The Euphrates is navigable from Sumeisat (the ancient Samosata), 1200 miles above its embouchure; and even 180 miles higher up, is a river "of imposing appearance," 120 yards wide and very deep.

The Tigris is often 250 yards wide at Diarbekr, which is not a hundred miles from its source, and is navigable in the flood time from the bridge of Diarbekr to Mosul, from which place it is descended at all seasons to Baghdad, and thence to the sea.

Its average width below Mosul is 200 yards, with a depth which allows the ascent of light steamers, unless when there is an artificial obstruction.

Above Mosul the width rarely exceeds 150 yards, and the depth is not more in places than three or four feet.

The Euphrates is 250 yards wide at Balbi, and averages 350 yards from its junction with the Khabour to Hit: its depth is commonly from fifteen to twenty feet.