I agree 1886 is quiet early...... But I'm afraid this is all there is: R with a smaller D . the D is _ and than immediatly just those figures 64088. Turning it a bit back and forward it's clearly visible. So... we have a real mystery? Maybe an American one..? Or is the UK the only one using in relief those Rd numbers?
But.... once written the above tex, I searched again on internet "Rd numbers America".... and what did I found ..: Agincourt 17 - his posting GMB January 02,2013 about Heisy US stemware. somewhere in it, he is talking about this number 64088. It should be of Scotney and Earnshaw 22 of december 1886... I couldn't believe my eyes. What a coincidence.
I'm curious to read Freds comment about this.
Would anybody be so kind to add the link, I havn't a clue how to do that...