of the River Mersey were conducted by Osborne Reynolds in England. In 

 these tests, sand was used as the bed material and the time element was 

 first considered. A linear-scale distortion factor of 33 was used. The 

 work of Reynolds was continued by L.F. Vemon-Har court (Gibson, 1936; 

 Rouse and Ince, 1957; Ippen, 1970), who used bed materials of sand and 

 lighter weight sediments such as charcoal and pumice. Vemon-Harcourt 

 expressed his thoughts on the basis for trusting the results of movable- 

 bed scale models as follows: 



"If I can succeed in demonstrating with the model that the 

 originally existing conditions can be reproduced typically; and 

 if, moreover, by placing regulating works in the model, the same 

 changes can be reproduced that were brought about by the training 

 works actually built, then I am sure that I can take the third 

 most important step, namely, of investigating, with every promise 

 of success, the probable effect of the projects that have been 

 proposed. ..." 



This principle of movable-bed model verification has since been proven 

 very reliable, although as yet there has been no rigorous proof of its suf- 

 ficiency. This is in contrast to the excellent derivations showing the 

 accuracy that can be obtained on fixed-bed models in which the phenomena 

 studied involve only two major forces, and where adequate equations are 

 known for the remaining, secondary forces. Most hydraulic and coastal 

 engineering problems fall within this category. 



The first hydraulic laboratory designed for experimental work on 

 movable-bed models began operating in 1898 in Dresden, Germany, under 

 the direction of Hubert Engels (Reynolds, 1929). The first hydraulic 

 laboratory at an American engineering school was founded at Lehigh Uni- 

 versity in 1887 by Mansfield Merrimen (Rouse and Ince, 1957). The Miami 

 Conservancy District, Ohio, constructed test facilities in 1915 to study 

 the hydraulic jump and the design of stilling basins. The hydraulic lab- 

 oratory of the University of Iowa was founded in 1918 (Rouse and Ince, 

 1957). At the insistence of John R. Freeman, a notable American hydrau- 

 lic engineer, who was impressed with the work of German hydraulic labora- 

 tories in the early twenties, a bill was passed in Congress that authorized 

 construction of a hydraulic laboratory in the United States. As a result 

 of this, and because of the magnitude and difficulty of the flood-control 

 problems caused by the 1927 flood on the Mississippi River, the U.S. Army 

 Engineer Waterways Experiment Station (WES) was founded in Vicksburg, Mis- 

 sissippi, in 1929 (Tiffany, 1968), Since then the WES has grown from a 

 small hydraulic laboratory with an annual dollar work volume near $50,000 

 and about a dozen civilian employees to a large, diverse engineering lab- 

 oratory of the U.S. Army, Corps of Engineers with an annual work program 

 of about $50 million in FY 1976 and more than 1,400 civilian employees. 



The conduct of hydraulic scale models was the primary mission of WES 

 at the outset and for several years thereafter. At present the Hydrau- 

 lics Laboratory of WES conducts both hydraulic research and hydraulic 



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