BOOK VIII. 319 



But to return to the stamping machines. Some usually set up four 

 machines of this kind in one place, that is to say, two above and the same 

 number below. By this plan it is necessary that the current which has been 

 diverted should fall down from a greater height upon the upper water- 

 wheels, because these turn axles whose cams raise heavier stamps. The 

 stamp-stems of the upper machines should be nearly twice as long as the stems 

 of the lower ones, because all the mortar-boxes are placed on the same level. 

 These stamps have their tappets near their upper ends, not as in the case of 

 the lower stamps, which are placed just above the bottom. The water flowing 

 down from the two upper water-wheels is caught in two broad races, from 

 which it falls on to the two lower water-wheels. Since all these machines 

 have the stamps very close together, the stems should be somewhat cut away, 

 to prevent the iron shoes from rubbing each other at the point where they are 

 set into the stems. Where so many machines cannot be constructed, by 

 reason of the narrowness of the valley, the mountain is excavated and 

 levelled in two places, one of which is higher than the other, and in this case 

 two machines are constructed and generally placed in one building. A 

 broad race receives in the same way the water which flows down from the 

 upper water-wheel, and similarly lets it fall on the lower water-wheel. The 

 mortar-boxes are not then placed on one level, but each on the level which 

 is appropriate to its own machine, and for this reason, two workmen are then 

 required to throw ore into the mortar-boxes. When no stream can be 

 diverted which will fall from a higher place upon the top of the water-wheel, 

 one is diverted which wiU turn the foot of the wheel ; a great quantity of 

 water from the stream is collected in one pool capable of holding it, and 

 from this place, when the gates are raised, the water is discharged against 

 the wheel which turns in the race. The buckets of a water-wheel of this 

 kind are deeper and bent back, projecting upward ; those of the former 

 are shallower and bent forward, inclining dovmward. 



Further, in the Julian and Rhaetian Alps^^ and in the Carpathian 

 Mountains, gold or even silver ore is now put under stamps, which are 

 sometimes placed more than twenty in a row, and crushed wet in a long mortar- 

 box. The mortar has two plates full of holes through which the ore, after 

 being crushed, flows out with the water into the transverse laimder placed 

 underneath, and from there it is carried down by two spouts into the heads of 

 the canvas strakes. Each head is made of a thick broad plank, which can be 

 raised and set upright, and to which on each side are fixed pieces projecting 

 upward. In this plank there are many cup-like depressions equal in size and 

 similar in shape, in each of which an egg could be placed. Right down in 

 these depressions are small crevices which can retain the concentrates of gold 

 or silver, and when the hollows are nearly filled with these materials, the 

 plank is raised on one side so that the concentrates will faU into a large bowl. 

 The cup-like depressions are washed out by dashing them with water. These 



^^The Julian Alps are a section east of the Carnic Alps and lie north of Trieste. The 

 term Rhaetian Alps is applied to that section along the Swiss Italian Boundary, about 

 north of Lake Como. 



