THE NATIONAL GEOGRAPHIC MAGAZINE 



411 



Photograph from U. S. Bureau of Mines 



LINING A MINE; WALL WITH ARTIFICIAL ROCK 



One of the frequent causes of mine cave-ins is the weathering of the slate of the roof 

 and side walls. It gradually crumbles or scales off and suffers a consequent weakening, 

 which may finally bring disaster. The cement gun covers the slate with a thin plaster, which 

 effectually shuts out the air and leaves it as unexposed to deterioration as it was during the 

 countless ages before the coal was removed. 



Before going down into the mine the 

 superintendent will give us each a miner's 

 lamp — at this particular mine the lamp 

 is a tiny teapot affair containing sperm 

 oil and with a spout full of cotton yarn. 

 Also, he will equip us with electric hand- 

 lamps, to be used in any emergency. 

 Then he will stick an extra ball of yarn 

 in his pocket and we will start for the 

 "cage," which is the mine name for an 

 elevator. 



the: descent into anthracite 



We step on, he presses a button, and 

 the hoisting engineer is notified that we 

 are ready to go down. Suddenly the cage 

 seems to drop ; then it seems to stop, and 

 the walls of the shaft appear fairly to fly 

 upward past us. Up, up, up they fly, 

 disclosing this stratum of rock and then 

 that. 



Arriving at the bottom, we soon find 

 that a coal mine is planned like a city. 

 There is one main street, or entry, and it 

 has been laid out with the nicety of a 

 grand boulevard. Parallel with this are 

 other entries, and across these entries 

 run other streets, at right angles, usually, 

 which are called headings. Lining all 

 these headings as houses line the streets 

 are the chambers, or rooms, in which the 

 miners work. 



When we stop at the bottom we feel 

 ourselves in a small-sized hurricane. It 

 is the air rushing down the shaft and 

 starting through the mine on its mission 

 of purification. Setting out down the 

 main entry, along a railroad track, we 

 soon hear a clanging bell and a whistle, 

 and presently there looms out of the dark- 

 ness a yellow light. As it approaches, we 

 see the outlines of what appears to be a 



