Langevin Develops Active Sonar for Submarine Detection and Fathometry (Great Events from History II: Science and Technology Series)
Article abstract: Langevin developed the first active ultrasonic underwater sonar transducer for detecting reflected sound from submerged objects and the seafloor.
Summary of Event
The concept of detecting submerged objects using acoustic waves impinging on and reflected from an underwater vessel has been argued as inherent in any detailed understanding of acoustic wave propagation in the ocean, sound velocity in liquids, viscous frictional damping of underwater sound, and sound radiation and diffraction patterns. Sir Isaac Newton’s Philosophiae Naturalis Principia Mathematica (1687) gives a formula for approximately calculating the depth of a water well from the elapsed time for a falling stone to be heard striking the water. Following the experiments by French physicists Daniel Colladon and Charles-François Sturm on Lake Geneva in 1826, employing submerged bells to measure acoustic sound velocity in water, the French astronomer François Arago proposed that it would be possible also to find the depth of a lake or ocean location by noting the round-trip travel time for a strong acoustic impulse to be reflected or echoed from the bottom. This suggestion apparently was tested first by the U.S. Navy in 1838, a study that confirmed the greater velocity, clarity, and constancy of a bell signaling underwater as compared with air. Later experiments in 1841 showed that whereas the acoustic self-noise from the...
(The entire section is 2094 words.)
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