Plate-glass is manufactured in this manner in thicknesses varying from 1 in.
In the deeper German pits, where great thicknesses of water-bearing strata have to be traversed, the first establishment expenses are so great that in order to increase output the shaft is sometimes provided with a complete double equipment of cages and engines.
Again, in North America, the greatest thicknesses are found along the mountainous regions on the west and on the east - reaching 12,000 ft.
The first consists of cutting up the various fabrics and materials employed into shapes suitable for forming the leaves, petals, &c.; this may be done by scissors, but more often stamps are employed which will cut through a dozen or more thicknesses at one blow.
It is, however, equally important that the glass as a whole should be flat and remains flat during the process of gradual cooling (annealing), otherwise great thicknesses of glass would have to be ground away at the projecting parts of the sheet.
