OP IRON BEAMS. 46k 



VIII. EXPERIMENT. 



Beam from the same model as that of experi-. 

 ment 3rd, the top rib in the casting being to 

 the bottom as I to 3i nearly. 



Distance between supports as before. 



Dimeosiont of crou •ectlon. 



Area of top rib = 1.05 x .32 = 0.34 inches.. 

 Area of bottom rib = 2.15 x >^6 = 1.20 „ 

 Thickness of vertical part = .33. 

 Area of cross section = 3.08 inches. 



Weight of casting 39^ lbs. ' ' 



Breakmg weight 8263 lbs. = 73 cwt. 89 lbs. It 



broke very near to the middle. 



The form of fracture was nearly as in the 



figure to experiment 1, but here Ini = 2.5 



and tr = ,^. 



Hence strength per inch of section = ^^ 

 = 2683lbs. Comparing this with the I'esult from' 

 the common beam in experiment 10, which 

 bore 2792 lbs. per inch, we have 2792 — 2683 

 ^ 109 =; defect. 



\ . /.Loss in ^strength = 2792"^ 1q nearly. ^ 

 • This beam was like all the rest cast erect, 

 but with the broad rib lowest by mistajce, 

 whPch* perhaps is the cause of the defect in 

 strength. 



