412 A Resultant System for the [Oct. 



A Resultant System for the Construction of Iron Tension Bridges. — By 

 Major Henry Goodwyn, Bengal Engineers. 



Description of the Frontispiece. 



The view of the wreck of the Brighton Chain Pier as here exhibit- 

 ed, is a fac-simile copy of PL 90, of the " Theory, Practice, and 

 Architecture of Bridges," published by Mr. Weale in 1843, in which 

 the following brief, yet speaking account is given. The span of each 

 curve is only 255 feet with a deflection of x+th. The damage to the 

 structure occurred in October 1833, when two curves and their platforms 

 were destroyed. The second from the land side had twenty suspending 

 rods carried completely away and many others seriously injured ; the 

 third division had 58 suspending rods destroyed. The chains were 

 greatly deranged, and three-fourths of the platform and railing com- 

 pletely destroyed ; the two divisions presenting an awful ruin. A 

 rapid undulation was produced in the platform during the storm, and 

 it sank nearly 6 feet on one side, presenting an inclined plane trans- 

 versely. 



It is remarkable, that notwithstanding the violent injury which the 

 Storm produced, the Longitudinal Iron bearing bar, with a Sectional 

 area of only 4 square inches, was not broken, though it suffered severe 

 torsion. A bar of the above Section supported the girders of the 

 roadway to which the planks were fastened, and which bars were upheld 

 by the stirrups at the lower ends of the suspending rods. 



These remarks are made with reference to paragraphs 3, 4, 5, and 6 

 of the following Memoir, and the frontispiece itself introduced as an 

 evidence of there being some great defect in the principle of construc- 

 tion which admits of a structure, which has been pronounced one of 

 Sir Samuel Brown's best works, being thus seriously deranged by merely 

 its own weight thus acted on. 



The following practical conclusions are chiefly drawn from the 

 demonstrated results of a " Memoir on the quantity of Iron necessary 

 in a Tension Chain Bridge," by the Rev. J. H. Pratt, and published in 

 the CLXXXVI. No. for January 1848, of the Journal of the Asiatic 

 Society of Calcutta, and although a modified Taper Chain system had 

 been drawn out and partially put into practice by me before the appear- 

 ance of Mr. Pratt's theory, its principles agree so entirely with my 



