Web site: https://www.butlersantiques.com/
This is a quite extraordinary pair of, well, what exactly are they? If they were taller, they would be mugs or tankards - but they aren't, and they have not been shortened because the rims have been finished 'hot', that is, they have not been ground down, but were finished when the glass was still semi-molten.
My original thought was that they were a pair of wine tasters, but as they will hold considerably more than an average wine glass, that seems highly unlikely. They each hold 300ml - more or less, because one is slightly larger than the other.
Whatever was the intended use by the original maker or owner seems unlikely ever to be known. The simple fact is that they are a delightful pair of....... ? The colour of the glass (known by experts as the 'metal') is excellent - exactly what would be expected to a top-flight English glass house late in the 18th century or the beginning of the 19th.
They have cylindrical bodies, the lower half of each is fluted, just like many decanters of the period, and the loop handles are cut and shaped to give a sound grip and with flat thumb-pieces.
I have just thought of the perfect use for this delightful pair of mugs - for champagne! My father and uncle used to drink Champagne from half-pint mugs at Christmas - very civilised!
Dimensions: 2.5", 6.3 cm. high, 4", 10.2 cm diameter