A spectrum of oscillations covering a wide range of wave numbers is specified for a homogeneous fluid in a finite volume. Considering the range dominated by gravity and low wave number acoustic modes, a correspondence is established between the latter and a certain field associated with the former. It is shown that these two forms of oscillations are governed by the Helmholtz equation, with gravity modes as the driving source. This equation is solved by Green's function methods and a point source solution is derived from which the eigensolutions can be constructed.