120- EULER (Léonard). Letters to a German princess, on various subjects of physics and philosophy. New edition, conforming to the original edition of the Academy of Sciences of St-Petersburg, revised and increased with various notes, by J.-B. Labey, and preceded by the eulogy of Euler by Condorcet. Paris, Vve Courcier, Bachelier, 1812, 2 vol. in-8, marbled fawn basane, smooth spine decorated, marbled edges (contemporary binding). Portrait and 9 folded plates. Corners worn. Stamp Pension Delafosse - Suresnes.