Michel Ferdinand d'Albert d'Ailly

Michel Ferdinand d'Albert d'Ailly, Duke of Chaulnes, as Hercules, by Jean-Marc Nattier.

Michel Ferdinand d'Albert, 5th Duke of Chaulnes (31 December 1714 – 23 September 1769), Duke of Picquigny and then Duke of Chaulnes from 1744, was a French astronomer, physicist and freemason.

Early life Compouned microscope of Albert d'Ailly, on display at Conservatoire national des arts et métiers. Michel Ferdinand d'Albert d'Ailly was the younger son of Marie Anne Romaine de Beaumanoir and Louis Auguste d'Albert d'Ailly, 4th Duke of Chaulnes (1676–1744). His elder brother was Charles François d'Albert d'Ailly, 5th Duke of Chaulnes (1707–1731).

His paternal grandfather was Charles Honoré d'Albert, 3rd Duke of Luynes. Among his cousins were Charles Philippe d'Albert de Luynes, the 4th Duke of Luynes as well as the astronomer Paul d'Albert de Luynes, Cardinal and Archbishop of Sens.

His final work was a thesis on a new triquetrum which was stronger and easier to use than previous models.

Personal life

He married Anne Josèphe Bonnier (1718–1787), who replaced the Viscountess of Beaune in 1766 as one of Queen Marie Leszczynska's ladies-in-waiting. Together, they were the parents of:

Louis Joseph d'Albert d'Ailly (1741–1792), who inherited the dukedom and married his cousin, Marie Paule Angélique d'Albert (1744–1781), a daughter of Charles Louis d'Albert de Luynes. She served as Lady of the Queen and accompany of the Dauphin (1770-1774).

He died in Paris in 1769. His eulogy was published in the 1769 volume of the anthology of the Académie des sciences.

Publications Nouvelle Méthode pour diviser les instruments de mathématiques, in Description des arts et métiers, published by the Académie des sciences, 1768, in-fol. 44 p. with 15 illustrations. , Paris, 1768, in-fol. 18 p. with 6 illustrations. With this method, the Duke managed to obtain, from a quadrant with a radius of 11 inches, almost the same precision as from a quadrant with a radius of six feet which was at the observatory. He had already published the principles of this work in a thesis of 1755. Some parts of it were also in the Journal de Physique. Six works in the anthology of the Académie des sciences.