"Ian Iveson" writes in
onder.co.uk:
RdM wrote

Hence my wondering whether the auction was of a similiar experiment
in high
speed recording; I have never otherwise heard of a "vinyl" 78rpm,

snip

Hi Ross

From Wikepedia:

"In the mid-40's, special DJ copies of records started being made of
vinyl also, for the same reason. These were all 78 RPM. During and
after World War II when shellac supplies were extremely limited, some
78 rpm records were pressed in vinyl instead of shellac (wax),
particularly the six-minute 12" (30 cm) 78 rpm records produced by
V-Disc for distribution to US troops in World War II. In the 40's,
radio transcriptions, which were usually on 16 inch records, but
sometimes 12 inch, were always made of vinyl, on 78 RPM."

Yikes! I often - usually - do a search but it didn't occur to me to just type
"vinyl 78rpm" into Google this time. I see I was thinking of old films when I
typed "acetate" too, although I'm doubtful about the "wax" after shellac.
Perhaps the author was thinking of the original wax masters.

In any case, it would appear that the vinyl 78's were designed to be played
back with a "normal" cartridge sporting a 78 stylus; there are cartridges
that will accept both LP & 78 styli, albeit at a higher tracking force for 78.

A little further down the results page shows www.historicmasters.org
re-pressing 78's onto vinyl from the original metal masters - at a price!

cheers, Ian

Regards;- Ross