For the total energy per un:it width along a wave length it is 

 necessary to multiply the energy per lonlt area by the wave length. 



Waves of Very Small Height 



By waves of very small height are understood waves for 

 which the ratio of height to length is l/lOO or less. The 

 simnlest v/ave theory deals with such waves, the form of which 

 can be represented by a sine curve (see fig. 3). In water of 

 constant depth, d_, such waves travel with the velocity 



V ^2^ 



C = /g ^li_ tanh 2tt1 



where _g is the acceleration due to gravity. 



If d/L is large , that is, if the wave length is small com - 

 pared to the depth , tanh 2TTd/L approaches unity and one obtains 



These waves are called deep-water xvaves, 



''^'^ 



If d/L is small , that is, if the wave length is large com - 

 pared to the depth , tanh 2Trd/L approaches 2 7Td/L and one obtains 



These waves are called shallow-water waves. 



In general, waves have the character of deep-water waves when 

 the depth to the bottom is greater than one half the wave length 

 (d>L/2). However, for shallow-water v/aves the depth must be less 

 than one twenty-fifth of the wave length (d<L/25) . 



