If a wind stress is suddenly imposed on an ocean at rest, inertial oscillations are produced according to the traditional f-plane solution. However, if the inertial period varies with latitude, this is true only for a short time, and the solution is strongly modified after only five periods or so because of 'β dispersion.' Some comparisons between f-plane and β-plane solutions are made to illustrate the effect. In particular, the way in which energy can move latitudinally, in the latter case, away from the region in which it is produced by the wind is illustrated. The main features of the β-plane results can be explained using WKB ray-tracing techniques. Although the model is very simple, it is not inconsistent with the internal wave experiment spectrum, which shows low-frequency energy propagating toward the southeast. It is suggested that this directionality in the spectrum at low frequencies may be associated with β dispersion.