2o6 ISAAC A. HOURWICH 



"A pit or hole is dug at an}^ likely point, in which is built 

 or launched a hull or scow, on which the dredging machinery 

 is placed. The ordinary surface water soon floats the dredge, 

 which then commences operations. The great endless chain 

 buckets elevate the gravel and earth, which pass through 

 grizzlies to separate the rocks and stones and earth. The 

 rocks are carried by elevating apparatus far to the rear of 

 the dredge, while the auriferous material passes through 

 the gold saving appliances, and the tailings or refuse pass 

 out over the stream. The dredge keeps cutting a new basin 

 for itself to float in as it digs away the bank ahead of it. Of 

 course, the orchard soon disappears under this system, but 

 the underlying gold in the gravel is worth far more than the 

 trees and their product." 



Quartz or deep mining developed naturally from alluvial 

 or placer mining. When the deposits in the beds of the 

 streams or higher up the flanks of the hill were exhausted, 

 the miners followed the lines of the mineral yielding gold 

 and finally came to the mother veins. The beginning of 

 quartz mining also belongs to the Spanish and Portuguese 

 period in the history of this continent. At first the method 

 was merely an adaptation of the processes of alluvial mining. 

 The gold deposit was laid bare by an open cut and worked 

 as nearly as possible like a placer mine. The following de- 

 scription of one of these open mines is quoted from an ac- 

 count of a visit made by Mr. Dawson, secretary of the United 

 States legation at Brazil, to the gold mining region of the state 

 of Minas Geraes : 



''In Brazil the veins are often of friable material, which 

 can easily be pulverized with the aid of running water, and 

 the country rock on either side of the vein is also frequently 

 of the same character. Wliere such veins were found, we 

 encountered the ancient open mines that are so characteristic 

 of Brazilian gold mining. It is evident that the old miners 

 knew nothing of the underground mining, and, except in 

 rare instances, their excavations are open to the top. These 

 great gullies were made with the assistance of running water 

 brought from considerable distances in canals carried along 

 a high level of the mountain flank. The water was conducted 



