THE HAND PROCESS

HEETS of flat glass made by the process described in the previous chapter were necessarily limited in size and very expensive. This furnished a great incentive to the study of modifications and development of the method so that larger sizes could be produced and at less cost.     The so-called "hand process" of blowing glass in a cylinder form and its subsequent flattening, as we know it today, is a slight advance of the old crown glass method. It is uncertain when this hand process was first started. Mention is made of its being used as far back as the eleventh century, but it did not come into general use until early in the nineteenth century. This hand process