[78-L] VTMC Strobe Disc

[Michael Biel]

During the discussions about how 78.26 rpm was chosen, I have debunked
the unsupportable idea that it was the result of a gear-ratio
calculation because all turntables at that time had continuously
variable speed governors.  The answer was, of course, the strobe disc. 
During a discussion I was asked once whether I had PROOF that Victor
Talking Machine Co. used a strobe disc, and I said that I had once seen
one and that Dennis Valente's company sold a reproduction of the strobe
side of the disc.

Well, now through the kind auspices of Tim Fabrizio, I have a Victor
Talking Machine Co. "60 Cycle Stroboscope Disc for testing speed of
talking machine turntables".  The speed it mentions in the instructions
is 78 revolutions, not 78.26, but a 78.00 strobe disc is impossible with
60 cycle lighting. 78 was always the simplified speed cited, never
78.00.  It is Part 18436, and it would be great if it would be possible
to place this part number in the chronology of Victor parts manufacture
to date it.  It is obvious that it is pre-RCA, so it is prior to 1929
but could be much earlier.

I have scanned both sides of the disc, and if you wish it to print for
yourself, contact me off-list.  I would also like to post it on a
graphics site as well.  

Mike Biel  mbiel at mbiel.com