taurus to 15 ° Leo.

The original installation site of the Ara Pacis Augustae was assigned to the solarium: on the site to the east of it, between Via in Lucina and Via del Corso, where the Palazzo Fiano-Almagià now stands.

The obelisk of the meridian instrument

The obelisk in Piazza di Montecitorio, formerly used as the gnomon of the Augusti Solarium

The obelisk, about 22 meters long, is made of rose granite and comes from the Aswan quarries in Upper Egypt. Pharaoh Psammetich II had it around 595 BC. In Heliopolis on the occasion of the first anniversary of his accession to the throne. The Romans transported it in 10 BC. Chr. To Rome to set him up as a gnomon on the field of Mars. It received a foundation and an almost 5 meter high base with an inscription honoring the emperor Augustus and consecrated to the Roman sun god Sol . Together with the ball serving as a node, a height of about 30 meters was reached.

The ancient dedicatory inscription reads:

IMP CAESAR DIVI F

AUGUSTUS
PONTIFEX MAXIMUS
IMP XII COS XI TRIB POT XIV
AEGUPTO IN POTESTATEM
POPULI ROMANI REDACTA
SOLI DONUM DEDIT

 Emperor Caesar Augustus

Son of the deified (Caesar)
Pontifex Maximus
Imperator for the 12th, consul for the 11th, holder of tribunician power for the 14th time
after Egypt was brought under the rule of
the Roman people
(this obelisk) was given to the sun as a gift

The excavations by the German Archaeological Institute

The initial interpretation as a sundial could not only be maintained for physical reasons (e.g. insufficient range of the umbra of the Nodus sphere). There were also considerable shortcomings in dealing with ancient texts. A comparison of the interpretation of the Pliny text in the 18th century by Euler, Boscovich, Marinoni and others. a. With the results of the archaeological finds in the 20th century and the virtual archeology of the 21st century, the descriptions of the contemporary witness Pliny are ultimately correct.

There has been speculation for a sundial for a long time, but there were also early indications of the mere existence of a meridian instrument. The new interpretation as a sundial became popular, which was favored by the not every day successful excavations up to 8 meters below today's level. They dug from a small cellar floor about 6 meters deep, that is, far below the foundations of the walls of a multi-storey old house in what is now the densely built-up city center of Rome. Impressive images of this exist.

literature

  • Edmund Buchner : The sundial of Augustus. Reprint from Römische Mitteilungen 1976 and 1980 and addendum on the excavation in 1980/1981 . von Zabern, Mainz 1982, ISBN 3-8053-0430-7 .
  • Romolo A. Staccioli: Guida di Roma Antica. Itinerari Archeologichi. Rizzoli, Milan 1986, ISBN 88-17-16585-9 .
  • Paul Zanker : Augustus and the power of images . Beck, Munich 1987, ISBN 3-406-32067-8 .
  • Michael Schütz: About the sundial of Augustus on the Marsfeld. In: Gymnasium . Volume 97, 1990, pp. 432–457 (Refutes essential aspects of Buchner's reconstruction. Briefly already in this: The Obelisk of Augustus. In: Sterne und Weltraum . Volume 27, 1988, pp. 575–576.)
  • Edmund Buchner: News about the Augustus sundial. In: Nürnberger Blätter to archeology . Volume 10, 1993-94, pp. 77-84 (response to Schütz's criticism).
  • Frans W. Maes: The sundial of the emperor Augustus. The rise and fall of a hypothesis. In: German Society for Chronometry. Annual Bulletin 2005. pp. 168-184.
  • Peter Heslin: Augustus, Domitian and the So-called Horologium Augusti. In: The Journal of Roman Studies . Volume 97, 2007, pp. 1-20.
  • Lothar Haselberger : A debate on the Horologium of Augustus. Controversy and clarifications, with responses by PJ Heslin and M. Schütz and additional remarks by R. Hannah and G. Alföldy . In: Journal of Roman Archeology . Volume 24, 2011, ISSN  1047-7594 , pp. 47-98.
  • Lothar Haselberger, Paolo Albèri Auber: The Horologium of Augustus: Debate and Context (= Journal of Roman Archeology. Supplementum 99). Portsmouth (Rhode Island) 2014, ISBN 978-0-9913730-3-1 .

Web links

Commons : Horologium Augusti  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d Edmund Buchner : The sundial of Augustus. Reprint from Römische Mitteilungen 1976 and 1980 and addendum on the excavation in 1980/1981 . Zabern, Mainz 1982, ISBN 3-8053-0430-7 .
  2. ↑ Pliny, Naturalis historia 36, 72 . The description as a meridian instrument is a bit cumbersome. Although only a single scaled line, the length of which is limited by the midday shadow of the obelisk at the winter solstice, is mentioned, the described “number line” was sometimes confused with a sundial “dial” with additional east-west extension.
  3. ↑ Michael Schütz: On the sundial of Augustus on the Marsfeld. In: Gymnasium. 97, 1990, p. 433.
  4. ^ Frans W. Maes: The sundial of the emperor Augustus. The rise and fall of a hypothesis. In: German Society for Chronometry. Annual Bulletin 2005, p. 172.
  5. ↑ a b Michael Schütz: On the sundial of Augustus on the Marsfeld. In: Gymnasium. 97, 1990, p. 455.
  6. ^ Frans W. Maes: The sundial of the emperor Augustus. The rise and fall of a hypothesis. In: German Society for Chronometry. Annual Bulletin 2005, p. 183.
  7. ↑ a b Angelo Maria Bandini : De Obelisco Caesaris Augusti e Campi Martii ruderibus nuper eruto. Rome 1750. (digitized version)
  8. ↑ Michael Schütz: On the sundial of Augustus on the Marsfeld. In: Gymnasium . 97, 1990, pp. 455-456 / M. Schütz in L. Haselberger: The Horologium of Augustus: Debate and Context. Portsmouth (Rhode Island) 2014, p. 44.Buchner found the foundation of the obelisk during excavations in winter 1995 at the location calculated by Schütz (Haselberger: The Horologium of Augustus: Debate and Context. Portsmouth (Rhode Island) 2014, p. 102, Figure 1, 103, 186f) without publishing this finding.
  9. ^ Romolo A. Staccioli: Guida di Roma Antica. Itinerari archeologichi. 1986, pp. 345f.
  10. ↑ CIL 6, 702 .
  11. ↑ Michael Schütz: On the sundial of Augustus on the Marsfeld. In: Gymnasium. 97, 1990, pp. 432-457.
  12. ↑ M. Hiermanseder: INTERPRETATION OF THE FUNCTION OF THE OBELISK OF AUGUSTUS IN ROME FROM ANTIQUE TEXTS TO PRESENT TIME VIRTUAL RECONSTRUCTION . In: ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences . XLII-2-W11. Copernicus GmbH, May 4, 2019, p. 615–622 ( int-arch-photogramm-remote-sens-spatial-inf-sci.net [accessed August 21, 2019]).
  13. ^ O. Richter: Topography of the city of Rome. Beck, Munich 1901, pp. 252-253. (on-line)
  14. ↑ Ground plan and elevation of the sundial with details of the fragment preserved today and details of the original installation site of the Ara Pacis by Friedrich Rakob In: Romolo A. Staccioli: Guida di Roma Antica. Itinerari archeologichi. Rizzoli, Milan 1986, ISBN 88-17-16585-9 , p. 346.


Coordinates: 41 ° 54 ′ 2 "  N , 12 ° 28 ′ 42.9"  E