510 THE STRENGTH 



Weight* Deflections in parts Returned to, 



in lbs. of an inch. (weights talcen off.) 



25648 55 



26152 .58 07 



26656 - - - - .61 top of beam a little twisted 



27160 .62 



27664 .65 



28168 - - - - .68 



28672 lbs. = 12 tons 16 cwt. With this 

 weight the beam broke, exactly in the middle, after 

 having borne it a minute or more. The fracture 

 took place by compression, a wedge being broke 

 out of the same form as that in experiment 

 28, but larger, see figure of beam in that 

 experiment. In this case, 



ac, the length of the wedge, = 13 inches. 

 h d, the depth of the wedge, — 5.8 „ 



The length of the wedge half way down it 

 was usually longer than at the top; in this 

 case it was 14 inches there, or one inch longer. 



XXXI. EXPERIMENT. 



Distance between supports, 4 feet 6 inches, 

 Depth of beam, 6.1 inches. 

 Weight of beam, 88 lbs. 



Dimensions of section in inches, (fig. experiment 28.) 



Area of top rib = 2.15 x .24 = .52 

 Area of bottom rib = 7.60 x .72 = 5,472. 



