The Size of France - Full Meridian of Glory - page 24

Fig. 12 Jean Dominique Cassini painted by Durangel in 1879, after an older original. Cassini
looks across a celestial globe out to the Paris Observatory, with one of his long telescopes
mounted on the roof. ©Observatoire de Paris
telescope impressed the court and the astronomers of the French Academy, particularly
Colbert. Ultimately a 34-feet (10.4 m) focal length telescope was ordered from
Campani and installed in the Observatory.
On the second floor of the completed Observatory building, Cassini created a
room for observations of the Sun's positions. Today this is known as the Cassini
Room and it is here Cassini repeated his experiments in Bologna and constructed
another meridiana , or sundial (see Chapter 4). Cassini timed and measured the
position of a shaft of sunlight that had passed through an aperture high on the south
side of the room and fallen on a north-south line on the floor. This line was the first
Paris Meridian, right on the building's line of symmetry.
Jean Dominique Cassini was not actually named Director of the Observatory,
nor was his son Jacques Cassini (1677-1756 and known as Cassini II) who suc-
ceeded him. The Observatory was under the control of the Academy and its members
could use its facilities to carry out any work they pleased if they could gather funding
for it. In this capacity, they would not have regarded themselves as being directed