466 THE STRENGTH 



XII. EXPERIMENT. 



The model of this beam differed from that 

 of the last, in having a broader bottom flange. 

 Ratio of ribs 1 to 5| nearly. 

 Distance of supports as before. 



■E 



' '^ Dimensions of section in inches. 



Area of top rib = 1. 56 X. 3 15=0.49 



Area of bottom rib=5.17 X .56=2.89 



Thickness of 1 „ ^ . . 



> = .34 inch, 

 vertical part J 



Area of section = 5 inches. 

 Weight of beam ::= 6/4 lbs. 



Weight in lbs. Deflections. 



8288 .24 inches. 



12698 .36 „ 



13706 .40 



14210 .42 



15218 - .45 



15722 .48 



16226 .49 „ 



16730 .53 „ 



with this last weight it broke, after having borne 

 it some minutes. It broke by tension very near 

 the middle. 16730 lbs. == 149 cwt. 42 lbs. 



Hence strength per square inch of section 

 = i^ ^ 334(5 lbs. Comparing this with the 

 result of experiment 13, we have, 3346— 2693 

 :=z 653 = excess. 



C53 



.*. Gain in strength = ^^ = .242 = } nearly. 



