equation (12.40). After multiplication of the deep water power 
spectrum by the spectrum amplification function, (12.32), the sub- 
sequent change of variables does not affect the potential energy 
of the waves at the point of observation. Nevertheless the potential 
energy at the point in the transition zone may be completely dif- 
ferent from the potential energy in deep water since the spectrum 
amplification function in general does not leave the total volume 
under [Ao*(p ,On*) 1° unaltered. 
The spectrum amplification function can change markedly upon 
the choice of different points, C, in the transition zone. In the 
short distance of thirty miles along the coast of New Jersey, it 
can vary tremendously. Consequently not only will the wave height 
vary over a distance in the transition zone which is very short com- 
pared to the deep water forecast parameters but also the "signifi- 
cant" period will vary from place to place. These points will be 
verified by examples in a later chapter. 
The wave record at the point of observation 
The wave record which will be observed by, say, a step resist- 
ance guage at the point Xp = 0, Yn = O is given by equation (12.41) 
where [Apy(# )]° is the integral over 6p of [Appu(# ,0,)]*. This 
function has all of the properties of the one described in Chapter 
7 and it can be derived from equation (12.37) by the exact same 
arguments given in Chapter 10 for the deep water case. In Chapter 
7, a wave record in the transition zone was shown to have the pro- 
perty that points chosen at random from it were normally distributed. 
The definition of the integral given in equation (7.1) and in sub- 
sequent equations can just as easily be applied to equation (12.41) 
ie} 
