COMA BERENICES.--This constellation lies between Canes Venatici and Virgo. Although it was not included among the old forty-eight constellations of Ptolemy, it is referred to by Al-Sufi as the Plat, or Tress of Hair, and he included its stars Flamsteed 12, 15, and 21 in the "extern" stars of Leo. It was originally formed by the poet Callimachus in the third century B.C., but was not generally accepted until reformed by Hevelius. Callimachus lived at Alexandria in the reigns of Ptolemy Philadelphus and Ptolemy Euergetes, and was chief librarian of the famous library of Alexandria from about B.C. 260 until his death in B.C. 240. Eratosthenes was one of his pupils. The history of the constellation is as follows: Berenice, wife of Ptolemy Euergetes, made a vow, when her husband was leaving her on a military expedition, that if he returned in safety she would cut off her hair and consecrate it in the temple of Mars. Her husband returned, and she fulfilled her vow. But on the next day the hair had disappeared--stolen from the temple--and Conon the mathematician showed Ptolemy seven stars near the constellation of the Lion which did not belong to any constellation. These were formed into a constellation and called Berenice's Hair. Conon is referred to by Catullus in the lines-- "Idem me ille Conon cœleste numine vidit E. Berenico vertice Cæsariem." Coma Berenices first occurs as a distinct constellation in the catalogue contained in the Rudolphine Tables formed by Kepler (epoch 1600) from the observations of Tycho Brahé.[451] Bayer substituted a sheaf of corn, an idea derived from an ancient manuscript. LEO MINOR.--This small constellation lies between Ursa Major and Leo, and east of the Lynx. It was formed by Halley about the year 1660; but is referred to by Al-Sufi, who includes one of its stars (Fl. 41) in the "extern" stars of Leo. There are, however, several brighter stars in the group. The brightest, Fl. 46, was measured 3·92 at Harvard. The star Fl. 37 was called _præcipua_ (or brightest) by Tycho Brahé, and rated 3, but as it was measured only 4·77 at Harvard it may possibly have diminished in brightness. SEXTANS.--This constellation lies south of Leo, and north and east of Hydra. It was formed by Hevelius about the year 1680. According to the Harvard photometric measures its brightest star is Fl. 15 (4·50).