The Origin of Manning's Formula

The formula for the resistance to the flow of water in open channels that Manning recommended in his address to the Institute of Civil Engineers of Ireland on December 4, 1889, is entirely different from the one, bearing his name, so widely used today. This situation has attracted the attention of a number of hydraulic engineers, and led to articles on the subject by at least seven different authors, from Chow in 1955 to the writer in 1962. It is only recently (1967) that information has come to light which seems to complete the curious history.