THE 
JOURNAL OF SCIENCE. 
AUGUST, 1884. 
I. A DESCRIPTION OF THE PROCESS 
OF “ HYDRAULIC MINING” IN CALIFORNIA, 
WITH EXPLANATIONS CONCERNING THE ORIGINATION 
OF GOLD-BEARING ALLUVIUM THERE, AND ELSEWHERE. 
By George O’Brien. 
UR knowledge of the primitive operations of the 
aboriginal inhabitants of the globe in pursuit of gold 
is barely traditional, as we are only aware that from 
very early times the precious metal was collected and highly 
prized by them, and that they chiefly extracted the visible 
gold, which existed in prodigious quantities on, or closely 
beneath, the surface of the earth, and of its being particu- 
larly abundant in Asia and Africa. But we can draw more 
positive conclusions as we survey remains of the rude but 
effective contrivances used by them in later, but still remote, 
periods, with full evidence as to the extent of their opera- 
tions, in the numerous perpendicular shafts located at short 
distances from each other, over large areas of auriferous 
gravel in India, as well as from precisely similar memorials 
of ancient workings which remain also further demonstra- 
tions, in the abandoned “ hill diggings,” and shifted beds, 
and beds of rivers, in Peru, South America, flowing between 
the sea and coast ranges of the Andes, descending in a north- 
easterly direction to the River Amazon, and that their much- 
coveted and enormous productions were the accumulated 
riches of the Incas, transferred as spoils of war to their 
Spanish conquerors in the sixteenth century. And for 
VOL. VI. (THIRD SERIES). 3G 
