1848.] 



Construction of Iron Tension Bridges. 



435 



Scantlings of Rods of Experiment No. 3. 



"Upper link. 



2 



3 



4 



5 



6 



7 



8 



9 



10 

 11 

 12 or centre, 



F4 



27 



64 



26 



64 



« 4 )>of one inch. 



<>4 

 23 



6 4 



fiT 

 20 



64 



19 



(T7 



18 



S4J 



Oblique rod J /; diameter. 

 Longitudinal beam at centre l /, y^J- ,/ . 



„ „ 7th space from centre V 1 %4*^ 



Explanation of the relative proportion between the Experiment and 



the real Bridge. 



Full section of two chains, one side of the real bridge. 



Upper link, 17 bars 2" X l // =34 // X 2>=68 square inches. 



Diameter of experimental upper link, I| of one inch. 



Area of which -178 and *178 X2 ch.=*346 section of two chains. 



•346 X 176=67*8, or section of real bridge. 

 Area of platform, real bridge, 468 X 1 1=5148 square feet : 



5148 X 120=617760 fts. on real bridge. 



617760=3156 ibs. total load for experiment. 

 196 



3152=57 lbs. on each point of experiment. 



Area of oblique rods of real bridge 2*405 each. 

 Diameter of rods of experiment \" or sectional area *012 : 



•012 X 196=2*352, or very nearly the section of real bridge. 

 Sectional arc of longitudinal beam of real bridge at centre, 37 inches ; 



remainder 27" beyond the 7th oblique rod. 



3 M 



