Straits of the, form the communication between the Sea of Marmora and the Archipelago. This channel, through which there flows a constant current out of the Sea of Marmora into the Archipelago, is upwards of 50 miles long, and varies in breadth from 1 mile towards its western to 10 miles at its eastern extremity. It derives its name from two ancient fortresses on either side of the river, of which one is built on the site of the ancient Sestos, and the other on the site of the ancient Abydos. About 20 miles to the west of these are two modern fortresses called the New Castles, and between the old and the new forts are military works of various descriptions. The total number of guns mounted on these fortresses is 689, some of which discharge stone shot, and require a charge of more than 3 cwt. of powder. It derived its ancient name of the Hellespont from the tradition of Phryxus and Helle, and is celebrated in ancient times for the bridge of boats built over it by Xerxes. It is memorable also as the scene of the death of Leander.