RELATIONS OF MINING ENGINEERING 637 



This brings us to the great mines of to-day, and if we draw a few 

 illustrations from the Calumet and Hecla Mine of Lake Superior, it 

 will, perhaps, serve as well as any. 



This represents both the primitive and the most modern things in 

 mining. It was discovered by a prehistoric pit evidently worked by 

 a race of advanced intelligence before the Europeans reached this 

 country and it is now equipped with the finest mining machinery 

 in the world. This mine is opened up by some fifteen shafts, more or 

 less, on the slope of the deposit which are about 400 feet apart. The 

 longest shaft is opened about 8000 feet down the slope. A vertical 

 shaft nearly a mile deep connects with this below. Every one hun- 

 dred feet, going down, there is a level or horizontal tunnel driven 

 along the deposit either way, and these 100 by 400 feet blocks of 

 copper-bearing rock are worked out by drilling and blasting with 

 dynamite. The roof is temporarily supported by carefully designed 

 timbering which holds up the roof until the rock is all worked out, and 

 then gradually crushes, letting the roof fall in. Every one of the levels 

 has been carefully surveyed so they will properly connect with each 

 other and the ends will not go beyond the boundary-lines, and they 

 are supplied with a railroad track and cars. Every shaft has been 

 surveyed, supplied with a track for the hoisting-skip and a hoisting- 

 rope, at the top of the shaft is a rock house with two immense rock 

 breakers, two great sheaves for turning the hoisting rope and a 

 hoisting engine powerful enough to lift at great speed the rope skip and 

 copper rock, weighing many tons, to the surface. Beneath the breakers 

 is a great rock bin and tracks for shipping the rock down to the mills 

 at Lake Linden, five miles away. 



Several great air compressors furnish air for the rock drills operated 

 by 3000 miners, more or less, producing 5000 tons or more of 

 copper rock per day. 



The mine has waterworks bringing the pure water of Lake Superior 

 up to 600 feet in height, four miles in distance, to supply the boilers 

 and also the company's houses. 



A huge revolving fan uses one shaft for ventilating the many miles 

 of shafts, levels, and stopes, giving the miners fresh air and removing 

 the powder smoke. 



The mine has machine-shop, foundry, blacksmith-shop, and car- 

 penter-shop, capable of doing the finest work on large or small scale. 



Going to the mills at the Lake, we find two large mills with about 

 eleven steam stamps each, 22 in all. Each of these stamps can crush 

 nearly 300 tons of copper rock per day and each has a large number 

 of jigs, Wilfley tables, and revolving tables for concentrating the 

 crushed rock. They appear like monster factories filled with busy 

 machines, and treat between 5000 and 6000 tons of copper rock per 

 day. 



