In the early 1860s a method was developed to produce cylinder glass more quickly and more easily. Molten glass was poured into a large bowl (or crucible) and a hot metal bait was dipped into this molten glass. Then the bait was drawn slowly in an upward motion, drawing a large glass cylinder after it.
It has fewer imperfections than the preceding cylinder glass, but the upward draw gives it a wavy character.
Most Victorian properties would have a version of this GD glass.