60 equals 1200 seconds which in turn must equal NAt, it follows 
from equation (10.39) that the analysis has approximately five de- 
grees of freedom. 
Table 16 then shows that adjacent peaks can vary by a factor of 
four above the true value and by a factor of one half below the true 
value in a power spectrum determined by these conditions. 
The spectra shown must probably be squared value for value to 
get a shape like a power spectrum, and if this is done the variation 
just described actually occurs. 
The resolution employed is very much greater than is needed, and 
replacement of the galvanometer by a square shouldered band pass cir- 
cuit about five times as wide as the one employed would be the first 
step in obtaining quantitative results from this instrument. This 
would result in twenty-five desrees of freedom and the shape of the 
spectra obtained would be much more regular. High resolution such as 
that employed in the above analyzer would require a record five times 
longer than the one given and very careful design considerations, es- 
pecially with reference to integration time constants, to yield reliable 
results. 
It would also be interesting for the reader to return to the 
Appendix to Part One and study the various spectra shown there in 
the light of these considerations. All the spectra shown, both in 
the Appendix and in the last figure, show important observational and 
theoretical properties of the sea surface, but they are not quanti- 
tative. They must be made quantitative to provide reliable and useful 
numerical results. 
119 
