THE 



ANNUAL OF SCIENTIFIC DISCOVERY. 



MECHANICS AND USEFUL ARTS. 



COMPLETION OF THE BRITANNIA TUBULAR BRIDGE. 



DURING the present year, one of the greatest works of modern en- 

 gineering art, the Britannia Tubular Bridge,* has been brought to a 

 successful completion. " As a matter of history," says the London 

 Times, " a chronological summary of the structure will be interesting. 

 On June 30, 1845, the bill sanctioning the construction of the Britan- 

 nia Bridge was passed by Parliament. In July the preliminary ex- 

 periments to determine the form of structure commenced ; April 13, 

 1846, the first workmen were engaged on the bridge; April 21, first 

 stone of the Britannia tower was laid ; June 13, 1847, the first vessels 

 arrived with iron at the Straits ; August 10, the first rivet was in- 

 serted ; February 22, 1849, the Caernarvon and Anglesey towers were 

 completed ; April, 1849, the pontoons were brought to bear ; May 4, 

 first tube was completed and platform cut away ; June 20, first tube 

 floated ; June 22, Last stone in Britannia tower laid ; November 9, 

 first tube deposited in permanent bed ; December 4, second tube float- 

 ed ; February 7, 1850, second tube deposited on permanent bed ; 

 March 3, Caernarvon small tube lowered ; March 5, first engine passed 

 through tube, and last rivet inserted ; March 18, single line of tube 

 opened for public traffic ; June 10, third tube of second line floated ; 

 July 11, third tube deposited ; July 25, last tube floated ; October 21, 

 second line of tubs opened for public traffic." 



Before the bridge was allowed to be used for the conveyance of 

 passengers and merchandise, it was subjected to very severe tests. 

 " The first and principal experiment consisted in passing two loco- 

 motive engines through the tube, and resting them at intervals in 

 the centre of the sections. At nine o'clock a train of twenty-eight 

 wagons and two locomotives, with 280 tons of coal, was drawn into 



* See Annual of Scientific Discovert/. 1830, p. 15. 

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