The New Student's Reference Work/Forth

Forth, a river and firth of Scotland. The river is formed by two head-streams, the Duchray and the Dhu, rising within a mile of Aberfoyle and not far from Ben Lomond. The Firth of Forth extends 51 miles eastward from Alloa to the German Ocean. Its waters are from three to thirty-seven fathoms deep. In 1882-89 a great railway bridge was built across the firth at Queens-ferry, being one and a quarter miles in length.