GLASS-MAKING. 



163 



cles, and similarly with the secondary part of the decoration. 

 This completes the rough work. 



The second process is that of " smoothing/' and is carried out by 

 means of wheels made of a natural stone found in Scotland, known 

 as the Craig Leigh stone. A large part of modern Edinburgh is 

 built out of this material. It is a compact silicious stone, wearing 

 very uniformly, and almost free from that tendency to crumble 

 which characterizes the majority of our native sandstones. The 

 stone wheels are about the same size as the iron wheels used in the 

 roughing process ; but their cutting edges, instead of being smooth, 

 are beveled, thus giving a sharp edge in the center of the face. 

 This is occasionally 

 sharpened by regrind- 

 ing, or by holding 

 pieces of flint against 

 the beveled faces of 

 the revolving wheel. 

 A tiny stream of wa- 

 ter falls constantly 

 against the face of the 

 stone. Each cut made 

 on the iron wheel is 

 gone over on the stone, 

 and, by the finer fric- 

 tion, the surface of the 

 facets becomes smooth 

 and transparent. The 

 carafe is slowly be- 

 coming an object of 

 beauty. 



Next in the order 

 of the processes comes 

 the polishing, which 

 is effected by wooden 

 wheels mounted as be- 

 fore and supplied with 

 pumice or rotten-stone. 

 Red willow is considered the best material for the polishing-wheel, 

 though poplar is also frequently used. The hard woods are found 

 to be less suitable for the purpose. The wooding — for so this third 

 process is called in the atelier — gives a fine finish to the smoothed 

 facets and adds greatly to their brilliancy. It is a process, how- 

 ever, which is only practicable in cases where the cutting is rather 

 deep. "Where it amounts to little more than a tracing, the wooden 

 wheel would be of slight use. 



Still a fourth process is required before the carafe is ready to 



Fig. 4. — The Sand-Blast in Operation. 



