The most common type of air twist found in mid-18th century English glasses is the multiple spiral air twist (MSAT). Double series air twists are occasionally found, but triple series twists are incredibly rare, with very few still in existence. This particular example has an ogee bowl leading into a stem with a central air core surrounded by a two ply heavy thread which is in turn surrounded by a three ply heavy thread. Because of the complexity of this, the third photo is a very large closeup of the stem so that the different elements can be discerned. The conical foot has a rough, snapped pontil.
The glass is 5" tall, with a bowl diameter of 1 3/4" and a foot diameter of 2 1/2". There are no cracks or chips, and no evidence of any restoration. Lead metal with good color, striations, and tooling.