| The instrument at the right, which I discovered in a basement
laboratory at Duke University, is clearly based on the design of the concertina.
Normally the box is closed, and one sees a series of pulls labelled 128,
132, 136, ...., 248, 252, 256. These are the frequencies (in Hz) of the
reeds visible in the lower picture with the box opened. The upper half
of the box contains bellows, actuated by moving its top up and down.
The spacing of the frequencies in steps of 4 Hz is very suggestive
of Koenig's tonometer.
Once reeds have been adjusted to the right frequency, they are quite stable
and do not drift in frequency. Therefore, I think that this is a frequency
standard, and that it was made after 1876, when Rudolph Koenig brought
his tonometer to the United States to display at the 1876 Centennial Exposition
in Philadelphia.
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