andrew wrote:
Whilst clearing out the loft at my mother's old house I have come across
some records. These were made in America in 1942 by her brother who was
training as RAF bomber crew. He died shortly after.

I think they are directly scribed into the plastic which is in poor nick,
possibly some mould growth. The discs are "Zenith Universal Recorder" and
probably done in some sort of booth.

I shall try and record them directly to wav files but before I attempt that
what precautions need I take? I have a problem in that my record deck only
has 33 and 45 rpm. Was mono 78 simply an amplitude modulation by depth of
the needle?

Think its lateral.

And a fairly big needle

You CAN get compatible needles to plug into standard cartridiges, and
there are still decks around that do 78.

AJH