The ocean is transparent to sound where slight irregularities within the ocean cause sound fluctuations, and thus set limits on the many uses of sound in the ocean, similar to the limits imposed by the atmosphere on ground-based telescopes. This 1979 book attempts to connect the known structure of the ocean volume with experimental results in long-range sound transmission. Theories of wave propagation through irregular media, developed for optical and radio wave transmission are found to be inapplicable in many respects due to the complications of ocean structure, particularly the combination of anisotropy and 'sound channel'. The authors extend wave propagation theory to account for the ocean complications and introduces the path-integral approach to the solution of the strong-scattering regime that solves many long-standing problems. The book is written at the post-graduate level, but has been carefully organised to give experimenters a grasp of important results without undue mathematics.

This book gives an account of certain observed irregularities on the rotation of the Earth, both in its rate of rotation (giving a variable length of day) and in the position of its axis. These irregularities are caused by events on and within the Earth and provide a means of studying a number of geophysical problems. Seasonal shifts in air masses and variable winds are causes of short-period fluctuations in the rotation. Climatic changes and their attendant sea levels are in part responsible for long-term fluctuations. Modern observations of the Moon and descriptions of ancient elipses both establish a secular increase in the length of day. The interpretation involves atmospheric, oceanic and bodily tides. The book provides a unified treatment of the rotation of the Earth, making this method of studying geophysical phenomena more readily accessible to geophysicists and others.