We've spoken often on this issue, and it's seemed nigh on impossible to find a suitable example of the impression, adequate in definition, that will photograph clearly enough to reproduce and not leave any doubt as to it's cause.
If you look in Charles Hajdamach's 'British Glass 1800 - 1914', page 35 plate 17, a gadget can be seen which I'm assuming must have been very similar in design to the one that was used on the drinking glass showing here - possibly a port glass - about 4.25" (110 m/m tall).
Originally I'd looked at the example of a gadget in Wilkinson - 'The Hallmarks of Antique Glass' - page 25... but his gadget looks to have a collar that lacks the larger cut-out of the Hajdamach gadget. You can visualize the design of this larger opening example leaving the exact impression showing on this port glass.
So there we are - not very exciting really - but it just struck me as remarkable that it has taken to long to find a suitable drinking glass foot, showing the impression of a gadget, with which to illustrate this point. In fact this impression is good enough to be seen in the main picture.
This drinking glass lacks finesse - irregular foot, horizontal striations, mostly round the upper half of the bowl, and a Y shaped shears mark under the foot. Almost certainly a pub/tavern glass from the last quarter of the C19, in my opinion.
I shall now probably see them everywhere
