AUTOGRAPH LETTERS SIGNED and 2 AUTOGRAPH POSTCARDS SIGNED, all to Cornelis Easton, dated between 1894 and 1925, all pen and ink, each 1 (fold.) leaf. All but two letters by esteemed astronomers, mainly on astronomical matters, publications and fellow astronomers: 1. Albertus Philppus KAPTEIJN (1848-1927) (postcard, dated "Den Haag, 16 Sept 22"); 2. Laurentius KNAPPERT (1863-1943, theologist) (ALS, dated "Leiden 9 mei 1923", 1 fold. leaf, 2p.); 3. Willem Jacob LUYTEN (1899-1994) (ALS, dated "Mt Hamilton 1922 Jan 25", 1 leaf, 2p.); 4. Albertus Antonie NIJLAND (1868-1936) (ALS, dated "'s-Gravenhage, 21 Juni 1922", 1 leaf, 2p.); 5. Antonie PANNEKOEK (1973-1960) (ALS, dated "Leuven 1 Februari '94", 1 fold. leaf, 3p. Extensively on astronomical matters; w. some pencil annots. by Easton); 6. Pieter Johannes VAN RHIJN (1886-1960) (ALS, dated "Groningen, 27 September 1918", 1 fold. leaf, 2p.); 7. Rudolph Hendrik SALTET (1853-1927, physician) (ALS, dated "O.Z. Achterburgwal 213, 19 April 1923", 1 fold. leaf, 2p.); 8. Hendricus Gerardus VAN DE SANDE BAKHUYZEN (1838-1923) (postcard, dated "Leiden 16 Sept. 1922". Thanking him for sending the publication on Kapteyn); 9. Johan STEIN (1871-1951) (ALS, dated "Amsterdam, 27 Febr. '22", 1 fold. leaf, 2p. On participation in the Astronomy Congress in Rome).