[GreenKeys] Tone frequency history?

[Jim Haynes]

The Hammond electronic organ generated all its frequencies with a machine
that spun wheels at the right speeds, the wheels having lobes that 
generated the tones electromagnetically.  Western Union had a carrier
telegraph system that use a tone generator made for them by Hammond
that generated all the necessary frequencies.  Someone pointed out that
the Hammond generator could not generate the exact frequencies needed
for the tempered musical scale because you can't make gears with a
non-integral number of teeth.  In the tempered scale the frequencies of
two adjacent notes differ by a ratio of the twelfth root of 2, so that
the frequency doubles over the 12 notes that make up an octave.

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 	"Ya can argue all ya wanna, but it's dif'rent than it was."
 	"No it ain't! No it ain't!  But ya gotta know the territory."
 		Meredith Willson, The Music Man