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 Cavaille-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, KDV, Netherlands

Hans van Oost
Kring van Draaiorgelvrienden, Netherlands

[ See the photograph at http://mmd.foxtail.com/Pictures/  -- Robbie