Achille Pierre Dionis du Séjour

Achille Pierre Dionis du Séjour was a French astronomer and mathematician.
Dionis du Séjour was born in Paris and was a distant relative of surgeon and anatomist Pierre Dionis. He served as an advisor to parliament before he was appointed to the French Academy of Sciences in 1765. In 1775 he was elected a Fellow of the Royal Society. He was appointed to the Paris group for the Estates-General of 1789 and was one of the 47 who joined the Estates of the Realm that year.
Dionis du Séjour died in Vernou-la-Celle-sur-Seine.

Publications

Traité des courbes algébriques, with Mathieu-Bernard Goudin Recherches sur le gnomonique et les rétrogradations des planètes, Traité des mouvements apparents des corps célestes, Essai sur les comètes Essai sur les disparitions périodiques de l'anneau de Saturne,