Page:Popular Mechanics 1928 01.pdf/77

 

of the great piles of sand and gravel discarded as worthless by the "Argonauts of Forty-nine," in their search for gold in California's mountains, new millions are being taken every year by a novel mechanical process, which does away with prospecting, makes mining a certainty and puts the yellow metal back as one of the most important products of the state. From ancient and often buried river beds, as well as from the mine dumps and tailings, handling nearly 100.000 tons a day, these great machines, the first of their kind in the world, are wringing wealth for their owners from sand and gravel running as low as eight cents a ton in gold.

These are the lowest-grade gold deposits ever worked by man. The mechanical miners that have reclaimed them are the largest in any branch of the mining industry, yet their operations are as carefully and as delicately carried on as those of any microscopic investigation ever undertaken in a laboratory.

There are six of these machines working the California mountains, digging their own paths, floating on their own rivers, piling up gravel and rock embankments, and searching out every fleck and flake of gold to a depth of more than eighty feet below their flat steel bottoms. More than 200 men are required to operate and keep them in repair; they work night and day, and consume as much electric power every twenty-four hours as a city of 60,000. They are built in the form of dry-land dredges, but they also operate on water.

Sifting a ton of sand and gravel to get eight cents' worth of gold would have been too delicate a task for the fingers of the miner of '49, and the results would not have kept him in beans and bacon, not to mention flour and molasses, since he was not able to "pan" much more than a ton of earth in a week. But the great scoops of the steel miner get it all, at a rate which has produced more than $50,000,000 since the dredges went to work. In that time they have handled approxi- 