I'd agree that 0.65 of a litre sounds a lot of liquid for a whisky measure/decanter - and as mentioned at the beginning, 19cm. seems to be outside the range of spirit measures in the books that I can see - the tallest being 14 cm. It's true that on the 'serving decanters' there is often a neck ring to indicate the level, there are equally as many that have less obvious means which indicate full capacity, and looking again at the positions of these 'indicators' many are placed at positions on the body well below neck rings. This would then provide a capacity less than Pete's 600 ml. Perhaps this example might be looked at again to see if there are any signs of notches, discreet mitre cuts etc. on the bulbous part of the body, which apart from the height is identical in design to known examples of spirit measures, from the period in question.
Stopperless, decanter shaped spirit measure do, apparently, go back to c. 1800, so would seem nothing untoward in there being a Georgian example offered on ebay, although what provenance is provided to substantiate this one I've no idea - it does look very similar to the example here, but then maybe designs never changed. I have respect for this particular seller, and would trust his judgment, usually, but the whole area of spirit measures/decanters is less well documented than many, so really not sure on this one.
Are there any illustrated similar examples which would have been used as modern French cafe thingies, with ground polished pontils and including some stones??
I stand ready to be corrected, always, and have been often.
The design, shape and thickness of tumbles and up and carafes appear much different to these chunky pieces, and the heavy external ribbing is a feature typical of the older measures.
And as for Mr. Salmond, I'm all for nationalism, but perhaps he should remember Johnson's words to Boswell............"the only thing of any use that a Scotsman sees, is the road to England" (I really am only joking, don't take it seriously, please - with a name like mine I'm half Scots, it's just that I'm not sure which half)