520 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



carnelian, moss-agate, mocha-stone, &c., is also worked. Material from other parts of the 

 world, not onlv agate and other varieties of chalcedony, but amethyst, citrine, rock-crystal, 

 and indeed almost all precious stones, including diamond, arc also cut there to a certain 

 extent. The rough material is imported from its place of origin by merchants who, 

 following an old custom, dispose of it to the lapidaries by public auction, which is held from 

 time to time in Oberstein or Idar. 



The workshops in which the agate-cutting is performed are now fitted with every 

 modern convenience, including grinding discs rotating in a horizontal plane, and steam- 

 power is used throughout. The arrangement of, and the methods adopted in, one 

 establishment do not differ essentially from those of any other. 



Besides the workshops fitted with modern appliances, there are still retained the mills 

 driven by water-power, which, with various modifications and improvements, have been in 

 use since early times. There are altogether about ^00 of these mills ; a series of them are 

 situated on the Idar stream, which flows into the Nahe close to Oberstein, and on which 

 the village of Idar is situated, and others on neighbouring streams. These are reserved 

 mainly for grinding work proper, boring and engraving being performed in special shops. 

 A grinding mill of this description is represented in Fig. 90. In these mills three or five 

 (in the figure three) grindstones of sandstone, which measure up to 5 feet in diameter, 

 are sunk in a pit and are made to revolve three times a second by means of a water-wheel. 

 The front surfaces of the grindstones are provided at either side with ridges and furrows so 

 that the agates can be ground to any desired form. 



The rough agate is first broken up with hannner and chisel ; the more valuable pieces , 

 are roughly cut into the shape they are to assume by a metal disc charged with emery 

 powder or, in recent times, with diamond powder. After this it is ground by being 

 pressed with considerable force against the cylindrical surface or in the groove of the 

 rotating grindstone, which is kept constantly wet by a stream of water. The workman, 

 who performs the operation, lies with his body in a hoUowed-out, trough-like bench, the 

 cuirass, which stands close to the grindstone. He is enabled to apply the requisite pressure 

 to the stone by pushing with his feet against two posts firmly fixed at the end of the bench. 

 The stone is held in the hands and turned about on the grindstone until it has assumed the 

 desired form. At each of the grindstones, which are about a foot in width, two workmen 

 can work when necessary, one on either side. During the process of grinding the agate 

 becomes phosphorescent and emits a brilliant reddish-white light. 



Fig. 90 is a diagrammatic representation of a grinding-mill, while Fig. 91 is a picture 

 of an actual workshop, namely, that of Herr August Wintermantel, at Waldkirch, in the 

 Black Forest. 



Vases, bowls, and such like objects are hollowed out by other workmen on a small 

 grindstone ; each process, in fact, is carried out by special workmen with the help of special 

 appliances. * 



The polishing machine imparts a high polish to cut stones, and leaves them completely 

 finished and ready for sale. It consists of a cylinder of hard wood on a disc of lead or tin, 

 and the polishing material is tripolite applied in a moist condition. This work is so simple 

 that it can be left in charge of children. The man and the two women represented to the 

 left in Fig. 90 are engaged in polishing. 



For some purposes stones require to be pierced, and the operation is performed by 

 rapidly rotating steel points charged with emery or diamond powder, or provided with a 

 fine diamond splinter. 



Engraved Agates wei-e regarded with great favour by the ancient Romans, and 



