in Chronology, an aliquot part of a natural day, usually a twenty-fourth, but sometimes a twelfth. Originally the word hora, or ὥρα, comes, according to some authors, from a surname of the sun, the father of hours, whom the Egyptians called Horus. But others derive it from the Greek ἀπολῦναι, to terminate, or distinguish; and others again from the word ὤρα, urine, conceiving that Trismegistus was the first who settled the division of hours, from observing an animal consecrated to Serapis, named cynocephalus, which made water twelve times a day, and as often in the night, at equal intervals.

An hour with us is a measure or quantity of time, equal to a twenty-fourth part of the natural day, or nycthemeron; or the duration of the twenty-fourth part of the earth's diurnal rotation. Fifteen degrees of the equator answer to an hour, though not precisely, but near enough for common use. The hour is divided into sixty minutes, the minute into sixty seconds, and so on. The most ancient hour is that of the twelfth part of the day. Herodotus, (lib. ii.) observes that the Greeks learned from the Egyptians, amongst other things, the method of dividing the day into twelve parts. The division of the day into twenty-four hours was not known to the Romans before the first Punic war. Until that time they only regulated their days by the rising and setting of the sun. They divided the twelve hours of their day into four, namely, prime, which commenced at six o'clock; third, at nine; sixth, at twelve; and none, at three. They also divided the night into four watches, each containing three hours.

HOURS, Horæ, in the ancient mythology, were certain goddesses, the daughters of Jupiter and Themis. At first they were only three in number, Eunomia, Dice, and Irene; but to these were afterwards added two more, Carpo and Thallo. Homer makes them the doorkeepers of heaven, and Ovid allots them the employment of harnessing the horses of the sun.

Hours, Hora, in the Roman Catholic church, are certain prayers performed at stated times of the day, as matins, vespers, lauds, and the like. The lesser hours are, prime, tierce, sext, and none, and they are called canonical hours, as being prescribed by the canons of the church in commemoration of the mysteries accomplished at those hours. These hours were anciently called cursus, cursus; and Mabillon has written a dissertation on them, entitled De Cursu Gallicano. The first constitution enjoining the observation of the canonical hours is dated in the ninth century; being found in a capitular of Heito, bishop of Basil, directed to his curates, importing that the priests shall never be absent at the canonical hours either by day or by night.