Geoscience Reference
In-Depth Information
(
To God best and greatest, [King Louis XV, benefactor of this church, and under the admin-
istration of Jean-Frédéric Phélypeaux, the Comte de Maurepas, Minister of State, and
Philibert Orry, Minister of State, Director General of the Kings Buildings] made this
sacred work in the name of the [Royal] Academy of Sciences, and with the advice of Pierre-
Charles Le Monnier of the same Academy and also a fellow of the [Royal] Society of
London. He determined it from the autumn equinox and winter solstice in the year 1743
.)
[Another decoration has been erased, the zodiacal sign of Scorpio according to Rougé
(2006).]
Ecce mensurabiles posuisti
dies meos et Substantia mea
tanquam nibilum ante te. Psal. XXXVIII
C'Est ainsi Seigneur que vous
avez donné des bornes à nos
jours et toute notre vie est un
rien à vos yeux.
[Again Latin and French versions of Psalm 39, verse 5.] (
Behold, thou hast made my days
as an handbreadth; and mine age is as nothing before thee
.)
The pillar is sometimes obscured by a jumble of piled up chairs, but if you can
slip through them you can read the long inscription on the gnomon's base.
Revolutionaries have neatly excised from it the names of the King, his aristocratic
ministers and his royal symbols. The removal of the names of the royalists occurred
during the period from 1793, when an official decree declared the suppression of
Christianity, on the basis that the Catholic Church was an institution of privilege and
its priests were associated too closely with the aristocrats. In place of Christianity,
the revolutionaries instituted the religion of Deism, focused on a
Supreme Being
,
who was thought to protect France. The church was taken over as a Temple of
Reason and became a house of worship for the Supreme Being. A plaque above the
main entrance of the church installed at that time declares that “The French people
recognize the Supreme Being and the immortality of the soul.” Later still, in 1801,
it became a Temple of Victory; the statues and paintings were removed, the tombs
desecrated, and the main altar destroyed. However, two pharmacists of the parish
convinced the revolutionaries that the
meridiana
was a scientific instrument and
should be preserved. Thus the gnomon was conserved (with the careful alterations
to the inscription) and the raised altar area surrounded by its balustrade was left
untouched, ultimately thanks to the portion of the meridian line that lay within.
Le Monnier observed the solstices at the Church between 1743 and 1791, an
astonishing half century of consistent scientific observations, and plotted the posi-
tion of the Sun on the meridian line throughout those nearly fifty years to better
than a millimeter. Le Monnier later worked at an observatory in Rue St-Honoré run
by the Capuchin order of monks and equipped with a wall mounted telescopes to
observe the positions of stars. He was able to confirm by his observations of the Sun
and the stars the obliquity of the Earth's axis, or its tilt. He found that the angle was
decreasing at the rate of about 45 arc seconds per century (the modern value is
46.85 seconds per century). This decrease at the present time is part of a longer
term periodic wobbling of the Earth's spinning axis.
