1900 – \”Celestial Mechanics and the New Century\” – Palais des Sciences, Paris
1901 – \”Observations of the Transit of Mercury\” – Observatoire de Lyon
1903 – \”Stellar Photography: Capturing the Night Sky\” – Société Astronomique de France, Paris
1904 – \”The Moons of Jupiter: A Photographic Study\” – Institut de France
1906 – \”Cometary Orbits and Celestial Prediction\” – Académie des Sciences, Paris
1907 – \”Solar Eclipse Observations from Algeria\” – Musée d\’Histoire Naturelle, Paris
1909 – \”Variable Stars of the Southern Hemisphere\” – Observatoire de Nice
1911 – \”Nebulae Classifications: New Discoveries\” – Royal Astronomical Society, London
1912 – \”Asteroid Belt Mapping Project\” – Sorbonne, Paris
1914 – \”War Time Astronomy: Maintaining Science\” – Observatoire de Strasbourg
1916 – \”Double Star Systems and Orbital Mechanics\” – Académie de Bordeaux
1918 – \”Post-War Astronomical Reconstruction\” – Observatoire de Paris
1920 – \”Einstein\’s Relativity and Stellar Observations\” – École Normale Supérieure
1922 – \”The Great Andromeda Nebula Controversy\” – Institut Astrophysique, Paris
1924 – \”Planetary Atmospheres: Spectroscopic Analysis\” – Observatoire de Meudon
1926 – \”Twenty-Five Years of Celestial Photography\” – Galerie Scientifique, Paris
1928 – \”The Expanding Universe: New Evidence\” – Collège de France
1930 – \”Search for Trans-Neptunian Objects\” – Observatoire de Toulouse
1931 – \”Radio Waves from Space: A New Frontier\” – Institut de Physique, Paris
1932 – \”A Career in Astronomy: Retrospective Exhibition\” – Musée des Arts et Métiers, Paris