Electronic techniques in oceanography

General factors governing the design of electronic equipment for oceanographic use, and the design of housings for withstanding high pressures are discussed briefly. Underwater acoustics is discussed in some detail. Electromagnetic waves do not travel far underwater, and acoustic waves are therefore used for many of the purposes for which electromagnetic waves are used in the atmosphere: echo-ranging and detection, telemetering, etc. Finally, two wave recorders are described: a shipborne wave recorder, and an f.m. pressure gauge which has a resolution of 1 part in 106 of full scale and which is suitable for digital recording and analysis.