Hooke (1968) developed a formula for the perturbation of electron density in the F2 region of the ionosphere by any spectral component of a gravity wave, the perturbation being manisfested as the corresponding spectral component of a traveling ionospheric disturbance (TID). We have used the phase portion of that formula to obtain the real part of the vertical component of the propagation constant of the causative gravity wave from that of a TID. With this we have compared the amplitude portion of Hooke's formula with the observed TID amplitude. Doing this over a range of height within a particular TID, we find relatively good agreement. It is suggested that further improvement would require using an electron density perturbation formula which takes account of ion diffusion.