Hello one and all,  I'm new to the Mechanical Music Digest, having
just discovered its existence a few days ago.  I don't know most of
the technical terms associated with mechanical music machines, so
please bear with me.

My family has three musical machines: a double-comb Regina table-top
music box that plays disks, a single-comb Regina table-top music box
that also plays disks, and a nifty Concert Roller Organ that plays
wooden cylinders.  We have 15 cylinders for the Roller Organ and 65
disks for the Reginas.  All had been owned by my grandfather and are
much loved by the entire family.

I have a question about the music box disks.  I find that they are
made of several different materials about which I know nothing but I am
curious to find out.  The majority of the disks we have are relatively
shiny silver metal.  Four or five of the disks are the same color as a
shiny copper penny, but I can't believe they are copper or they would
have tarnished by now, right?

One or two of the disks are heavy dull gray metal.  I can't even
imagine what _those_ are made of.  Can anyone provide an answer about
metals used in making these three types of disks, and perhaps even
their age based on the materials used?  I'd be much obliged!

Also, I find that there is one disk in particular that will _not_
play on either of the Reginas.  Has anyone else run into that problem?
The disk is not damaged in any way that I can determine from a visual
inspection.

I'm looking forward to participating, in my own small way, in this
fascinating forum.  Thank you for all the wonderful information each of
you has provided over the years; I've learned so much from "thumbing
through" the MMD Archives in the last several days.

Most sincerely,

Diane H Kay