well defined band width, and the waves must have come from a distant 
source. Local chop below periods of 6 seconds would be undetectable. 
This second spectrum as shown on the upper right of figure 44 
is the electronically analyzed spectrum of the classical wave record 
53-X. The electronic analysis was first given by Klebba [1949], 
Seiwell [1949b] gave the same electronic analysis and stated that 
the analysis “does not permit a reliable interpretation of the physi- 
cal properties" [of the record]. 
Seiwell [1949b] then proceeded to interpret the record in terms 
of a cyclic component of 12.25 seconds and a superimposed series of 
random fluctuations. His results were debated by Deacon [1951] at 
the National Bureau of Standards Symposium on Gravity Waves. 
Tukey and Hamming analyzed Seiwell's autocorrelation data and 
the results of the analysis were quoted a few pages back. The power 
spectrum analysis of the autocorrelation data from record 53-X is 
given in figure 41. The quotation from Tukey and Hamming and the 
theoretical results contained in this paper effectively refute the 
claim of a cyclic component. 
Tukey and Hamming were limited at the very start by inadequate 
data since the original record was too short, the lags were too close 
together, and there were not enough lags. Their results consequently 
yielded a spectrum which has practically no resolution over the band 
of frequencies of importance. From their analysis and from figure 
44, it is not too difficult to see how Seiwell might have reached his 
erroneous conclusions since the swell did have a rather narrow band 
width. However, the important point is that the electronic analysis 
in this particular case, when properly interpreted, yields the most 
nearly correct qualitative spectrum. 
116 
