Geoscience Reference
In-Depth Information
Chapter 4
The Meridian and the Sun
At the time the astronomers of the Lapland expedition, including Maupertuis and
Le Monnier, returned to Paris, builders were in the final stages to complete the
Church of St. Sulpice. The Church has gained notoriety from its role in Dan Brown's
bestseller,
The Da Vinci Code
(Chapter 9) and modern pilgrims can be seen, the
novel under their arm, wandering around the nave. The Church authorities have even
complained about the increase in visitors, who talk amongst themselves as they
inspect this astronomical treasure. The noise disturbs the confessions in the south
transept and the contemplation of those who wait their turn on the chairs nearby.
Places
Church of St. Sulpice
The church stands near the center of Paris, on the left bank of the River Seine, north-west
of the Palais de Luxembourg and about 200 meters west of the Paris Meridian. Its location
is close to the meridian by chance, since the church was founded at the beginning of the 12th
century well before the meridian was mapped out. It was a small church, several times
enlarged between the 14th and 17th centuries, but in the first part of the 17th century it
became too small to satisfy the pretensions of the inhabitants of the wealthy area that had
grown around it (Terrien 2000). Starting in 1642 the original church was progressively razed
to ground level and completely replaced by the present enormous church, the second largest
(after Notre Dame) in Paris. The building of the church was accompanied by financial crisis
so the building was completed in two stages: The first stage, which completed the eastern
half of the church, lasted from 1646-1678 and then stalled (held up by financial problems).
The second stage was completed between 1719 and 1732, with the façade completed in
1776. The proportions of the St. Sulpice Church and its solid classical columns are thought
by some to be rather graceless but importantly it contains two unequalled treasures of art
and science, namely a set of three murals by the French romantic painter Eugène Delacroix
(1798-1863), who lived nearby, and the
meridiana
by Pierre Le Monnier.
The church is the home to a
meridiana
, built by Pierre Le Monnier (Gotteland
and Camus 1997, Heilbron 2001, Kiner 2005, Rougé 2006).
Meridiana
is Italian
for sundial, used in the English language for a scientific instrument that observes
the passage of the Sun across the meridian. The
meridiana
works on principles
drawn from nature; there are a million natural examples in copses, woods and for-
ests. Every sunny day the Sun produces dappling of the ground beneath the trees
under the canopy of leaves. The mass of leaves contains numerous small gaps, each
of which acts as a pinhole camera and each hole can image the Sun on the ground,
the ground acting as the image plane in the camera. The image plane is angled off
