Protection for underwater instruments

Waterproof cases for instruments, especially cameras, electronic flash lamps, and sonar drivers, are considered for external pressures up to 20,000 psi (pounds per square inch) which is adequate for the greatest known depths in the sea. Equations, charts, and experimentally determined values of failure are given for cylinders, end caps, and windows of various materials. Several types of pressure-resisting electric connections are shown and a pressure-testing facility is described.