Caruso's Turntable

Greetings:  Richard Simonton's contribution regarding turntable
speed was one of the most informative so far.  I was intrigued by
this comment (and Robbie's follow-up about Victor recording turntables):

> The 78 RPM speed (actually 78.26) apparently derived earlier from
> the use of non-synchronous disc lathe motors in the days before
> electrical recording...

In my collection, I have a recording of Caruso singing "Il Fior che
avevi a me tu dato" from Carmen.  The recording date was 7 November
1909.  My copy is a late 1920s HMV (U.K) pressing, which I had assumed
was pressed from an original master (abbreviated "POM").  Listening
carefully one evening, I detected an unmistakable 60 Hz hum on the
recording.  Nuts!  It couldn't be POM, must be a transfer.

A collector friend of mine had the same performance on an original
edition disc, which also had the hum!  I carefully auditioned several
other Victor recordings from 1908-10, all recorded in New York, all
POM, and _all_ had 60-cycle (or thereabouts) hum in the grooves.

My uneducated presumption is that the electric drive motor on the
recording turntable mechanically transmitted 60 Hz noise to the master
disc, cutter head, or both.  I have not detected similar hum on Victor
acoustics from other periods.

Caruso recorded two performances of the Flower Song from Carmen on that
November day, once in French, and once in Italian.  I have POM copies
of each.  Curiously enough, they are different in pitch by at least 25%
of a semi-tone.  Another conundrum...

Cheers

Doug Rhodes