[Huygens, Christian], a Dutch geometrician, physicist, and astronomer, born at The Hague; published the first scientific work on the calculation of probabilities, improved the telescope, broached the undulatory theory of light, discovered the fourth satellite of Saturn, invented the pendulum clock, and stands as a physicist midway between Galileo and Newton (1629-1093).
[Hydaspes], the ancient name of the Jhelum, the northernmost tributary of the Indus.
[Hyder Ali], a Mohammedan ruler of Mysore; raised himself to be commander-in-chief of the army; organised it on the French model; unseated the rajah; conquered Calicut, Bednor, and Kananur; waged war successfully against the English and the Mahrattas, and left his kingdom to his son [Tippoo Saib] (q. v.) (1728-1782).
[Hyderabad] (370), the capital of the Nizam's dominions in the Deccan, is 6 m. in circumference, strongly protected all round by a belt of rocky desert, and a centre of Mohammedanism in India. Also the capital of Sind (58), near the apex of the delta of the Indus; manufactures silks, pottery, and lacquered ware, and is strongly fortified.
[Hydra, The Lernean], a monstrous reptile inhabiting a marsh, with a number of heads, that grew on again as often as they were chopped off, and the destruction of which was one of the twelve labours of Hercules, an act which symbolises the toil expended in draining the fens of the world for man's habitation.
[Hygeia], in the Greek mythology the Goddess of Health, and daughter of Æsculapius; is represented as a virgin in a long robe, with a cup in her hand and a serpent drinking out of it.
[Hymen], in the Greek mythology the God of Marriage, son of Apollo, and one of the Muses, represented as a boy with wings; originally a nuptial song sung at the departure of the bride from her parental home.
[Hymer], a frost Jötun, whose cows are icebergs; splits rocks with the glance of his eye.
[Hymettus], a mountain in Attica, famous for its honey and marble.
[Hypatia], a far-famed lady teacher of Greek philosophy in Alexandria, distinguished for her beauty and purity of life, who, one day in 415, on her return home from her lecture-room, was massacred in the streets of the city, at the instance, of both Jews and Christians, as a propagator of paganism.