The Discovery of Underwater Acoustics: Pre-1800s
Leonardo da Vinci, 1490
Aristotle (384–322 BC) was among the first to note that sound could be heard in water as well as in air. Nearly 2000 years later, Leonardo da Vinci (1452-1519) made the observation quoted above that ships could be heard at great distances underwater. Almost 200 years after da Vinci’s observation, the physical understanding of acoustical process was advancing rapidly with Marin Mersenne and Galileo independently discovering the laws of vibrating strings, which Mersenne published in his work L’Harmonie Universelle in the late 1620’s. Mersenne’s remarks regarding the nature and behavior of sound and his early experimental measurements on the speed of sound in air during the mid to late 1600’s are considered to provide the foundation for acoustics. Several decades later, in 1687, Sir Isaac Newton published the first mathematical theory of how sound travels, in his great work, Philosophiae Naturalis Principia Mathematica. Although Newton focused on sound in air, the same basic mathematical theory applies to sound in water.
In 1743, Abbé J. A. Nollet conducted a series of experiments to settle a dispute about whether sounds could travel through water. With his head underwater, he reported hearing a pistol shot, bell, whistle, and shouts. He also noted that an alarm clock clanging in water could be heard easily by an underwater observer, but not in air, clearly demonstrating sound travels through water.