hist2_en

Garnier made various sketches ("But it happened that if the architect was rather satisfied with them, the astronomers were not at all") but he finally presented a design which was unanimously adopted by the Bureau des Longitudes on December 3rd, 1879.

Indeed this plan was quite original and ambitious. In fact, Garnier suggested to build a city of astronomy, including buildings to house the instruments, offices and lodgings for the astronomers.

General view of the Observatory according to Garnier's plans

The whole construction included fifteen pavilions or main buildings each at a distance fulfilling scientific requirements, and with different styles according to their functions, but giving an impression of general harmony.

Once the inner road was laid out and fitted up, and the summit levelled, the first scientific buildings were built prior to the dwelling houses. The domain was enclosed by 3, 60 kilometers long wall. The construction site lasted 7 years.

Bischoffsheim wanted as a director, a man able to manage the installation of his observatory and to lead it to a high level scientific establishment.

Felix Tisserand, director of the Toulouse Observatory recommended to him Henri Perrotin, a former pupil. Perrotin visited the main observatories of Europe, in order to study their fittings and organization and, on January 1881, he settled down at the Mont Gros.

A few months later, the mobile meridian circle was set up in its building. Then, with this instrument and the help of the telegraph, Perrotin was able to determine the longitude of the Mont Gros with respect to those of the observatories of Montsouris (Paris) and Brera (Milan).

The same year, the spectroscope built in Paris by Louis Thollon was set up in the Pavilion of Physics. With this spectroscope, then the most powerful of this type, Thollon began his systematic observations of the Sun.

In Spring 1882, the buildings were in good progress but none of the ordered instruments was completed. In the meantime, Bischoffsheim decided to fund two scientific missions.

The first one, was led by Thollon, accompanied by André Puiseux and Charles Trépied, the future director of the Algiers Observatory, they went to Siouth, in Egypt, to observe the total eclipse of Sun, in May 17th, 1882. Other foreign astronomers (Lockyer, Schuster, Tacchini) joined the group.

The second was aimed to observe the transit of Venus, in December 6th,1882, followed in Avila (Spain), whereas Perrotin observed it in Patagonia in Carmen de Patagonès, on the banks of the Rio Négro.

Back to the Mont Gros, in February, 1883, the director found the dome of the small equatorial finished. The 38cm-refractor was set up next June, and the micrometric measures of double stars, as well as the observations of comets and small planets (asteroids) could really start.

The year after, latitude of the Mont Gros was determined. The two coordinates establishing the position of the Observatory were then accurately known : longitude, 7°18' 11'' East, and latitude, 43° 43' 11'' North.

Garnier's " city of astronomy "