Johann Scheibler (1777-1837)
Johann Scheibler was a wealthy industrialist specializing in textile manufacture, but he also had strong amateur interests in science and music. Amazingly he found time during the 1830s to prove that the average concert A of Viennese concert pianos was 440Hz and also to develop a method for tuning pianos in equal temperament with unprecedented accuracy. In both endeavors he deployed his invention, the tuning fork tonometer, which comprised 56 precision engineered tuning forks. In 1834 the German academy of sciences endorsed Scheibler's pitch (the so-called Stuttgart pitch) as the German national standard, but it took until 1926 for this standard to become global.
Jules Antoine Lissajous (1822-1880)
The middle of the 19th century witnessed an international race towards scientific and technical standardization. In France, after receiving news of Scheibler's achievement, the government set up a commission to establish a French standard pitch. This group of experts included the scientist Jules Lissajous (1822-1880) who, with the committee's approval, created a standard tuning fork at 335Hz. In the process he invented an optical method for calibrating tuning forks using so-called Lissajous figures (see photo), which proved to be of great utility in many other fields (such as in the calibration of television transmission in the 20th century).
Herman von Helmholtz (1821-1894)
Herman von Helmholtz was one of the finest scientists of the 19th century and his decisive contribution to the science of sound was but a fraction of his entire output. Amongst his many other achievements in acoustics Helmholtz performed some ingenious experiments using tuning fork-based instruments. Most notably he invented the world's first sound synthesizer in a bid to demonstrate his theory about the complex nature of speech and musical sounds.
Rudolph Koenig (1832-1901)
The Parisian scientific instrument maker Rudolph Koenig did a great deal to bring experimental acoustics into the mainstream of physics. Originally he trained as a violin maker under Jean Baptise Vuillaume (1798-1875), but later devoted his life to building instruments for the study of acoustics. He perfected the tuning fork and built instruments designed by Helmholtz and others, as well as inventing his own. The Whipple Museum has a number of instruments built by Koenig.