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.
Tiberius Julius Celsus Polemaeanus Tiberius Julius Celsus Polemaeanus (Greek: Τιβέριος Ιούλιος Κέλσος Πολεμαιανός, "Tibérios Ioúlios Kélsos Polemaianós" ) commonly known as Celsus (ca. 45 – before ca. 120) was an Ancient Greek Roman citizen who became a Roman senator, and served as a Roman consul as the colleague of Lucius Stertinius Avitus. Celsus Polemaeanus was a wealthy and popular citizen and benefactor of Ephesus, and was buried in a sarcophagus beneath the famous Library of Celsus, which was built as a mausoleum in his honor by his son Tiberius Julius Aquila Polemaeanus.