Editing Tunnel boring machine (section)

=== 1900s ===
During the late 19th and early 20th century, inventors continued to design, build, and test TBMs for tunnels for railroads, subways, sewers, water supplies, etc. TBMs employing rotating arrays of drills or hammers were patented.<ref>See:
* Bancroft 1908, pp. 66, 125, 127, 146.
*Thales Lindsey, "Improved machine for tunneling rock," {{US patent|55,514}} (issued: June 12, 1866).
*Pedro Unanue, "Tunneling machine," {{US patent|732,326}} (filed: December 23, 1901; issued: June 30, 1903).
*Russell B. Sigafoos, "Rotary tunneling machine," {{US patent|901,392}} (filed: May 18, 1907; issued: October 20, 1908).
*George A. Fowler, "Tunnel driving machine," {{US patent|891,473}} (filed: July 30, 1907 ; issued: June 23, 1908).</ref> TBMs that resembled giant [[hole saw]]s were proposed.<ref>See:
* Bancroft 1908, pp. 66, 85, 106.
* Wilson, Charles. Machine for excavating tunnels," {{US patent|17,650}} (issued: June 23, 1857).
* Stanley, Reginald. U.K. Patent no. 1,449 (issued: February 1, 1886); "Tunneling-machine" (issued: August 7, 1894).
* Mitchell, Jonas L. "Tunneling-machine," {{US patent|537,899}} (filed: April 3, 1893 ; issued: April 23, 1895).</ref> Other TBMs consisted of a rotating drum with metal tines on its outer surface,<ref>See:
*William F. Cooke and George Hunter, U.K. patent no. 433 (issued: August 10, 1866). Available online at: [http://www.aditnow.co.uk/documents/personal-album-54/Tunnelerpatent2.pdf AditNow] {{Webarchive|url=https://web.archive.org/web/20160304195336/http://www.aditnow.co.uk/documents/personal-album-54/Tunnelerpatent2.pdf |date=2016-03-04 }}.
*''Patents for Inventions. bridgments of Specifications relating to Mining, Quarrying, Tunnelling, and Well-sinking'' (London, England: Office of the Commissioners of Patents for Inventions, 1874), [https://books.google.com/books?id=jXNUAAAAYAAJ&pg=RA1-PA275 p. 275.] {{Webarchive|url=https://web.archive.org/web/20230728205632/https://books.google.com/books?id=jXNUAAAAYAAJ&pg=RA1-PA275 |date=2023-07-28 }}
*{{harvnb|Maidl et al.|2008}}</ref> or a rotating circular plate covered with teeth,<ref>See:
* Bancroft 1908, pp. 146, 165.
*John P. Karns, "Tunneling-machine," {{US patent|848,107}} (filed: November 29, 1905; issued: March 26, 1907).
*Olin S. Proctor, "Tunneling-machine," {{US patent|900,951}} (filed: February 17, 1908; issued: October 13, 1908).</ref> or revolving belts covered with metal teeth.<ref>See:
* Bancroft 1908, p. 145.
*William A. Lathrop, "Machine for cutting headings," {{US patent|816,923}} (filed: August 31, 1903; issued: April 3, 1906).</ref> However, these TBMs proved expensive, cumbersome, and unable to excavate hard rock; interest in TBMs therefore declined. Nevertheless, TBM development continued in potash and coal mines, where the rock was softer.<ref>For example:
*In Germany, the ''Eisener Bergmann'' (iron miner) was developed in 1916 by Schmidt, Kranz & Co. for potash mines; its boring head consisted of a large rotating roller that was fitted with cutters  See: {{harvnb|Maidl et al.|2008}}
*In the U.S., the McKinlay Entry Driver, a track-mounted TBM or "continuous miner", was invented in 1918 for use in coal mines.  Its boring head consisted of metal tines on two, side-by-side rotating arms. See: Thomas W. Garges (November 13, 2003) William N. Poundstone lecture: "Underground Mining Technology Evolution", p. 8. Available online at:  [http://www2.cemr.wvu.edu/~wwwmine/poundstonelec/GargesThomastxt.pdf Benjamin M. Statler College of Engineering and Mineral Resources, West Virginia University] {{Webarchive|url=https://web.archive.org/web/20161020162943/http://www2.cemr.wvu.edu/~wwwmine/poundstonelec/GargesThomastxt.pdf |date=2016-10-20 }}</ref>

A TBM with a bore diameter of {{convert|14.4|m|ftin|abbr=on}} was manufactured by The Robbins Company for Canada's [[Niagara Tunnel Project]]. The machine was used to bore a hydroelectric tunnel beneath [[Niagara Falls]]. The machine was named "Big Becky" in reference to the Sir [[Adam Beck]] hydroelectric dams to which it tunnelled to provide an additional hydroelectric tunnel.