Marc, I have a reference section on movements included in the book "Omega: A Journey Through Time", or AJTT as it is referred to here.
I usually will use the movement serial number to establish a time period and then reference AJTT for identification.
I can't stress enough how valuable that book has been to me.
It is currently out of print, but I believe Darren
@DLT222 has a copy or two for sale.
It isn't cheap but mine has paid for itself several times over.
Some movements have an identifying inscription (usually buried under the balance bridge or deviously hidden somewhere) and some of the old movements are referred to by ligne number, which is an old French method of measurement.
http://en.wikipedia.org/wiki/Ligne
.
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