One of these dykes, which produces an artificial cascade or cataract, is described by Tavernier (part i. 1. ii. p. 226) and Thevenot (part ii. 1. i. p. 193). The Persians, or Assyrians, laboured to interrupt the navigation of the river (Strabo, 1. xvi. p. 1075 [p. 740]. D'Anville, l'Euphrate et le Tigre, p. 98, 99).