When Sonar was Called Submarine Signalling

Abstract

In the decade preceding the conclusion of World War II, sonar advanced from an empirical art to a rational science. This important branch of applied acoustics was isolated from its brothers by a strong wall of security. That wall has been penetrated occasionally in the later years, but the section built before 1946 has only recently been removed by U. S. Department of Defense Directive 5200.9. Now that we are free to do so, it is amusing, and perhaps instructive, to recall the early developments of modern sonar, and the framework of comparative ignorance in which they were achieved. This historical review exemplifies the vital role of measurements in any technological advance.