English: Title: Bulletin - United States National Museum

Identifier: bulletinunitedst2401966unit Year: 1877 (1870s) Authors: United States National Museum; Smithsonian Institution; United States. Dept. of the Interior Subjects: Science Publisher: Washington : Smithsonian Institution Press, [etc. ]; for sale by the Supt. of Docs. , U. S. Govt Print. Off. Contributing Library: Smithsonian Libraries Digitizing Sponsor: Smithsonian Libraries

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Text Appearing Before (PREVIOUS) Image: (Different picture) Caption: Figure 28. Thames Tunnel in use by London Underground railway. (Illustrated London News, 1869?)

Text Appearing After (THIS) Image: Figure 29. Placing a segment of cast-iron lining in Greathead's Tower Subway, 1869. To the rear is the shield's diaphragm or bulk-head. MHT model -1 1/2" scale. (Smithsonian photo 49260-B.)

BEACH'S BROADWAY SUBWAY

Almost simultaneously with the construction of the Tower Subway, the first American shield tunnel was driven by Alfred Ely Beach (1826-1896. Beach, as editor of the Scientific American and inventor of, among other things, a successful typewriter as early as 1856, was well known and respected in technical circles. He was not a civil engineer, but had become concerned with New York's pressing traffic problem (even then) and as a solution, developed plans for a rapid-transit subway to extend the length of Broadway. He invented a shield as an adjunct to this system, solely to permit driving of the tunnel without disturbing the overlying streets. An active patent attorney as well. Beach must certainly have known of and studied the existing patents for tunneling shields, which were, without exception, British. In certain aspects his shield resembled the one patented by Barlow in 1864, hut never built. However, work on the Beach tunnel started in 1869, so close in time to that on the Tower PAPER 41: TUNNEL ENGINEERING - A MUSEUM TREATMENT 227

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