The number which finally resulted in the above computations is 
an important number for beach erosion problems. The result is 
valuable, but it is still a long way from the data which are actually 
needed. The wave direction is unknown, and the form of the breakers 
and the angle they make with the coast upon breaking cannot be deter- 
mined from one pressure recorder and from the theories presented 
herein. 
What percentage of the wave power moves sand at the beach, what 
percentage might have been surf beat actually flowing outward, what 
percentage is dissipated by friction when the waves finally break, 
and what percentage goes into the kinetic energy of a littoral cur- 
rent (if the waves are at a slight angle to the beach) are all 
questions for future theoretical investigation. 
Wave record analyzers 
Wave record spectrum analyzers have been reported in the liter- 
ature by Barber and Ursell [1948] and Klebba [1946]. Wave record 
autocorrelators have been described by Seiwell [1950a] and Rudnick 
[1951]. The spectrum analyzers yield some function which is supposed 
to be some sort of spectrum of the record. They have no scale for 
the amplitude of the spectrum, and they have not been adequately 
calibrated.” Until the work of Wiener [1949] and Tukey and Hamming 
[1949] there was no way to interpret such analyses and there was 
considerable confusion on how the machines were to be constructed 
and on the design of the electronic circuits needed. 
*As far as is known as of the date of this paper. 
Aro 
