20 ANNUAL OF SCIENTIFIC DISCOVERY. 



vessel, not behind the vessel, nor on each side of it, with far greater 

 velocity than that of the vessel itself. After having made experiments on 

 a small scale, the author took vessels on a large scale, had them dragged by 

 horses, and in other ways, through the water, and l>y positive observations 

 and measurement found that this was really what became of the water dis- 

 placed by the bow of the boat. On one occasion he drew so large a number 

 of boats along a canal in one direction, on a certain day, that the waves 

 carried a great part of the water from one end of the canal to the other, and 

 in the evening the water in the canal was found raised eighteen inches at 

 one end, and depressed to the same extent at the other. The velocity with 

 which the travelling wave moved was found to depend entirely on the depth 

 of the water. 



At 3 feet deep the wave travels 6 miles an hour 



U Cj U U U g U (I 



(C 7 U U U JO CC 



:. j ( -| U U U J2 " *' 



" 15 " " " 15 " " 



20 " " u 18 " " 



" 30 " " " 20 " " 



" 40 " " " 25 " " 



" 50 " " " 30 " " 



In addition to a constant velocity, this wave has a constant shape, a 

 drawing of which was exhibited by the author. And a most extraordinary 

 circumstance was, that its form corresponded exactly with the form of bow 

 which he had previously, and from altogether different considerations, con- 

 structed as the form of least resistance. Moreover, he found that what he 

 had endeavored to do in constructing that form, viz., move the particles of 

 water gradually out of the way, from one position of rest to another, the 

 travelling wave also did ; for on closely observing the water in the experi- 

 mental trough under the action of such a wave, he observed that it lifted 

 every particle of water over which it passed out of one place forward into 

 another place, and there left it perfectly at rest. In the travelling wave, 

 therefore, as in ordinary waves, the particles of water composing it were 

 continually being replaced by others, while the wave itself advanced without 

 apparent change. The foregoing facts convinced the author that the form 

 of bow which he had adopted, and which has since been called the " wave 

 form," was analogous and conformable to the nature of water and of wave 

 motion. 



Like many others, the author at first thought that the stern of a vessel 

 ought to be of the same form as the bow; but thought it proper to under- 

 take a series of experiments, with the view of ascertaining what happened 

 when a hole in the water had to be filled up. Where did the water that 

 filled it come from? and how did it come? He first found that the hollow 

 made in the water had no tendency to travel with an independent velocity 

 of its own, but moved just as fast, and only as fast, as the body which pro- 

 duced it. He then discovered that the currents of water rushing into such 

 a hollow, from different directions, met, and produced a wave, which he 

 called the " following wave," or the "refilling" or "replacing wave," and 

 which always moved with the velocity of the ship, and had nothing to do 

 with the depth of the water. The " following wave" also repeated itself in 

 an endless series astern of the vessel. The author explained that the nature 

 of this wave required that the stern of the ship should be formed of cycloidal 

 curves, and showed how this fact was applied in actual construction. 



