Mnaseas is reckoned to have been a pupil of a scholar who was chief librarian at what library?
Eratosthenes Eratosthenes of Cyrene ( ; Greek: Ἐρατοσθένης ὁ Κυρηναῖος , ] ;  – ) was a Greek mathematician, geographer, poet, astronomer, and music theorist. He was a man of learning, becoming the chief librarian at the Library of Alexandria. He invented the discipline of geography, including the terminology used today.
Joseph Bowles Joseph Bowles (1692 or 1693 – 1729) was an English librarian, who served as Bodley's Librarian, the head of the Bodleian Library at the University of Oxford, from 1719 until his death.