1842-1849 40, 108, 154, 98, 64 p., 4to, paperbound (plain contemporary wrappers). Author's dedication to Prof. Dr. Van Breda. Library stamps.Collection of 'Observations' as published in: Mémoires de L'Academie Royale de Belgique. Includes also: Observations sur la Métérologie. Phénomènes périodiques naturels. The years 1841, 1843, 1844, 1847 & 1848. We added the year 1872 (75 p.).