638 MINING ENGINEERING 



There are two immense pumps lifting a quantity of water, sufficient 

 for one of our large Eastern cities, for the mill work. 



The shops of the mine are in the main duplicated at the mills. An 

 idea of the importance of this mine to the people may be obtained 

 when it is 'stated that the Calumet and Tamarack mines together 

 support a population of about 13,000, and the mills about 5000 more, 

 speaking some seventeen different languages, who are being trans- 

 formed into American citizens. They have their schools and churches, 

 and furnish a market for farm and garden produce. All of this would 

 not have existed but for the mines. 



The development of gold placer-working is of interest and deserves 

 to stand out by itself. The miner washed his sand or gravel in a pan; 

 settling the gold to the bottom, and working off the gravel over the 

 edge, he recovered a few particles of gold from each panful. It was 

 back-breaking work, and he could only pan perhaps a few hundred 

 pounds per day. The rocker or cradle with little depression or riffles 

 followed with two tons per day, the torn or little sluices with riffles 

 with ten or twenty tons, the riffle-sluice with a capacity measured 

 only by its width and the quantity of gravel that could be brought to 

 it. The increased quantity was obtained by the giant or jet of water 

 issuing from a nozzle five to nine inches in diameter under a head of 

 200 to 1000 feet, capable of moving thousands of tons of gravel to the 

 riffle-sluice several miles long, saving many thousands of dollars of 

 gold. At this stage an opposing interest appeared in the farmer on the 

 low land whose river was filled with debris and his farm flooded with 

 water. To overcome this difficulty, various schemes of retaining-dams 

 were devised and found to a very limited degree successful. Later 

 came the dredger, which for certain deposits holds the field to-day. 

 It is a flat-boat floating on its own little pond with a chain-bucket 

 dredging-tool at the bow, a screen and riffle-tables to save the gold, 

 and a stacker or elevator to pile up the refuse at the stern. This boat 

 performs the curious feat of traveling across the country carrying 

 its pond with it, cutting away the gravel in front and building it up 

 behind. These dredgers mine, for about six cents per cubic yard, 

 2000 yards per day, and the gravel may run from ten cents to one 

 dollar per cubic yard. 



The dredger is self-contained, saves the gold, and does not infringe 

 upon the rights of the farmer. 



V 



Summing up Development 



And so through the various stages, the development of mining has 

 gone on until we have the large modern mine equipped with fine 

 machinery for excavating and tramming, those with powerful hoisting 



