Hypsicles of Alexandria (Ὑψικλῆς ὁ Ἀλεξανδρεύς) was a Hellenistic mathematician and astronomer active in the 2nd century BCE. Identified by his ethnonym, he worked within the intellectual milieu of Alexandria [1]. His primary chronological anchor is the composition of what is now Book XIV of Euclid's Elements, dated to around 150 BCE based on internal references [1][2].

His two known works are the treatise forming **Book XIV of Euclid's *Elements*** (Ἐπιγραφομένη τοῦ Εὐκλείδου Στοιχείων βιβλίον ιδʹ), which compares the regular dodecahedron and icosahedron [1][2][3], and the astronomical text Ἀναφορικός (Anaphoricus, On the Ascension of Stars), which applies arithmetical progressions to the rising times of zodiacal signs [1][2].

Hypsicles's significance stems from his contributions to geometry and mathematical astronomy. Book XIV of the Elements is an important extension of solid geometry, preserved within the Euclidean corpus [1][2][3]. His Anaphoricus helped transmit the division of the circle into 360 degrees to the Greco-Roman world and its method for calculating rising times influenced later astronomers like Ptolemy [1][2].

Sources 1. Encyclopædia Britannica: https://www.britannica.com/biography/Hypsicles 2. Stanford Encyclopedia of Philosophy: https://plato.stanford.edu/entries/euclid/ 3. Perseus Digital Library: http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0104%3Aentry%3Dhypsicles-bio-1