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Page:Popular Science Monthly Volume 34.djvu/624

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THE POPULAR SCIENCE MONTHLY.

ready for the process of gathering. The impurities floating on the surface of the "metal" are first removed by skimming, much as the housewife does with her preserves. When the crucible was originally put into the furnace a fire-clay ring was placed in the bottom of it, and now floats on the bath. By removing all the scum from the interior of this ring the gatherer always has a clear surface from which to draw. The blow-pipe which he uses is simply a wrought-iron pipe about five feet long. It is provided at one end with a mouth-piece and wooden handle; the other end is thickened and somewhat flared, after the manner of a trumpet. This is dipped into the molten metal, and when withdrawn brings

PSM V34 D624 Crown glass in decorative work.jpg
Crown Glass in Decorative Work.

with it a small lump of glass. By a dexterous turn of the pipe this plastic mass is formed into the shape of a symmetrical oval. The dipping process is several times repeated until a considerable mass of glass adheres to the end of the pipe. When window glass of double thickness is to be made, at least four or five gatherings are necessary. It is at the final dip that the gatherer's greatest skill is called into requisition. It is a pleasure to watch him as he seemingly toys with his blow-pipe. But each little movement is done with a purpose. The mass of glass on the end of his pipe is the result of successive gatherings, and must now be brought into a state of perfect homogeneity. To accomplish this, the last glass added is made to completely overlap the whole mass. The ball is then brought almost to a liquid condition, and seems ready to fall from the pipe. In less skillful hands, it would certainly come to grief. By a quick turn of the implement, however, the