Hi ,
I am pretty sure that copies of the Glass Cone are available to non members at a small cost , they were available to buy at the recent Cambridge Glass Fair,
btw , Lynn glass , with the rings are 18thc , not 17th , c 1740 ish to 1800 ish,although there is still some doubt if Kings lynn was actually the place of manufacture of these very individual glasses,there being no solid archaeological evidence available.
Cheers ,
Peter.