COAL 



1447 



COAL 



main passage. All the coal is taken out except 

 pillars, three or four feet square, which are left 

 at frequent intervals to support the roof. The 

 map of the passages in a coal mine would look 

 like the map of a city's streets, except that the 

 passages in the mine are more irregular and 

 are narrower. 



The coal is loosened by hand picks and drills, 

 by machinery and by blasting. Hand tools are 

 now used only when the miner begins a new 

 excavation, and then only so long as is neces- 

 sary to make an opening in which a machine 

 drill or pick can be placed. These machines 

 are driven by compressed air or electricity and 

 will cut into the coal at from six to twelve 

 inches a minute. One of these machines is a 

 chain-cutter, which has knives attached to the 

 links; the chain moves in either a horizontal 

 or a vertical direction, and as the chain moves 

 over the coal the knives cut a channel. The 

 machine is mounted on a carriage so it can cut 

 into the coal several feet. The miner usually 

 makes his cut as near the bottom of the vein 

 as possible; then he breaks the coal down by 

 blasting with a light charge of powder. 



The loosened coal is loaded into cars, which 

 are run into the main track, where in large 

 mines they are joined into trains and hauled to 

 the shaft by small locomotives. In some mines 

 these cars are hauled more than a mile. 



Dangers and Remedies. Nearly 3,000 men 

 are annually killed by accidents in the coal 

 mines of the United States alone. For every 

 177,000 tons of coal mined one man lays down 

 his life. In other countries the hazards of coal 

 mining are about as serious. Nearly half of 

 these deaths result from falls of roofs and coal. 

 To counteract this danger pillars of coal are 

 left in the mine to support the roof. Explo- 

 sions of gas and coal dust account for about 

 one-fifth of these fatal accidents. The re- 

 mainder result chiefly from blasting, moving 

 oars and electricity. 



The gases which accumulate in coal mines, 

 especially soft-coal mines, are fire damp, which 

 is very explosive; carbon dioxide, which suffo- 

 cates those who breathe it; and carbon oxide, 

 the white damp of the mines, both poisonous 

 and easily set afire. Gas explosions are gener- 

 ally local and in themselves usually do not 

 cause the sacrifice of much life. They set off, 

 however, the much-dreaded coal-dust explo- 

 sions. Following an explosion, miners are 

 sometimes suffocated by the formation of car- 

 bon dioxide or choke damp. Canary birds have 

 been found very useful in detecting choko 



A Booklet on Goal 



Use three sheets of paper 9 x 12 

 inches, or larger, and fold once, mak- 

 ing twelve pages. 



Cover page Story of Coal in center, 

 made in "black diamonds." 



Illustrations: At left side ferns 

 and other vegetation. At lower right 

 side pile of coal. 



Inside cover Blank. 



Page one Essay, Origin of Coal 

 "Buried Sunshine." 



Illustrations : Rank fern vegetation, 

 coal with fern-leaf impression. 



Page two Essay, Mining of Coal. 



Illustration : At left shaft connect- 

 ed at bottom with cross-section of mine 

 with miners at work. 



Page three Essay, Kinds of Coal 

 anthracite, semi-anthracite, bitumi- 

 nous, lignite. 



Illustration : Lumps of coal of vari- 

 ous sizes. 



Page four Essay, Uses of Coal in 

 heating, manufacturing, transportation. 



Illustration : Stove, furnace, steel 

 mill, engine. 



Page five Essay, Coal in My Coun- 

 t>j importance, location, development. 



Illustration : Outline map with 

 shaded coal fields. 



Graphic : Ten leading counties. 



Page six Essay, Coal in My State 

 or Province. 



Illustration : Map with shaded area. 



Graphic : Leading states or prov- 

 inces. 



Page seven Essay, Coal in Canada, 

 or Coal in the United States. 



Illustration : Shaded map. 



Page eight Original page suggested 

 by teacher. 



Inside back cover Blank. 



Back cover Poem on coal. 



damp, since they usually fall from their perches 

 from its effect, before men breathing the same 

 air feel distress. The after-effects on men 

 are very serious. 



In recent years there has been a world-wide 

 movement toward studying the causes and the 

 prevention of coal mine explosions. The re- 

 sources of science and engineering have been 

 drawn upon in devising methods and apparatus 

 for rescuing miners quickly from danger fol- 

 lowing an explosion. Men wearing helmets and 

 armed with artificial breathing devices enter 

 the death-laden atmosphere below and bring 

 the victims to the surface, where many are 

 revived. The United States Bureau of Mines 



