HUYGENS, CHRISTIAN. Opera varia. Leyden: Janssonios Vander, 1724. Engraved portrait and 56 engraved folding plates. 2 volumes (containing 4 parts) in one [complete], contemporary vellum, some chipping at edges; plates lightly evenly browned, occasional browning or staining to text, wormtrack in lower margins of first volume (including plate margins slightly). Included at end is Huygens' Opera Astronomica [vol. III]. Contains all the author's works, except those included in the Opera posthuma. Sotheran I, 2058 -- Opera reliqua. Amsterdam: Janssonio-Waesbergios, 1728. 57 (of 58) engraved folding plates. Includes at end Opuscula Posthuma, tomus primus. Amsterdam: Janssonio-Waesbergios, 1728. Sotheran I, 2061. Together 4 volumes bound in two, uniformly bound in contemporary vellum, some chipping at edges; some browning and staining to text and plates. (2)