Encyclopædia Britannica, Ninth Edition/Tigris
After the junction of the eastern and western branches (see the accompanying map) the river pursues a winding course, generally south-east, for about 800 miles, via Mosul and Baghdad, to the point of union with the Euphrates at Kurna, whence it becomes known as the Shattu 'l-Arab, and falls into the sea some 70 miles farther down. Between Mosul and Baghdad the Tigris receives from its left the Great and the Little Zab and other tributaries from the Kurdish Mountains. Below the confluence of the latter it is joined by the Diyála, also from the left, while on the right canals and watercourses connect it more or less directly with the Euphrates, which in the vicinity of Baghdad it approaches to within 30 or 35 miles. The Tigris is navigable for light freight-bearing steamers up to Baghdad, and for vessels of lighter draught to 20 miles below Mosul, but thence to Diarbekr only for rafts. "But owing to the rapidity of the current the traffic is all down stream, carried on mainly by a primitive style of craft, which is broken up at Baghdad and transported by camels back to Mosul. The journey between these points occupies three or four days during the floods and from twelve to fourteen at other times."
- The Tigris is the Hiddekel of the Bible, the Diklat or Idiklat of the cuneiform monuments. The old Persian form Tigrâ ("swift as an arrow"), whence Tigris, seems to be connected etymologically with these names. The modern Arabic name is Dijla (Aramaic Deḳlath, Dīglā).