In comparison with some of the folk whose comments have graced these pages, bat20 is always courteous and polite - but despite his comments IMHO I'd suggest that it is worth pursuing provenance/attribution/age and use, particularly with an item that we don't see everyday - though whether this piece is categorically a whale oil lamp base is perhaps not yet proven? I don't think we're getting too hung up about about this one, so far, and I'm all for pursuing more info - therein lays half the fun - and I can see why this piece has given rise for speculation on age. Anyone who has dabbled in this hobby has goofed at some time or another - it's embarrassing to say the least when you get proven wrong - this one may be late C18 to early C19 but equally could be late C19, it really isn't an easy thing to pigeon hole with accuracy.
For me too glass is just a hobby - to go with probably half a dozen other collecting interests - though must say some of us can be a lot more passionate than others.
if we can nail something down and provide age and use then at least we're helping those who come after us.
copies have been the bane of glass collector's lives for three hundred years - and life doesn't become much easier just because a piece isn't a copy of a well known shape or design from a given period - in fact it can be the opposite as with a piece like this, where it's an obscure utility item that would be unlikely to get the copy treatment. We all have blind spots in the world of glass, mine are whale oil lamps, coloured glass and very expensive glass.