In the summer of 2002, while researching the writing of Milestones of Hydrology. I noticed that Ven Te Chow had mentioned the Froude number in his popular textbook, 1 but had not elaborated on its origins. The Froude number, a fundamental principle of open-channel hydraulics, is defined as the ratio of the mean velocity (Manning or Chezy) to the relative celerity of small surface perturbations, i.e., the relative Lagrange celerity.

In an effort to tell the story accurately, I consulted several books on Froude and, to my surprise, learned that he had not developed the Froude number. Furthermore, Froude's major work, published in 1871, had dealt not with open-channel hydraulics, but with ship stability and hydrodynamics.

Froude's contributions to society, however, were of such importance that he was highly regarded by his peers and followers. After his death, to honor his memory, they attributed to him the concept which now bears his name. Thus, the moral of the story is: A great man's glory is controlled less by his own actions than by those of his followers.

 1 Chow, V. T. (1959). "Open-channel hydraulics," McGraw-Hill, New York.

Ski-jump spillway at Tocantins dam, Para, Brazil

Ski-jump spillway at Tocantins dam, Para, Brazil.