 Only three primary sources mention Hypatia of Alexandria, apart from other secondary ones".He added that none of Hypatia's work has survived but it is thought, from secondary sources, that her main fields of study and work were geometry and astronomy.Mampaso claimed that Hypatia invented the hydrometer, an instrument still in use today, and that probably her father Theon of Alexandria, together with Hypatia, invented the astrolabe.