THE TECHNOLOGIST. [Jan. 1, 1{ 



256 ON THE GOLD MINES OF CANADA, ETC. 



deposits, and whole square miles, which were before inaccessible, have 

 yielded up their precious metal. It sometimes happens, from the irre- 

 gular distribution of the gold in the diluvium in California, that the 

 upper portions of a deposit do not contain gold enough to be washed by 

 the ordinary methods ; and would thus have to be removed, at a consi- 

 derable expense, in order to reach the higher portions below. By the 

 hydraulic method, however, the cost of cutting away and excavating is 

 so trifling, that there is scarcely any bank of earth which will not pay 

 the expense of washing down in order to reach the richer deposits of gold 

 beneath. 



The aqueducts or canals for the mining districts of California are 

 seldom constructed by the gold workers themselves, but by capitalists, 

 who rent the water to the miners. The cost of one of these canals, car- 

 rying the waters of a branch of the Yuba River to Nevada County, was 

 estimated at a million of dollars ; and another one, thirty miles in 

 length, running to the same district, cost 500,000 dols. The assessed 

 value of these various canals in 1857 was stated to be over four millions 

 of dollars, of which value one-half was in the single county of Eldorado. 

 The Bear River and Auburn Canal is sixty miles in length, three feet 

 deep and four feet wide at the top, and cost in all 1,600,000 dols. ; not- 

 withstanding which, the water-rents were so great that it is stated to 

 have paid a yearly dividend of twenty per cent., while other similar 

 canals paid from three, to five and six per cent., and even more, monthly. 

 The price of the water was fixed at so much the inch, for each day of 

 eight or ten hours. The price was at first about three dollars, but by 

 competition has now been greatly reduced. 



From these statements, it will be seen that the great riches which 

 have of late years been drawn from the gold mines of California, have 

 not been obtained without the expenditure of large amounts of money 

 and engineering skill. This last is especially exhibited in the construc- 

 tion of these great canals, and the application of the hydraulic method 

 to the washing of auriferous deposits, which were unavailable by the 

 ordinary modes of working, on account of their distance from the 

 water-courses, or by reason of the small quantity of gold which they 

 contain. 



In order to judge of the applicability of this method of washing to 

 our own auriferous deposits, a simple calculation based upon the experi- 

 ments at the Riviere du Loup will be of use. It has been shown that 

 the washing of the ground over an area of one acre, a: id with an average 

 depth of two feet, equal to 87,120 cubic feet, gave, in round numbers, 

 about 5,000 pennyweights of gold, or one and thirty-eight hun- 

 dredths grains to the cubic foot ; which is equal to one and three- 

 quarters grains of gold to the bushel. Now, according to Mr. Blake, 

 earth containing one forty-fourth part of this amount, or one twenty- 

 fifth of a grain of gold, can be profitably washed by the hydraulic 

 method, while the labour of two men, with a proper jet of water, suf- 



