After a deal of research I am satisfied that this is a leech bowl of the mid 18th century, the construction and material of the metal is definately from this period.
Strange and Rare page 27 item 85 was mentioned but this item is certainly of a much later date, and may even relate to a little inkwell I have which is certainly of early C20th American origin.
http://i9.tinypic.com/3zid4xk.jpgIn this same publication page 67 item 233 you will find a Goldfish bowl C1770 that would appear to be of equally delicate manufacture.
Frank you mentioned that the "Doctor would need several assistants to hold them in place". This bowl would simply be used to hold a few leeches.
Imagine the scene. Her Ladyship has gone down with a dose of the screaming abdabs, the physic decides she needs bleeding, the servant is despatched to the pharmacy to get some leech's, he takes with him the leech bowl, the leech's are placed in the bowl and a muslin tied over to keep them in but allows them to breath, the leech's are then placed strategically on Her Ladyship and suck away merrily.
Just for interest here is some of my glass collection, most of it is still packed as we moved house recently.
http://i10.tinypic.com/47m98jr.jpghttp://i10.tinypic.com/2dkicec.jpghttp://i10.tinypic.com/2v3376o.jpgIan
:wink: