84 ' A, M. Mayer—Reseurches in Acoustics. 
We have seen that the harmonic curve is the curve which 
corresponds to the motion which causes the sensation of a sim- 
ple sound, but a molecule of vibrating air or a point on the 
reference to the curves projected by such motions; for he has 
shown that only one series of sinusoidal resolution is possible. 
Fourier’s theorem can be expressed as follows: The con- 
stants O, O,, C,, &., and a,,@,, &e., can be determined so that 
a period of the curve can be defined by the following equation hs 
. (27x : 27x ; 
y=C+C, sin (= +a,)+C, sin(2 $ag)}4.--: 
But Fourier’s theorem is the statement of a mathematical 
possibility, and it does not necessarily follow that it can be 1m- 
decomposition of crac forms, such as the the- 
of expression of this theorem, as well as 
for a demonstration of it, see pp. 52 and 60 of Donkin’s Acoustics—the most ad- 
irabl vay itton on the uiaihamalibel Cadody of pound 
