TWO VOLUME SET. RARE historical critical monograph on the principles of mathematical analysis by Pierre Léon Boutroux (1880-1922), an eminent French mathematician and historian of science, chiefly known for his work in the history and philosophy of mathematics. [BOTH VOLUMES]: 245x165mm. [XII+547] + [512] pages. Quarter-cloth marbled board rebound Hardcover. Cover yellowing, damp-stained/stained and rubbed. Cover bottom edge peeling. Cover corners and spine edges slightly bumped. Pen/pencil inscriptions on front whitepage and title-page. Small stamp on title page. Pages yellowing. [VOL.I]: Spine front hinge wrinkled. Small ink inscription on front whitepage upper corner. [VOL.II]: Inner cover and few pages bottom and inner edges damp-stained, especially near binding - NO damage to text. Binding slightly visible between several pages. Some pages browning. [SUMMARY]: This extremely rare two volume monograph on mathematical analysis by one of the foremost French mathematicians and historians of science has sustained some damage (mostly external), but is otherwise in good reading condition.