He constructed a tonometer of 670 tuning forks which ranged in pitch from 16 to 4,096 hertz. In 1876 the acoustic instrument maker Rudolph Koenig expanded the idea of a tonometer from a single octave to the entire range of human hearing. His most advanced design consisted of 56 forks, which together covered the range of a single octave (from A220 to A440) at 4 wavelength intervals. Scheibler constructed many tonometers during his life, and different sets would have different numbers of tuning forks. It was the German silk manufacturer (and acoustic researcher) Johann Scheibler who first suggested this instrument, in 1834, and it was he who built the first one. Maintained in motion by batteries, the resonating forks far exceed the accuracy of conventional mechanical watches.Ī “Tonometer” is a carefully constructed set of tuning forks which were used, by comparison, to determine the pitch of other sounds. One notable exception has been the introduction, around 1960, of tiny quartz tuning forks in high-precision watches. In the 20th century, the development of electronic technologies for measurement and precision timing quickly replaced technologies that employed mechanical tuning forks. Albert Michelson, for example, used light reflected from the vibrating tines of a tuning fork to make his historic measurements of the speed of light. Specialized techniques were developed to use them for measuring different kinds of vibrations, and they were frequently used as high-precision timing standards. By the last decades of the 19th century, tuning forks were among the most precise of all scientific instruments. In the 19th century, advances in manufacturing made it possible to create extremely precise tuning forks, which were made in sets and used as tone generators to identify and measure other sounds.

Strong used his fork as a pitch standard to tune musical instruments, a task for which they are still used today. The invention of the tuning fork is generally credited to the British musician, John Shore, in 1711. Shortening the length of the tines allows them to vibrate faster and thus produce a higher sound. Longer tines vibrate more slowly and thus produce a lower tone. The tone a fork makes is determined primarily by the length of its “tines” (or prongs). When struck it produces several tones – a fundamental and at least one harmonic – but the fork’s shape tends to minimize the harmonics and within a few seconds only the fundamental can be heard. Technically, a tuning fork is an acoustic resonator.

Tuning fork waves