474 THE STRENGTH 



Distance between supports as before. 

 Weight of casting 39i lbs. 



Weights. Deflections. 



6218 .28 inches. 



7138 .33 „ 



Breaking weight = 7598 lbs. 



The area of a cross section at the place of 

 fracture in this beam was not taken; but 

 assuming it at 3.08 inches, which is about a 

 mean between the other areas from the same 

 model, we have ^^ = 2466 lbs. = strength per 

 inch of section. 



This beam was cast, with the others preceding 

 it, for comparison ; but as there seems to be 

 some difference in the iron, it is not safe to 

 attempt any. The experiments however will 

 have their use, as is mentioned further on. 



XVIII. EXPERIMENT. 



Beam from the same model as that in expt. 16. 



Distance of supports as before. 



Dimensions of section in inches. 



Top rib = 2.3 x .28 = .64 

 Bottom rib =6.61 x .54 = 3.57 

 Thickness of vertical part ;= .34. 

 Area of section = 5.86 inches. 



Weight of casting 68i Ibs.^ ^^ i^noir: 



