%2 fiLcuta 



Figure |2. Interior of completed rowER Sub- 

 way. (Thornbury, Old and .\ Lot 'on, )HH~, 

 vol. i. p. 126.) 



Broadw.is to stop a block away under the south side 

 of Murray Street. The total distance was about $12 

 feet. Work was carried on at night in total secrecy, 

 the actual tunneling taking 58 nights. At the Warren 

 Streel terminal, a waiting room was excavated and a 

 large Roots blower installed for propulsion of the single 

 passenger ear. The plan was similar to that used 

 with the model in 1867: the cylindrical ear fitted i [ " 

 circular tunnel with only slight circumferential clear- 

 ance. The blower created a plenum within the wait- 

 ing room and tunnel area behind the car of about 

 0.25 pounds per square inch, resulting in a thrusl on 

 1 of almost a ton. not accounting lor blowby. 



The ear was thus blown along its course, and was 

 returned by reversing the blower's suction .md dis- 

 charge duets to produce an equivalent vacuum within 

 the tunnel. 



The system opened in February of 1870 and re- 

 mained in operation for about a year. Beach was 

 ultimately subdued by the hostile influences of Boss 

 Tweed, and the project was completely abandoned. 

 Within a very lew more years the first commercially 

 operated elevated line was built, bin the subwav, did 

 not achieve legitimate status in New York until the 

 opening of the [nterborough line in 1904. Ironically, 

 its route traversed Broadway lor almost the length of 

 the island. 



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; \ i 1 1 1 \i section through ili' 1 

 fiead shield used at the rower Subway, 1869. I he 

 first one-piece shield of circular section. (Cop- 

 perthwatte, Tunnel Shields and the Usi I 

 Air in Subaqu 



The Beach shield operated with perfect success in 

 this brief trial, although the loose sandy sml encoun- 

 tered was admittedly not a severe u-st of its qualities. 

 No diaphragm was used: insie.nl .1 series hi 8 hori- 

 zontal shelves with sharpened leading edges extended 

 across the front opening of the shield. The out- 

 standing feature of the machine was the substitution 

 for the propelling screws used by Brunei and 

 Greathead of 18 hydraulic rams, set around its 

 circumference, rhese were fed l>\ .1 single 

 operated pump, seen in the center of figure 34. By 

 this means the course of the shield's forward move- 

 ment could be controlled with a convenient 1 



PAPER 41: TUNNE1 ENGINEERING \ MUSEUM TRI \ I Ml N 1 



229 



