OF IRON BEAMS. 455 



Breaking weight = 73681bs. = 65 Cwt. 881bs. 

 It broke obliquely about 4 inches from the 

 middle^ the top inclining to it. 



The form of fracture at the top of the beam 

 was nearly the same as in Experiment 1 -, here 

 tr =: .55 inches: see second figure to that 

 experiment. 



To find the strength per inch of section, as 



7368 



in the last experiment, we have ^^ z= 2567lbs. 

 per inch. 



Comparing this as above with the result of 

 experiment 4, gives 2584 — 2567 = 17 zz defect. 



17 1 



.'. Loss in strength z= ^^ = ,0066 or — . 



III. EXPERIMENT.* 



Beam with top to bottom rib as 1 to 4. 

 Dist. between supports, 4ft. Gins. Depth of beam, 5 Jins. 



Dimensions of cross sectioo in incbcA. 



Area of top rib = 1.07 x .30 zz .32 

 Area of bottom rib = 2.1 x .57 zz 1.2 

 Thickness of^ _ 

 vertical part. 5 ~ 



Area of cross section = 3.02. 



Weight of casting = 40 lbs. 



• At the preceding experiments and at several of the latter 

 ones, Mr. John Kennedy was present, as well as Mr. Ewart who 

 attended them generally. 



