Having read the very interesting postings about frequency meters in 991217 MMDigest I could not resist posting a picture of a device that may have been the first frequency meter ever made.
It is a tiny instrument based on the principle of a siren. It was designed in the 19th century by a Frenchman, Mr. Cagnard-Latour, and probably built by organ maker Claude Gavioli. The siren is equipped with two small indicator faces with hands, like a meter for measuring water or gas consumption.
The siren was tuned to a pipe by throttling the sirens wind supply, and when it sounded in tune with the pipe the frequency could be established by counting the speed with which the hands of the two indicators were turning around.
Primitive as it would seem, it was used by the famous French organ builder Cavaillé-Coll for his experiments. Afterwards it was returned to the Gaviolis, and now the little machine is part of the collection of the Utrecht museum "van Speelklok tot Pierement".
Hans van Oost
Kring van Draaiorgelvrienden, Netherlands
Sat, 18 Dec 1999 21:48:13 +0100