Europe 2013: Rome - The Last Day

Dateline Rome - 26/10/13

Pack up today - at least later. First we saw a building on our first day that intrigued us. It was labelled Santa Maria degli Angeli e Martires. The front of this basilica was a broken circle.

So today's plan was to visit this Basilica which was just a short walk from our apartment.

The Basilica sits on the Piazza della Repubblica and one end of the Via Nazionale, at the other end of which (sorta, there is a jog in the street to avoid a significant? building ) sits the Vittorio Emanuelle, which is visible from the Piazza.

Each side of the Via Nazionale has a curved building around the road and Fountain

Across the piazza

The fountain

Part of the Baths of Diocletian

The other day we passed a round building in the Via Viminale that was labeled Baths of Diocletian. Well these baths must have been huge because here we are about 500 metres away from our original building and this building, now labeled Planetario was part of the baths, as was the Basilica of Santa Maria degli Angeli e ... which this is the entry to...

The anti-chamber of the basilica, the dome is original although the pater painted on may not be.

Looking up at the dome and the central lantern. This would have been open in the roman period.

This is a vast space

The Altar

This church has a very interesting feature set into the floor

The meridian line[edit]

Diagram of Bianchini's meridian, from hisDe Calendario (1703): the ray on the right comes from the sun, and hits the line at solar noon through the year; the ray on the left is from Polaris

Bianchini's gnomon projects the sun's image onto his line just before solar noon, around 11:54 in late October

At the beginning of the eighteenth century, Pope Clement XI commissioned the astronomer, mathematician, archaeologist, historian and philosopher Francesco Bianchini to build a meridian line, a sort of sundial, within the basilica. Completed in 1702, the object had a threefold purpose: the pope wanted to check the accuracy of the Gregorian reformation of the calendar, to produce a tool to predict Easter exactly, and, not least, to give Rome a meridian line as important as the one Giovanni Domenico Cassini had recently built in Bologna's cathedral, San Petronio. Alan Cook remarked, "The disposition, the stability and the precision are much better than those of the famous meridian... in Bologna".^[1]

This church was chosen for several reasons: (1) Like other baths in Rome, the building was already naturally southerly oriented, so as to receive unobstructed exposure to the sun; (2) the height of the walls allowed for a long line to measure the sun's progress through the year more precisely; (3) the ancient walls had long since stopped settling into the ground, ensuring that carefully calibrated observational instruments set in them would not move out of place; and (4) because it was set in the former baths of Diocletian, it would symbolically represent a victory of the Christian calendar over the earlier pagan calendar.

The meridian solar line made by Francesco Bianchini.

Bianchini's sundial was built along the meridian that crosses Rome, at longitude 12° 30' E. At solar noon, which varies according to the equation of time from around 10:54 a.m. UTCin late October to 11.24 a.m. UTC in February (11:54 to 12:24 CET),^[2] the sun shines through a small hole in the wall to cast its light on this line each day. At the summer solstice, the sun appears highest, and its ray hits the meridian line at the point closest to the wall. At the winter solstice, the ray crosses the line at the point furthest from the wall. At eitherequinox, the sun touches the line between the these two extremes. The longer the meridian line, the more accurately the observer can calculate the length of the year. The meridian line built here is 45 meters long and is composed of bronze, enclosed in yellow-white marble.

In addition to using the line to measure the sun's meridian crossing, Bianchini also added holes in the ceiling to mark the passage of stars. Inside the interior, darkened by covering the windows, Polaris, Arcturus and Sirius were observed through these holes with the aid of a telescope to determine their right ascensions and declinations.^[3] The meridian line was restored in 2002 for the tricentenary of its construction, and it is still operational today.

(From wikipedia)