Synopses & Reviews
Synopsis
Excerpt from The Harmonic Formula of Fourier and Bessel and Its Application to the Study of the Diurnal Variation, of the Atmospheric Pressure in Manila During the Period 1890-1909
The greater number of the phenomena studied in meteorology are periodic, and the curves which represent them are consequently periodic curves - that is to say, curves which represent the movement of a point 'which passes an indefinite number of times over the same path in the same time.
Fourier proved that any periodic curve could be resolved into a series of harmonic curves of periods 1, is, a, etc., of the given curve, and that only one combination of these elementary curves was possible to reproduce a specified curve. This corresponds with the fact observed by Helmholtz that the same composite sound is always resolved into the same elementary sounds.
Prescinding for the moment from the practical utility which this resolution of curves may have in meteorology, let us examine how the formula which we are study ing is nothing more than the analytical expression of periodic curves in terms of their harmonic components.
A harmonic curve is one Which represents graphically the harmonic motion of a point.
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