Spectrum number three is from a paper by Rudnick [1951].* The 
record was taken offshore from Guam and additional information on 
the record can be found in a paper by Miller [1949]. The spectral 
analysis was made on Klebba's machine. If again the dash and dash-dot 
curves can be interpreted as before, this record strongly suggests 
the simultaneous presence of a local "sea" and a "swell" from a dis- 
tance. The contribution from the "swell" rises significantly above 
the level of the "sea" record at the same frequencies. As would be 
expected the correlogram of the record is quite irregular, and it would 
be difficult to detect the simultaneous sea and swell conditions on 
the basis of it alone. 
The three small spectra on the lower right were taken from the 
paper by Barber and Ursell [1948]. They were made at Pendeen England 
on 14 March 1945 at 2100 and on 15 March 1945 at 1700 and 1900. The 
third spectrum is from swell and the first two spectra are from the 
same storm after it had moved closer to the coast of England and 
intensified. 
According to Barber and Ursell, the analyzer responds only to 
certain frequencies which have an integral number of cycles around 
the wheel on which the record is placed. Barber and Ursell [1948] 
make the following statement: 
"The record is fastened around the circumference of a wheel 
which rotates about a horizontal axis carrying the record past 
an optical system which throws the record a horizontal line 
of light. The reflected light illuminates light-sensitive 
cells whose electrical output is, therefore, a continued repe- 
tition of the curve on the record. This electrical output is 
*In this very interesting paper, Rudnick reports that wave records 
are Gaussian. This important discovery was thus first published 
by him in 1951. His paper was not known to the author when Part 
One was published. 
117 
