by Attic writers called Egesta, an ancient city of Sicily, stood at the head of a deep bay on the north coast near the western extremity of the island, 6 miles from the sea, and 34 W. of Panormus. It seems to have occupied the summit of a small hill overlooking a ravine, through which flowed a river. The situation is very bleak and exposed. Laying aside the traditionary legends which ascribe the foundation of the city to emigrants from Troy, we may ascertain, on more certain grounds, that it was neither founded by the natives of Sicily nor by Greek colonists; although from intercourse with the Greek cities in the vicinity, it early acquired a civilized character, quite different from the barbarous natives. Segesta was for a long period engaged in almost perpetual conflicts with Selinus, on the south coast of the island. These petty feuds would have been little worthy of mention, had they not led indirectly to a most important event in Greek history, the fall of the Athenian power in the Peloponnesian War. For the event that more than any other led to the fatal issue of that war was the disastrous result of the great Athenian expedition to Sicily (416–413 B.C.), and that was undertaken at the request of the Segestans, when their enemies of Selinus were hard pressing them, having obtained the assistance of Syracuse. After the Athenian fleet and army had been annihilated in the fruitless siege of Syracuse, the Segestans, unable to contend single-handed with their foes, made an alliance with Carthage. The troops of that nation speedily landed in Sicily in 410 B.C.; took and destroyed Selinus and Himera, and established firmly the power of their country in the west of Sicily. For a long time Segesta adhered firmly to the Carthaginian interest, Segment and resisted a siege by Dionysius of Syracuse in 397 B.C., while, though it was taken ninety years after by Agathocles, it afterwards regained its liberty. But, on the first breaking out of war between Carthage and Rome 264 B.C., it was one of the cities that earliest deserted the cause of the former. Hence it was always treated with especial favour by the Romans. No important event in subsequent history brings into notice the name of Segesta; it gradually fell into decay, and was finally abandoned on account of the ravages of the Saracens. Except some vestiges of the walls, the only remains now to be seen of the city are a temple and a theatre.

SEGMENT of a circle, is that part of the circle which is contained between a chord and an arc.

SEIGNI, Bernardo, a Florentine historian, was born at Florence about the end of the fifteenth century. He studied law at Padua, pursued merchandise at Aquila, returned to Florence, where he was employed in state affairs by Duke Cosimo I. Segni translated the Rhetoric, Ethic, Politic, and the treatise on the Soul, of Aristotle into Italian, and subsequently engaged in a Storia Fiorentina dall'anno 1527 all'anno 1555. As he kept his history secret during his life, it was remarkable for the conscientious spirit in which it was written, and Segni will go down to posterity as one of the very best writers which Italy has produced. His history is decidedly superior to those of Varchi, Nardi, and Nerli, who have treated of nearly the same period. Segni died in 1559.