Geoscience Reference
In-Depth Information
garden central to the avenue of lime trees running directly to the south face of the
main Observatory building. Here there are enclosures of several auxiliary meridian
telescopes in the garden and the private areas visible around.
Usually it is not possible to walk through the Observatory area but guided tours of
the Observatory are available by advance appointment. An Arago disk is mounted
on the patio on the south side of the building and in the parquet of the Observatory's
ground floor. By circling the Observatory grounds to the east you pass the Rue
Méchain (named after the astronomer Pierre Méchain, and where the studio of
Tamara de Lempicka was situated in the 1930's) and come into Rue Cassini (named
after the family of astronomers). The front entrance to the Observatory lies ahead, a
proud statue of Urbain Leverrier at the center of its front courtyard. Leverrier discovered
the planet Neptune by inferring its existence and position from its effect on the planet
Uranus. There are two Arago disks in the courtyard nearby.
The Observatory was established during the reign of King Louis XIV. In 1665-
1666, Jean-Baptiste Colbert (1619-1683), an influential minister and at the time the
finance minister and secretary of state for the King's court, founded the Academy of
Sciences of Paris. A group of its members immediately made a proposal to the King,
through Colbert, to establish an observatory in Paris for scientific investigations.
One notable physics experiment carried out at the Observatory was that of Jean-
Bernard-Léon Foucault (1819-1868), who with the help of Arago constructed a
Foucault pendulum in the 11 meter high Salle Méridienne, or central hall for the
Observatory.
6th Arrondissement
Av. de l'Observatoire
In front of the observatory is Arago Medallion Number 40. It is the west of the axis
of the Observatory and shows how the present Paris Meridian is offset from
Cassini's original (see the section on the Observatory). The meridian continues
along the western part of Avenue de l'Observatoire. This wide avenue leads to the
open areas of the Jardin de Marco Polo, the Jardin de Robert Cavelier de la Salle
(explorer of the Americas) and the Jardin du Luxembourg, which lie one after
another between the Observatory and the Senate House. In the distance above the
Senate House is Montmartre, with the Cathedral of Sacré Coeur on the hilltop. Left
of the Cathedral is the Moulin de la Galette (see below). Near here, now hidden
among trees and buildings, is a sighting column used by the astronomers at the
Observatory as a calibration point for their telescopes. The axis from the Observatory
to this column is the Paris Meridian.
The catalogue lists 34 medallions between here and the River Seine, the remaining
ones of the Left Bank. Arago medallion Number 44 lies west of and outside the entrance
to the Jardin de Marco Polo, on a triangular traffic island in the Place Camille Jullian.
