The air-drawn stem, if not an English invention, was certainly brought to great perfection here at an early period. We must seek the origin of this device in the large ‘blows,’ often of very irregular shape, that fill the knop or bulb on the stems of earlier glasses.[255] This ‘blow’ is sometimes prolonged into a sort of tail which passes down nearly to the foot. In other cases we find several smaller ‘tears’ in the same bulb, formed, it appears, by puncturing, while it is still soft, the little mass of glass destined to form the bulb, and then covering it with a second gathering. These air-beaded stems are mostly of Low Country origin; but they are of interest to us, as we may probably regard them as the starting-point of the air-twists which are formed by drawing out and twisting the original spherical mass, containing one or more of these bubbles or tears. It may be mentioned that in a general way a loose, widely spaced spiral is characteristic of the earlier glasses, while the tightly twisted stems are only found on late examples. This applies also to the spirals on the rib-twisted stems of plain glass. There is another point that should not be overlooked: this is that the twist on eighteenth-century glasses always descends from right to left, while in modern imitations the reverse direction is generally taken. Perhaps the earliest type of English glass is one with a waisted bowl, engraved with a full-blown rose, and supported on a rib-twisted stem; but those on stems loosely air-twisted may sometimes be as old. There is a glass in the British Museum with a bell-shaped bowl engraved with a rose, a pink, and a third flower of undetermined species; this we may take as a good type of the earlier drinking-glass. The bowl is divided from the air-twisted stem by a hollow bulb containing a sixpence of Charles II. dated 1679. It will be noted how closely the berry-like stamps on the bulb resemble the prunts on the stem of a _roemer_; they occur again on the already mentioned posset-cup from Chastleton. Such decoration may, perhaps, be regarded as characteristic of the English glass of the end of the seventeenth century. The opaque-twisted stem formed, on the same system as the Venetian _vetro di trina_, from rods containing threads of opaque white glass or _latticinio_, is on the other hand not a specially English type. Such stems were in great favour in the Low Countries and in the north of France, and it is even possible that the rods of glass from which our English examples are formed may have been imported from Venice or from the Netherlands.[256] The white lines are sometimes combined with air-twists to form complicated patterns.