Page:The American Cyclopædia (1879) Volume VIII.djvu/24

 16 GLASS ward, being flattened at the end with the battledore, that at 3. A lump of glass is now attached to the flat end of the bowl (4), which the workman with the pucellas, while rotating the pipe on the long arms of the chair in which he sits, transforms into the shape shown at 5. A globe is now attached to the end of this stem (6), which is afterward opened and flattened into the form represented at 7. A punty tipped with a small knob of hot glass is next stuck to the foot of the wine glass, which is severed from the blowpipe at the dotted line shown at 8! The top of the glass is then trimmed with shears (9), after which it is flashed and finished as at 10. It is now severed from the end of the punty by a sharp blow and carried by a boy to the anneal- ing oven on the end of a forked rod. In the manufacture of articles by the method of press- ing, a hollow mould is used made of steel or iron, with its interior surface so designed as to give the object the required shape and figura- tion. This mould may be in one piece or consist Fio. 11. Process of Making a Wine Glass. of several parts, which are opened when the moulded glass is taken put. The process will be illustrated by describing the production of a tumbler. A lump of glass is gathered from the pot on the end of a punty by the " gatherer," and being held over the open mould, a suffi- cient quantity is cut off with a pair of scissors by another workman and drops into the mould. This is now pushed under a hand press, and a smooth iron plunger is brought down into the mould with such force that the hot glass is made to fill the entire space between the inside of the mould and the plunger, whose size and shape are the same as those of the interior of the tumbler. The plunger being raised up, the mould is taken from the press and turned over, when the tumbler is made to drop out bottom side up. A punty with a piece of hot glass at one end is now attached to the bot- tom of the tumbler, which is heated at an- other furnace and smoothed by being skilfully rubbed with a wooden tool while rotated on the arms of the workman's chair ; after which it is taken on a fork to the annealing oven. By this process articles can be produced with a rapidity not attainable in the case of blown glass, and therefore with less cost; but the FIG. 12. Hand Press. latter is generally preferred. The glass com- monly used for window panes is one of the hardest varieties, and of unsuitable quality for shaping into vessels or manufacturing by cut- ting or grinding. Besides plate glass, which is also used for windows of a more expensive character, there are two kinds of window glass, known as crown and sheet from the different processes of manufacture ; the former being first blown into a globe or sphere and flattened out into a circular disk, while the latter is formed into a cylinder which is af- terward opened out into a sheet. In making crown glass, the workman gathers from the pot on the end of a blowpipe the requisite amount of molten glass, which is usually about 9 Ibs. The pipe being cooled to admit of handling, the lump is rolled upon the marver to give it a conical form, and a boy blowing at the same time through the tube causes the glass to swell. It is now heated by hold- ing it in the furnace, and is then again rolled and enlarged by blowing. The most of the glass is worked down to the end of the con- ical or pear-shaped lump, the upper part being hollow. The solid end is called the bullion. This being softened in the furnace, the tube is laid across a rest and twirled around, while the glass is blown into a globe. During the ex- pansion it is important to keep the bullion point in a line with the axis of the pipe. This is done by a boy holding against the bullion point a piece of iron terminating in a small cup, while the workman constantly twirls and blows through the pipe resting upon an iron support. The globe at the end of the tube is now pointed toward the flame of the furnace, and being constantly twirled, the end toward the fire flattens out, the bullion point still form- ing a prominence of thicker metal in the