stulm

plural stulms

1. businessA shaft, conduit, adit, or gallery to drain a mine.

   … they have to advance the lower stulm on each side of the tunnel … the advancement of the stulm, … it must be finished, including the graveling.

   1881, United States Bureau of Foreign Commerce, Commercial Relations of the United States: Reports from the Consuls of the United States on the Commerce, Manufactures, Etc., of Their Consular Districts, U.S. Government Printing Office, page 494

   1 more example

   … an upper chamber, a stulm, a lower chamber in open communication with the lower end of the head shaft, and arranged at substantially the level of the stulm, and a downwardly extending sill divinding the lower end of the shaft from the stulm so that the lower chamber is at normal pressure and the shaft is at negative pressure.

   1932, Official Gazette of the United States Patent Office, Volume 414, Digitized edition, U.S. Government Patent Office, published 2008, page 709