under the curve would be computed with proper regard for positive 
and negative areas. A similar computation with sin 2rt/T would 
pe carried out. Then by proper correction factors and by ele- 
mentary computations, the amplitude and phase of the first har- 
monic could be found. 
If this were done for an actual wave record, or for the one 
sketched, the amplitude of the first harmonic would undoubtedly 
come out to be negligible. Infact if tT were, say, one hundred 
seconds, in most records, the amplitude of the harmonic components 
would not become appreciable until n were equal to five or six. 
It would become a maximum with n about twelve (if the signifi- 
cant period was near eight seconds) and die out again as n 
became higher than 25 or 30. 
Such a computation would’ be extremely tedious. But it would 
emphasize the fact that the areas of low wave height are essent- 
ially caused by the phase cancellation of a great many sinusoidal 
waves of low amplitude and the fact that the areas of high wave 
height are essentially caused by the phase reinforcement of the 
Same sinusoidal waves of low amplitude. 
The representation thus obtained would be a true representa- 
tion of the one wave group studied. However, if the representation 
for the actual wave record were compared to the actual wave record, 
it would only match up for the one wave group chosen. It would 
not match the followinz or preceding wave groups because they are 
not exact duplicates of the chosen wave group. The other wave 
groups would vary in amplitude and phase, they would not occur at 
regularly spaced time intervals, and they might possibly have a 
different apparent overiod and/or frequency spectrum. Also 
= 30) 
