thanks xlarge - and your new pix appear to show that there is a pontil depression - ground then polished - under the foot of these glasses,
and am sure you know all about pontil rods and the removal of pontil scars, which is the process that creates the depression under the foot of vases, drinking glasses etc. If you use a loupe/lens it's probably still possible to see the remains of grinding and polishing where the pontil scar was removed, and this same method will likely also show you similar grinding marks remaining on the sides of the glasses.
This feature indicates quality and probably some age, but beyond that my knowledge fails - sorry.
Some examples of glass - no matter how hard we try for an identification - remain without attribution, and as you've spent much time looking without success, you may have to accept that either you'll not succeed, or it may be some years in the coming. I'm still struggling to see these glasses as C19 - appreciate the wheel engraving isn't a problem, nor perhaps the cutting, but it's that overall shape that gives a headache.
In your searching for an answer, have you been aware of seeing C19 drinking glasses with this waisted shape anywhere? There was a fashion - somewhere in the early to mid C19 - for barrel shaped (convex) drinking glasses - the opposite shape of these.
Again, thanks for the pix, but we appear to be in the dark at the moment. catshome's optimism must now lead us on, hopefully, to something positive
