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Coal Measures and Coal Mining in Iowa, including paleontology and a discussion on the coal formation; also the methods of mining by Russell T. Hartman, 1898

Coal Measures and Coal Mining in Iowa by Russell T. Hartman, 1898, Page 200

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[page]200.[/page] entries are driven as in the room and pillar method. The walls of the entries are also opened as in the room and pillar method but instead of leaving pillars as long as from one entry to another, only short pillars (b b) are left. After forming these pillars the work proceeds as in the long-walled method. [image: sketch of entry, pillars (each labeled b), openings (each labeled a)] [caption]Figure 14[/caption] In every well conducted mine there is a system of tramways for the purpose of conveying the coal to the foot of the shaft. Through the entries these tramways are built of iron or steel rails while in the rooms they are usually of wood. The cars used in the mines hold from one half ton to a ton of coal. The tractive force may be by mules, by electricity, by rope haulage, or by steam or compressed
 
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