Ernest LAUGIER, Astronomer (1812 - 1872) - 1 autograph lette - Lot 553

Ernest LAUGIER, Astronomer (1812 - 1872) - 1 autograph letter signed, 1 autograph Manuscript and 1 Lithograph: LAUGIER's Autograph Manuscript of an article "Note sur le mouvement propre de SIRIUS en distance polaire" (SIRIUS L'Étoile la plus brillante du Ciel discovered in 1844 by Bessel; confirmed in 1862) - 1p 1/2 in-4°, bearing erasures and corrections, with added indications, in another hand, for publication. Laugier explains that the tendency until now has been to assume that "when the mean positions of the stars are transported from one epoch to another, the proper motions of the stars are uniform". He is keen to prove that a small number of stars are exceptions, and SIRIUS is the most remarkable. He gives a highly technical demonstration, giving the mathematical formula for calculating the polar distance at different periods (from 1690 to 1852) + Letter A.S. from Astronomer LAUGIER, 1p in-8° - to the Editor for whom this manuscript is intended: "I have the honor of sending you the little note on the proper motion of SIRIUS, which you kindly asked me for.... I have done my best to shorten it without losing its intelligibility. I hope I haven't omitted anything essential. Please forgive the bad handwriting. I haven't had time to clean it up...". + Litho (39 x 28 cm), after a photograph by Pierson. Impr. Lemercier et Cie Paris, 1869.