These are often called 'propeller knops' (Boulton 1985). The qualification large is used to differentiate them from the next time they came into fashion about seventy years later, when the knop was much less prominent. A similar distinction exists between the distinction between the baluster and balustroid stem groups of the eighteenth century. It is more likely that a find from an English archaeological site would be one of these earlier ones than a later one, because so much of the later glass was recycled. This type is mainly confined to the 1690s, and like the previous group was probably introduced by the 'Dutch' court.
For notes on the 17th Century glass classification used Click here. Unlike the classifications of some earlier stem forms, the basic form of this stem does not include a strengthening merese at either the stem- to-bowl or the stem-to-foot junctions.