by a depth equal to that of the average depth of the ocean is 
very small. Note that this is not the case in the Cauchy-Poisson 
problem where the spectrum is a white noise spectrun. 
The wave length of a sinusoidal wave when surface tension is 
considered, is greater than the values employed here if the per- 
iod is very small. For the range of the parameters considered 
this effect is very small. Again this is not the case in the 
Cauchy-Poisson problem. 
The effect of internal viscosity has been shown to be negli- 
gible by Sverdrup and Munk [1947] for the dominant spectral com- 
ponents employed although Johnson [1949] has shown that it is 
important for very short period waves. Internal viscosity would 
not be important until the group had traveled a distance equi- 
valent to several times around the earth. * 
The action of the air against the traveling wave group or 
of some type of internal eddy viscosity in the motion is possibly 
an important effect which could modify its actual travel. For 
the present, there will be no speculation about the modification 
of the solution obtained in this section by these mechanisms. 
*See Lamb [1932], sec. 348 equation (9). For the ten second 
spectral component, traveling with the grouv velocity of a 
ten second wave, the distance the zroup would travel before 
dying down to the 1fe of its former height due to molecular 
viscosity would be of the order of 10° kilometers. 
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