Page:Popular Science Monthly Volume 34.djvu/625

Rh gatherer throws the fold of glass into a spiral form, and so works it to the end of the mass. This leaves a perfectly clear and semi-plastic ball. The pipe is now withdrawn from the furnace and taken to an open wooden mold, or trough, where the glass is formed into a pear-shaped mass. The mold is kept constantly wet, to prevent its burning. The water, in contact with the red hot glass, assumes the spheroidal condition, and looks like so many globules of mercury. The gatherer's duty is now at an end, and he returns to the melting furnace to repeat the operations of gathering until the crucibles are emptied of their contents. The blow-pipe and its red-hot burden, meanwhile, have been taken in charge by the blower.



On the continent of Europe the same furnace is generally used for both melting and blowing, but in England and America it has been found more advantageous to employ separate furnaces. They are very similar in construction. The blowing furnaces have, however, somewhat larger side-openings, and the gas, instead of being introduced at the ends, is burned directly under the openings, or blow-holes. The furnace simply provides an intensely hot chamber for controlling the temperature of the glass under manipulation. On each side of the furnace, and directly in front of the blow-holes, there is a wide platform built over a cellar, or pit, perhaps ten feet deep. Long openings in this platform run at right angles to the furnace, and permit the blower, when occasion demands, to swing his pipe and its burden in the pit beneath.

The sheet-glass factories of Pittsburgh are equipped as thoroughly as any in the world. The division of labor is everywhere carried to the extreme. Each man knows how to do a particular thing, and does it. The blower, for instance, into whose hands the red-hot ball of glass has just been consigned, is supposed to know little or nothing about the other operations involved in glass-making. He begins at a certain point, and leaves off at a certain point. The skill with which he effects his part in the many transformations required in the genesis of a pane of glass is, however, the most attractive in a process nowhere devoid of interest.

His first act is to grasp the pipe, and, with the ball of glass still resting in the wooden mold, blow through the mouth-piece