hames 1 1 \m i in use by London Underground railway. ( Illustrated London News, 1869?) 



1 igure ag l'i \< wc v segment of 

 cast-iron lining in * rreathi 

 Tower Subway, 1869. to the rear 



is the shield's diaphragm or hulk- 

 head. MHT model — I 1 .-" scale. 

 1 Smithsonian photo ao.'ho B.) 



Bl VUI s HROADW VI SUBW \"i 



Almost simultaneously with the construction ol the 

 Tower Subway, the first American shield tunnel was 

 driven by Allied I I. Bi a< h I ' ■ 1 Bi a. h. as 



editor of the Scientific American and inventor of, aj il; 



other things, a successful typewriter as early as 1856, 

 was well known and respe< ted in technical I 

 lie was not a civil engineer, but had become con- 

 cerned with New York's pressing traffii problem 



1 even then) and as a solution, developed plans for a 

 rapid-transit siiliwuv to extend the length ol Broadway. 

 He invented a shield as an adjunct to this system, 

 solely 10 permit driving of the tunnel without dis- 

 turbing the overly ing streets. 



An active patent attorney as well. Beach must 

 certainly have known ol' 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 \ MUSEUM TREATMENT 



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