Koenig’s flame analyzer was, next to the Koenig sound synthesizer, one of the clearest expressions of Hermann von Helmholtz’s theory that complex sounds were made up of a Fourier spectrum of elemental or pure tones. It was also part of a drive to visualize sound in the 1860s. This was the first form of sound analyzer developed by Koenig around 1865. It was based on the fundamental ut2 (lower c on the piano), with seven other harmonics for demonstrating timbre in this limited range. The resonators covered a range from UT2 to Ut5 (128 to 1024 Hz), could each be rendered visible with a connection to a manometric flame capsule. The resonators connected to a gas-filled capsule with a rubber tube. If activated, the distinctive pattern would appear in the 4-sided rotating mirror. A human voice, for example, would activate a series of capsules revealing its rich harmonic structure. A tuning fork, representing a pure, elemental tone, would only activate one resonator and capsule. For his vowel studies between 1965 and 1872, Koenig invented an analyzer with adjustable resonators that could cover range of 65 notes.

Provenance details:

This analyzer was part of the earliest days of physics teaching at Western University in London, Ontario (1920s). In the late nineteenth century, Canadian scientists such as J.C. McLennan worked at his teaching laboratory in Canada in the 1870s and 80s, which was emulated at other schools such as Queen’s, Western and McGill. This particular apparatus probably came from Toronto having been obtained c. 1920 by Raymond Compton Dearle, who had done a PHD at the University of Toronto under J.C. McLennan.

The French connection is also significant. In the late nineteenth century, every college and university in Canada and the United States bought instruments from Paris. Scientists deemed them an essential part of early research and teaching. In the early 1870s, shortly after arriving in Boston, Alexander Bell used the Koenig instruments at MIT for his research on visible speech. He was particularly impressed with the manometric flame instruments and went out of his way to meet Koenig at the 1876 Exhibition in Philadelphia.

See also:
Koenig’s 1889 catalogue (nos. 242a)
https://www.sil.si.edu/DigitalCollections/trade-literature/scientific-instruments/files/51736/