456 THE STRENGTH 



Ultimate deflection, upwards of | inch. 

 Breaking weight, 8270 lbs. z= 73 cwt. 94 lbs. 

 It broke nearly in the middle. 



The form of fracture was nearly as in expt. 1, 

 and trziL .6: see figure to that experiment. 



Dividing the breaking weight by the area gives 



the strength per inch of section = ~-^ 2737 lbs. 



But experiment 4th gives 2584 lbs. per inch. 

 Hence 2737 - 2584 z= 153 = excess. 



.-. Gain in strength zi i^^ = ~ nearly. 



IV. EXPERIMENT. 



Beam cast in common form from Messrs. 



Fairbairn and Lillie's model. 

 Dist. between supports and depth of beam as before. 



Dimensions of section in inches. 



Thickness at A = .32 

 „ B = .44 



„ C = .47 

 FE = 2.27 

 DE zz .52 



Area of section = 3.2 inches. 

 Weight of casting = 40i lbs. 

 Deflection with 5758 lbs. .25 inches. 

 J, „ 7138 „ .37 5, 



Breaking weight = 8270 lbs. 



