File:The Americana - a universal reference library, comprising the arts and sciences, literature, history, biograhy, geography, commerce, etc., of the world (1903) (14771352784).jpg

Identifier: americanaunivers15beac (find matches)
Title: The Americana : a universal reference library, comprising the arts and sciences, literature, history, biograhy, geography, commerce, etc., of the world
Year: 1903 (1900s)
Authors: Beach, Frederick Converse, 1848-1918 Rines, George Edwin, 1860- Scientific American, inc
Subjects: Encyclopedias and dictionaries
Publisher: New York : Scientific American compiling dept.
Contributing Library: University of California Libraries
Digitizing Sponsor: Internet Archive

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onnection withthe .shield. The intensity of this air pressureis determined by the depth of the tunnel be-low tlic surface of the water above it. It isevident that a greater intensity of pressure The friction on the outside of the shell ofthe shield against the surrounding materialmay be over 1,000 pounds per square foot ormuch less than that. The amount of nomi-nal hydraulic jack power required may beroughly taken at 4,000 to 6,000 pounds toevery square foot of frictional surface on theoutside of the shell of the shield. Some of the principal later tunnels whichhave been or are to be constructed by theaid of shields, in addition to the early tunnelsof Brunei and others, are the Sarnia tunnelunder the Saint Clair River, near Detroit,Mich, (already described); the East Bostontunnel, a part of the rapid transit system ofthe city of Boston; the two parallel single-track electric trolley tunnels now being com-pleted (1904) under the North River betweenlioboken and New York, and the tunnels
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1. Entrance to first liroachvay Tunnel, X. V. City, constnicteil in iS6q liy AlficJ E. Bench. 2. Tlie first Broadway Tunnel Car jiropelleil by air pressure, devised by Alfred E. Beach, and operated in 1S71. TUNNELS AND TUNNELING Name of Shield Concorde Siphon Clichy Siphon Mersey East River City and South London Glasgow District Waterloo and City Glasgow Harbor Hudson River St. Clair River Clichy Tunnel Clichy Tunnel Blackwall Waterloo Station I -cngth in Feet Diameter Tail Body Front Total 6.75 2.SI 2.5s 1.16 6.67 8.39 2.51 2.55 1.16 6.16 9-97 S.61 2.98 2.98 11.58 10.99 3.SI 0.32 3.67 7.51 10.99 2.6s 2.82 I.or 6.49 12.07 2.65 2.82 1.01 6.49 12.99 2-75 2.98 1.24 6.98 17.25 2.75 2.98 1.08 8.49 19.91 4.82 2.98 S.67 10.49 21.52 4.00 2.98 11.2S 15.25 23.7-19.8 4.00 2.98 6.88 17.22 23.8-19.4 7.44 11.90 4.46 23.65 27.00 6.98 5.90 6.59 19.48 24.86 3-34 s.s< 1.14 10.00 under the North and East rivers about to becompleted by the Pennsylvania RailroadCompany. The following tables of double-t

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