Solarium Augusti
As Solarium Augusti or Horologium Augusti a large astronomical measuring instrument with a ball on a 30 meter high obelisk is called a gnomon, which was built on the Campus Martius in Rome under Emperor Augustus.
It is considered incomparably large meridian instrument ( lunch Weiser, annual calendar ), as it is already the witness Pliny had described. The exposed by the German Archaeological Institute piece meridian line is about 1.6 meters above the original level of the Campus Martius. It is believed that the destroyed Augustan instrument at the time of the Emperor Domitian was built on the caused by flooding of the Tiber now higher Campus Martius again. The plant probably made with the Mausoleum of Augustus, the associated parking facilities and the Ara Pacis, a structural unit and was one of the most important political sign of the power of the Emperor Augustus.
According to studies by the German Archaeological Institute, who were accompanied and took place 1970-1981 by elaborate excavations, this system was interpreted for several years as an extremely large sundial.
The meridian instrument of the Emperor Augustus
An Obelisk ( Obelisco di Montecitorio ) from Heliopolis in Egypt, the Augustus in the year 10 BC, had erected, served as about 30 meter high gnomon. Its supplementation with a likewise large ( expansion at least 200 meters) flat dial to a sundial but was not detected. Was excavated one about 6.6 meters long piece of a scaled meridian line, after which the Solarium Augusti as a functioning with the solar meridian instrument (annual calendar, lunch Weiser ) is considered today. The site is located approximately 1.6 meters above the level of the Campus Martius in the time of Augustus. It is attributed to a renewal of the original described by Pliny Meridian Instruments, which took place around the time of the Emperor Domitian.
The broken into five parts obelisk and its original base in 1748 were unearthed. Some 40 years later he was re-assembled, crowned with a new ball and socket together with 1792 at its current location, about 250 meters south to the Italian Parliament on the Piazza di Montecitorio erected. The umbra of an original, similarly large ( about 75 cm in diameter) and the same ( about 30 meters) placed ball as Nodus extends approximately 80 meters. The to-read on the associated meridian noon shadow of this ball is removed at the winter solstice in Rome about 65 meters from the Obelisk. The meridian line is inserted as a bronze line in the bottom panels and has between the two solstice points a length of about 55 meters. Cross the meridian line are attached longer marks as separators between the signs of the zodiac and shorter for the 30 - degree scale of the zodiac in bronze. The shadow of the ball thus showed the location of the sun in the zodiac. The until now exposed portion of the meridian line has a length of 6.60 m, divided by 27 short transverse lines for grading and one long transverse line as a separator between adjacent characters. It is along the meridian line with the Greek names of the characters inscribed: On the west side, it ranges from 19 ° [ KRI ] OS (Aries) to 16 ° TAUR [ OS] ( Taurus ), on the east side, symmetrically to 14 ° [ LE ] ON (Lion ) to 11 ° PARTH [ ENOS ] ( Virgin ). The degree distances increase from south to north to 19 cm to 30 cm. From this one can calculate (M. Schütz, unpublished ) that the shadow-casting ball, which crowned the obelisk, about 17.7 meters south of the dividing line Leo Virgo at a height of about 30 to 31 m must have been located. Zodiac sign Virgo at the long separation line Leo Virgo is the Greek inscription ETESIAI PAUONTAI that Etesian listen to. With Etesian winds were referred, the very regularly every summer occurred (today: Meltemi ). In the 15 ° Taurus brand is the inscription THEROUS ARCHE, the beginning of summer. According to ancient custom of the summer did not start with the summer solstice, but this was the middle of summer; So the summer went from 15 ° to 15 ° Taurus Leo. Besides this under the property Via del Campo Marzio 48 exposed fragment further parts were found during excavations under the church of San Lorenzo in Lucina.
The original site of the Ara Pacis Augustae was assigned to the Solarium: east in the area of between Via in Lucina and Via del Corso, where today the Palazzo Fiano - Almagia stands.
The Obelisk of Meridian Instruments
The approximately 22 -meter obelisk is made of red granite and comes from the quarries of Aswan in Upper Egypt. Pharaoh Psammetichus II had built it around 595 BC in Heliopolis on the occasion of the first anniversary of his accession to the throne. The Romans in 10 BC transported him to Rome to set it up as a gnomon on the Field of Mars. He received a foundation and an almost 5 meter high pedestal, with a honorable the Emperor Augustus and the Roman sun god Sol sacred inscription. Along with serving as the nodus ball about 30 meters in height have been achieved.
The ancient consecration inscription reads:
AUGUSTUS PONTIFEX MAXIMUS IMP XII COS XI TRIB POT XIV AEGUPTO IN POTESTATEM POPULI ROMANI REDACTA SOLI DONUM DEdit
Son of the deified ( Caesar ) Pontifex Maximus Imperator to 12, consul for 11, owner of tribunician power for the 14th time after Egypt under the rule of the Roman people was brought has ( this obelisk ) where the sun as a gift
The excavations by the German Archaeological Institute
The initial interpretation as a sundial could not be maintained not only for physical reasons (eg, insufficient coverage of the umbra of the Nodus ball ). There were also significant shortcomings when dealing with ancient texts.
There was speculation for a long time for a sundial, but also early evidence for the existence of a ledigliche Meridian Instruments. The recent interpretation as a sundial was still popular, which was favored by the unusual successful excavations to 8 feet below the present level. They dug out of a small basement floor about 6 feet in depth, that is far below the foundations of the walls of a multi-storey old house in the densely built-up is now downtown Rome. Of these, there are impressive pictures.