Many articles of glassware are formed with the aid of moulds. Take as an illustration the manufacture of tumblers and honey pots. A quantity of glass is gathered on the blow-iron, marvered, and blown out into an elongated bulb, which is introduced into a mould divided in two halves, which open or shut by hinges, a handle being fixed on either half to facilitate the operation. The interior of the mould is made to the shape of the article, and as the bulb of hot glass is introduced it is shut, and the workman blows down his blow-iron and extends the glass until it expands and fills the space within the mould, giving the complete form of the article with a surplus of metal just where the blow-iron is attached to the glass at the top. These tops are then cut off and finished, either by the workman re-heating the article by attaching the bottom to a pontil and shearing off the top edges, or the glass is annealed in its unfinished state and the top surplus portion cut off by an automatic machine specially constructed for cracking off such goods. [Illustration: GLASSWARE BLOWN IN MOULDS SHOWING PORTIONS CRACKED OFF (_a_) Tumbler. (_b_) Honey Pot. ] Such machines consist of a set of revolving tables upon which the glass articles are centred, and each in turn revolves in front of a thin, pointed, hot jet of gas flame, which impinges on the glass at the height at which the glass is to be cracked off. After one or two revolutions in front of this hot pencil of flame, it is removed, and, by applying a cold steel point so adjusted as to touch the part where the jet has heated the glass, a chill is imparted which causes the upper portion of the glass to crack away in a clear, sharp line round the glass. This top portion of surplus glass is thrown aside and returned to the furnace for re-melting as cullet. The tumbler or honey pot is then conveyed to another machine which fire-polishes the edges to a smooth finish. This machine consists of a circular revolving frame carrying small supports, which themselves rotate on their own centres. Upon each support an article is placed to be fire-polished and the frame carries them round, and they travel into another section of the machine, passing under a hooded chamber, which is heated by a fierce jet of flame. The jet of flame, which is localised on to the top edges of the tumblers or other goods passing through the hood, gives just sufficient heat to melt and round off the sharp edges of the glassware where they have been cracked off by the previous machines. By using these machines in this way labour is considerably economised, and as many as 300 or more articles an hour can be cracked off and fire-polished with unskilled labour. These machines are extensively adopted in the manufacture of electric light bulbs, shades, lamp chimneys, and tumblers.