File:RetreatingLongwall.png
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Summary
| Description |
English: Origional caption: "Fig. 36. Block system of Retreating Long-wall, West Virginia." Plan of a multi-panel longwall retreat mine, circa 1917. Edge detection has been used to convert the figure to a line drawing. |
| Date | |
| Source | Percentage of Extraction on of Bituminous Coal with Special Reference to Illinois Conditions, Engineering Experiment Station Bulletin No. 100, University of Illinois, page 115. |
| Author | C. M. Young |
Licensing
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This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See this page for further explanation.
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File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 15:54, 20 August 2009 | | 768 × 821 (60 KB) | Douglas W. Jones | {{Information |Description={{en|1=Origional caption: "Fig. 36. Block system of Retreating Long-wall, West Virginia." Plan of a multi-panel longwall retreat mine, circa 1917. Edge detection has been used to convert the figure to a line drawing.}} |Sour |
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