Spons' dictionary of engineering, civil, mechanical, military, and naval; with technical terms in French, German, Italian, and Spanish (1871)
Spon, Edward, Byrne, Oliver, Spon, Ernest · London, New York : E. & F.N. Spon · leaf 222
COAL MINING. 978 excavated at one operation. The ventilation of the mine is at the same tîmeconsiderably simplified the current of air having altogether a shorter and less tortuous course to follow from the downcast shafts P to the upcast U, as shown by the arrows. The thick dotted line M M shows… … ably with the course of the fault. By the long-wall system a working face of 430 yds. is here obtained in a single length without interruption, as shown at W ; and in the lower portion of the workings along the fault M M another face has been opened of the same total length, but divided into two…
Engineering
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