A general scheme for the derivation of wave solutions in general relativity is developed. Some solutions describing the flow of gravitational waves are discussed. Singular electromagnetic fields corresponding to one particular solution are also discussed.

The flow from a line source to a line sink in a multiply connected region is discussed. It is shown that the transport from source to sink passes through the interior region and the Stewartson layers as well as through the Ekman layers.

The mass transport velocity field is determined for surface waves which propagate from a region with a clean free surface into a region beneath an inextensible surface film. The waves are assumed to be incident normally on the edge of the film. Determination of this velocity field requires the investigation of a mixed boundary value problem for the bi-harmonic equation, the solution of which is obtained using the Wiener–Hopf technique. Streamlines for the mean motion of the fluid particles are thus obtained. It is found that considerable vertical displacement of fluid is possible due to the presence of the surface film.

A uniformly valid asymptotic solution for waves on a shearing current is presented. This solution is more general than the previous WKB solutions because it is valid at and near a caustic. Far from the caustic line, the solution reduces to the WKB solution. It predicts that an incident wave will be reflected from a straight caustic with the same amplitude and a ½π phase shift.

The efficacy of making a careful choice of strain measure in problems of solid mechanics was recognized and fully exploited by Hill(1–4). He brought coherence to fundamental stress and strain analysis by the introduction of the idea of conjugate pairs of stress and strain measures, and provided a platform for the further development of constitutive relations for solid materials.